IPCC Fourth Assessment Report, Working Group III: Technical Summary
Originally published by our Content Partner: Intergovernmental Panel on Climate Change (other articles)
This Technical Summary should be cited as:
Barker T., I. Bashmakov, L. Bernstein, J. E. Bogner, P. R. Bosch, R. Dave, O. R. Davidson, B. S. Fisher, S. Gupta, K. Halsnæs, G.J. Heij, S. Kahn Ribeiro, S. Kobayashi, M. D. Levine, D. L. Martino, O. Masera, B. Metz, L. A. Meyer, G.-J. Nabuurs, A. Najam, N. Nakicenovic, H. -H. Rogner, J. Roy, J. Sathaye, R. Schock, P. Shukla, R. E. H. Sims, P. Smith, D. A. Tirpak, D. Urge-Vorsatz, D. Zhou, 2007: Technical Summary. In: Climate Change 2007: Mitigation. Contribution of Working Group III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change Metz, O. R. Davidson, P. R. Bosch, R. Dave, L. A. Meyer (eds),Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.
1 Introduction
Structure of the report, the rationale behind it, therole of cross-cutting themes and framing issues.
The main aim of this report is to assess options formitigating climate change. Several aspects link climate changewith development issues. This report explores these links indetail, and illustrates where climate change and sustainabledevelopment are mutually reinforcing.
Economic development needs, resource endowments andmitigative and adaptive capacities differ across regions. Thereis no one-size-fits-all approach to the climate change problem,and solutions need to be regionally differentiated to reflectdifferent socio-economic conditions and, to a lesser extent,geographical differences. Although this report has a globalfocus, an attempt is made to differentiate the assessment ofscientific and technical findings for the various regions.
Given that mitigation options vary significantly betweeneconomic sectors, it was decided to use the economic sectorsto organize the material on short- to medium-term mitigationoptions. Contrary to what was done in the Third AssessmentReport, all relevant aspects of sectoral mitigation options,such as technology, cost, policies etc., are discussed together,to provide the user with a comprehensive discussion of thesectoral mitigation options.
Consequently, the report has four parts. Part A (Chapters 1and 2) includes the introduction and sets out the frameworksto describe mitigation of climate change in the context of otherpolicies and decision-making. It introduces important concepts(e.g., risk and uncertainty, mitigation and adaptation relationships,distributional and equity aspects and regional integration) anddefines important terms used throughout the report. Part B(Chapter 3) assesses long-term stabilization targets, how to getthere and what the associated costs are, by examining mitigationscenarios for ranges of stability targets. The relation betweenadaptation, mitigation and climate change damage avoided is alsodiscussed, in the light of decision-making regarding stabilization(Art. 2 UNFCCC). Part C (Chapters 4–10) focuses on the detaileddescription of the various sectors responsible for greenhouse gas(GHG) emissions, the short- to medium-term mitigation optionsand costs in these sectors, the policies for achieving mitigation,the barriers to getting there and the relationship with adaptationand other policies that affect GHG emissions. Part D (Chapters11–13) assesses cross-sectoral issues, sustainable developmentand national and international aspects. [11] covers theaggregated mitigation potential, macro-economic impacts,technology development and transfer, synergies, and trade-offswith other policies and cross-border influences (or spill-overeffects). Chapter 12 links climate mitigation with sustainabledevelopment. Chapter 13 assesses domestic climate policiesand various forms of international cooperation. This TechnicalSummary has an additional Chapter 14, which deals with gaps in knowledge.
Past, present and future: emission trends
Emissions of the GHGs covered by the Kyoto Protocolincreased by about 70% (from 28.7 to. 49.0 GtCO2-eq) from1970–2004 (by 24% from 1990–2004), with carbon dioxide (CO2) being the largest source, having grown by about 80% (seeFigure TS.1). The largest growth in CO2 emissions has come frompower generation and road transport. Methane (CH4) emissionsrose by about 40% from 1970, with an 85% increase from thecombustion and use of fossil fuels. Agriculture, however, is thelargest source of CH4 emissions. Nitrous oxide (N2O) emissionsgrew by about 50%, due mainly to increased use of fertilizerand the growth of agriculture. Industrial emission of N2O fellduring this period (high agreement, much evidence) [1.3].
Emissions of ozone-depleting substances (ODS) controlledunder the Montreal Protocol (which includes GHGschlorofluorocarbons (CFCs), hydrochlorofluorocarbons(HCFCs)), increased from a low level in 1970 to about7.5 GtCO2-eq in 1990 (about 20% of total GHG emissions,not shown in the Figure TS.1), but then decreased to about1.5 GtCO2-eq in 2004, and are projected to decrease further dueto the phase-out of CFCs in developing countries. Emissionsof the fluorinated gases (F-gases) (hydrofluorocarbons (HFCs), perfluorocarbons (PFCs) and SF6) controlled under the KyotoProtocol grew rapidly (primarily HFCs) during the 1990s asthey replaced ODS to a substantial extent and were estimatedat about 0.5 GtCO2eq in 2004 (about 1.1% of total emissionson a 100-year global warming potential (GWP) basis) (highagreement, much evidence) [1.3].
[[Image:figure-ts-1-l.png.jpeg|frame|center|Figure TS.1a: Global anthropogenic greenhouse gas emissions, 1970–2004. One hundred year global warming potentials (GWPs) from IPCC 1996 (SAR) were used to convert emissions to CO2-eq. (see the UNFCCC reporting guidelines). Gases are those reported under UNFCCC reporting guidelines. The uncertainty in the graph is quite large for CH4 and N2O (in the order of 30-50%) and even larger for CO2 from agriculture and forestry. [Figure 1.1a].]]
Notes:
1) Other N2O includes industrial processes, deforestation/ savannah burning, waste water and waste incineration.
2) Other is CH4 from industrial processes and savannah burning.
3) Including emissions from bioenergy production and use
4) CO2 emissions from decay (decomposition) of above ground biomass that remains after logging and deforestation and CO2 from peat fires and decay of drained peat soils.
5) As well as traditional biomass use at 10% of total, assuming 90% is from sustainable biomass production. Corrected for the 10% of carbon in biomass that is assumed to remain as charcoal after combustion.
6) For large-scale forest and scrubland biomass burning averaged data for 1997-2002 based on Global Fire Emissions Data base satellite data.
7) Cement production and natural gas flaring.
8) Fossil fuel use includes emissions from feedstocks.
[[Image:figure-ts-1-2-l.png.jpeg|frame|center|Figure TS.1b: Global anthropogenic greenhousegas emissions in 2004
[Figure 1.1b].]]
Atmospheric CO2 concentrations have increased by almost100 ppm since their pre-industrial level, reaching 379 ppm in2005, with mean annual growth rates in the 2000-2005 periodhigher than in the 1990s. The total CO2-equivalent (CO2-eq)concentration of all long-lived GHGs is now about 455 ppmCO2-eq. Incorporating the cooling effect of aerosols, other airpollutants and gases released from land-use change into theequivalent concentration, leads to an effective 311-435 ppmCO2-eq concentration (high agreement, much evidence).
Considerable uncertainties still surround the estimates ofanthropogenic aerosol emissions. As regards global sulphuremissions, these appear to have declined from 75 ± 10 MtS in 1990 to 55-62 MtS in 2000. Data on non-sulphur aerosols aresparse and highly speculative. (medium agreement, mediumevidence).
In 2004, energy supply accounted for about 26% of GHGemissions, industry 19%, gases released from land-use changeand forestry 17%, agriculture 14%, transport 13%, residential,commercial and service sectors 8% and waste 3% (see FigureTS.2). These figures should be seen as indicative, as someuncertainty remains, particularly with regards to CH4 and N2Oemissions (error margin estimated to be in the order of 30-50%)and CO2 emissions from agriculture and forestry with an evenhigher error margin (high agreement, medium evidence) [1.3].
Notes to Figure TS.2a and 2b:
1) Excluding refineries, coke ovens etc., which are included in industry.
2) Including international transport (bunkers), excluding fisheries. Excluding off-road agricultural and forestry vehicles and machinery.
3) Including traditional biomass use. Emissions in Chapter 6 (IPCC Fourth Assessment Report, Working Group III: Technical Summary) are also reported on the basis of end-use allocation (including the sector’s share in emissions caused by centralized electricity generation) so that any mitigation achievements in the sector resulting from lower electricity use are credited to the sector.
4) Including refineries, coke ovens etc. Emissions reported in Chapter 7 (IPCC Fourth Assessment Report, Working Group III: Technical Summary) are also reported on the basis of end-use allocation (including the sector’s share in emissions caused by centralized electricity generation) so that any mitigation achievements in the sector resulting from lower electricity use are credited to the sector.
5) Including agricultural waste burning and savannah burning (non-CO2). CO2 emissions and/or removals from agricultural soils are not estimated in this database.
6) Data include CO2 emissions from deforestation, CO2 emissions from decay (decomposition) of above-ground biomass that remains after logging and deforestation, and CO2 from peat fires and decay of drained peat soils. Chapter 9 reports emissions from deforestation only.
7) Includes landfill CH4, wastewater CH4 and N2O, and CO2 from waste incineration (fossil carbon only).
Figure TS.3 identifies the individual contributions to energy relatedCO2 emissions from changes in population, income percapita (gross domestic product (GDP) expressed in terms ofpurchasing-power parity per person - GDPppp/cap[1] ), energyintensity (Total Primary Energy Supply (TPES)/GDPppp), andcarbon intensity (CO2/TPES). Some of these factors boost CO2emissions (bars above the zero line), while others lower them(bar below the zero line). The actual change in emissions perdecade is shown by the dashed black lines. According to FigureTS.3, the increase in population and GDP-ppp/cap (and thereforeenergy use per capita) have outweighed and are projected tocontinue to outweigh the decrease in energy intensities (TPES/GDPppp) and conceal the fact that CO2 emissions per unit ofGDPppp are 40% lower today than during the early 1970s andhave declined faster than primary energy per unit of GDPpppor CO2 per unit of primary energy. The carbon intensity ofenergy supply (CO2/TPES) had an offsetting effect on CO2emissions between the mid 1980s and 2000, but has since beenincreasing and is projected to have no such effect after 2010(high agreement, much evidence) [1.3].
In 2004, Annex I countries had 20% of the world’spopulation, but accounted for 46% of global GHG emissions,and the 80% in Non-Annex I countries for only 54%. Thecontrast between the region with the highest per capita GHGemissions (North America) and the lowest (Non-Annex ISouth Asia) is even more pronounced (see Figure TS.4a):5% of the world’s population (North America) emits 19.4%,while 30.3%(Non-Annex I South Asia) emits 13.1%.A different picture emerges if the metric GHG emissions perunit of GDPppp is used (see Figure TS.4b). In these terms,Annex I countries generated 57% of gross world product witha GHG intensity of production of 0.68 kg CO2-eq/US$ GDPppp(non-Annex I countries 1.06 kg CO2-eq/US$ GDPppp) (highagreement, much evidence) [1.3].
Note: Countries are grouped according to the classification of the UNFCCC and its Kyoto Protocol; this means that countries that have joined the European Union since then are still listed under EIT Annex I. A full set of data for all countries for 2004 was not available. The countries in each of the regional groupings include: EIT Annex I: Belarus, Bulgaria, Croatia, Czech Republic, Estonia, Hungary, Latvia, Lithuania, Poland, Romania, Russian Federation, Slovakia, Slovenia, Ukraine Europe Annex II & M&T: Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Liechtenstein, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland, United Kingdom; Monaco and Turkey JANZ: Japan, Australia, New Zealand. Middle East: Bahrain, Islamic Republic of Iran, Israel, Jordan, Kuwait, Lebanon, Oman, Qatar, Saudi Arabia, Syria, United Arab Emirates, Yemen Latin America & the Caribbean: Antigua & Barbuda, Argentina, Bahamas, Barbados, Belize, Bolivia, Brazil, Chile, Colombia, Costa Rica, Cuba, Dominica, Dominican Republic, Ecuador, El Salvador, Grenada, Guatemala, Guyana, Haiti, Honduras, Jamaica, Mexico, Nicaragua, Panama, Paraguay, Peru, Saint Lucia, St. Kitts-Nevis-Anguilla, St. Vincent-Grenadines, Suriname, Trinidad and Tobago, Uruguay, Venezuela Non-Annex I East Asia: Cambodia, China, Korea (DPR), Laos (PDR), Mongolia, Republic of Korea, Viet Nam. South Asia: Afghanistan, Bangladesh, Bhutan, Comoros, Cook Islands, Fiji, India, Indonesia, Kiribati, Malaysia, Maldives, Marshall Islands, Micronesia, (Federated States of), Myanmar, Nauru, Niue, Nepal, Pakistan, Palau, Papua New Guinea, Philippine, Samoa, Singapore, Solomon Islands, Sri Lanka, Thailand, Timor-Leste, Tonga, Tuvalu, Vanuatu North America: Canada, United States of America. Other non-Annex I: Albania, Armenia, Azerbaijan, Bosnia Herzegovina, Cyprus, Georgia, Kazakhstan, Kyrgyzstan, Malta, Moldova, San Marino, Serbia, Tajikistan, Turkmenistan, Uzbekistan, Republic of Macedonia Africa: Algeria, Angola, Benin, Botswana, Burkina Faso, Burundi, Cameroon, Cape Verde, Central African Republic, Chad, Congo, Democratic Republic of Congo, Côte d’Ivoire, Djibouti, Egypt, Equatorial Guinea, Eritrea, Ethiopia, Gabon, Gambia, Ghana, Guinea, Guinea-Bissau, Kenya, Lesotho, Liberia, Libya, Madagascar, Malawi, Mali, Mauritania, Mauritius, Morocco, Mozambique, Namibia, Niger, Nigeria, Rwanda, Sao Tome and Principe, Senegal, Seychelles, Sierra Leone, South Africa, Sudan, Swaziland, Togo, Tunisia, Uganda, United Republic of Tanzania, Zambia, Zimbabwe.
Global energy use and supply – the main drivers of GHGemissions – is projected to continue to grow, especially asdeveloping countries pursue industrialization. Should there be no change in energy policies, the energy mix supplied to runthe global economy in the 2025–30 timeframe will essentiallyremain unchanged, with more than 80% of energy supply basedon fossil fuels with consequent implications for GHG emissions.On this basis, the projected emissions of energy-related CO2in 2030 are 40–110% higher than in 2000, with two thirdsto three quarters of this increase originating in non-Annex Icountries, though per capita emissions in developed countrieswill remain substantially higher, that is 9.6 tCO2/cap to15.1 tCO2/cap in Annex I regions versus 2.8 tCO2/cap to5.1 tCO2/cap in non-Annex I regions (high agreement, muchevidence) [1.3].
For 2030, projections of total GHG emissions (Kyoto gases)consistently show an increase of 25–90% compared with 2000,with more recent projections higher than earlier ones (highagreement, much evidence).
For 2100, the SRES[2] range (a 40% decline to 250% increasecompared with 2000) is still valid. More recent projections tendto be higher: increase of 90% to 250% compared with 2000(see Figure TS.5). Scenarios that account for climate policies,whose implementation is currently under discussion, also showglobal emissions rising for many decades.
Developing countries (e.g., Brazil, China, India and Mexico)that have undertaken efforts for reasons other than climatechange have reduced their emissions growth over the past threedecades by approximately 500 million tonnes CO2 per year; thatis, more than the reductions required from Annex I countriesby the Kyoto Protocol. Many of these efforts are motivated byeconomic development and poverty alleviation, energy securityand local environmental protection. The most promising policyapproaches, therefore, seem to be those that capitalize onnatural synergies between climate protection and developmentpriorities to advance both simultaneously (high agreement,medium evidence) [1.3].
International response
The United Nations Framework Convention on ClimateChange (UNFCCC) is the main vehicle for promotinginternational responses to climate change. It entered into forcein March 1994 and has achieved near universal ratification – 189of the 194 UN member states (December 2006). A Dialogueon Long-Term Cooperation Action to Address Climate Change by Enhancing Implementation of the Convention was set up atCMP1[3] in 2005, taking the form of an open and non-bindingexchange of views and information in support of enhanced implementation of the Convention.
The first addition to the treaty, the Kyoto Protocol, wasadopted in 1997 and entered into force in February 2005. Asof February 2007, 168 states and the European EconomicCommunity have ratified the Protocol. Under Article 3.1 of theKyoto Protocol, Annex I Parties in aggregate agreed to reducetheir overall GHG emissions to at least 5% below 1990 levels.The entry into force of the Kyoto Protocol marks a first, thoughmodest, step towards achieving the ultimate objective of theUFCCC to avoid dangerous anthropogenic interference withthe climate system. Its full implementation by all the Protocolsignatories, however, would still be far from reversing overall global GHG-emission trends. The strengths of the KyotoProtocol are its provision for market mechanisms such asGHG-emission trading and its institutional architecture. One
weakness of the Protocol, however, is its non-ratification bysome significant GHG emitters. A new Ad Hoc Working Group(AWG) on the Commitments of Annex I Countries under theKyoto Protocol beyond 2012 was set up at CMP1, and agreed atCMP2 that the second review of Article 9 of the Kyoto Protocolwill take place in 2008.
There are also voluntary international initiatives to developand implement new technologies to reduce GHGemissions. These include: the Carbon Sequestration LeadershipForum (promoting CO2 capture and storage); the Hydrogenpartnership; the Methane to Markets Partnership, and the Asia-Pacific Partnership for Clean Development and Climate (2005), which includes Australia, USA, Japan, China, India and South-Korea. Climate change has also become an important growingconcern of the G8 since its meeting in Gleneagles, Scotland in2005. At that meeting, a plan of action was developed whichtasked the International Energy Agency, the World Bank andthe Renewable Energy and Energy Efficiency Partnership withsupporting their efforts. Additionally, Gleneagles created aClean Energy, Climate Change and Sustainable DevelopmentDialogue process for the largest emitters. The InternationalEnergy Agency (IEA) and the World Bank were charged withadvising that dialogue process [1.4].
Article 2 of the Convention and mitigation Article 2 of the UNFCCC requires that dangerous interferencewith the climate system be prevented and hence the stabilizationof atmospheric GHG concentrations at levels and within a timeframe that would achieve this objective. The criteria in Article 2that specify (risks of) dangerous anthropogenic climate changeinclude: food security, protection of ecosystems and sustainableeconomic development. Implementing Article 2 implies dealingwith a number of complex issues: What level of climate change is dangerous? Decisions made in relation to Article 2 would determine thelevel of climate change that is set as the goal for policy, and havefundamental implications for emission-reduction pathways aswell as the scale of adaptation required. Choosing a stabilizationlevel implies balancing the risks of climate change (fromgradual change and extreme events, and irreversible change ofthe climate, including those to food security, ecosystems andsustainable development) against the risks of response measuresthat may threaten economic sustainability. Although anyjudgment on ‘dangerous interference’ is necessarily a social andpolitical one, depending on the level of risk deemed acceptable,large emission reductions are unavoidable if stabilization is tobe achieved. The lower the stabilization level, the earlier theselarge reductions have to be realized (high agreement, muchevidence) [1.2]. (IPCC Fourth Assessment Report, Working Group III: Technical Summary)
Sustainable development:
Projected anthropogenic climate change appears likely toadversely affect sustainable development, with the effectstending to increase with higher GHG concentrations (WGII AR4, Chapter 19). Properly designed climate change responsescan be an integral part of sustainable development and the twocan be mutually reinforcing. Mitigation of climate change canconserve or enhance natural capital (ecosystems, the environmentas sources and sinks for economic activities) and prevent oravoid damage to human systems and, thereby contribute tothe overall productivity of capital needed for socio-economicdevelopment, including mitigative and adaptive capacity. Inturn, sustainable development paths can reduce vulnerability toclimate change and reduce GHG emissions (medium agreement,much evidence) [1.2].
Distributional issues:
Climate change is subject to a very asymmetric distributionof present emissions and future impacts and vulnerabilities.Equity can be elaborated in terms of distributing the costs of mitigation or adaptation, distributing future emission rightsand ensuring institutional and procedural fairness. Because theindustrialized nations are the source of most past and currentGHG emissions and have the technical and financial capabilityto act, the Convention places the heaviest burden for the firststeps in mitigating climate change on them. This is enshrinedin the principle of ‘common but differentiated responsibilities’(high agreement, much evidence) [1.2].
Timing:
Due to the inertia of both climate and socio-economic systems, the benefits of mitigation actions initiated now mayresult in significant avoided climate change only after severaldecades. This means that mitigation actions need to start in theshort term in order to have medium- and longer-term benefitsand to avoid lock-in of carbon-intensive technologies (highagreement, much evidence) [1.2].
Mitigation and adaptation:
Adaptation and mitigation are two types of policy responseto climate change, which can be complementary, substitutableor independent of each other. Irrespective of the scale of mitigation measures, adaptation measures will be requiredanyway, due to the inertia in the climate system. Over the next20 years or so, even the most aggressive climate policy cando little to avoid warming already ‘loaded’ into the climatesystem. The benefits of avoided climate change will only accruebeyond that time. Over longer time frames, beyond the nextfew decades, mitigation investments have a greater potential toavoid climate change damage and this potential is larger thanthe adaptation options that can currently be envisaged (mediumagreement, medium evidence) [1.2].
Risk and uncertainty:
An important aspect in the implementation of Article 2 isthe uncertainty involved in assessing the risk and severity ofclimate change impacts and evaluating the level of mitigation action (and its costs) needed to reduce the risk. Giventhis uncertainty, decision-making on the implementationof Article 2 would benefit from the incorporation of riskmanagement principles. A precautionary and anticipatoryrisk-management approach would incorporate adaptation andpreventive mitigation measures based on the costs and benefitsof avoided climate change damage, taking into accountthe (small) chance of worst-case outcomes (medium agreement,medium evidence) [1.2].
2 Framing issues
Climate change mitigation and sustainabledevelopment
There is a two-way relationship between climate change anddevelopment. On the one hand vulnerability to climate changeis framed and strongly influenced by development patterns andincome levels. Decisions about technology, investment, trade,poverty, community rights, social policies or governance, whichmay seem unrelated to climate policy, may have profoundimpacts on emissions, the extent of mitigation required, and thecost and benefits that result [2.2.3].
On the other hand, climate change itself, and adaptationand mitigation policies could have significant positive impactson development in the sense that development can be made more sustainable. This leads to the notion that climate changepolicies can be considered 1) in their own right (‘climate first’);or 2) as an integral element of sustainable- development policies(‘development first’). Framing the debate as a sustainabledevelopment problem rather than a solely environmental onemay better address the needs of countries, while acknowledgingthat the driving forces for emissions are linked to the underlyingdevelopment path [2.2.3].
Development paths evolve as a result of economic and socialtransactions, which are influenced by government policies,private sector initiatives and by the preferences and choices ofconsumers. These include a broad number of policies relatedto nature conservation, legal frameworks, property rights, ruleof law, taxes and regulation, production, security and safety offood, consumption patterns, human and institutional capacitybuilding efforts, R&D, financial schemes, technology transfer,energy efficiency and energy options. These policies do notusually emerge and become implemented as part of a generaldevelopment-policy package, but are normally targeted towardsmore specific policy goals like air-pollution standards, foodsecurity and health issues, GHG-emission reduction, incomegeneration by specific groups,or development of industries forgreen technologies. However, significant impacts can arise fromsuch policies on sustainability and greenhouse mitigation andthe outcomes of adaptation. The strong relationship betweenmitigation of climate change and development applies in bothdeveloped and developing countries. Chapter 12 and to someextent Chapters 4–11 address these issues in more detail [2.2.5;2.2.7].
Emerging literature has identified methodological approachesto identify, characterize and analyze the interactions betweensustainable development and climate change responses. Severalauthors have suggested that sustainable development can beaddressed as a framework for jointly assessing social, human,environmental and economic dimensions. One way to addressthese dimensions is to use a number of economic, environmental,human and social indicators to assess the impacts of policieson sustainable development, including both quantitative andqualitative measurement standards (high agreement, limitedevidence) [2.2.4].
Decision-making, risk and uncertainty
Mitigation policies are developed in response to concernsabout the risk of climate change impacts. However, decidingon a proper reaction to these concerns means dealing with uncertainties. Risk refers to cases for which the probabilityof outcomes and its consequences can be ascertained throughwell-established theories with reliable, complete data, whileuncertainty refers to situations in which the appropriate datamay be fragmentary or unavailable. Causes of uncertaintyinclude insufficient or contradictory evidence as well as humanbehaviour. The human dimensions of uncertainty, especiallycoordination and strategic behaviour issues, constitute a majorpart of the uncertainties related to climate change mitigation(high agreement, much evidence) 2.3.4.
Decision-support analysis can assist decision makers,especially if there is no optimum policy that everybody canagree on. For this, a number of analytical approaches areavailable, each with their own strengths and weaknesses, whichhelp to keep the information content of the climate changeproblem within the cognitive limits of the large number ofdecision makers and support a more informed and effectivedialogue among the many parties involved. There are, however,significant problems in identifying, measuring and quantifyingthe many variables that are important inputs to any decision supportanalysis framework – particularly impacts on naturalsystems and human health that do not have a market value, andfor which all approaches are simplifications of the reality (highagreement, much evidence) [2.3.7].
When many decision makers with different value systemsare involved in a decision, it is helpful to be as clear as possibleabout the value judgments underpinning any analytic outcomesthey are expected to draw on. This can be particularly difficultand subtle where analysis aims to illuminate choices associatedwith high levels of uncertainty and risk (medium agreement,medium evidence) 2.3.7.
Integrated assessments can inform decision makers of therelationship between geophysical climate change, climate impactpredictions, adaptation potentials and the costs of emission reductions and the benefits of avoided climate changedamage. These assessments have frameworks to deal withincomplete or imprecise data.
To communicate the uncertainties involved, this reportuses the terms in Table TS.1 to describe the relative levelsof expert agreement on the respective statements in the light of the underlying literature (in rows) and the number andquality of independent sources qualifying under IPCC rules[4] upon which a finding is based (in columns). The other approaches of ‘likelihood’ and ‘confidence’ are not usedin this report as human choices are concerned, and none ofthe other approaches used provides sufficient characterization of the uncertainties involved in mitigation (high agreement,much evidence) [2.4].
Table TS.1: Qualitative definition of uncertainty 2.2.
Costs, benefits, concepts including privateand social cost perspectives and relationshipswith other decision-making frameworks
There are different ways of defining the potential for mitigationand it is therefore important to specify what potentialis meant. ‘Potential’ is used to express the degree of GHG reduction that can be achieved by a mitigation option with agiven cost per tonne of carbon avoided over a given period,compared with a baseline or reference case. The measure is usually expressed as million tonnes carbon- or CO2-equivalentemissions avoided compared with baseline emissions [2.4.3].
Market potential is the mitigation potential based on privatecosts and private discount rates[6], which might be expectedto occur under forecast market conditions, including policiesand measures currently in place, noting that barriers limit actual uptake.
Economic potential is the amount of GHG mitigation, whichtakes into account social costs and benefits and social discountrates[[[7]]] assuming that market efficiency is improved by policiesand measures and barriers are removed. However, currentbottom:up and top-down studies of economic potential havelimitations in considering life-style choices and in including allexternalities such as local air pollution.
Technical potential is the amount by which it is possibleto reduce GHG emissions by implementing a technology orpractice that has already been demonstrated. There is no specificreference to costs here, only to ‘practical constraints’, althoughimplicit economic considerations are taken into account in somecases. (high agreement, much evidence) [2.4.3].
Studies of market potential can be used to inform policymakers about mitigation potential with existing policies andbarriers, while studies of economic potentials show what might be achieved if appropriate new and additional policies wereput into place to remove barriers and include social costs andbenefits. The economic potential is therefore generally greaterthan the market potential.
Mitigation potential is estimated using different types ofapproaches. There are two broad classes – “bottom:up” and“top-down” approaches, which primarily have been used to assess the economic potential:
- bottom:up studies are based on assessment of mitigationoptions, emphasizing specific technologies and regulations.They are typically sectoral studies taking the macro-economyas unchanged. Sector estimates have been aggregated, asin the TAR, to provide an estimate of global mitigation potential for this assessment.
- Top-down studies assess the economy-wide potential ofmitigation options. They use globally consistent frameworksand aggregated information about mitigation options and capture macro-economic and market feedbacks.
bottom:up studies in particular are useful for the assessmentof specific policy options at sectoral level, e.g. options forimproving energy efficiency, while top-down studies are usefulfor assessing cross-sectoral and economy-wide climate changepolicies, such as carbon taxes and stabilization policies. Bottomupand top-down models have become more similar since theTAR as top-down models have incorporated more technologicalmitigation options (see [11]) and bottom:up models haveincorporated more macroeconomic and market feedbacks aswell as adopting barrier analysis into their model structures.
Mitigation and adaptation relationships;capacities and policies
Climate change mitigation and adaptation have somecommon elements, they may be complementary, substitutable,independent or competitive in dealing with climate change, and also have very different characteristics and timescales [2.5].
Both adaptation and mitigation make demands on thecapacity of societies, which are intimately connected to socialand economic development. The responses to climate change depend on exposure to climate risk, society’s natural and manmadecapital assets, human capital and institutions as well asincome. Together these will define a society’s adaptive andmitigative capacities. Policies that support development andthose that enhance its adaptive and mitigative capacities may,but need not, have much in common. Policies may be chosento have synergetic impacts on the natural system and thesocio-economic system but difficult trade-offs may sometimeshave to be made. Key factors that determine the capacity ofindividual stakeholders and societies to implement climatechange mitigation and adaptation include: access to resources;markets; finance; information, and a number of governanceissues (medium agreement, limited evidence) [2.5.2].
Distributional and equity aspects
Decisions on climate change have large implications forlocal, national, inter-regional and intergenerational equity,and the application of different equity approaches has major implications for policy recommendations as well as for thedistribution of the costs and benefits of climate policies [2.6].
Different approaches to social justice can be appliedto the evaluation of the equity consequences of climate changepolicies. As the IPCC Third Assessment Report (TAR) suggested,given strong subjective preferences for certain equity principlesamong different stakeholders, it is more effective to look forpractical approaches that combine equity principles. Equityapproaches vary from traditional economic approaches to rights-based approaches. An economic approach would be to assesswelfare losses and gains to different groups and the society atlarge, while a rights-based approach would focus on rights,for example, in terms of emissions per capita or GDP allowedfor all countries, irrespective of the costs of mitigation or themitigative capacity. The literature also includes a capabilityapproach that puts the emphasis on opportunities and freedom,which in terms of climate policy can be interpreted as thecapacity to mitigate or to adapt or to avoid being vulnerable toclimate change (medium agreement, medium evidence) [2.6.3].
Technology research, development, deployment,diffusion and transfer
The pace and cost of any response to climate changeconcerns will also depend critically on the cost, performance,and availability of technologies that can lower emissions in the future, although other factors such as growth in wealth andpopulation are also highly important [2.7].
Technology simultaneously influences the size of the climatechange problem and the cost of its solution. Technology isthe broad set of competences and tools covering know-how,experience and equipment, used by humans to produce servicesand transform resources. The principal role of technology inmitigating GHG emissions is in controlling the social costof limiting the emissions. Many studies show the significanteconomic value of the improvements in emission-mitigatingtechnologies that are currently in use and the developmentand deployment of advanced emission-mitigation technologies(high agreement, much evidence) [2.7.1].
A broad portfolio of technologies can be expected to playa role in meeting the goal of the UNFCCC and managing therisk of climate change, because of the need for large emission reductions, the large variation in national circumstances andthe uncertainty about the performance of individual options.Climate policies are not the only determinant of technologicalchange. However, a review of future scenarios (see Chapter 3)indicates that the overall rate of change of technologies in theabsence of climate policies might be as large as, if not largerthan, the influence of the climate policies themselves (highagreement, much evidence) [2.7.1].
Technological change is particularly important over thelong-term time scales characteristic of climate change. Decadeorcentury-long time scales are typical for the lags involved between technological innovation and widespread diffusion andof the capital turnover rates characteristic of long-lived energycapital stock and infrastructures.
Many approaches are used to split up the process oftechnological change into distinct phases. One is to considertechnological change as roughly a two-part process: 1)conceiving, creating and developing new technologies orenhancing existing technologies – advancing the ‘technologicalfrontier’; 2) the diffusion or deployment of these technologies.Our understanding of technology and its role in addressing climatechange is improving continuously. The processes by whichtechnologies are created, developed, deployed and eventuallyreplaced, however, are complex (see Figure TS.6) and no simpledescriptions of these processes exist. Technology developmentand deployment is characterized by two public goods problems.First, the level of R&D is sub-optimal because private decisionmakerscannot capture the full value of private investments.Second, there is a classical environmental externality problem, inthat private markets do not reflect the full costs of climate change(high agreement, much evidence) [2.7.2].
Note: important overlaps and feedbacks exist between the stylized technology life-cycle phases illustrated here. The figure therefore does not suggest a ‘linear’ model of innovation. It is important to recognize the need for finer terminological distinction of ‘technology’, particularly when discussing different mitigation and adaptation options.
Three important sources of technological change are R&D, learning and spill-overs.
- R &D encompasses a broad set of activities in which firms,governments or other entities expend resources specificallyto gain new knowledge that can be embodied in new or
- improved technology.
- Learning is the aggregate outcome of complex underlyingsources of technology advance that frequently includeimportant contributions from R&D, spill-overs andeconomies of scale.
- Spill-overs refer to the transfer of the knowledge or theeconomic benefits of innovation from one individual, firm,industry or other entity, or from one technology to another.
On the whole, empirical and theoretical evidence stronglysuggest that all three of these play important roles in technologicaladvance, and there is no compelling reason to believe that oneis broadly more important than the others. As spill-overs fromother sectors have had an enormous effect on innovation in theenergy sector, a robust and broad technological base may beas important for the development of technologies pertinent toclimate change as explicit climate change or energy research.A broad portfolio of research is needed, because it is notpossible to identify winners and losers ex-ante. The sources oftechnological change are frequently subsumed under the generaldrivers ‘supply push’ (e.g., via R&D) or ‘demand pull’ (e.g.,via learning). These are, however, not simply substitutes, butmay have highly complementary interactions (high agreement,much evidence) [2.7.2].
On technology transfer, the main findings of the IPCCSpecial Report on Methodological and Technological Issuesof Technology Transfer (2000) remain valid: that a suitable enabling environment needs to be created in host and recipientcountries (high agreement, much evidence) [2.7.3].
Regional Dimensions
Climate change studies have used various different regionaldefinitions, depending on the character of the problem consideredand differences in methodological approaches. The multitudeof possible regional representations hinders the comparabilityand transfer of information between the various types of studiesdone for specific regions and scales. This report largely haschosen a pragmatic ways of analysing regional information andpresenting findings [2.8].
3 Issues related to mitigationin the long-term context
Baseline scenario drivers
Population projections are now generally lower than in theIPCC Special Report on Emission Scenarios (SRES), based onnew data indicating that birth rates in many parts of the worldhave fallen sharply. So far, these new population projectionshave not been implemented in many of the new emissionsscenarios in the literature. The studies that have incorporatedthem result in more or less the same overall emissions levels,due to changes in other driving factors such as economic growth(high agreement, much evidence) [3.2.1].
Economic growth perspectives have not changed much. Thereis a considerable overlap in the GDP numbers published, witha slight downwards shift of the median of the new scenarios byabout 7% compared with the median in the pre-SRES scenarioliterature. The data suggest no appreciable change in thedistribution of GDP projections. Economic growth projectionsfor Africa, Latin America and the Middle East are lower than inthe SRES scenarios (high agreement, much evidence) [3.2.1].
Baseline scenario emissions (all gases and sectors)
The resulting span of energy-related and industrial CO2emissions in 2100 across baseline scenarios in the post-SRESliterature is very large, ranging from 17 to around 135 GtCO2-eq(4.6-36.8 GtC) [8]about the same as the SRES range (Figure TS.7).Different reasons may contribute to the fact that emissions have notdeclined despite somewhat lower projections for population andGDP. All other factors being equal, lower population projectionswould result in lower emissions. In the scenarios that use lowerprojections, however, changes in other drivers of emissions havepartly offset the consequences of lower populations. Few studiesincorporated lower population projections, but where they did,they showed that lower population is offset by higher rates ofeconomic growth, and/or a shift toward a more carbon-intensiveenergy system, such as a shift to coal because of increasing oiland gas prices. The majority of scenarios indicate an increase inemissions during most of the century. However, there are somebaseline (reference) scenarios both in the new and older literaturewhere emissions peak and then decline (high agreement, muchevidence) [3.2.2].
Note: Two vertical bars on the right extend from the minimum to maximum of the distribution of scenarios and indicate the 5th, 25th, 50th, 75th and the 95th percentiles of the distributions by 2100.
</div>
Baseline land-related GHG emissions are projected toincrease with growing cropland requirements, but at a slowerrate than energy-related emissions. As far as CO2 emissions from land-use change (mostly deforestation) are concerned,post-SRES scenarios show a similar trend to SRES scenarios: aslow decline, possibly leading to zero net emissions by the endof the century.
Emissions of non-CO2 GHGs as a group (mostly fromagriculture) are projected to increase, but somewhat less rapidlythan CO2 emissions, because the most important sources of CH4 and N2O are agricultural activities, and agriculture isgrowing less than energy use. Emission projections from therecent literature are similar to SRES. Recent non-CO2 GHG emission baseline scenarios suggest that agricultural CH4and N2O emissions will increase until the end of this century,potentially doubling in some baselines. While the emissions ofsome fluorinated compounds are projected to decrease, manyare expected to grow substantially because of the rapid growthrate of some emitting industries and the replacement of ODSwith HFCs (high agreement, medium evidence) [3.2.2].
Noticeable changes have occurred in projections of theemissions of the aerosol precursors SO2 and NOx since SRES.Recent literature shows a slower short-term growth of these emissions than SRES. As a consequence also the long-termranges of both emissions sources are lower in the recent literature.Recent scenarios project sulphur emissions to peak earlier andat lower levels than in SRES. A small number of new scenarioshave begun to explore emission pathways for black and organiccarbon (high agreement, medium evidence) [3.2.2].
In general, the comparison of SRES and new scenarios in theliterature shows that the ranges of the main driving forces andemissions have not changed very much.
GDP metrics
For long-term scenarios, economic growth is usually reportedin the form of growth in GDP or gross national product (GNP).To get a meaningful comparison of the real size of economicactivities over time and between countries, GDP is reported inconstant prices taken from a base year.
The choice of the conversion factor, Market Exchange Rate(MER) or Purchasing Power Parity (PPP), depends on thetype of analysis being undertaken. However, when it comes tocalculating emissions (or other physical measures like energy),the choice between MER and PPP-based representations ofGDP should not matter, since emission intensity will change (ina compensating manner) when the GDP numbers change. Thus,if a consistent set of metrics is employed, the choice of metricshould not appreciably affect the final emission level. A numberof new studies in the literature concur that the actual choiceof exchange rates does not itself have an appreciable effecton long-term emission projections. In the case of SRES, theemissions trajectories are the same whether economic activitiesin the four scenario families are measured in MER or PPP.
There are studies that find some differences in emissionlevels between PPP and MER-based estimates. These resultsdepend critically on convergence assumptions, among other things. In some of the short-term scenarios (with a horizon to2030) a bottom:up approach is taken where assumptions aboutproductivity growth and investment/saving decisions are themain drivers of growth in the models. In long-term scenarios,a top-down approach is more commonly used where theactual growth rates are more directly prescribed on the basisof convergence or other assumptions about long-term growthpotentials. Different results can also be due to inconsistenciesin adjusting the metrics of energy efficiency improvement whenmoving from MER to PPP-based calculations.
Evidence from the limited number of new PPP-basedstudies indicates that the choice of metric for GDP (MER orPPP) does not appreciably affect the projected emissions, when the metrics are used consistently. The differences, if any, aresmall compared with the uncertainties caused by assumptionson other parameters, for example, technological change. Thedebate clearly shows, however, the need for modellers to bemore transparent in explaining conversion factors as well astaking care in making assumptions on exogenous factors (highagreement, much evidence) [3.2.1].
Stabilization scenarios
A commonly used target in the literature is stabilization ofCO2 concentrations in the atmosphere. If more than one GHG isstudied, a useful alternative is to formulate a GHG-concentrationtarget in terms of CO2-equivalent concentration or radiativeforcing, thereby weighting the concentrations of the differentgases by their radiative properties. Another option is to stabilizeor target global mean temperature. The advantage of radiative-forcingtargets over temperature targets is that the calculationof radiative forcing does not depend on climate sensitivity.The disadvantage is that a wide range of temperature impactsis possible for each radiative-forcing level. Temperaturetargets, on the other hand, have the important advantage ofbeing more directly linked to climate change impacts. Anotherapproach is to calculate the risks or the probability of exceedingparticular values of global annual mean temperature rise sincepre-industrial times for specific stabilization or radiative-forcingtargets.
There is a clear and strong correlation between theCO2-equivalent concentrations (or radiative forcing) andthe CO2-only concentrations by 2100 in the published studies,because CO2 is the most important contributor to radiative forcing.Based on this relationship, to facilitate scenario comparison andassessment, stabilization scenarios (both multi-gas and CO2-only studies) have been grouped into different categories thatvary in the stringency of the targets (Table TS.2).
Table TS.2: Classification of recent (Post-Third Assessment Report) stabilization scenarios according to different stabilization targets and alternative stabilization metrics 3.5.
| Category | Additional radiative forcing (W/m2) | CO2 concentration (ppm) | CO2-eq concentration (ppm) | Global mean temperature increase above pre-industrial at equilibrium, using “best estimate” climate sensitivitya), b) (ºC) | Peaking year for CO2 emissionsc) | Change in global CO2 emissions in 2050 (% of 2000 emissions)c) | No. of assessed scenarios |
|---|---|---|---|---|---|---|---|
| I | 2.5-3.0 | 350-400 | 445-490 | 2.0-2.4 | 2000 - 2015 | -85 to -50 | 6 |
| II | 3.0-3.5 | 400-440 | 490-535 | 2.4-2.8 | 2000 - 2020 | -60 to -30 | 18 |
| III | 3.5-4.0 | 440-485 | 535-590 | 2.8-3.2 | 2010 - 2030 | -30 to +5 | 21 |
| IV | 4.0-5.0 | 485-570 | 590-710 | 3.2-4.0 | 2020 - 2060 | +10 to +60 | 118 |
| V | 5.0-6.0 | 570-660 | 710-855 | 4.0-4.9 | 2050 - 2080 | +25 to +85 | 9 |
| VI | 6.0-7.5 | 660-790 | 855-1130 | 4.9-6.1 | 2060 - 2090 | +90 to +140 | 5 |
| Total | 177 | ||||||
Notes:
a) Note that global mean temperature at equilibrium is different from expected global mean temperatures in 2100 due to the inertia of the climate system.
b) The simple relationships Teq = T2×CO2 × ln([CO2]/278)/ln(2) and ΔQ = 5.35 × ln ([CO2]/278) are used. Non-linearities in the feedbacks (including e.g., ice cover and carbon cycle) may cause time dependence of the effective climate sensitivity, as well as leading to larger uncertainties for greater warming levels. The best-estimate climate sensitivity (3 ºC) refers to the most likely value, that is, the mode of the climate sensitivity PDF consistent with the WGI assessment of climate sensitivity and drawn from additional consideration of Box 10.2, Figure 2, in the WGI AR4.
c) Ranges correspond to the 15th to 85th percentile of the Post-Third Assessment Report (TAR) scenario distribution. CO2emissions are shown, so multi-gas scenarios can be compared with CO2-only scenarios.
Essentially, any specific concentration or radiative-forcingtarget requires emissions to fall to very low levels as the removalprocesses of the ocean and terrestrial systems saturate. Higherstabilization targets do push back the timing of this ultimateresult beyond 2100. However, to reach a given stabilizationtarget, emissions must ultimately be reduced well belowcurrent levels. For achievement of the stabilization categoriesI and II, negative net emissions are required towards the end ofthe century in many scenarios considered (Figure TS. 8) (highagreement, much evidence) [3.3.5].
The timing of emission reductions depends on the stringencyof the stabilization target. Stringent targets require an earlierpeak in CO2 emissions (see Figure TS.8). In the majority of thescenarios in the most stringent stabilization category (I), emissionsare required to decline before 2015 and be further reduced to lessthan 50% of today’s emissions by 2050. For category III, globalemissions in the scenarios generally peak around 2010–2030,followed by a return to 2000 levels on average around 2040. Forcategory IV, the median emissions peak around 2040 (FigureTS.9) (high agreement, much evidence).
Notes: Panels give costs measured as percentage loss of GDP (top), and carbon price (bottom). Left-hand panels for 2030, middle panels for 2050 and right-hand panels for 2100. Individual coloured lines denote selected studies with representative cost dynamics from very high to very low cost estimates. Scenarios from models sharing similar baseline assumptions are shown in the same colour. The grey shaded range represents the 80th percentile of TAR and post-TAR scenarios. Solid lines show representative scenarios considering all radiatively active gases. Dashed lines represent multi-gas scenarios where the target is defined by the six Kyoto gases (other multi-gas scenarios consider all radiatively active gases). CO2 stabilization scenarios are added based on the relationship between CO2 concentration and the radiative-forcing targets given in Figure 3.16.
</div>
The costs of stabilization depend on the stabilization targetand level, the baseline and the portfolio of technologiesconsidered, as well as the rate of technological change. Global mitigation costs[9] rise with lower stabilization levels andwith higher baseline emissions. Costs in 2050 for multi-gasstabilization at 650 ppm CO2-eq (cat IV) are between a 2% loss or a one procent increase[10] of GDP in 2050. For 550 ppmCO2-eq (cat III) these costs are a range of a very small increaseto 4% loss of GDP[[[11]]]. For stabilization levels between 445 and535 ppm CO2-eq. costs are lower than 5.5% loss of GDP, butthe number of studies is limited and they generally use lowbaselines.
A multi-gas approach and inclusion of carbon sinksgenerally reduces costs substantially compared with CO2emission abatement only. Global average costs of stabilizationare uncertain, because assumptions on baselines and mitigationoptions in models vary a lot and have a major impact. Forsome countries, sectors or shorter time periods, costs could vary considerably from the global and long-term average (highagreement, much evidence) [3.3.5].
Recent stabilization studies have found that land-usemitigation options (both non-CO2 and CO2) provide cost-effectiveabatement flexibility in achieving 2100 stabilizationtargets. In some scenarios, increased commercial biomassenergy (solid and liquid fuel) is significant in stabilization,providing 5–30% of cumulative abatement and potentially 10–25% of total primary energy over the century, especially as a netnegative emissions strategy that combines biomass energy withCO2 capture and storage.
The baseline choice is crucial in determining the nature andcost of stabilization. This influence is due mainly to differentassumptions about technological change in the baseline scenarios.
The role of technologies
Virtually all scenarios assume that technological andstructural changes occur during this century, leading to relativereduction of emissions compared with the hypothetical case of attempting to ‘keep’ the emission intensities of GDP andeconomic structures the same as today (see Chapter 2, Section2.9.1.3].
Baseline scenarios usually assume significant technologicalchange and diffusion of new and advanced technologies. Inmitigation scenarios there is additional technological change ‘induced’ through various policies and measures. Long-termstabilization scenarios highlight the importance of technologyimprovements, advanced technologies, learning by doing and endogenous technology change both for achievingthe stabilization targets and for cost reduction. While thetechnology improvement and use of advanced technologies have been introduced in scenarios largely exogenously in mostof the literature, new literature covers learning-by-doing andendogenous technological change. These newer scenarios showhigher benefits of early action, as models assume that earlydeployment of technologies leads to benefits of learning andcost reductions (high agreement, much evidence) [3.4].
The different scenario categories also reflect differentcontributions of mitigation measures. However, all stabilizationscenarios concur that 60–80% of all reductions would come from the energy and industry sectors. Non-CO2 gases and land-usewould contribute the remaining 30–40% (see for illustrativeexamples Figure TS. 10). New studies exploring more stringentstabilization levels indicate that a wider portfolio of technologiesis needed. Those could include nuclear, carbon capture andstorage (CCS) and bio-energy with carbon capture and geologicstorage (BECS) (high agreement, much evidence) [3.3.5].
Mitigation and adaptation in the light of climate changeimpacts and decision-making under uncertainties
Concern about key vulnerabilities and notions of what isdangerous climate change will affect decisions about long-termclimate change objectives and hence mitigation pathways. Keyvulnerabilities traverse different human and natural systems andexist at different levels of temperature change. More stringentstabilization scenarios achieve more stringent climate targetsand lower the risk of triggering key vulnerabilities related toclimate change. Using the ‘best estimate’ of climate sensitivity[12], the most stringent scenarios (stabilizing at 445–490 ppm CO2-eq) could limit global mean temperature increases to 2-2.4°Cabove pre-industrial, at equilibrium, requiring emissions topeak within 10 years and to be around 50% of current levels by2050. Scenarios stabilizing at 535-590 ppm CO2-eq could limitthe increase to 2.8-3.2°C above pre-industrial and those at 590-710 CO2-eq to 3.2-4°C, requiring emissions to peak within thenext 25 and 55 years respectively (see Figure TS.11) 3.5.
Notes: Middle (black) line – ‘best estimate’ climate sensitivity of 3°C; upper (red) line – upper bound of likely range of climate sensitivity of 4.5°C; lower (blue) line – lower bound of likely range of climate sensitivity of 2°C. Coloured shading shows the concentration bands for stabilization of GHGs in the atmosphere corresponding to the stabilization scenario categories I to VI as indicated in Table TS.2.
</div>
The risk of higher climate sensitivities increases theprobability of exceeding any threshold for specific keyvulnerabilities. Emission scenarios that lead to temporaryovershooting of concentration ceilings can lead to higher ratesof climate change over the century and increase the probabilityof exceeding key vulnerability thresholds. Results from studies exploring the effect of carbon cycle and climate feedbacksindicate that the above-mentioned concentration levels and theassociated warming of a given emissions scenario might be anunderestimate. With higher climate sensitivity, earlier and morestringent mitigation measures are necessary to reach the sameconcentration level.
Decision-making about the appropriate level of mitigationis an iterative risk-management process considering investmentin mitigation and adaptation, co-benefits of undertaking climatechange decisions and the damages due to climate change.It is intertwined with decisions on sustainability, equity anddevelopment pathways. Cost-benefit analysis, as one of theavailable tools, tries to quantify climate change damage inmonetary terms (as social cost of carbon (SCC) or time-discounteddamage). Due to large uncertainties and difficultiesin quantifying non-market damage, it is still difficult to estimateSCC with confidence. Results depend on a large number ofnormative and empirical assumptions that are not known withany certainty. Limited and early analytical results from integratedanalyses of the costs and benefits of mitigation indicate thatthese are broadly comparable in magnitude, but do not as yetpermit an unambiguous determination of an emissions pathwayor stabilization level where benefits exceed costs. Integratedassessment of the economic costs and benefits of differentmitigation pathways shows that the economically optimal timingand level of mitigation depends upon the uncertain shape andcharacter of the assumed climate change damage cost curve.
To illustrate this dependency:
- if the climate change damage cost curve grows slowly andregularly, and there is good foresight (which increases thepotential for timely adaptation), later and less stringent mitigation is economically justified;
- alternatively if the damage cost curve increases steeply, orcontains non-linearities (e.g. vulnerability thresholds or evensmall probabilities of catastrophic events), earlier and morestringent mitigation is economically justified (high agreement,much evidence) [3.6.1].
Linkages between short term and long term
For any chosen GHG-stabilization target, near-term decisionscan be made regarding mitigation opportunities to help maintaina consistent emissions trajectory within a range of long-termstabilization targets. Economy-wide modelling of long-termglobal stabilization targets can help inform near-term mitigationchoices. A compilation of results from short-and long-termmodels using scenarios with stabilization targets in the 3–5 W/m2range (category II to III), reveals that in 2030, for carbon pricesof less than 20 US$/tCO2-eq, emission reductions of in therange of 9-18 GtCO2-eq/yr across all GHGs can be expected.For carbon prices less than 50 US$/tCO2-eq this range is 14–23GtCO2-eq/yr and for carbon prices less than US$100/tCO2-eq itis 17-26 GtCO2-eq/yr. (high agreement, much evidence).
Three important considerations need to be remembered withregard to the reported marginal costs. First, these mitigationscenarios assume complete ‘what’ and ‘where’ flexibility; thatis, there is full substitution among GHGs, and reductions takeplace anywhere in the world as soon as the models begin theiranalyses. Second, the marginal costs of realizing these levels ofmitigation increase in the time horizon beyond 2030. Third, atthe economic-sector level, emission-reduction potential for allGHGs varies significantly across the different model scenarios(high agreement, much evidence) [3.6.2].
A risk management or ‘hedging’ approach can assist policy-makersto advance mitigation decisions in the absence of a long-termtarget and in the face of large uncertainties related to the costof mitigation, the efficacy of adaptation and the negative impactsof climate change. The extent and the timing of the desirablehedging strategy will depend on the stakes, the odds and societies’attitudes to risks, for example, with respect to risks of abruptchange in geophysical systems and other key vulnerabilities.A variety of integrated assessment approaches exist to assessmitigation benefits in the context of policy decisions related tosuch long-term climate goals. There will be ample opportunityfor learning and mid-course corrections as new informationbecomes available. However, actions in the short term willlargely determine long-term global mean temperatures and thus what corresponding climate change impacts can be avoided.Delayed emission reductions lead to investments that lock in moreemission-intensive infrastructure and development pathways.This significantly constrains the opportunities to achieve lowerstabilization levels and increases the risk of more severe climatechange impacts. Hence, analysis of near-term decisions shouldnot be decoupled from analysis that considers long-term climatechange outcomes (high agreement, much evidence) 3.5.2.
4 Energy supply
Status of the sector and development until 2030
Global energy demand continues to grow, but with regionaldifferences. The annual average growth of global primary energyconsumption was 1.4% per year in the 1990–2004 period. Thiswas lower than in the previous two decades due to the economictransition in Eastern Europe, the Caucasus and Central Asia,but energy consumption in that region is now moving upwardsagain (Figure TS.12) (high agreement, much evidence) [4.2.1].
Rapid growth in energy consumption per capita is occurringin many developing countries. Africa is the region with thelowest per capita consumption. Increasing prices of oil and gascompromise energy access, equity and sustainable developmentof the poorest countries and interfere with reaching poverty reductiontargets that, in turn, imply improved access toelectricity, modern cooking and heating fuels and transportation(high agreement, much evidence) [4.2.4].
Total fossil fuel consumption has increased steadily duringthe past three decades. Consumption of nuclear energy hascontinued to grow, though at a slower rate than in the 1980s. Large hydro and geothermal energy are relatively static.Between 1970 and 2004, the share of fossil fuels dropped from86% to 81%. Wind and solar are growing most rapidly, butfrom a very low base (Figure TS.13) (high agreement, muchevidence) [4.2].
Most business-as-usual (BAU) scenarios point to continuedgrowth of world population (although at lower rates thanpredicted decades ago) and GDP, leading to a significant growth in energy demand. High energy-demand growth rates in Asia(3.2% per year 1990–2004) are projected to continue and tobe met mainly by fossil fuels (high agreement, much evidence)[4.2].
Absolute fossil fuel scarcity at the global level is not asignificant factor in considering climate change mitigation.Conventional oil production will eventually peak, but it is uncertain exactly when and what the repercussions will be. Theenergy in conventional natural gas is more abundant than inconventional oil but, like oil, is not distributed evenly aroundthe globe. In the future, lack of security of oil and gas suppliesfor consuming nations may drive a shift to coal, nuclear powerand/or renewable energy. There is also a trend towards moreefficient and convenient energy carriers (electricity, and liquidand gaseous fuels) instead of solids (high agreement, muchevidence) [4.3.1].
In all regions of the world, emphasis on security of supplyhas grown since the Third Assessment Report (TAR). This iscoupled with reduced investments in infrastructure, increasedglobal demand, political instability in key areas and thethreats of conflict, terrorism and extreme weather events.New energy infrastructure investments in developing countriesand upgrades of capacity in developed countries opens a windowof opportunity for exploiting the co-benefits of choices inthe energy mix in order to lower GHG emissions from whatthey otherwise would be (high agreement, much evidence)4.1.
The conundrum for many governments has become how bestto meet the ever growing demand for reliable energy serviceswhile limiting the economic costs to their constituents, ensuringenergy security, reducing dependence on imported energysources and minimizing emissions of the associated GHGs andother pollutants. Selection of energy-supply systems for eachregion of the world will depend on their development, existinginfrastructure and the local comparative costs of the availableenergy resources (high agreement, much evidence) [4.1].
If fossil fuel prices remain high, demand may decreasetemporarily until other hydrocarbon reserves in the form of oilsands, oil shales, coal-to-liquids, gas-to-liquids etc. become commercially viable. Should this happen, emissions willincrease further as the carbon intensity increases, unless carbondioxide capture and storage (CCS) is applied. Due to increasedenergy security concerns and recent increases in gas prices,there is growing interest in new, more efficient, coal-based power plants. A critical issue for future GHG emissions is howquickly new coal plants are going to be equipped with CCStechnology, which will increase the costs of electricity. Whetherbuilding ‘capture ready’ plants is more cost-effective thanretrofitting plants or building a new plant integrated with CCSdepends on economic and technical assumptions. Continuinghigh fossil fuel prices may also trigger more nuclear and/orrenewable energy, although price volatility will be a disincentivefor investors. Concerns about safety, weapons proliferation andwaste remain as constraints for nuclear power. Hydrogen mayalso eventually contribute as an energy carrier with low carbonemissions, dependent on the source of the hydrogen and thesuccessful uptake of CCS for hydrogen production from coalor gas. Renewable energy must either be used in a distributedmanner or will need to be concentrated to meet the intensiveenergy demands of cities and industries, because, unlike fossilfuel sources, the sources of renewable energy are widelydistributed with low energy returns per exploited area (mediumagreement, medium evidence) [4.3].
If energy demand continues to grow along the current trajectory,an improved infrastructure and conversion system will, by 2030,require a total cumulative investment of over US$2005 20 trillion(20 x 1012). For comparison, the total capital investment by theglobal energy industry is currently around 300 billion US$ peryear (300 x 109) (medium agreement, medium evidence) [4.1].
Global and regional emission trends
With the exception of the countries in Eastern Europe, theCaucasus and Central Asia (where emissions declined post-1990but are now rising again) and Europe (currently stable), carbonemissions have continued to rise. Business-as-usual emissionsto 2030 will increase significantly. Without effective policyactions, global CO2 emissions from fossil fuel combustion arepredicted to rise at a minimum of more than 40%, from around25 GtCO2-eq/yr (6.6 GtC-eq) in 2000 to 37-53 GtCO2-eq/yr(10-14 GtC-eq) by 2030 [4.2.3].
In 2004, emissions from power generation and heat supplyalone were 12.7 GtCO2-eq (26% of total emissions) including2.2 GtCO2eq from CH4. In 2030, according to the World Energy Outlook 2006 baseline, these will have increased to17.7 GtCO2-eq. (high agreement, much evidence) [4.2.2].
Description and assessment of mitigationtechnologies and practices, options, potentialsand costs in the electricity generation sector
The electricity sector has a significant mitigation potentialusing a range of technologies (Table TS.3). The economicpotential for mitigation of each individual technology is based on what might be a realistic deployment expectation ofthe various technologies using all efforts, but given practicalconstraints on rate of uptake, public acceptance, capacity building and commercialization. Competition between optionsand the influence of end-use energy conservation and efficiencyimprovement is not included [4.4].
Table TS.3: Potential GHG emissions avoided by 2030 for selected electricity generation mitigation technologies (in excess of the IEA World Energy Outlook (2004) Reference baseline) employed in isolation with estimated mitigation potential shares spread across each cost range (2006 US$/tCO2-eq) 4.19.
| Regional groupings | Mitigation potential; total emissions saved in 2030 (GtCO2-eq) | Mitigation potential (%) for specific carbon price ranges (US$/tCO2-eq avoided) | |||||
|---|---|---|---|---|---|---|---|
| <0 | 0-20 | 20-50 | 50-100 | >100 | |||
| Fuel switch and plant efficiency | OECDa | 0.39 | 100 | ||||
| EITb | 0.04 | 100 | |||||
| Non-OECD | 0.64 | 100 | |||||
| World | 1.07 | ||||||
| Nuclear | OECD | 0.93 | 50 | 50 | |||
| EIT | 0.23 | 50 | 50 | ||||
| Non-OECD | 0.72 | 50 | 50 | ||||
| World | 1.88 | ||||||
| Hydro | OECD | 0.39 | |||||
| EIT | 0.00 | ||||||
| Non-OECD | 0.48 | 25 | 35 | 40 | |||
| World | 0.87 | ||||||
| Wind | OECD | 0.45 | 35 | 40 | 25 | ||
| EIT | 0.06 | 35 | 45 | 20 | |||
| Non-OECD | 0.42 | 35 | 50 | 15 | |||
| World | 0.93 | ||||||
| Bio-energy | OECD | 0.20 | 20 | 25 | 40 | 15 | |
| EIT | 0.07 | 20 | 25 | 40 | 15 | ||
| Non-OECD | 0.95 | 20 | 30 | 45 | 5 | ||
| World | 1.22 | ||||||
| Geothermal | OECD | 0.09 | 35 | 40 | 25 | ||
| EIT | 0.03 | 35 | 45 | 20 | |||
| Non-OECD | 0.31 | 35 | 50 | 15 | |||
| World | 0.43 | ||||||
| Solar PV and concentrated solar power | OECD | 0.03 | 20 | 80 | |||
| EIT | 0.01 | 20 | 80 | ||||
| Non-OECD | 0.21 | 25 | 75 | ||||
| World | 0.25 | ||||||
| CCS + coal | OECD | 0.28 | 100 | ||||
| EIT | 0.01 | 100 | |||||
| Non-OECD | 0.20 | 100 | |||||
| World | 0.49 | ||||||
| CCS + gas | OECD | 0.09 | 100 | ||||
| EIT | 0.04 | 30 | 70 | ||||
| Non-OECD | 0.09 | 100 | |||||
| World | 0.22 | ||||||
Notes:
a) Organization for Economic Cooperation and Development
b) Economies in Transition
A wide range of energy-supply mitigation options areavailable and cost effective at carbon prices of <20US$/tCO2including fuel switching and power-plant efficiency improvements, nuclear power and renewable energy systems.CCS will become cost effective at higher carbon prices. Otheroptions still under development include advanced nuclearpower, advanced renewables, second-generation biofuels and,in the longer term, the possible use of hydrogen as an energycarrier (high agreement, much evidence) 4.4.
Since the estimates in Table TS.3 are for the mitigationpotentials of individual options without considering the actualsupply mix, they cannot be added. An additional analysis of thesupply mix to avoid double counting was therefore carried out.For this analysis, it was assumed that the capacity of thermalelectricity generation capacity would be substituted graduallyand new power plants would be built to comply with demand,under the following conditions:
- Switching from coal to gas was assumed for 20% of the coalplants, as this is the cheapest option.
- The replacement of existing fossil fuel plants and the buildingof new plants up to 2030 to meet increasing power demandwas shared between efficient fossil fuel plants, renewables,nuclear and coal and gas-fired plants with CCS. Noearly retirement of plants or stranded assets was assumed.
- Low- or zero-carbon technologies are employed proportionalto their estimated maximum shares in electricity generationin 2030. These shares are based on the literature, taking intoaccount resource availability, relative costs and variability ofsupply related to intermittency issues in the power grid, andwere differentiated according to carbon cost levels.
The resulting economic mitigation potential for theenergy-supply sector by 2030 from improved thermal power plantefficiency, fuel switching and the implementation ofmore nuclear, renewables, fuel switching and CCS to meetgrowing demand is around 7.2 GtCO2-eq at carbon prices<100 US$/tCO2-eq. At costs <20 US$/tCO2-eq the reduction potential is estimated at 3.9 GtCO2-eq (Table TS.4). At thiscarbon price level, the share of renewable energy in electricitygeneration would increase from 20% in 2010 to about 30%in 2030. At carbon prices <50 US$/tCO2-eq, the share wouldincrease to 35% of total electricity generation. The share ofnuclear energy would be about 18% in 2030 at carbon prices<50 US$/tCO2-eq, and would not change much at higher pricesas other technologies would be competitive.
For assessment of the economic potential, maximumtechnical shares for the employment of low- or zero-carbontechnologies were assumed and the estimate is thereforeat the high end of the wide range found in the literature.If, for instance, only 70% of the assumed shares is reached, themitigation potential at carbon prices <100 US$/tCO2-eq wouldbe almost halved. Potential savings in electricity demand inend-use sectors reduce the need for mitigation measures in thepower sector. When the impact of mitigation measures in thebuilding and industry sectors on electricity demand (outlined in[11]) is taken into account, a lower mitigation potentialfor the energy-supply sector results than the stand-alone figurereported here (medium agreement, limited evidence) [4.4].
Table TS.4: Projected power demand increase from 2010 to 2030 as met by new, more efficient additional and replacement plants and the resulting mitigation potential above the World Energy Outlook 2004 baseline 4.20]].
| Power plant efficiencies by 2030 (based on IEA 2004a)a (%) | Existing mix of power generation in 2010 ( TWh) | Generation from additional new plant by 2030 (TWh) | Generation from new plant replacing old, existing 2010 plant by 2030 (TWh) | Share of mix of generation of total new and replacement plant built by 2030 including CCS at various carbon prices (US$/tCO2-eq)b | Total GtCO2-eq avoided by fuel switching, CCS and displacing some fossil fuel generation with low-carbon options of wind, solar, geothermal, hydro, nuclear and biomass | |||||
|---|---|---|---|---|---|---|---|---|---|---|
| <20 US$/ TWh | <50 US$/ TWh | <100 US$/ TWh | <20 US$/t | <50 US$/t | <100 US$/t | |||||
| OECD | 11,302 | 2942 | 4521 | 7463 | 1.58 | 2.58 | 2.66 | |||
| Coal | 41 | 4079 | 657 | 1632 | 889 | 121 | 0 | |||
| Oil | 40 | 472 | –163C | 189 | 13 | 2 | 0 | |||
| Gas | 48 | 2374 | 1771 | 950 | 1793 | 637 | 458 | |||
| Nuclear | 33 | 2462 | –325 | 985 | 2084 | 2084 | 1777 | |||
| Hydro | 100 | 1402 | 127 | 561 | 1295 | 1295 | 1111 | |||
| Biomass | 28 | 237 | 168 | 95 | 263 | 499 | 509 | |||
| Other renewables | 63 | 276 | 707 | 110 | 1116 | 1544 | 1526 | |||
| CCS | 0 | 1282 | 2082 | |||||||
| Economies In Transition (EIT) | 1746 | 722 | 698 | 1420 | 0.32 | 0.42 | 0.49 | |||
| Coal | 32 | 381 | 13 | 152 | 72 | 46 | 29 | |||
| Oil | 29 | 69 | –8 | 28 | 11 | 7 | 4 | |||
| Gas | 39 | 652 | 672 | 261 | 537 | 357 | 240 | |||
| Nuclear | 33 | 292 | –20 | 117 | 442 | 442 | 442 | |||
| Hydro | 100 | 338 | 35 | 135 | 170 | 170 | 170 | |||
| Biomass | 48 | 4 | 7 | 2 | 47 | 109 | 121 | |||
| Other renewables | 36 | 10 | 23 | 4 | 142 | 167 | 191 | |||
| CCS | 0 | 123 | 222 | |||||||
Notes:
a) Implied efficiencies calculated from WEO 2004 (IEA, 2004b) = Power output (EJ)/Estimated power input (EJ). See Appendix 1, [11].
b) At higher carbon prices, more coal, oil and gas power generation is displaced by low- and zero-carbon options. Since nuclear and hydro are cost competitive at <20US$/tCO2-eq in most regions (Chapter 4 (IPCC Fourth Assessment Report, Working Group III: Technical Summary) , Table 4.4.4), their share remains constant.
c) Negative data depicts a decline in generation, which was included in the analysis.
Interactions of mitigation options with vulnerabilityand adaptation
Many energy systems are themselves vulnerable to climatechange. Fossil fuel based offshore and coastal oil and gasextraction systems are vulnerable to extreme weather events.Cooling of conventional and nuclear power plants may become problematic if river waters are warmer. Renewable energy resources can also be affected adversely by climatechange (such as solar systems impacted by changes in cloud cover; hydropower generation influenced by changes in river discharge, glaciers and snow melt; windpower influenced bychanging wind velocity; and energy crop yields reduced by drought and higher temperatures). Some adaptation measuresto climate change, like air-conditioning and water pumps useenergy and may contribute to even higher CO2 emissions, andthus necessitate even more mitigation (high agreement, limitedevidence) [4.5.5].
Effectiveness of and experience with climatepolicies, potentials, barriers, opportunities andimplementation issues
The need for immediate short-term action in order to makeany significant impact in the longer term has become apparent, ashas the need to apply the whole spectrum of policy instruments,since no single instrument will enable a large-scale transitionin energy-supply systems on a global basis. Large-scale energyconversion technologies have a life of several decades andhence a turnover of only 1–3% per year. That means that policydecisions taken today will affect the rate of deployment ofcarbon-emitting technologies for several decades. They willhave profound consequences on development paths, especiallyin a rapidly developing world [4.1].
Economic and regulatory instruments have been employed.Approaches to encourage the greater uptake of low-carbonenergy-supply systems include reducing fossil fuel subsidies and stimulating front-runners in specific technologies throughactive government involvement in market creation (such as inDenmark for wind energy and Japan with solar photovoltaic(PV)). Reducing fossil fuel subsidies has been difficult, as itmeets resistance by vested interests. In terms of support forrenewable-electricity projects, feed-in-tariffs have been moreeffective than green certificate trading systems based on quotas.However, with increasing shares of renewables in the powermix, the adjustment of such tariffs becomes an issue. Tradablepermit systems and the use of the Kyoto flexible mechanismsare expected to contribute substantially to emission reductions(medium agreement, medium evidence) [4.5].
Integrated and non-climate policies and co-benefitsof mitigation policies
Co-benefits of GHG mitigation in the energy supply sectorcan be substantial. When applying cost-effective energy efficiencymeasures, there is an immediate economic benefit to consumers from lower energy costs. Other co-benefits in terms ofenergy supply security, technological innovation, air-pollutionabatement and employment also typically result at the localscale. This is especially true for renewables which can reduceimport dependency and in many cases minimize transmissionlosses and costs. Electricity, transport fuels and heat suppliedby renewable energy are less prone to price fluctuations, but inmany cases have higher costs. As renewable energy technologiescan be more labour-intensive than conventional technologiesper unit of energy output, more employment will result. Highinvestment costs of new energy system infrastructures can,however, be a major barrier to their implementation.
Developing countries that continue to experience higheconomic growth will require significant increases in energyservices that are currently being met mainly by fossil fuels.Increasing access to modern energy services can have multiplebenefits. Their use can help improve air quality, particularly inlarge urban areas, and lead to a decrease in GHG emissions.An estimated 2400 GW of new power plants plus the relatedinfrastructure will need to be built in developing countriesby 2030 to meet increased consumer demand, requiring aninvestment of around 5 trillion US$ (5 x 1012). If well directed,such large investments provide opportunities for sustainabledevelopment. The integration of development policies withGHG mitigation objectives can deliver the advantages mentionedabove and contribute to development goals pertaining toemployment, poverty and equity. Analysis of possible policiesshould take into account these co-benefits. However, it shouldbe noted again that, in specific circumstances, pursuing air pollutionabatement or energy security aims can lead to moreenergy use and related GHG emissions.
Liberalization and privatization policies to develop freeenergy markets aim to provide greater competition and lowerconsumer prices but have not always been successful in this regard, often resulting in a lack of capital investment andscant regard for environmental impacts (high agreement, muchevidence) 4.5.2; 4.5.3; 4.5.4.
Technology research, development,diffusion and transfer
Investment in energy technology R&D has declined overallsince the levels achieved in the late 1970s that resulted from theoil crisis. Between 1980 and 2002, public energy-related R&Dinvestment declined by 50% in real terms. Current levels haverisen, but may still be inadequate to develop the technologiesneeded to reduce GHG emissions and meet growing energydemand. Greater public and private investment will be requiredfor rapid deployment of low-carbon energy technologies.Improved energy conversion technologies, energy transportand storage methods, load management, co-generation andcommunity-based services will have to be developed (highagreement, limited evidence) [4.5.6].
Long-term outlook
Outlooks from both the IEA and World Energy Council projectincreases in primary energy demand of between 40 and 150% by2050 over today’s demand, depending on the scenarios for population and economic growth and the rate of technology development.Electricity use is expected to grow by between 110 and 260%.Both organizations realize that business-as-usual scenarios arenot sustainable. It is well accepted that even with good decision makingand co-operation between the public and private sectors,the necessary transition will take time and the sooner it is begun thelower the costs will be (high agreement, much evidence) [4.2.3].
5 Transport and its infrastructure
Status and development of the sector
Transport activity is increasing around the world as economiesgrow. This is especially true in many areas of thedeveloping world where globalization is expanding tradeflows, and rising personal incomes are amplifying demand for motorizedmobility. Current transportation activity is mainlydriven by internal combustion engines powered by petroleumfuels (95% of the 83 EJ of world transport energy use in 2004).As a consequence, petroleum use closely follows the growth intransportation activity. In 2004, transport energy amounted to26% of total world energy use. In the developed world, transportenergy use continues to increase at slightly more than 1% per year;passenger transport currently consumes 60–75% of total transportenergy there. In developing countries, transport energy use is risingfaster (3 to 5% per year) and is projected to grow from 31% in2002 to 43% of world transport energy use by 2025 5.2.2.
Transport activity is expected to grow robustly over the nextseveral decades. Unless there is a major shift away from currentpatterns of energy use, projections foresee a continued growth inworld transportation energy use of 2% per year, with energy useand carbon emissions about 80% above 2002 levels by 2030 [5.2.2].In developed economies, motor vehicle ownership approachesfive to eight cars for every ten inhabitants (Figure TS.14). Inthe developing world, levels of vehicle ownership are muchlower; non-motorized transport plays a significant role, andthere is a greater reliance on two- and three-wheeled motorizedvehicles and public transport. The motorization of transport inthe developing world is, however, expected to grow rapidly inthe coming decades. As incomes grow and the value oftravellers’ time increases, travellers are expected to choosefaster modes of transport, shifting from non-motorized toautomotive, to air and high-speed rail. Increasing speedhas generally led to greater energy intensity and higherGHG emissions.
In addition to GHG emissions, the motorization of transporthas created congestion and air-pollution problems in large citiesall around the world (high agreement, much evidence) 5.5.4.
Note: data are for 1900–2002, but the years plotted vary by country, depending on data availability.
</div>
Emission trends
In 2004, the contribution of transport to total energy-relatedGHG emissions was about 23%, with emissions of CO2 andN2O amounting to about 6.3-6.4 GtCO2-eq. Transport sector CO2 emissions (6.2 GtCO2-eq. in 2004) have increased byaround 27% since 1990 and its growth rate is the highest amongthe end-user sectors. Road transport currently accounts for 74%of total transport CO2 emissions. The share of non-OECDcountries is 36% now and will increase rapidly to 46% by 2030if current trends continue (high agreement, medium evidence)[5.2.2].
The transport sector also contributes small amounts of CH4and N2O emissions from fuel combustion and F-gases fromvehicle air-conditioning. CH4 emissions are between 0.1–0.3%of total transport GHG emissions, N2O between 2.0 and 2.8%(all figures based on US, Japan and EU data only). Emissionsof F gases (CFC-12 + HFC-134a + HCFC-22) worldwide in2003 were 4.9% of total transport CO2 emissions (mediumagreement, limited evidence) [5.2.1].
[[Image:figure-ts-15-l.png.jpegFigure TS.15: Historical and projected CO2 emissions from transport 5.4.]]
Estimates of CO2 emissions from global aviation increasedby a factor of about 1.5, from 330 MtCO2/yr in 1990 to480 MtCO2/yr in 2000, and accounted for about 2% of total anthropogenic CO2 emissions. Aviation CO2 emissions areprojected to continue to grow strongly. In the absence ofadditional measures, projected annual improvements in aircraft fuel efficiency of the order of 1–2% will be largely surpassedby traffic growth of around 5% each year, leading to a projectedincrease in emissions of 3–4% per year (high agreement, mediumevidence). Moreover, the overall climate impact of aviation ismuch greater than the impact of CO2 alone. As well as emittingCO2, aircraft contribute to climate change through the emissionof nitrogen oxides (NOx), which are particularly effectivein forming the GHG ozone when emitted at cruise altitudes.Aircraft also trigger the formation of condensation trails, orcontrails, which are suspected of enhancing the formationof cirrus clouds, which add to the overall global warmingeffect. These effects are estimated to be about two to fourtimes greater than those of aviation’s CO2 alone, even withoutconsidering the potential impact of cirrus cloud enhancement.The environmental effectiveness of future mitigation policiesfor aviation will depend on the extent to which these non-CO2effects are also addressed (high agreement, medium evidence)5.2.2.
All of the projections discussed above assume that world oilsupplies will be more than adequate to support the expectedgrowth in transport activity. There is ongoing debate, however,about whether the world is nearing a peak in conventional oilproduction that would require a significant and rapid transitionto alternative energy sources. There is no shortage of alternativeenergy sources, including oil sands and oil shales, coal-toliquids,biofuels, electricity and hydrogen. Among thesealternatives, unconventional fossil carbon resources wouldproduce the least expensive fuels most compatible with theexisting transportation infrastructure. Unfortunately, tappinginto these fossil resources to power transportation wouldincrease upstream carbon emissions and greatly increase theinput of carbon into the atmosphere 5.3.
Description and assessment of mitigation technologiesand practices, options, potentials and costs
Transport is distinguished from other energy-using sectorsby its predominant reliance on a single fossil resource and bythe infeasibility of capturing carbon emissions from transportvehicles with any known technologies. It is also important to view GHG-emission reductions in conjunction with air pollution,congestion and energy security (oil import) problems. Solutionstherefore have to try to optimize improvement of transportationproblems as a whole, not just GHG emissions [5.5.4].
There have been significant developments in mitigationtechnologies since the Third Assessment Report (TAR),and significant research, development and demonstration programmes on hydrogen-powered fuel-cell vehicles have beenlaunched around the globe. In addition, there are still manyopportunities for improvement of conventional technologies.Biofuels continue to be important in certain markets and havemuch greater potential for the future. With regard to non-CO2emissions, vehicle air-conditioning systems based on low GWPrefrigerants have been developed [5.3].
Road traffic: efficient technologies and alternative fuels
Since the TAR, the energy efficiency of road vehicles hasimproved by the market success of cleaner directed-injectionturbocharged (TDI) diesels and the continued market penetrationof many incremental efficiency technologies; hybrid vehicleshave also played a role, though their market penetration iscurrently small. Further technological advances are expectedfor hybrid vehicles and TDI diesel engines. A combination ofthese with other technologies, including materials substitution,reduced aerodynamic drag, reduced rolling resistance, reducedengine friction and pumping losses, has the potential toapproximately double the fuel economy of ‘new’ light-dutyvehicles by 2030, thereby roughly halving carbon emissions pervehicle mile travelled (note that this is only for a new car andnot the fleet average) (medium agreement, medium evidence)[5.3.1].
Biofuels have the potential to replace a substantial part,but not all, petroleum use by transport. A recent IEA reportestimated that the share of biofuels could increase to about 10% by 2030 at costs of 25 US$/tCO2-eq, which includes a smallcontribution from biofuels from cellulosic biomass. The potentialstrongly depends on production efficiency, the developmentof advanced techniques such as conversion of cellulose byenzymatic processes or by gasification and synthesis, costs,and competition with other uses of land. Currently the cost andperformance of ethanol in terms of CO2 emissions avoided isunfavourable, except for production from sugarcane in low-wagecountries (Figure TS.16) (medium agreement, mediumevidence) [5.3.1].
The economic and market potential of hydrogen vehiclesremains uncertain. Electric vehicles with high efficiency(more than 90%), but low driving range and short battery life have a limited market penetration. For both options, theemissions are determined by the production of hydrogen andelectricity. If hydrogen is produced from coal or gas with CCS (currently the cheapest way) or from biomass, solar, nuclearor wind energy, well-to-wheel carbon emissions could benearly eliminated. Further technological advances and/or cost reductions would be required in fuel-cells, hydrogen storage,hydrogen or electricity production with low- or zero-carbonemissions, and batteries (high agreement, medium evidence)
[5.3.1].
Note: prices exclude taxes.
</div>
The total mitigation potential in 2030 of the energy-efficiencyoptions applied to light duty vehicles would be around 0.7–0.8 GtCO2-eq in 2030 at costs lower than 100 US$/tCO2. Dataare not sufficient to provide a similar estimate for heavy-dutyvehicles. The use of current and advanced biofuels, as mentionedabove, would give an additional reduction potential of another600–1500 MtCO2-eq in 2030 at costs lower than 25 US$/tCO2(low agreement, limited evidence) [5.4.2].
A critical threat to the potential for future reduction ofCO2 emissions from use of fuel economy technologies is thatthey can be used to increase vehicle power and size rather than to improve the overall fuel economy and reduce carbonemissions. The preference of the market for power and size hasconsumed much of the potential for GHG mitigation reductionachieved over the past two decades. If this trend continues, itwill significantly diminish the GHG mitigation potential of theadvanced technologies described above (high agreement, muchevidence) 5.3.
Air traffic
The fuel efficiency of civil aviation can be improvedby a variety of means including technology, operation andmanagement of air traffic. Technology developments mightoffer a 20% improvement in fuel efficiency over 1997 levelsby 2015, with a 40–50% improvement likely by 2050. Ascivil aviation continues to grow at around 5% each year, such improvements are unlikely to keep carbon emissions fromglobal air travel from increasing. The introduction of biofuelscould mitigate some of aviation’s carbon emissions, if biofuelscan be developed to meet the demanding specifications of theaviation industry, although both the costs of such fuels and theemissions from their production process are uncertain at thistime (medium agreement, medium evidence) [5.3.3].
Aircraft operations can be optimized for energy use (withminimum CO2 emissions) by minimizing taxiing time, flying atoptimal cruise altitudes, flying minimum-distance great-circle routes, and minimizing holding and stacking around airports.The GHG-reduction potential of such strategies has beenestimated at 6–12%. More recently, researchers have begun toaddress the potential for minimizing the total climate impactof aircraft operations, including ozone impacts, contrails andnitrogen oxides emissions. The mitigation potential in 2030for aviation is 280 MtCO2/yr at costs <100 US$/tCO2 (mediumagreement, medium evidence) [5.4.2].
Marine transport
Since the TAR, an International Maritime Organization(IMO) assessment found that a combination of technicalmeasures could reduce carbon emissions by 4–20% in olderships and 5–30% in new ships by applying state-of-the-artknowledge, such as hull and propeller design and maintenance.However, due to the long lifetime of engines, it will take decades before measures on existing ships are implementedon a significant scale. The short-term potential for operationalmeasures, including route-planning and speed reduction, rangedfrom 1–40%. The study estimated a maximum reduction ofemissions of the world fleet of about 18% by 2010 and 28% by2020, when all measures were to be implemented. The data donot allow an estimate of an absolute mitigation potential figureand the mitigation potential is not expected to be sufficient tooffset the growth in shipping activity over the same period(medium agreement, medium evidence) [5.3.4].
Rail transport
The main opportunities for mitigating GHG emissionsassociated with rail transport are improving aerodynamics,reduction of train weight, introducing regenerative braking andon-board energy storage and, of course, mitigating the GHGemissions from electricity generation. There are no estimatesavailable of total mitigation potential and costs [5.3.2].
Modal shifts and public transport
Providing public transports systems and their relatedinfrastructure and promoting non-motorized transport cancontribute to GHG mitigation. However, local conditionsdetermine how much transport can be shifted to less energy intensivemodes. Occupancy rates and the primary energysources of the transport modes further determine the mitigationpotential [5.3.1].
The energy requirements of urban transport are stronglyinfluenced by the density and spatial structure of the builtenvironment, as well as by the location, extent and nature of the transport infrastructure. Large-capacity buses, light-rail transitand metro or suburban rail are increasingly being used forthe expansion of public transport. Bus Rapid Transit systemshave relatively low capital and operational costs, but it isuncertain if they can be implemented in developing countrieswith the same success as in South America. If the share ofbuses in passenger transport were to increase by 5–10%, thenCO2 emissions would fall by 4-9% at costs in the orderof US$ 60-70/tCO2 [5.3.1].
More than 30% of the trips made by cars in Europe are forless than 3 km and 50% for less than 5 km. Although the figuresmay differ for other continents, there is potential for mitigationby shifting from cars to non-motorized transport (walking andcycling), or preventing a growth of car transport at the expenseof non-motorized transport. Mitigation potentials are highlydependent on local conditions, but there are substantial co-benefitsin terms of air quality, congestion and road safety (highagreement, much evidence) [5.3.1].
Overall mitigation potential in the transport sector
The overall potential and cost for CO2 mitigation can only bepartially estimated due to lack of data for heavy-duty vehicles,rail transport, shipping and modal split change/ public transportpromotion. The total economic potential for improved efficiencyof light-duty vehicles and aeroplanes and substituting biofuelsfor conventional fossil fuels, for a carbon price up to 100 US$/tCO2-eq, is estimated to be about 1600–2550 MtCO2. This is anunderestimate of potential for mitigation in the transport sector(high agreement, medium evidence) [5.4.2].
Effectiveness of and experience with climatepolicies, potentials, barriers and opportunities/implementation issues
Policies and measures for surface transport
Given the positive effects of higher population densities onpublic transport use, walking, cycling and CO2 emissions, betterintegrated spatial planning is an important policy element in thetransportation sector. There are some good examples for largecities in several countries. Transportation Demand Management(TDM) can be effective in reducing private vehicle travel ifrigorously implemented and supported. Soft measures, suchas the provision of information and the use of communicationstrategies and educational techniques have encouraged achange in personal behaviour leading to a reduction in theuse of the car by 14% in an Australian city, 12% in a Germancity and 13% in a Swedish city (medium agreement, mediumevidence) [5.5.1].
Fuel-economy standards or CO2 standards have been effectivein reducing GHG emissions, but so far, transport growthhas overwhelmed their impact. Most industrialized and somedeveloping countries have set fuel-economy standards for newlight-duty vehicles. The forms and stringency of standards varywidely, from uniform, mandatory corporate average standards,through graduated standards by vehicle weight class or size,to voluntary industry-wide standards. Fuel economy standardshave been universally effective, depending on their stringency,in improving vehicle fuel economy, increasing on-road fleet averagefuel economy and reducing fuel use and carbonemissions. In some countries, fuel-economy standards havebeen strongly opposed by segments of the automotive industryon a variety of grounds, ranging from economic efficiency tosafety. The overall effectiveness of standards can be significantlyenhanced if combined with fiscal incentives and consumerinformation (high agreement, much evidence) [5.5.1].
Taxes on vehicle purchase, registration, use and motor fuels,as well as road and parking pricing policies are importantdeterminants of vehicle-energy use and GHG emissions. Theyare employed by different countries to raise general revenue,to partially internalize the external costs of vehicle use or tocontrol congestion of public roads. An important reason for fuelor CO2 tax having limited effects is that price elasticities tend tobe substantially smaller than the income elasticities of demand.In the long run, the income elasticity of demand is a factor1.5–3 higher than the price elasticity of total transport demand,meaning that price signals become less effective with increasingincomes. Rebates on vehicle purchase and registration taxes forfuel-efficient vehicles have been shown to be effective. Roadand parking pricing policies are applied in several cities, withmarked effects on passenger car traffic (high agreement, muchevidence) [5.5.1].
Many governments have introduced or are intending toimplement policies to promote biofuels in national emissionabatement strategies. Since the benefit of biofuels for CO2 mitigation comes mainly from the well-to-tank part, incentivesfor biofuels are more effective climate policies if they are tiedto entire well-to-wheels CO2 efficiencies. Thus preferentialtax rates, subsidies and quotas for fuel blending should becalibrated to the benefits in terms of net CO2 savings over theentire well-to-wheel cycle associated with each fuel. In order toavoid the negative effects of biofuel production on sustainabledevelopment (e.g., biodiversity impacts), additional conditionscould be tied to incentives for biofuels.
Policies and measures for aviation and marine transport
In order to reduce emissions from air and marine transportresulting from the combustion of bunker fuels, new policyframeworks need to be developed. Both the International Civil Aviation Organization (ICAO) and IMO have studiedoptions for limiting GHG emissions. However, neither has yetbeen able to devise a suitable framework for implementing policies. ICAO, however, has endorsed the concept of an open,international emission-trading system implemented through avoluntary scheme, or the incorporation of international aviationinto existing emission-trading systems.
For aviation, both fuel or emission charges and tradingwould have the potential to reduce emissions considerably.The geographical scope (routes and operators covered), the amount of allowances to be allocated to the aviation sector andthe coverage of non-CO2 climate impacts will be key designelements in determining the effectiveness of emissions tradingfor reducing the impacts of aviation on climate. Emissioncharges or trading would lead to an increase in fuel costs thatwill have a positive impact on engine efficiency [5.5.2].
Current policy initiatives in the shipping sector are mostlybased on voluntary schemes, using indexes for the fuel efficiencyof ships. Environmentally differentiated port dues are being used in a few places. Other policies to limit shippingemissions would be the inclusion of international shippingin international emissions-trading schemes, fuel taxes and regulatory instruments (high agreement, medium evidence)[5.5.2].
Integrated and non-climate policies affecting emissions ofGHGs and co-benefits of GHG mitigation policies
Transport planning and policy have recently placed moreweight on sustainable development aspects. This includesreducing oil imports, improved air quality, reducing noise pollution, increasing safety, reducing congestion and improvingaccess to transport facilities. Such policies can have importantsynergies with reducing GHG emissions (high agreement,medium evidence) 5.5.5.
6 Residential and commercial buildings
Status of the sector and emission trends
In 2004, direct GHG emissions from the buildings sector (excludingemissions from electricity use) were about 5 GtCO2-eq/yr (3 GtCO2-eq/yr CO2; 0.1 GtCO2-eq/yr N2O; 0.4 GtCO2-eq/yr CH4 and 1.5 GtCO2-eq/yr halocarbons). The last figureincludes F-gases covered by the Montreal protocol and about0.1–0.2 GtCO2-eq/yr of HFCs. As mitigation in this sectorincludes many measures aimed at saving electricity, themitigation potential is generally calculated including electricitysaving measures. For comparison, emission figures of thebuilding sector are often presented including emissions fromelectricity use in the sector . When including the emissionsfrom electricity use, energy-related CO2 emissions from thebuildings sector were 8.6 Gt/yr, or 33% of the global total in2004. Total GHG emissions, including the emissions fromelectricity use, are then estimated at 10.6 Gt CO2eq/yr (highagreement, medium evidence) [6.2].
Future carbon emissions from energy use in buildings
The literature for the buildings sector uses a mixture ofbaselines. Therefore, for this chapter, a building sector baselinewas defined, somewhere between SRES B2 and A1B2, with 14.3GtCO2-eq GHG emissions (including emissions from electricityuse) in 2030. The corresponding emissions in the SRES B2and A1B scenarios are 11.4 and 15.6 GtCO2. In the SRES B2scenario (Figure TS.17), which is based on relatively lowereconomic growth, North America and Non-Annex I East Asiaaccount for the largest portion of the increase in emissions. Inthe SRES A1B scenario, which shows rapid economic growth,all the CO2 emissions increase is in the developing world: Asia,Middle East and North Africa, Latin America, and Sub-SaharanAfrica, in that order. Overall, average annual CO2 emissiongrowth between 2004 and 2030 is 1.5% in Scenario B2 and2.4% in Scenario A1B (high agreement, medium evidence) [6.2,6.3].
Note: Dark red – historic emissions; light red – projection according to SRES B2 scenario. EECCA=Countries of Eastern Europe, the Caucasus and Central Asia.
</div>
Mitigation technologies and practices
Measures to reduce GHG emissions from buildings fall intoone of three categories: 1) reducing energy consumption[13] andembodied energy in buildings; 2) switching to low-carbon fuels,including a higher share of renewable energy; 3) controllingemissions of non-CO2 GHG gases. Many current technologiesallow building energy consumption to be reduced through betterthermal envelopes[14], improved design methods and buildingoperations, more efficient equipment,and reductions in demandfor energy services. The relative importance of heating andcooling depends on climate and thus varies regionally, whilethe effectiveness of passive design techniques also dependson climate, with important distinctions between hot-humidand hot-arid regions. Occupant behaviour, including avoidingunnecessary operation of equipment and adaptive rather thaninvariant temperature standards for heating and cooling, isalso a significant factor in limiting building energy use (highagreement, much evidence) [6.4].
Mitigation potential of the building sector
Substantial CO2 emission reduction from energy use inbuildings can be achieved over the coming years comparedwith projected emissions. The considerable experience in awide variety of technologies, practices and systems for energyefficiency and an equally rich experience with policies andprogrammes that promote energy efficiency in buildings lend considerable confidence to this view. A significant portion ofthese savings can be achieved in ways that reduce life-cyclecosts, thus providing reductions in CO2 emissions that have anet negative cost (generally higher investment cost but loweroperating cost) (high agreement, much evidence) 6.5.
These conclusions are supported by a survey of 80 studies(Table TS.5), which show that efficient lighting technologiesare among the most promising GHG-abatement measures in buildings in almost all countries, in terms of both cost effectivenessand potential savings. By 2020, approximately760 Mt of CO2 emissions can be abated by the adoption of leastlife-cycle cost lighting systems globally, at an average costof -160 US$/tCO2 (i.e., at a net economic benefit). In terms ofthe size of savings, improved insulation and district heating inthe colder climates and efficiency measures related to spacecooling and ventilation in the warmer climates come first inalmost all studies, along with cooking stoves in developingcountries. Other measures that rank high in terms of savingspotential are solar water heating, efficient appliances andenergy-management systems.
Table TS.5: GHG emissions reduction potential for the buildings stock in 2020a 6.2.
| Economic region | Countries/country groups reviewed for region | Potential as % of national baseline for buildingsb | Measures covering the largest potential | Measures providing the cheapest mitigation options |
|---|---|---|---|---|
|
Developed countries |
USA, EU-15, Canada, Greece, Australia, Republic of Korea, United Kingdom, Germany, Japan |
Technical: Economic (2-eq): Market: |
1. Shell retrofit, inc. insulation, esp. windows and walls; 2. Space heating systems; 3. Efficient lights, especially shift to compact fluorescent lamps (CFL) and efficient ballasts. |
1. Appliances such as efficient TVs and peripherals (both on-mode and standby), refrigerators and freezers, ventilators and air-conditioners; 2. Water heating equipment; 3. Lighting best practices. |
|
Economies in Transition |
Hungary, Russia, Poland, Croatia, as a group: Latvia, Lithuania, Estonia, Slovakia, Slovenia, Hungary, Malta, Cyprus, Poland, the Czech Republic |
Technical: Economic (2eq): Market: |
1. Pre- and post- insulation and replacement of building components, esp. windows; 2. Efficient lighting, esp. shift to CFLs; 3. Efficient appliances such as refrigerators and water heaters. |
1. Efficient lighting and its controls; 2. Water and space heating control systems; 3. Retrofit and replacement of building components, esp. windows. |
|
Developing countries |
Myanmar, India, Indonesia, Argentine, Brazil, China, Ecuador, Thailand, Pakistan, South Africa |
Technical: Economic (2eq): Market: |
1. Efficient lights, esp. shift to CFLs, light retrofit, and kerosene lamps; 2. Various types of improved cooking stoves, esp. biomass stoves, followed by LPG and kerosene stoves; 3. Efficient appliances such as air-conditioners and refrigerators. |
1. Improved lights, esp. shift to CFLs light retrofit, and efficient kerosene lamps; 2. Various types of improved cooking stoves, esp. biomass based, followed by kerosene stoves; 3. Efficient electric appliances such as refrigerators and air-conditioners. |
Notes:
a) Except for EU-15, Greece, Canada, India, and Russia, for which the target year was 2010, and Hungary, Ecuador and South Africa, for which the target was 2030.
b) The fact that the market potential is higher than the economic potential for developed countries is explained by limitation of studies considering only one type of potential, so information for some studies likely having higher economic potential is missing.
c) Both for 2010, if the approximate formula of Potential 2020 = 1 – ( 1 – Potential 2010)20/10 is used to extrapolate the potential as percentage of the baseline into the future (the year 2000 is assumed as a start year), this interval would be 38%–79%.
d) Both for 2010, if suggested extrapolation formula is used, this interval would be 22%–44%.
e) The last figure is for 2010, corresponds to 72% in 2020 if the extrapolation formula is used.
f) The first figure is for 2010, corresponds to 24% in 2020 if the extrapolation formula is used.
As far as cost effectiveness is concerned, efficient cookingstoves rank second after lighting in developing countries, whilethe measures in second place in the industrialized countriesdiffer according to climatic and geographic region. Almostall the studies examining economies in transition (typically incooler climates) found heating-related measures to be the mostcost effective, including insulation of walls, roofs, windowsand floors, as well as improved heating controls for districtheating. In developed countries, appliance-related measures aretypically identified as the most cost-effective, with upgrades ofcooling-related equipment ranking high in warmer climates.Air-conditioning savings can be more expensive than otherefficiency measures but can still be cost-effective, because theytend to displace more expensive peak power.
In individual new buildings, it is possible to achieve 75%or more energy savings compared with recent current practice,generally at little or no extra cost. Realizing these savings requiresan integrated design process involving architects, engineers,contractors and clients, with full consideration of opportunitiesfor passively reducing the energy demands of buildings [6.4.1].
Addressing GHG mitigation in buildings in developingcountries is of particular importance. Cooking stoves can bemade to burn more efficiently and combust particles morecompletely, thus benefiting village dwellers through improvedindoor-air quality, while reducing GHG emissions. Localsources of improved, low GHG materials can be identified. Inurban areas, and increasingly in rural ones, there is a need forall the modern technologies used in industrialized countries toreduce GHG emissions [6.4.3].
Emerging areas for energy savings in commercial buildingsinclude the application of controls and information technologyto continuously monitor, diagnose and communicate faults in commercial buildings (‘intelligent control’); and systemsapproaches to reduce the need for ventilation, cooling, anddehumidification. Advanced windows, passive solar design, techniques for eliminating leaks in buildings and ducts, energy efficientappliances, and controlling standby and idle powerconsumption as well as solid-state lighting are also important inboth residential and commercial sectors (high agreement, muchevidence) [6.5].
Occupant behaviour, culture and consumer choice and use oftechnologies are major determinants of energy use in buildings andplay a fundamental role in determining CO2emissions. However,the potential reduction through non-technological options israrely assessed and the potential leverage of policies over these ispoorly understood (high agreement, medium evidence).
There are opportunities to reduce direct emissions offluorinated gases in the buildings sector significantly through theglobal application of best practices and recovery methods, withmitigation potential for all F-gases of 0.7 GtCO2-eq in 2015.Mitigation of halocarbon refrigerants mainly involves avoidingleakage from air conditioners and refrigeration equipment(e.g., during normal use, maintenance and at end of life) andreducing the use of halocarbons in new equipment. A key factordetermining whether this potential will be realized is the costsassociated with implementation of the measures to achieve theemission reduction. These vary considerably, from a net benefitto 300 US$/tCO2-eq. (high agreement, much evidence) [6.5].
Mitigation potential of the building sector
There is a global potential to reduce approximately 30%of the projected baseline emissions from the residential andcommercial sectors cost effectively by 2020 (Table TS.6). At least a further 3% of baseline emissions can be avoided at costsup to 20 US$/tCO2-eq and 4% more if costs up to 100 US$/tCO2-eq are considered. However, due to the large opportunitiesat low costs, the high-cost potential has only been assessed toa limited extent, and thus this figure is an underestimate. Usingthe global baseline emission projections for buildings[15], theseestimates represent a reduction of about 3.2, 3.6, and 4.0 Gtonsof CO2-eq in 2020, at zero, 20 US$/tCO2-eq, and 100 US$/tCO2-eq, respectively (high agreement, much evidence) [6.5].
Table TS.6: Global CO2 mitigation potential projections for 2020, as a function of costs 6.3.
| World regions | Baseline emissions in 2020 | CO2 mitigation potentials as share of the baseline CO2 emission projections in cost categories in 2020 (costs in US$/tCO2-eq) | CO2 mitigation potentials in absolute values in cost categories in 2020, GtCO2-eq (costs in US$/tCO2-eq) | ||||||
|---|---|---|---|---|---|---|---|---|---|
| GtCO2-eq | <0 | 0-20 | 20-100 | <100 | <0 | 0-20 | 20-100 | <100 | |
| Globe | 11.1 | 29% | 3% | 4% | 36% | 3.2 | 0.35 | 0.45 | 4.0 |
| OECD (-EIT) | 4.8 | 27% | 3% | 2% | 32% | 1.3 | 0.10 | 0.10 | 1.6 |
| EIT | 1.3 | 29% | 12% | 23% | 64% | 0.4 | 0.15 | 0.30 | 0.85 |
| Non-OECD | 5.0 | 30% | 2% | 1% | 32% | 1.5 | 0.10 | 0.05 | 1.6 |
Note: The aggregated global potential as a function of cost and region is based on 17 studies that reported potentials in detail as a function of costs.
The real potential is likely to be higher, because not all end-use efficiency options were considered by the studies; non-technological options and their often significant co-benefits were omitted as were advanced integrated high-efficiency buildings. However, the market potential is much smaller than the economic potential.
Given limited information for 2030, the 2020 findings for the economic potential to 2030 have been extrapolated to enable comparisons with other sectors. The estimates are given in Table TS.7. Extrapolation of the potentials to 2030 suggests that, globally, about 4.5, 5.0 and 5.6 GtCO2-eq/yr could be reduced at costs of <0, <20 and <100 US$/tCO2-eq respectively. This is equivalent to 30, 35, and 40% of the projected baseline emissions. These figures are associated with significantly lower levels of certainty than the 2020 ones due to very limited research available for 2030 (medium agreement, low evidence).
Table TS.7: Global CO2 mitigation potential projections for 2030, as a function of cost, based on extrapolation from the 2020 numbers, in GtCO2 6.4]].
| Mitigation option | Region | Baseline projections in 2030 | Potential costs at below 100 US$/tCO2-eq | Potential in different cost categories | |||
|---|---|---|---|---|---|---|---|
| <0 US$/tCO2 | 0-20 US$/tCO2 | 20-100 US$/tCO2 | |||||
| Low | High | <0 US$/tC | 0-73 US$/tC | 73-367 US$/tC | |||
| Electricity savingsa) | OECD | 3.4 | 0.75 | 0.95 | 0.85 | 0.0 | 0.0 |
| EIT | 0.40 | 0.15 | 0.20 | 0.20 | 0.0 | 0.0 | |
| Non-OECD/EIT | 4.5 | 1.7 | 2.4 | 1.9 | 0.1 | 0.1 | |
| Fuel savings | OECD | 2.0 | 1.0 | 1.2 | 0.85 | 0.2 | 0.1 |
| EIT | 1.0 | 0.55 | 0.85 | 0.20 | 0.2 | 0.3 | |
| Non-OECD/EIT | 3.0 | 0.70 | 0.80 | 0.65 | 0.1 | 0.0 | |
| Total | OECD | 5.4 | 1.8 | 2.2 | 1.7 | 0.2 | 0.1 |
| EIT | 1.4 | 0.70 | 1.1 | 0.40 | 0.2 | 0.3 | |
| Non-OECD/EIT | 7.5 | 2.4 | 3.2 | 2.5 | 0.1 | 0.0 | |
| Global | 14.3 | 4.8 | 6.4 | 4.5 | 0.5 | 0.7 | |
Note:
a) The absolute values of the potentials resulting from electricity savings in Table TS.8 and [11 (IPCC Fourth Assessment Report, Working Group III: Technical Summary) ], Table 11.3 do not coincide due to application of different baselines; however, the potential estimates as percentage of the baseline are the same in both cases. Also Table 11.3 excludes the share of emission reductions which is already taken into account by the energy supply sector, while Table TS.7 does not separate this potential.
The outlook for the long-term future, assuming options inthe building sector with a cost up to US$ 25/tCO2-eq, identifiesa potential of about 7.7 GtCO2eq reductions in 2050.
Interactions of mitigation options with vulnerabilityand adaptation
If the world experiences warming, energy use for heating intemperate climates will decline (e.g., Europe, parts of Asia andNorth America), and for cooling will increase in most world regions. Several studies indicate that, in countries with moderateclimates, the increase in electricity for additional cooling willoutweigh the decrease for heating, and in Southern Europea significant increase in summer peak demand is expected.Depending on the generation mix in particular countries, the neteffect of warming on CO2 emissions may be an increase evenwhere overall demand for final energy declines. This causes apositive feedback loop: more mechanical cooling emits moreGHGs, thereby exacerbating warming (medium agreement,medium evidence).
Investments in the buildings sector may reduce the overallcost of climate change by simultaneously addressing mitigationand adaptation. The most important of these synergies includesreduced cooling needs or energy use through measures suchas application of integrated building design, passive solarconstruction, heat pumps with high efficiency for heatingand cooling, adaptive window glazing, high-efficiency appliancesemitting less waste heat, and retrofits including increasedinsulation, optimized for specific climates, and storm-proofing.Appropriate urban planning, including increasing green areas aswell as cool roofs in cities, has proved to be an efficient wayof limiting the ‘heat island’ effect, thereby reducing coolingneeds and the likelihood of urban fires. Adaptive comfort,where occupants accept higher indoor (comfort) temperatureswhen the outside temperature is high, is now often incorporated indesign considerations (high agreement, medium evidence) [6.9].
Effectiveness of and experience with policies forreducing CO2 emissions from energy use in buildings
Realizing such emissions reductions up to 2020 requires therapid design, implementation and enforcement of strong policiespromoting energy efficiency for buildings and equipment,renewable energy (where cost-effective), and advanced designtechniques for new buildings (high agreement, much evidence)[6.5].
There are, however, substantial barriers that need to beovercome to achieve the high indicated negative and low costmitigation potential. These include hidden costs, mismatches between incentives and benefits (e.g., between landlords andtenants), limitations in access to financing, subsidies on energyprices, as well as fragmentation of the industry and the designprocess. These barriers are especially strong and diverse inthe residential and commercial sectors; overcoming them istherefore only possible through a diverse portfolio of policyinstruments combined with good enforcement (high agreement,medium evidence).
A wide range of policies has been shown in many countriesto be successful in cutting GHG emissions from buildings.Table TS.8 summarizes the key policy tools applied and compares them according to the effectiveness of the policyinstrument, based on selected best practices. Most instrumentsreviewed can achieve significant energy and CO2 savings. Inan evaluation of 60 policy evaluations from about 30 countries,the highest CO2 emission reductions were achieved throughbuilding codes, appliance standards and tax-exemption policies.Appliance standards, energy-efficiency obligations and quotas,demand-side management programmes and mandatory labelingwere found to be among the most cost-effective policytools. Subsidies and energy or carbon taxes were the least cost-effectiveinstrument. Information programmes are also costeffective, particularly when they accompany most other policy measures (medium agreement, medium evidence) [6.8].
Table TS.8: The impact and effectiveness of selected policy instruments aimed at mitigating GHG emissions in the buildings sector using best practices 6.6.
| Policy instrument | Emission reduction effectivenessa | Cost-effectivenessb | Special conditions for success, major strengths and limitations, co-benefits |
|---|---|---|---|
| Appliance standards | High | High | Factors for success: periodic update of standards, independent control, information, communication and education. |
| Building codes | High | Medium | No incentive to improve beyond target. Only effective if enforced. |
| Public leadership programmes, inc. procurement regulations | High | High/Medium | Can be used effectively to demonstrate new technologies and practices. Mandatory programmes have higher potential than voluntary ones. Factor for success: ambitious energy efficiency labelling and testing. |
| Energy efficiency obligations and quotas | High | High | Continuous improvements necessary: new EE measures, short term incentives to transform markets, etc. |
| Demand-side management programmes | High | High | Tend to be more cost-effective for commercial sector than for residences. |
| Energy performance contracting/ESCO supportC | High | Medium | Strength: no need for public spending or market intervention, co-benefit of improved competitiveness. |
| Energy efficiency certificate schemes | Medium | Medium | No long-term experience. Transaction costs can be high. Institutional structures needed. Profound interactions with existing policies. Benefits for employment. |
| Kyoto Protocol flexible mechanismsd | Low | Low | So far limited number of CDM &JI projects in buildings. |
| Taxation (on CO2 or fuels) | Low | Low | Effect depends on price elasticity. Revenues can be earmarked for further efficiency. More effective when combined with other tools. |
| Tax exemptions/ reductions | High | High | If properly structured, stimulate introduction of highly efficient equipment and new buildings. |
| Capital subsidies, grants, subsidised loans | High | Low | Positive for low-income households, risk of free-riders, may induce pioneering investments. |
| Labelling and certification programmes | Medium/High | High | Mandatory programmes more effective than voluntary ones. Effectiveness can be boosted by combination with other instruments and regular updates. |
| Voluntary and negotiated agreements | Medium/High | Medium | Can be effective when regulations are difficult to enforce. Effective if combined with financial incentives, and threat of regulation. |
| Education and information programmes | Low/Medium | High | More applicable in residential sector than commercial. Success condition: best applied in combination with other measures. |
| Mandatory audit and energy management requirement | High, but variable | Medium | Most effective if combined with other measures such as financial incentives. |
| Detailed billing and disclosure programmes | Medium | Medium | Success conditions: combination with other measures and periodic evaluation. |
Notes:
a) includes ease of implementation; feasibility and simplicity of enforcement; applicability in many locations; and other factors contributing to overall magnitude of realized savings.
b) Cost-effectiveness is related to specific societal cost per carbon emissions avoided.
Policies and measures that aim at reducing leakage ordiscourage the use of refrigerants containing fluorine mayreduce emissions of F-gases substantially in future years (highagreement, medium evidence) [6.8.4].
The limited overall impact of policies so far is due to severalfactors: 1) slow implementation processes; 2) the lack of regularupdating of building codes (requirements of many policies areoften close to common practices, despite the fact that CO2-neutral construction without major financial sacrifices is alreadypossible) and appliance standards and labelling; 3) inadequatefunding; 4) insufficient enforcement. In developing countries andeconomies in transition, implementation of energy-efficiencypolicies is compromised by a lack of concrete implementationcombined with poor or non-existent enforcement mechanisms.Another challenge is to promote GHG-abatement measures forthe building shell of existing buildings due to the long timeperiods between regular building retrofits and the slow turnoverof buildings in developed countries (high agreement, muchevidence) [6.8].
Co-benefits and links to sustainable development
Energy efficiency and utilization of renewable energy inbuildings offer synergies between sustainable developmentand GHG abatement. The most relevant of these for the least developed countries are safe and efficient cooking stoves that,while cutting GHG emissions, significantly reduce mortality andmorbidity by reducing indoor air pollution. Safe and efficientcooking stoves also reduce the workload for women andchildren who typically gather the fuel for traditional stoves anddecrease the demands on scarce natural resources. Reduction inoutdoor air pollution is another significant co-benefit.
In general, in developed and developing countries, improvedenergy efficiency in buildings and the clean and efficient use oflocally available renewable energy resources results in:
- substantial savings in energy-related investment, since efficiency is less costly than new supply;
- funds freed up for other purposes, such as infrastructureinvestments;
- improved system reliability and energy security;
- increased access to energy services;
- reduced fuel poverty;
- improvement of local environmental quality;
- positive effects on employment, by creating new businessopportunities and through the multiplier effects ofspending money saved on energy costs in another way.
There is increasing evidence that well-designed energy-efficientbuildings often promote occupant productivity and health (highagreement, medium evidence) [6.9].
Support from industrialized countries for the developmentand implementation of policies to increase energy efficiency ofbuildings and equipment in developing countries and economiesin transition could contribute substantially to reductions inthe growth of CO2 emissions and improve the welfare of thepopulation. Devoting international aid or other public and privatefunds aimed at sustainable development to energy efficiency andrenewable energy initiatives in buildings can achieve a multitudeof development objectives and result in long-lasting impacts. Thetransfer of knowledge, expertise and know-how from developedto developing countries can facilitate the adoption of photovoltaics(PV), including PV-powered light emitting diode-based (LED)lighting, high-insulation building materials, efficient appliancesand lighting, integrated design, building energy-managementsystems, and solar cooling. However, capital financing will alsobe needed [6.8.3].
Technology research, development, deployment,diffusion and transfer
Although many practical and cost-effective technologiesand practices are available today, research and development isneeded in such areas as: high-performance control systems[16];advanced window glazing; new materials for insulated panels;various systems to utilize passive and other renewable energysources; phase-change materials to increase thermal storage;high-performance ground-source reversible heat pumps;integrated appliances and other equipment to use waste heat;novel cooling technologies, and the use of community-widenetworks to supply heating, cooling and electricity to buildings.Demonstrations of these technologies and systems, and trainingof professionals, are necessary steps toward bringing those newtechnologies to market [6.8.3].
Long-term-outlook
Long-term GHG reduction in buildings needs to start soonbecause of the slow turnover of the building stock. To achievelarge-scale savings in new buildings in the longer term, new approaches to integrated design and operation of buildingsneed to be taught, spread, and put into large-scale practice assoon as possible. Such training is currently not available for themajority of professionals in the building industry. Because of theimportant role of non-technological opportunities in buildings,ambitious GHG reductions may require a cultural shift towardsa society that embraces climate protection and sustainabledevelopment among its fundamental values, leading to socialpressure for building construction and use with much reducedenvironmental footprints (high agreement, medium evidence)6.8.1.
7 Industry
Status of the sector, development trendsand implications
Energy-intensive industries, iron and steel, non-ferrousmetals, chemicals and fertilizer, petroleum-refining, cement, andpulp and paper, account for about 85% of the industry sector’s energy consumption in most countries. Since energy use in othersectors grew faster, the sector’s share in global primary energyuse declined from 40% in 1971 to 37% in 2004 [7.1.3].
Much of this energy-intensive industry is now located indeveloping countries. Overall, in 2003, developing countriesaccounted for 42% of global steel production, 57% ofglobal nitrogen fertilizer production, 78% of global cementmanufacture, and about 50% of global aluminium production.In 2004, developing countries accounted for 46% of final energyuse by industry, developed country for 43% and economies intransition for 11%. Many facilities (for aluminium, cementand fertilizer industries) in developing nations are new and include the latest technology with lowest specific energy use.However, as in industrialized countries, many older, inefficientfacilities remain. This creates a huge demand for investment indeveloping countries to improve energy efficiency and achieveemission reductions. The strong growth of energy-intensiveindustries during the 20th century is expected to continue aspopulation and GDP increase 7.1.3.
Though large-scale production dominates these energy-intensiveindustries globally, small- and medium-sizedenterprises (SMEs) have significant shares in many developing countries. While regulations and international competitionare moving large industrial enterprises towards the use ofenvironmentally sound technology, SMEs may not have the economic or technical capacity to install the necessary controlequipment or are slower to innovate. These SME limitationscreate special challenges for efforts to mitigate GHG emissions(high agreement, much evidence) [7.1.1].
Emission trends (global and regional)
Direct GHG emissions from industry are currently about7.2 GtCO2-eq. As the mitigation options discussed in thischapter include measures aimed at reducing the industrialuse of electricity, emissions including those from electricityuse are important for comparison. Total industrial sectorGHG emissions were about 12 GtCO2-eq in 2004, about 25%of the global total. CO2 emissions (including electricity use)from the industrial sector grew from 6.0 GtCO2 in 1971to 9.9 GtCO2 in 2004. In 2004, developed nations accountedfor 35% of total energy-related CO2 emissions, economiesin transition for 11% and developing nations for 53% (seeFigure TS.18). Industry also emits CO2 from non-energyuses of fossil fuels and from non-fossil fuel sources. In 2000,these were estimated to total 1.7 GtCO2 (high agreement,much evidence) [7.1.3].
Note: Dark red – historic emissions; light red – projections according to SRES B2 scenario. Data extracted from Price et al. (2006).
EECCA = Countries of Eastern Europe, the Caucasus and Central Asia.
</div>
Industrial processes also emit other GHGs, including HFC-23 from the manufacture of HCFC-22; PFCs from aluminiumsmelting and semiconductor processing; SF6 from use in flatpanel screens (liquid crystal display) and semi-conductors,magnesium die casting, electrical equipment, aluminiummelting, and others, and CH4 and N2O from chemical industrysources and food-industry waste streams. Total emissionfrom these sources was about 0.4 GtCO2-eq in 2000 (mediumagreement, medium evidence) [7.1.3].
The projections for industrial CO2 emissions for 2030under the SRES-B22 scenarios are around 14 GtCO2 (includingelectricity use) (see Figure TS.18). The highest average growthrates in industrial-sector CO2 emissions are projected fordeveloping countries. Growth in the regions of Central andEastern Europe, the Caucasus and Central Asia, and DevelopingAsia is projected to slow in both scenarios for 2000–2030.CO2 emissions are expected to decline in the Pacific OECD,North America and Western Europe regions for B2 after 2010.For non-CO2 GHG emissions from the industrial sector,emissions by 2030 are projected to increase globally by afactor of 1.4, from 470 MtCO2-eq. (130 MtC-eq) in 1990to 670 MtCO2-eq (180 MtC-eq.) in 2030 assuming no furtheraction is taken to control these emissions. Mitigation effortsled to a decrease in non-CO2 GHG emissions between1990 and 2000, and many programmes for additional controlare underway (see Table TS.9) (high agreement, mediumevidence) [7.1.3].
Table TS.9: Projected industrial sector emissions of non-CO2 GHGs, MtCO2-eq/yr Table 7.3]].
| Region | 1990 | 2000 | 2010 | 2030 |
|---|---|---|---|---|
| Pacific OECD | 38 | 53 | 47 | 49 |
| North America | 147 | 117 | 96 | 147 |
| Western Europe | 159 | 96 | 92 | 109 |
| Central and Eastern Europe | 31 | 21 | 22 | 27 |
| EECCA | 37 | 20 | 21 | 26 |
| Developing Asia | 34 | 91 | 118 | 230 |
| Latin America | 17 | 18 | 21 | 38 |
| Sub Saharan Africa | 6 | 10 | 11 | 21 |
| Middle East and North Africa | 2 | 3 | 10 | 20 |
| World | 470 | 428 | 438 | 668 |
Note: Emissions from refrigeration equipment used in industrial processes included; emissions from all other refrigeration and air-conditioning applications excluded.
Description and assessment of mitigationtechnologies and practices, options and potentials,costs and sustainability
Historically, the industrial sector has achieved reductionsin energy intensity and emission intensity through adoptionof energy efficiency and specific mitigation technologies, particularly in energy-intensive industries. The aluminiumindustry reported >70% reduction in PFC-emission intensity overthe period 1990–2004 and the ammonia industry reported thatplants designed in 2004 have a 50% reduction in energy intensitycompared with those designed in 1960. Continuing to modernizeammonia-production facilities around the world will result infurther energy-efficiency improvements. Reductions in refiningenergy intensity have also been reported 7.4.3, 7.4.4.
The low technical and economic capacity of SMEs posechallenges for the diffusion of sound environmental technology,though some innovative R&D is taking place in SMEs.
A wide range of measures and technologies have the potentialto reduce industrial GHG emissions. These technologies can begrouped into the categories of energy efficiency, fuel switching,power recovery, renewables, feedstock change, product changeand material efficiency (Table TS.10). Within each category,some technologies, such as the use of more efficient electricmotors, are broadly applicable across all industries, whileothers, such as top-gas pressure recovery in blast furnaces, areprocess-specific.
Table TS.10: Examples of industrial technology for reducing GHG emissions (not comprehensive). Technologies in italics are under demonstration or development Table 7.5]].
| Sector | Energy efficiency | Fuel switching | Power recovery | Renewables | Feedstock change | Product change | Material efficiency | Non-CO2 GHG | CO2 capture and storage |
|---|---|---|---|---|---|---|---|---|---|
|
Sector wide |
Benchmarking; Energy management systems; Efficient motor systems, boilers, furnaces, lighting and heating/ventilation/air conditioning; Process integration |
Coal to natural gas and oil |
Cogeneration |
Biomass, Biogas, PV, Wind turbines, Hydropower |
Recycled inputs |
Oxy-fuel combustion, CO2 separation from flue gas | |||
|
Iron & steel |
Smelt reduction, Near net shape casting, Scrap preheating, Dry coke quenching |
Natural gas, oil or plastic injection into the BF |
Top-gas pressure recovery, By-product gas combined cycle |
Charcoal |
Scrap |
High strength steel |
Recycling, High strength steel, Reduction process losses |
n/a |
Hydrogen reduction, oxygen use in blast furnaces |
|
Non-ferrous metals |
Inert anodes, Efficient cell designs |
Scrap |
Recycling, thinner film and coating |
PFC/SF6 controls |
|||||
|
Chemicals |
Membrane separations, Reactive distillation |
Natural gas |
Pre-coupled gas turbine, Pressure recovery turbine, H2 recovery |
Recycled plastics, bio-feedstock |
Linear low density polyethylene, high-perf. plastics |
Recycling, Thinner film and coating, Reduced process losses |
N2O, PFCs, CFCs and HFCs control |
CO2 storage from ammonia, ethylene oxide processes | |
|
Petroleum refining |
Membrane separation Refinery gas |
Natural gas |
Pressure recovery turbine, hydrogen recovery |
Biofuels |
Bio-feedstock |
(reduction in transport not included here) |
Control technology for N2O/CH4 |
From hydrogen production | |
|
Cement |
Precalciner kiln, Roller mill, fluidized bed kiln |
Waste fuels, Biogas, Biomass |
Drying with gas turbine, power recovery |
Biomass fuels, Biogas |
Slags, pozzolanes |
Blended cement Geo-polymers |
n/a |
Oxyfuel combustion in kiln | |
|
Glass |
Cullet preheating Oxyfuel furnace |
Natural gas |
Air bottoming cycle |
n/a |
Increased cullet use |
High-strength thin containers |
Recycling |
n/a |
OxyfuelL combustion |
|
Pulp and paper |
Efficient pulping, Efficient drying, Shoe press, Condebelt drying |
Biomass, Landfill gas |
Black liquor gasification combined cycle |
Biomass fuels (bark, black liquor) |
Recycling, Non-wood fibres |
Fibre orientation, Thinner paper |
Reduction cutting and process losses |
n/a |
Oxyfuel combustion in lime kiln |
|
Food |
Efficient drying, Membranes |
Biogas, Natural gas |
Anaerobic digestion, Gasification |
Biomass, By-products, Solar drying |
Reduction process losses, Closed water use |
Later in the period to 2030, there will be a substantial additionalpotential from further energy- efficiency improvements andapplication of Carbon Capture and Storage (CCS) [17] and non-GHG process technologies. Examples of such new technologiesthat are currently in the R&D phase include inert electrodesfor aluminium manufacture and hydrogen for metal production(high agreement, much evidence) 7.3, 7.4.
Mitigation potentials and costs in 2030 have been estimatedin an industry-by-industry assessment of energy-intensiveindustries and an overall assessment of other industries. The approach yielded mitigation potentials of about 1.1 GtCO2-eqat a cost of <20 US$/tCO2 (74 US$/tC-eq); about 3.5 GtCO2-eq at costs below <50 US$/tCO2 (180 US$/tC-eq); and about4 GtCO2-eq/yr (0.60–1.4 GtC-eq/yr) at costs
A recently completed global study for nine groups oftechnologies indicates a mitigation potential for the industrialsector of 2.5-3.0 GtCO2-eq/yr (0.68-0.82 GtC-eq/yr) in 2030at costs of <25 US$/tCO2 (< 92US$/tC) (2004$). While theestimate of mitigation potential is in the range found in thisassessment, the estimate of mitigation cost is significantlylower (medium agreement, medium evidence) [7.5].
Interaction of mitigation options with vulnerabilityand adaptation
Linkages between adaptation and mitigation in theindustrial sector are limited. Many mitigation options (e.g.,energy efficiency, heat and power recovery, recycling) are notvulnerable to climate change and therefore create no adaptationlink. Others, such as fuels or feedstock switching (e.g. tobiomass or other renewable energy sources) may be vulnerable to climate change [7.8].
Effectiveness of and experience with climatepolicies, potentials, barriers and opportunities/implementation issues
Full use of available mitigation options is not being made ineither industrialized or developing nations. In many areas of theworld, GHG mitigation is not demanded by either the marketor government regulation. In these areas, companies will investin GHG mitigation to the extent that other factors provide areturn for their investments. This return can be economic; forexample, energy-efficiency projects that provide an economicpay-out, or can be in terms of achieving larger corporate goals,for example, a commitment to sustainable development. Theeconomic potential as outlined above will only be realized ifpolicies and regulations are in place. Relevant in this respectis that, as noted above, most energy-intensive industries arelocated in developing countries. Slow rate of capital stockturnover is also a barrier in many industries, as is the lack ofthe financial and technical resources needed to implementmitigation options, and limitations in the ability of industrialfirms, particularly small and medium-sized enterprises, toaccess and absorb information about available options (highagreement, much evidence) [7.9.1].
Voluntary agreements between industry and government toreduce energy use and GHG emissions have been used sincethe early 1990s. Well-designed agreements, which set realistictargets and have sufficient government support, often as partof a larger environmental policy package, and a real threatof increased government regulation or energy/GHG taxesif targets are not achieved, can provide more than business-as-usual energy savings or emission reductions. Some haveaccelerated the application of best available technology andled to reductions in emissions compared with the baseline,particularly in countries with traditions of close cooperationbetween government and industry. However, the majority ofvoluntary agreements have not achieved significant emissionreductions beyond business-as-usual. Corporations, sub-nationalgovernments, non-government organizations (NGOs)and civil groups are adopting a wide variety of voluntary actions,independent of government authorities, which may limit GHGemissions, stimulate innovative policies, and encourage thedeployment of new technologies. By themselves, however, theygenerally have limited impact.
Policies that reduce the barriers to adoption of cost-effective,low-GHG emission technologies (e.g., lack of information,absence of standards and unavailability of affordable financingfor first purchases of modern technology) can be effective.Many countries, both developed and developing, have financialschemes available to promote energy saving in industry.According to a World Energy Council survey, 28 countriesprovide some sort of grant or subsidy for industrial energy-efficiencyprojects. Fiscal measures are also frequently used tostimulate energy savings in industry. However, a drawback tofinancial incentives is that they are often also used by investorswho would have made the investment without the incentive.Possible solutions to improve cost-effectiveness are to restrictschemes to specific target groups and/or techniques (selectedlists of equipment, only innovative technologies), or use a directcriterion of cost-effectiveness [7.9.3].
Several national, regional or sectoral CO2 emissionstrading systems either exist or are being developed. Thefurther refinement of these trading systems could be informedby evidence that suggests that in some important aspects,participants from industrial sectors face a significantly differentsituation to those from the electricity sector. For instance, responses to carbon emission price in industry tend to be slowerbecause of the more limited technology portfolio and absenceof short-term fuel-switching possibilities, making predictableallocation mechanisms and stable price signals a more importantissue for industry [7.9.4].
As noted in the TAR, industrial enterprises of all sizes arevulnerable to changes in government policy and consumerpreferences. That is why a stable policy regime is so important for industry (high agreement, much evidence) [7.9].
Integrated and non-climate policies affectingemissions of greenhouse gases
Policies aimed at balancing energy security, environmentalprotection and economic development can have a positiveor negative impact on mitigation. Sustainable development policies focusing on energy efficiency, dematerialization, anduse of renewables support GHG mitigation objectives. Waste managementpolicies reduce industrial sector GHG emissionsby reducing energy use through the re-use of products. Air-pollutantreduction measures can have synergy with GHG-emissionsreduction when reduction is achieved by shifting tolow-carbon fuels, but do not always reduce GHG emissions asmany require the use of additional energy.
In addition to implementing the mitigation options discussedabove, achieving sustainable development will requireindustrial development pathways that minimize the need for future mitigation (high agreement, medium evidence). Largecompanies have greater resources, and usually more incentives,to factor environmental and social considerations into theiroperations than small and medium enterprises (SMEs), butSMEs provide the bulk of employment and manufacturingcapacity in many countries. Integrating SME development strategy into broader national strategies for development isconsistent with sustainable development objectives. Energy intensiveindustries are now committing to a number of measures towards human capital development, health andsafety, community development etc., which are consistent withthe goal of corporate social responsibility (high agreement, much evidence) 7.8.
Co-benefits of greenhouse gas mitigation policies
The co-benefits of industrial GHG mitigation include: reducedemissions of air pollutants, and waste (which in turn reduceenvironmental compliance and waste disposal costs), increasedproduction and product quality, lower maintenance andoperating costs, an improved working environment, and otherbenefits such as decreased liability, improved public image andworker morale, and delaying or reducing capital expenditures.The reduction of energy use can indirectly contribute to reducedhealth impacts of air pollutants particularly where no air-pollutionregulation exists (high agreement, much evidence) [7.10].
Technology research, development, deployment,diffusion and transfer
Commercially available industrial technology providesa very large potential to reduce GHG emissions. However,even with the application of this technology, many industrialprocesses would still require much more energy than thethermodynamic ideal, suggesting a large additional potential forenergy-efficiency improvement and GHG mitigation potential.In addition, some industrial processes emit GHGs that areindependent of heat and power use. Commercial technology toeliminate these emissions does not currently exist for some ofthese processes, for example, development of an inert electrodeto eliminate process emissions from aluminium manufactureand the use of hydrogen to reduce iron and non-ferrous metalores. These new technologies must also meet a host of othercriteria, including cost competitiveness, safety and regulatoryrequirements, as well as winning customer acceptance.Industrial technology research, development, deployment anddiffusion are carried out both by governments and companies,ideally in complementary roles. Because of the large economicrisks inherent in technologies with GHG emission mitigationas the main purpose, government programmes are likely tobe needed in order to facilitate a sufficient level of researchand development. It is appropriate for governments to identifyfundamental barriers to technology and find solutions toovercome these barriers, but companies should bear the risksand capture the rewards of commercialization.
In addition, government information, energy audits, reporting,and benchmarking programmes promote technology transfer anddiffusion. The key factors determining private-sector technologydeployment and diffusion are competitive advantage, consumeracceptance, country-specific characteristics, protection ofintellectual property rights, and regulatory frameworks (mediumagreement, medium evidence) [7.11].
Long-term outlook
Many technologies offer long-term potential for mitigatingindustrial GHG emissions, but interest has focused on three areas:biological processing, use of hydrogen and nanotechnology.
Given the complexity of the industrial sector, achieving lowGHG emissions is the sum of many cross-cutting and individualsector transitions. Because of the speed of capital stock turnoverin at least some branches of industry, inertia by ‘technologylock-in’ may occur. Retrofitting provides opportunities in themeantime, but basic changes in technology occur only whenthe capital stock is installed or replaced (high agreement, muchevidence) [7.12].
8 Agriculture
Status of the sector, future trends in production andconsumption, and implications
Technological developments have allowed remarkableprogress in agricultural output per unit of land, increasingper capita food availability despite a consistent decline in percapita agricultural land area (high agreement, much evidence).However, progress has been uneven across the world, with ruralpoverty and malnutrition remaining in some countries. The share of animal products in the diet has increased progressivelyin developing countries, while remaining constant in thedeveloped world (high agreement, much evidence).
Production of food and fibre has more than kept pace withthe sharp increase in demand in a more populated world, sothat the global average daily availability of calories per capita has increased, though with regional exceptions. However, thisgrowth has been at the expense of increasing pressure on theenvironment and dwindling natural resources, and has not solvedproblems of food security and widespread child malnutrition inpoor countries (high agreement, much evidence).
The absolute area of global arable land has increased toabout 1400 Mha, an overall increase of 8% since the 1960s (5%decrease in developed countries and 22% increase in developingcountries). This trend is expected to continue into the future,with a projected additional 500 Mha converted to agriculturefrom 1997–2020, mostly in Latin America and Sub-SaharanAfrica (medium agreement, limited evidence).
Economic growth and changing lifestyles in some developingcountries are causing a growing demand for meat anddairy products. From 1967–1997, meat demand in developing countries rose from 11 to 24 kg per capita per year, achieving anannual growth rate of more than 5% by the end of that period.Further increases in global meat demand (about 60% by 2020)are projected, mostly in developing regions such as South andSoutheast Asia, and Sub-Saharan Africa (medium agreement,much evidence) [8.2].
Emission trends
For 2005, agriculture accounted for an estimated emissionof 5.1 to 6.1 GtCO2-eq (10–12% of total global anthropogenicemissions of GHGs). CH4 contributed 3.3 GtCO2-eq and N2O 2.8 GtCO2-eq. Of global anthropogenic emissions in2005, agriculture accounted for about 60% of N2O and about50% of CH4 (medium agreement, medium evidence). Despite large annual exchanges of CO2 between the atmosphere andagricultural lands, the net flux is estimated to be approximatelybalanced, with net CO2 emissions of only around 0.04 GtCO2/yr (emissions from electricity and fuel use in agriculture arecovered in the buildings and transport sector respectively) (lowagreement, limited evidence) [8.3].
Trends in GHG emissions in agriculture are responsive toglobal changes: increases are expected as diets change andpopulation growth increases food demand. Future climate change may eventually release more soil carbon (though theeffect is uncertain as climate change may also increase soilcarbon inputs through high production). Emerging technologiesmay permit reductions of emissions per unit of food produced,but absolute emissions are likely to grow (medium agreement,medium evidence).
Without additional policies, agricultural N2O and CH4emissions are projected to increase by 35–60% and ~60%,respectively, to 2030, thus increasing more rapidly than the14% increase of non-CO2 GHG observed from 1990 to 2005(medium agreement, limited evidence) [8.3.2].
Both the magnitude of the emissions and the relativeimportance of the different sources vary widely among worldregions (Figure TS.19). In 2005, the group of five regionsconsisting mostly of non-Annex I countries were responsiblefor 74% of total agricultural emissions [8.3].
Figure TS.19: Historic and projected N2O and CH4 emissions (MtCO2-eq.) in the agricultural sector of ten world regions, 1990–2020 8.2.
Note: EECCA=Countries of Eastern Europe, the Caucasus and Central Asia.
Mitigation technologies, practices, options,potentials and costs
Considering all gases, the economic potentials for agricultural mitigation by 2030 are estimated to be about 1600, 2700 and4300 MtCO2-eq/yr at carbon prices of up to 20, 50 and 100 US$/tCO2-eq, respectively for a SRES B2 baseline (see Table TS.11)(medium agreement, limited evidence) [8.4.3].
Table TS.11: Estimates of global agricultural economic GHG mitigation potential (MtCO2-eq/yr) by 2030 under different assumed carbon prices for a SRES B2 baseline 8.7.
| Carbon price (US$/tCO2-eq) | |||
|---|---|---|---|
| Up to 20 | Up to 50 | Up to 100 | |
| OECD | 330 (60-470) | 540 (300-780) | 870 (460-1280) |
| EIT | 160 (30-240) | 270 (150-390) | 440 (230-640) |
| Non-OECD/EIT | 1140 (210-1660) | 1880 (1040-2740) | 3050 (1610-4480) |
Note: figures in brackets show standard deviation around the mean estimate, potential excluding energy-efficiency measures and fossil fuel offsets from bioenergy.
Improved agricultural management can reduce net GHGemissions, often affecting more than one GHG. The effectivenessof these practices depends on factors such as climate, soil typeand farming system (high agreement, much evidence).About 90% of the total mitigation arises from sink enhancement(soil C sequestration) and about 10% from emission reduction(medium agreement, medium evidence). The most prominentmitigation options in agriculture (with potentials shown in MtCO2eq/yr for carbon prices up to 100 US$/tCO2-eq by 2030) are(see also Figure TS.20):
- restoration of cultivated organic soils (1260)
- improved cropland management (including agronomy,nutrient management, tillage/residue management andwater management (including irrigation and drainage)and set-aside / agro-forestry (1110)
- improved grazing land management (including grazingintensity, increased productivity, nutrient management,fire management and species introduction (810)
- restoration of degraded lands (using erosion control,organic amendments and nutrient amendments (690).
Figure TS.20: Potential for GHG agricultural mitigation in 2030 at a range of carbon prices for a SRES B2 baseline 8.9.
Note: B2 scenario shown, though the pattern is similar for all SRES scenarios. Energy-efficiency measures (770 MtCO2-eq) are included in the mitigation potential of the buildings and energy sector.
Lower, but still substantial mitigation potential is provided by:
- rice management (210)
- livestock management (including improved feedingpractices, dietary additives, breeding and other structuralchanges, and improved manure management (improvedstorage and handling and anaerobic digestion) (260)
(medium agreement, limited evidence).
In addition, 770 MtCO2-eq/yr could be provided by 2030by improved energy efficiency in agriculture. This amount is,however, for a large part included in the mitigation potential of buildings and transport 8.4.
At lower carbon prices, low cost measures most similarto current practice are favoured (e.g., cropland managementoptions), but at higher carbon prices, more expensive measures with higher mitigation potentials per unit area are favoured(e.g., restoration of cultivated organic / peaty soils; FigureTS.20) (medium agreement, limited evidence) [8.4.3].
GHG emissions could also be reduced by substitution offossil fuels by energy production from agricultural feedstocks(e.g., crop residues, dung, energy crops), which are counted in energy end-use sectors (particularly energy supply andtransport). There are no accurate estimates of future agriculturalbiomass supply, with figures ranging from 22 EJ/yr in 2025to more than 400 EJ/yr in 2050. The actual contribution ofagriculture to the mitigation potential by using bio-energydepends, however, on the relative prices of fuels and the balance of demand and supply. Top-down assessmentsthat include assumptions on such a balance estimate theeconomic mitigation potential of biomass energy suppliedfrom agriculture to be 70–1260 MtCO2-eq/yr at up to 20 US$/tCO2-eq, and 560–2320 MtCO2-eq/yr at up to 50 US$/tCO2-eq. There are no estimates for the additional potential from top-down models at carbon prices up to 100 US$/tCO2-eq,but the estimate for prices above 100 US$/tCO2-eqis 2720 MtCO2-eq/yr. These potentials represent mitigation of 5–80%, and 20–90% of all other agricultural mitigation measurescombined, at carbon prices of up to 20, and up to 50 US$/tCO2-eq, respectively. Above the level where agricultural productsand residues form the sole feedstock, bio-energy competes withother land-uses for available land, water and other resources.The mitigation potentials of bio-energy and improved energyefficiency are not included in Table TS.11 or Figure TS.20, asthe potential is counted in the user sectors, mainly transportand buildings, respectively (medium agreement, mediumevidence) [8.4.4].
The estimates of mitigation potential in the agriculturalsector are towards the lower end of the ranges indicated in theSecond Assessment Report (SAR) and TAR. This is due mainlyto the different time scales considered (2030 here versus 2050in TAR). In the medium term, much of the mitigation potentialis derived from removal of CO2 from the atmosphere and itsconversion to soil carbon, but the magnitude of this process willdiminish as soil carbon approaches maximum levels, and long-termmitigation will rely increasingly on reducing emissionsof N2O, CH4, and CO2 from energy use, the benefits of whichpersist indefinitely (high agreement, much evidence) [8.4.3].
Interactions of mitigation options with vulnerabilityand adaptation
Agricultural actions to mitigate GHGs could: a) reducevulnerability (e.g. if soil carbon sequestration reduces theimpacts of drought) or b) increase vulnerability (e.g., if heavy dependence on biomass energy makes energy supply moresensitive to climatic extremes). Policies to encourage mitigationand/or adaptation in agriculture may need to consider theseinteractions (medium agreement, limited evidence). Similarly,adaptation-driven actions may either a) favour mitigation (e.g.,return of residues to fields to improve water-holding capacitywill also sequester carbon) or b) hamper mitigation (e.g., useof more nitrogen fertilizer to overcome falling yields, leadingto increased N2O emissions). Strategies that simultaneouslyincrease adaptive capacity, reduce vulnerability and mitigateclimate change are likely to present fewer adoption barriersthan those with conflicting impacts. For example increasingsoil organic matter content can both improve fertility andreduce the impact of drought, improving adaptive capacity,making agriculture less vulnerable to climate change, while alsosequestering carbon (medium agreement, medium evidence)[8.5].
Effectiveness of climate policies: opportunities,barriers and implementation issues
Actual levels of GHG mitigation practices in the agriculturalsector are below the economic potential for the measuresreported above (medium agreement, limited evidence). Little progress in implementation has been made because of the costsof implementation and other barriers, including: pressure onagricultural land, demand for agricultural products, competingdemands for water as well as various social, institutional andeducational barriers (medium agreement, limited evidence).Soil carbon sequestration in European croplands, for instance,is likely to be negligible by 2010, despite significant economicpotential. Many of these barriers will not be overcome withoutpolicy/economic incentives (medium agreement, limitedevidence) [8.6].
Integrated and non-climate policies affectingemissions of greenhouse gases
The adoption of mitigation practices will often be drivenlargely by goals not directly related to climate change.This leads to varying mitigation responses among regions,and contributes to uncertainty in estimates of future globalmitigation potential. Policies most effective at reducingemissions may be those that also achieve other societal goals.Some rural development policies undertaken to fight poverty,such as water management and agro-forestry, are synergisticwith mitigation (medium agreement, limited evidence). Forexample, agro-forestry undertaken to produce fuel woodor to buffer farm incomes against climate variation mayalso increase carbon sequestration. In many regions,agricultural mitigation options are influenced most bynon-climate policies, including macro-economic, agriculturaland environmental policies. Such policies may be based on UNconventions (e.g., Biodiversity and Desertification), but are oftendriven by national or regional issues. Among the most beneficialnon-climate policies are those that promote sustainable use of soils, water and other resources in agriculture since these helpto increase soil carbon stocks and minimize resource (energy,fertilizer) waste (high agreement, medium evidence) [8.7].
Co-benefits of greenhouse gas mitigation policies
Some agricultural practices yield purely ‘win-win’ outcomes,but most involve trade-offs. Agro-ecosystems are inherentlycomplex. The co-benefits and trade-offs of an agricultural practice may vary from place to place because of differences inclimate, soil or the way the practice is adopted (high agreement,medium evidence).
In producing bio-energy, for example, if the feedstock is cropresidues, soil organic matter may be depleted as less carbon isreturned, thus reducing soil quality; conversely, if the feedstockis a densely-rooted perennial crop, soil organic matter may bereplenished, thereby improving soil quality.
Many agricultural mitigation activities show synergy with thegoals of sustainability. Mitigation policies that encourage efficientuse of fertilizers, maintain soil carbon and sustain agriculturalproduction are likely to have the greatest synergy with sustainabledevelopment (high agreement, medium evidence).
For example, increasing soil carbon can also improve foodsecurity and economic returns. Other mitigation options haveless certain impacts on sustainable development. For example,the use of some organic amendments may improve carbonsequestration, but impacts on water quality may vary dependingon the amendment. Co-benefits often arise from improvedefficiency, reduced cost and environmental co-benefits.Trade-offs relate to competition for land, reduced agriculturalproductivity and environmental stresses (medium agreement,limited evidence) [8.4.5].
Technology research, development, deployment,diffusion and transfer
Many of the mitigation strategies outlined for the agriculturesector employ existing technology. For example, reduction inemissions per unit of production will be achieved by increases incrop yields and animal productivity. Such increases in productivitycan occur through a wide range of practices − better management,genetically modified crops, improved cultivars, fertilizer-recommendationsystems, precision agriculture, improved animalbreeds, improved animal nutrition, dietary additives and growthpromoters, improved animal fertility, bio-energy feed stocks,anaerobic slurry digestion and CH4 capture systems − all of whichreflect existing technology (high agreement, much evidence).Some strategies involve new uses of existing technologies.For example, oils have been used in animal diets for manyyears to increase dietary energy content, but their role andfeasibility as a CH4 suppressant is still new and not fully defined.For some technologies, more research and development willbe needed [8.9].
Long-term outlook
Global food demand may double by 2050, leading tointensified production practices (e.g., increasing use of nitrogenfertilizer). In addition, projected increases in the consumption of livestock products will increase CH4 and N2O emissions iflivestock numbers increase, leading to growing emissions inthe baseline after 2030. (high agreement, medium evidence). Agricultural mitigation measures will help to reduce GHGemissions per unit of product, relative to the baseline. However,until 2030 only about 10% of the mitigation potential is related to CH4 and N2O. Deployment of new mitigation practices forlivestock systems and fertilizer applications will be essential toprevent an increase in emissions from agriculture after 2030.
Projecting long-term mitigation potentials is also hamperedby other uncertainties. For example, the effects of climatechange are unclear: future climate change may reduce soilcarbon-sequestration rates, or could even release soil carbon,though the effect is uncertain as climate change may alsoincrease soil carbon inputs through higher plant production.Some studies have suggested that technological improvementscould potentially counteract the negative impacts of climatechange on cropland and grassland soil carbon stocks, makingtechnological improvement a key factor in future GHGmitigation. Such technologies could, for example, act throughincreasing production, thereby increasing carbon returns tothe soil and reducing the demand for fresh cropland. (highagreement, medium evidence) [8.10].
9 Forestry
Since the TAR, new mitigation estimates have becomeavailable from the local scale to the global scale. Major economicreviews and global assessments have become available. There is early research into the integration of mitigation andadaptation options and the linkages to sustainable development.There is increased attention on reducing emissions fromdeforestation as a low cost mitigation option, one that willhave significant positive side effects. There is some evidencethat climate change impacts can also constrain the mitigationpotential of forests.
Status of the sector, development trends includingproduction and consumption, and implications
Global forest cover is 3952 million ha (Table TS.12), about30% of the world’s land area. Most relevant for the carbon cycleis that between 2000 and 2005 gross deforestation continued ata rate of 12.9 million ha/yr, mainly as a result of convertingforests to agricultural land, but also due to expansion ofsettlements and infrastructure, often for logging. In the 1990s,gross deforestation was slightly higher, 13.1 million ha/yr. Dueto afforestation, landscape restoration and natural expansion offorests, the net loss of forest between 2000 and 2005 was 7.3million ha/yr, with the largest losses in South America, Africaand Southeast Asia. This net rate of loss was lower than the8.9 million ha/yr loss in the 1990s (medium agreement, mediumevidence) [9.2.1].
Table TS.12: Estimates of forest area, net changes in forest area (negative numbers indicating decrease), carbon stock in living biomass and growing stock in 1990, 2000 and 2005 9.1.
| Region | Forest area (mill. ha) | Annual change (mill. ha/yr) | Carbon stock in living biomass (MtCO2) | Growing stock in 2005 | |||
|---|---|---|---|---|---|---|---|
| 2005 | 1990-2000 | 2000-2005 | 1990 | 2000 | 2005 | (million m3) | |
| Africa | 635.412 | -4.4 | -4.0 | 241267 | 228067 | 222933 | 64957 |
| Asia | 571.577 | -0.8 | 1.0 | 150700 | 130533 | 119533 | 47111 |
| Europe a) | 1001.394 | 0.9 | 0.7 | 154000 | 158033 | 160967 | 107264 |
| North and Central America | 705.849 | -0.3 | -0.3 | 150333 | 153633 | 155467 | 78582 |
| Oceania | 206.254 | -0.4 | -0.4 | 42533 | 41800 | 41800 | 7361 |
| South America | 831.540 | -3.8 | -4.3 | 358233 | 345400 | 335500 | 128944 |
| World | 3952.026 | -8.9 | -7.3 | 1097067 | 1057467 | 1036200 | 434219 |
Note:
a) including whole Russian Federation
Emission sources and sinks; trends
On the global scale, during the last decade of the 20th century,deforestation in the tropics and forest regrowth in the temperatezone and parts of the boreal zone remained the major factorsresponsible for CO2 emissions and removals, respectively(Table TS.12, Figure TS.21). Emissions from deforestation inthe 1990s are estimated at 5.8 GtCO2/yr.
Figure TS.21: Historical forest carbon balance (MtCO2) per region, 1855–2000 9.2.
Notes: green = sink. EECCA =Countries of Eastern Europe, the Caucasus and Central Asia. Data averaged per 5-year period; year marks starting year of period.
However, the extent to which the loss of carbon due totropical deforestation is offset by expanding forest areas andaccumulating woody biomass in the boreal and temperate zone is an area of disagreement between actual land observationsand estimates using top-down models. The top-down methodsbased on inversion of atmospheric transport models estimatethe net terrestrial carbon sink for the 1990s, the balance ofsinks in northern latitudes and sources in the tropics, to beabout 9.5 GtCO2. The new estimates are consistent with theincrease previously found in the terrestrial carbon sink in the1990s over the 1980s, but the new sink estimates and the rate ofincrease may be smaller than previously reported. The residualsink estimate resulting from inversion of atmospheric transportmodels is significantly higher than any global sink estimatebased on land observations.
The growing understanding of the complexity of the effectsof land-surface change on the climate system shows theimportance of considering the role of surface albedo, the fluxes of sensible and latent heat, evaporation and other factors informulating policy for climate change mitigation in the forestsector. Complex modelling tools are needed to fully considerthe climatic effect of changing land surface and to managecarbon stocks in the biosphere, but are not yet available. Thepotential effect of projected climate change on the net carbonbalance in forests remains uncertain 9.4.
As even the current functioning of the biosphere isuncertain, projecting the carbon balance of the global forestrysector remains very difficult. Generally, there is a lack ofwidely accepted studies and thus a lack of baselines. Trendsfor development in non-OECD countries, and thus of thedeforestation rate, are unclear. In OECD countries and ineconomies in transition, development of management trends,the wood market, and impacts of climate change remain unclear.Long-term models as reported in Chapter 3, show baseline CO2 emissions from land-use change and forestry in 2030 that arethe same or slightly lower than in 2000 (medium agreement,medium evidence) 9.4.
Description and assessment of mitigationtechnologies and practices, options and potentials,costs and sustainability
Terrestrial carbon dynamics are characterized by long periodsof small rates of carbon uptake per hectare, interrupted by shortperiods of rapid and large releases of carbon during disturbancesor harvest. While individual stands in a forest may be sources orsinks, the carbon balance of the forest is determined by the sumof the net balance of all stands.
Options available to reduce emissions by sources and/orincrease removals by sinks in the forest sector are grouped intofour general categories:
- maintaining or increasing the forest area;
- maintaining or increasing the site-level carbon density;
- maintaining or increasing the landscape-level carbon density and
- increasing off-site carbon stocks in wood products and enhancing product and fuel substitution.
Each mitigation activity has a characteristic time sequenceof actions, carbon benefits and costs (Figure TS.22). Relativeto a baseline, the largest short-term gains are always achievedthrough mitigation activities aimed at avoiding emissions(reduced deforestation or degradation, fire protection, slashburning, etc.).
Figure TS.22: Generalized summary of the options available in the forest sector and their type and timing of effects on carbon stocks and the timing of costs [Figure 9.4].
All forest-management activities aimed at increasing site-leveland landscape-level carbon density are common practices thatare technically feasible, but the extent and area over which theycan be implemented could be increased considerably. Economicconsiderations are typically the main constraint, because retainingadditional carbon on site delays revenues from harvest.
In the long term, a sustainable forest-management strategyaimed at maintaining or increasing forest carbon stocks, whileproducing an annual yield of timber, fibre or energy from the forest, will generate the largest sustained mitigation benefit.
Figure TS.23: Comparison of outcomes of economic mitigation potential at <100 US$/tCO2-eq in 2030 in the forestry sector, as based on top-down global models versus the regional modelling results [Figure 9.13].
Regional modelling assessments
bottom:up regional studies show that forestry mitigationoptions have the economic potential (at costs up to 100 US$/tCO2-eq) to contribute 1.3-4.2 MtCO2/yr (average 2.7 GtCO2/yr) in 2030 excluding bio-energy. About 50% can be achieved ata cost under 20 US$/tCO2 (1.6 GtCO2/yr) with large differencesbetween regions. The combined effects of reduced deforestationand degradation, afforestation, forest management, agroforestryand bio-energy have the potential to increase from thepresent to 2030 and beyond. This analysis assumes gradualimplementation of mitigation activities starting now (mediumagreement, medium evidence) [9.4.4].
Global top-down models predict mitigation potentials of13.8 GtCO2-eq/yr in 2030 at carbon prices less than or equalto 100 US$/tCO2. The sum of regional predictions is 22% of this value for the same year. Regional studies tend to use moredetailed data and consider a wider range of mitigation options,and thus may more accurately reflect regional circumstancesand constraints than simpler, more aggregated global models.However, regional studies vary in model structure, coverage,analytical approach and assumptions (including baselineassumptions). Further research is required to narrow the gap inthe estimates of mitigation potential from global and regionalassessments (medium agreement, medium evidence) [9.4.3].
The best estimate of the economic mitigation potentialfor the forestry sector at this stage therefore cannot be morecertain than a range between 2.7 and 13.8 GtCO2/yr in 2030, for costs <100 US$/tCO2; for costs <20 US$/tCO2 the range is1.6 to 5 GtCO2/yr. About 65% of the total mitigation potential(up to 100 US$/tCO2-eq) is located in the tropics and about50% of the total could be achieved by reducing emissions fromdeforestation (low agreement, medium evidence).
Forestry can also contribute to the provision of bio-energy fromforest residues. The potential of bio-energy, however, is counted inthe power supply, transportation (biofuels), industry and buildingsectors (see [11] for an overview). Based on bottom:upstudies of potential biomass supply from forestry, and assumingthat all of that will be used (which depends entirely on the cost offorestry biomass compared with other sources) a contribution inthe order of 0.4 GtCO2/yr could come from forestry.
Global top-down models are starting to provide insight onwhere and which of the carbon mitigation options can best beallocated on the globe (Figure TS.24).
Figure TS.24: Allocation of global afforestation activities as given by two global top-down models. Top: location of bioenergy and carbon plantations in the world in 2100; bottom: percentage of a grid cell afforested in 2100 [Figure 9.11].
Interactions of mitigation options with vulnerabilityand adaptation
Mitigation activities for forestry can be designed to becompatible with adapting to climate change, maintaining biodiversityand promoting sustainable development. Comparing environmental and social co-benefits and costs with the carbonbenefit will highlight trade-offs and synergies and help promotesustainable development.
The literature on the interaction between forestry mitigation andclimate change is in its infancy. Forests are likely to be impactedby climate change, which could reduce their mitigation potential.A primary management adaptation option is to reduce as manyancillary stresses on the forest as possible. Maintaining widelydispersed and viable populations of individual species minimizesthe probability of localized catastrophic events causing speciesextinction. Formation of protected areas or nature reserves is anexample of mitigation as well as adaptation. Protecting areas(with corridors) also leads to conservation of biodiversity, in turnreducing vulnerability to climate change.
Forestry-mitigation projects provide adaptation co-benefitsfor other sectors. Examples include agro-forestry reducing thevulnerability to drought of rain-fed crop income, mangroves reducing the vulnerability of coastal settlements, and shelter beltsslowing desertification (medium agreement, medium evidence) [9.5].
Effectiveness of and experience with climatepolicies, potentials, barriers and opportunities/implementation issues
Forestry can make a very significant contribution to a lowcost global mitigation portfolio that provides synergies withadaptation and sustainable development. Chapter 9 of this report identifies a whole set of options and policies to achievethis mitigation potential. However, this opportunity has so farnot been taken because of the current institutional context, lackof incentives for forest managers and lack of enforcement ofexisting regulations. Without better policy instruments, only asmall portion of this potential is likely to be realized.
Realization of the mitigation potential requires institutionalcapacity, investment capital, technology, R&D and transfer, aswell as appropriate (international) policies and incentives. Inmany regions, their absence has been a barrier to implementationof forestry-mitigation activities. Notable exceptions exist,however, such as regional successes in reducing deforestationrates and implementing afforestation programmes (highagreement, much evidence).
Multiple and location-specific strategies are required to guidemitigation policies in the sector. The optimum choices dependon the current state of the forests, the dominant drivers of forestchange, and the anticipated future dynamics of the forests withineach region. Participation of all stakeholders and policy-makersis necessary to promote mitigation projects and design an optimalmix of measures. Integration of mitigation in the forestry sectorinto land-use planning could be important in this respect.
Most existing policies to slow tropical deforestation have hadminimal impact due to lack of regulatory and institutional capacityor countervailing profitability incentives. In addition to morededicated enforcement of regulations, well-constructed carbonmarkets or other environmental service payment schemes mayhelp overcome barriers to reducing deforestation by providingpositive financial incentives for retaining forest cover.
There have been several proposals to operationalize activitiespost 2012, including market-based as well as non-market basedapproaches; for example, through a dedicated fund to voluntarilyreduce emissions from deforestation. Policy measures such assubsidies and tax exemptions have been used successfully toencourage afforestation and reforestation both in developed anddeveloping countries. Care must be taken, however, to avoidpossible negative environmental and social impacts of large-scaleplantation establishment.
Despite relative low costs and many potential positive sideeffects of afforestation and reforestation under the CleanDevelopment Mechanism (CDM), not many project activities are yet being implemented due to a number of barriers, includingthe late agreement on and complexity of the rules governingafforestation and reforestation CDM project activities. The requirements for forestry mitigation projects to become viableon a larger scale include certainty over future commitments,streamlined and simplified rules, and reductions in transactioncosts. Standardization of project assessment can play animportant role in overcoming uncertainties among potentialbuyers, investors and project participants (high agreement,medium evidence) [9.6].
Forests and Sustainable Development
While the assessment in the forestry chapter identifiesremaining uncertainties about the magnitude of the mitigationbenefits and costs, the technologies and knowledge required to implement mitigation activities exist today. Forestry can makea significant and sustained contribution to a global mitigationportfolio, while also meeting a wide range of social, economicand ecological objectives. Important co-benefits can be gainedby considering forestry mitigation options as an element ofbroader land-management plans.
Plantations can contribute positively, for example, toemployment, economic growth, exports, renewable energysupply and poverty alleviation. In some instances, plantationsmay also lead to negative social impacts such as loss of grazingland and source of traditional livelihoods. Agro-forestry canproduce a wide range of economic, social and environmental benefits; probably wider than large-scale afforestation. Sinceancillary benefits tend to be local rather than global, identifyingand accounting for them can reduce or partially compensate the costs of the mitigation measures (high agreement, medium evidence) [9.7].
Technology research, development, deployment,diffusion and transfer
The deployment, diffusion and transfer of technologiessuch as improved forest-management systems, forest practicesand processing technologies including bio-energy, are key to improving the economic and social viability of the differentmitigation options. Governments could play a critical role inproviding targeted financial and technical support, promoting the participation of communities, institutions and NGOs (highagreement, much evidence) [9.8].
Long-term outlook
Uncertainties in the carbon cycle, the uncertain impacts ofclimate change on forests and its many dynamic feedbacks,time-lags in the emission-sequestration processes, as well asuncertainties in future socio-economic paths (e.g., to whatextent deforestation can be substantially reduced in the comingdecades) cause large variations in future carbon balanceprojections for forests.
Overall, it is expected that in the long-term, mitigationactivities will help increase the carbon sink, with the netbalance depending on the region. Boreal primary forests willeither be small sources or sinks depending on the net effect ofenhancement of growth versus a loss of soil organic matter andemissions from increased fires. Temperate forests will probably continue to be net carbon sinks, favoured also by enhancedforest growth due to climate change. In the tropical regions,human-induced land-use changes are expected to continue to drive the dynamics for decades. Beyond 2040, depending veryparticularly on the effectiveness of policies aimed at reducingforest degradation and deforestation, tropical forests may become net sinks, depending on the influence of climate change.Also, in the medium to long term, commercial bio-energy isexpected to become increasingly important.
Developing optimum regional strategies for climate changemitigation involving forests will require complex analysesof the trade-offs (synergies and competition) in land-usebetween forestry and other land-uses, trade-offs betweenforest conservation for carbon storage and other environmentalservices such as biodiversity and watershed conservation and sustainable forest harvesting to provide society with carbon-containingfibre, timber and bio-energy resources, and tradeoffsamong utilization strategies of harvested wood products aimed at maximizing storage in long-lived products, recycling,and use for bio-energy [9.9].
10 Waste management
Status of the sector, development trendsand implications
Waste generation is related to population, affluence andurbanization. Current global rates of post-consumer wastegeneration are estimated to be 900-1300 Mt/yr. Rates have been increasing in recent years, especially in developingcountries with rapid population growth, economic growth andurbanization. In highly developed countries, a current goal isto decouple waste generation from economic driving forcessuch as GDP — recent trends suggest that per capita rates ofpost-consumer waste generation may be peaking as a resultof recycling, re-use, waste minimization, and other initiatives(medium agreement, medium evidence) 10.2.
Post-consumer waste is a small contributor to global GHGemissions (<5%), with landfill CH4 accounting for >50%of current emissions. Secondary sources of emissions are wastewater CH4 and N2O; in addition, minor emissions of CO2result from incineration of waste containing fossil carbon. Ingeneral, there are large uncertainties with respect to quantificationof direct emissions, indirect emissions and mitigation potentialsfor the waste sector, which could be reduced by consistentand coordinated data collection and analysis at the nationallevel. There are currently no inventory methods for annualquantification of GHG emissions from waste transport, nor forannual emissions of fluorinated gases from post-consumer waste(high agreement, much evidence) [10.3].
It is important to emphasize that post-consumer wasteconstitutes a significant renewable energy resource that canbe exploited through thermal processes (incineration and industrial co-combustion), landfill gas utilization and use ofanaerobic digester biogas. Waste has an economic advantage incomparison to many biomass resources because it is regularlycollected at public expense. The energy content of waste canbe most efficiently exploited using thermal processes: duringcombustion, energy is obtained directly from biomass (paperproducts, wood, natural textiles, food) and from fossil carbonsources (plastics, synthetic textiles). Assuming an averageheating value of 9 GJ/t, global waste contains >8 EJ ofavailable energy, which could increase to 13 EJ (nearly 2% ofprimary energy demand) in 2030 (medium agreement, mediumevidence) [10.1]. Currently, more than 130 million tonnes/yr ofwaste are combusted worldwide, which is equivalent to >1 EJ/yr.The recovery of landfill CH4 as a source of renewable energy wascommercialized more than 30 years ago with a current energyvalue of >0.2 EJ/yr. Along with thermal processes, landfillgas and anaerobic digester gas can provide important localsources of supplemental energy (high agreement, much evidence)10.3.
Because of landfill gas recovery and complementarymeasures (increased recycling and decreased landfilling throughthe implementation of alternative technologies), emissions of CH4 from landfills in developed countries have been largelystabilized. Choices for mature, large-scale waste managementtechnologies to avoid or reduce GHG emissions comparedwith landfilling include incineration for waste-to-energyand biological processes such as composting or mechanical-biologicaltreatment (MBT). However, in developing countries,landfill CH4 emissions are increasing as more controlled(anaerobic) landfilling practices are being implemented. Thisis especially true for rapidly urbanizing areas where engineeredlandfills provide a more environmentally acceptable waste disposalstrategy than open dumpsites by reducing diseasevectors, toxic odours, uncontrolled combustion and pollutantemissions to air, water and soil. Paradoxically, higher GHGemissions occur as the aerobic production of CO2 (by burningand aerobic decomposition) is shifted to anaerobic productionof CH4. To a large extent, this is the same transition to sanitarylandfilling that occurred in many developed countries during1950–1970. The increased CH4 emissions can be mitigated byaccelerating the introduction of engineered gas recovery, aidedby Kyoto mechanisms such as CDM and Joint Implementation(JI). As of late October 2006, landfill gas recovery projectsaccounted for 12% of the average annual Certified EmissionReductions (CERs) under CDM. In addition, alternative wastemanagement strategies such as recycling and composting can beimplemented in developing countries. Composting can providean affordable, sustainable alternative to engineered landfills,especially where more labour-intensive, lower-technologystrategies are applied to selected biodegradable waste streams(high agreement, medium evidence) [10.3].
Recycling, re-use and waste minimization initiatives, bothpublic and private, are indirectly reducing GHG emissions bydecreasing the mass of waste requiring disposal. Depending onregulations, policies, markets, economic priorities and localconstraints, developed countries are implementing increasinglyhigher recycling rates to conserve resources, offset fossil fueluse, and avoid GHG generation. Quantification of globalrecycling rates is not currently possible because of varyingbaselines and definitions; however, local reductions of >50%have been achieved. Recycling could be expanded practically inmany countries to achieve additional reductions. In developingcountries, waste scavenging and informal recycling are commonpractices. Through various diversion and small-scale recyclingactivities, those who make their living from decentralized wastemanagement can significantly reduce the mass of waste thatrequires more centralized solutions. Studies indicate that low-technologyrecycling activities can also generate significantemployment through creative microfinance and other small-scaleinvestments. The challenge is to provide safer, healthierworking conditions than currently experienced by wastescavengers at uncontrolled dumpsites (medium agreement,medium evidence) [10.3].
For wastewater, only about 60% of the global populationhas sanitation coverage (sewerage). For wastewater treatment,almost 90% of the population in developed countries but lessthan 30% in developing countries has improved sanitation(including sewerage and waste water treatment, septic tanks,or latrines). In addition to GHG mitigation, improved sanitationand wastewater management provide a wide range of health andenvironmental co-benefits (high agreement, much evidence)10.3.
With respect to both waste and wastewater managementin developing countries, two key constraints to sustainabledevelopment are the lack of financial resources and the selectionof appropriate and truly sustainable technologies for a particularsetting. It is a significant and costly challenge to implementingwaste and wastewater collection, transport, recycling, treatmentand residuals management in many developing countries.However, the implementation of sustainable waste andwastewater infrastructure yields multiple co-benefits to assistwith the implementation of Millennium Development Goals(MDGs) via improved public health, conservation of waterresources, and reduction of untreated discharges to air, surfacewater, groundwater, soils and coastal zones (high agreement,much evidence) [10.4].
Emission trends
With total 2005 emissions of approximately 1300 MtCO2-eq/yr, the waste sector contributes about 2–3% of total GHGemissions from Annex I and EIT countries and 4–5% from non-Annex I countries (see Table TS.13). For 2005–2020, business-as-usual (BAU) projections indicate that landfill CH4 willremain the largest source at 55–60% of the total. Landfill CH4emissions are stabilizing and decreasing in many developedcountries as a result of increased landfill gas recovery combinedwith waste diversion from landfills through recycling, wasteminimization and alternative thermal and biological wastemanagement strategies. However, landfill CH4 emissions areincreasing in developing countries because of larger quantities ofmunicipal solid waste from rising urban populations, increasingeconomic development and, to some extent, the replacementof open burning and dumping by engineered landfills. Withoutadditional measures, a 50% increase in landfill CH4 emissionsfrom 2005 to 2020 is projected, mainly from the Non-AnnexI countries. Wastewater emissions of CH4 and N2O fromdeveloping countries are also rising rapidly with increasingurbanization and population. Moreover, because the wastewateremissions in Table TS.13 are based on human sewage only andare not available for all developing countries, these emissionsare underestimated (high agreement, medium evidence) [10.1,[10.3], 10.4].
Table TS.13: Trends for GHG emissions from waste using 1996 and 2006 UNFCCC inventory guidelines, extrapolations and BAU projections (MtCO2-eq, rounded) 10.3.
| Source | 1990 | 1995 | 2000 | 2005 | 2010 | 2015 | 2020 | Notes | |
|---|---|---|---|---|---|---|---|---|---|
| Landfill CH4 | 550 | 585 | 590 | 635 | 700 | 795 | 910 | Averaged using 1996/2006 guidelines | |
| Wastewater CH4 | 450 | 490 | 520 | 590 | 600 | 630 | 670 | 1996 guidelines | |
| Wastewater N2O | 80 | 90 | 90 | 100 | 100 | 100 | 100 | 1996 guidelines | |
| Incineration | CO2 | 40 | 40 | 50 | 50 | 50 | 60 | 60 | 2006 guidelines |
| Total | 1120 | 1205 | 1250 | 1375 | 1450 | 1585 | 1740 |
Description and assessment of mitigationtechnologies and practices, options and potentials,costs and sustainability
Existing waste management technologies can effectivelymitigate GHG emissions from this sector – a wide rangeof mature, low- to high-technology, environmentally effective strategies are commercially available to mitigateemissions and provide co-benefits for improved public healthand safety, soil protection, pollution prevention and localenergy supply. Collectively, these technologies can directlyreduce GHG emissions (through landfill CH4 recovery andutilization, improved landfill practices, engineered wastewater management, utilization of anaerobic digester biogas) or avoidsignificant GHG generation (through controlled composting oforganic waste, state-of-the-art incineration, expanded sanitationcoverage). In addition, waste minimization, recycling and reuserepresent an important and increasing potential for indirectreduction of GHG emissions through the conservation of rawmaterials, improved energy and resource efficiency and fossilfuel avoidance. For developing countries, environmentallyresponsible waste management at an appropriate level oftechnology promotes sustainable development and improvespublic health (high agreement, much evidence) [10.4]. Because waste management decisions are often madelocally without concurrent quantification of GHG mitigation,the importance of the waste sector for reducing global GHG emissions has been underestimated (high agreement, mediumevidence) 10.4. Flexible strategies and financial incentivescan expand waste management options to achieve GHGmitigation goals – in the context of integrated waste management,local technology decisions are a function of many competingvariables, including waste quantity and characteristics, costand financing issues, regulatory constraints and infrastructurerequirements, including available land area and collection/transportation considerations. Life-cycle assessment (LCA)can provide decision-support tools (high agreement, muchevidence) [10.4]. Landfill CH4 emissions are directly reduced throughengineered gas extraction and recovery systems consistingof vertical wells and/or horizontal collectors. In addition,landfill gas offsets the use of fossil fuels for industrial orcommercial process heating, onsite generation of electricityor as a feedstock for synthetic natural gas fuels. Commercialrecovery of landfill CH4 has occurred at full scale since 1975with documented utilization in 2003 at 1150 plants recovering105 MtCO2–eq/yr. Because there are also many projects that flare gas without utilization, the total recovery is likely to beat least double this figure (high agreement, medium evidence)10.4. A linear regression using historical data from theearly 1980s to 2003 indicates a growth rate for landfill CH4utilization of approximately 5% per year. In addition to landfillgas recovery, the further development and implementationof landfill ‘biocovers’ can provide an additional low cost,biological strategy to mitigate emissions since landfill CH4(and non-methane volatile organic compounds (NMVOCs))emissions are also reduced by aerobic microbial oxidation inlandfill-cover soils (high agreement, much evidence) [10.4]. Incineration and industrial co-combustion for waste-to-energyprovide significant renewable energy benefits and fossil fueloffsets at >600 plants worldwide, while producing very minorGHG emissions compared with landfilling. Thermal processeswith advanced emission controls are a proven technology butmore costly than controlled landfilling with landfill gas recovery(high agreement, medium evidence) [10.4]. Controlled biological processes can also provide importantGHG mitigation strategies, preferably using source-separated wastestreams. Aerobic composting of waste avoids GHG generationand is an appropriate strategy for many developed and developingcountries, either as a stand-alone process or as part of mechanicalbiological treatment. In many developing countries, notably Chinaand India, small-scale low-technology anaerobic digestion has alsobeen practised for decades. Since higher-technology incinerationand composting plants have proved unsustainable in a number ofdeveloping countries, lower-technology composting or anaerobicdigestion can be implemented to provide sustainable wastemanagement solutions (high agreement, medium evidence) [10.4]. For 2030, the total economic reduction potential for CH4emissions from landfilled waste at costs of <20 US$/tCO2-eqranges between 400 and 800 MtCO2-eq. Of this total, 300–500 MtCO2-eq/yr has negative cost (Table TS.14). For the longterm, if energy prices continue to increase, there will be moreprofound changes in waste management strategies related toenergy and materials recovery in both developed and developingcountries. Thermal processes, which have higher unit coststhan landfilling, become more viable as energy prices increase.Because landfills continue to produce CH4 for many decades,both thermal and biological processes are complementary toincreased landfill gas recovery over shorter time frames (highagreement, limited evidence) [10.4].
| Region | Projected emissions in 2030 (MtCO2-eq) | Total economic mitigation potential at <100 US$/tCO2-eq (MtCO2-eq) | Economic mitigation potential (MtCO2-eq) at various cost categories (US$/tCO2-eq) | |||
|---|---|---|---|---|---|---|
| <0 | 0-20 | 20-50 | 50-100 | |||
| OECD | 360 | 100-200 | 100-120 | 20-100 | 0-7 | 1 |
| EIT | 180 | 100 | 30-60 | 20-80 | 5 | 1-10 |
| Non-OECD | 960 | 200-700 | 200-300 | 30-100 | 0-200 | 0-70 |
| Global | 1500 | 400-1000 | 300-500 | 70-300 | 5-200 | 10-70 |
1) Costs and potentials for wastewater mitigation are not available.
2) Regional numbers are rounded to reflect the uncertainty in the estimates and may not equal global totals.
3) Landfill carbon sequestration not considered.
4) The timing of measures limiting landfill disposal affects the annual mitigation potential in 2030. The upper limits assume that landfill disposal is limited in the coming years to 15% of the waste generated globally. The lower limits reflect a more realistic timing for implementation of measures reducing landfill disposal.
Effectiveness of and experience with climatepolicies, potentials, barriers and opportunities/implementation issues
Because landfill CH4 is the dominant GHG from this sector,a major strategy is the implementation of standards thatencourage or mandate landfill CH4 recovery. In developed countries, landfill CH4 recovery has increased as a result ofdirect regulations requiring landfill gas capture, voluntarymeasures including GHG-emissions credits trading and financialincentives (including tax credits) for renewable energy or greenpower. In developing countries, it is anticipated that landfill CH4recovery will increase during the next two decades as controlledlandfilling is phased in as a major waste disposal strategy. JIand the CDM have already proved to be useful mechanisms forexternal investment from industrialized countries, especiallyfor landfill gas recovery projects where the lack of financing isa major impediment. The benefits are twofold: reduced GHGemissions with energy benefits from landfill CH4 plus upgradedlandfill design and operations. Currently (late October 2006),under the CDM, the annual average CERs for the 33 landfill gas recovery projects constitute about 12% of the total. Mostof these projects (Figure TS.25) are located in Latin-Americancountries (72% of landfill gas CERs), dominated by Brazil(9 projects; 48% of CERs) (high agreement, medium evidence)[10.4].
Note: Includes 11 MtCO2-eq/yr CERs for landfill CH4 out of 91 MtCO2-eq/yr total. Projects <100,000 CERs/yr are located in Israel, Bolivia, Bangladesh and Malaysia. </div> In the EU, landfill gas recovery is mandated at existingsites, while the landfilling of organic waste is being phased outvia the landfill directive (1999/31/EC). This directive requires, by 2016, a 65% reduction relative to 1995 in the mass ofbiodegradable organic waste that is landfilled annually. As aresult, post-consumer waste is being diverted to incineration andto mechanical and biological treatment (MBT) before landfillingto recover recyclables and reduce the organic carbon content.In 2002, EU waste-to-energy plants generated about 40 million GJof electrical and 110 million GJ of thermal energy, while between1990 and 2002, landfill CH4 emissions in the EU decreased byalmost 30% due to the landfill directive and related nationallegislation (high agreement, much evidence) 10.5. Integrated and non-climate policies affecting emissions ofgreenhouse gases: GHG mitigation as the co-benefit of wastepolicies and regulations; role of sustainable development GHG mitigation is often not the primary driver, but is itselfa co-benefit of policies and measures in the waste sector thataddress broad environmental objectives, encourage energy recovery from waste, reduce use of virgin materials, restrictchoices for ultimate waste disposal, promote waste recyclingand re-use and encourage waste minimization. Policies andmeasures to promote waste minimization, re-use and recyclingindirectly reduce GHG emissions from waste. These measuresinclude Extended Producer Responsibility (EPR), unit pricing(or PAYT/‘Pay As You Throw’) and landfill taxes. Othermeasures include separate and efficient collection of recyclablestogether with both unit pricing and landfill tax systems. SomeAsian countries are encouraging ‘circular economy’ or ‘soundmaterial-cycle society’ as a new development strategy whosecore concept is the circular (closed) flow of materials andthe use of raw materials and energy through multiple phases.Because of limited data, differing baselines and other regionalconditions, it is not currently possible to quantify the globaleffectiveness of these strategies in reducing GHG emissions(medium agreement, medium evidence) [10.5]. In many countries, waste and wastewater managementpolicies are closely integrated with environmental policiesand regulations pertaining to air, water and soil quality aswell as to renewable energy initiatives. Renewable-energyprogrammes include requirements for electricity generationfrom renewable sources, mandates for utilities to purchasepower from small renewable providers, renewable energy taxcredits, and green power initiatives, which allow consumers tochoose renewable providers. In general, the decentralization of electricity generation capacity via renewables can providestrong incentives for electrical generation from landfill CH4 andthermal processes for waste-to-energy (high agreement, muchevidence) [10.5]. Although policy instruments in the waste sector consistmainly of regulations, there are also economic measures in anumber of countries to encourage particular waste managementtechnologies, recycling and waste minimization. These includeincinerator subsidies or tax exemptions for waste-to-energy.Thermal processes can most efficiently exploit the energy valueof post-consumer waste, but must include emission controlsto limit emissions of secondary air pollutants. Subsidiesfor the construction of incinerators have been implementedin several countries, usually combined with standards forenergy efficiency. Tax exemptions for electricity generatedby waste incinerators and for waste disposal with energyrecovery have also been adopted (high agreement, muchevidence) [10.5]. The co-benefits of effective and sustainable waste andwastewater collection, transport, recycling, treatment and disposalinclude GHG mitigation, improved public health, conservationof water resources and reductions in the discharge of untreatedpollutants to air, soil, surface water and groundwater. Becausethere are many examples of abandoned waste and wastewaterplants in developing countries, it must be stressed that a keyaspect of sustainable development is the selection of appropriatetechnologies that can be sustained within the specific localinfrastructure (high agreement, medium evidence) [10.5].
Technology research, development and diffusion
In general, the waste sector is characterized by maturetechnologies that require further diffusion in developingcountries. Advances under development include: * Landfilling: Implementation of optimized gas collectionsystems at an early stage of landfill development toincrease long-term gas collection efficiency. Optimizationof landfill biodegradation (bioreactors) to provide greaterprocess control and shorter waste degradation lifetimes.Construction of landfill ‘biocovers’ that optimize microbialoxidation of CH4 and NMVOCs to minimize emissions. * Biological processes: For developing countries, lower-technology,affordable sustainable composting and anaerobicdigestion strategies for source-separated biodegradablewaste. * Thermal processes: Advanced waste-to-energy technologiesthat can provide higher thermal and electrical efficienciesthan current incinerators (10–20% net electrical efficiency). * Increased implementation of industrial co-combustion usingfeedstocks from various waste fractions to offset fossil fuels.Gasification and pyrolysis of source-separated waste fractionsin combination with improved, lower-cost separationtechnologies for production of fuels and feedstocks. * Recycling, re-use, waste minimization, pre-treatment (improvedmechanical-biological treatment processes) Innovationsin recycling technology and process improvements resulting in decreased use of virgin materials, energy conservation,and fossil fuel offsets. Development of innovative but low-technologyrecycling solutions for developing countries. * Wastewater: New low-technology ecological designs forimproved sanitation at the household and small communitylevel, which can be implemented sustainably for efficient small-scale wastewater treatment and water conservation inboth developed and developing countries (high agreement,limited evidence) 10.6.
Long-term outlook, systems transitions
To minimize future GHG emissions from the waste sector,it is important to preserve local options for a wide range ofintegrated and sustainable management strategies. Furthermore, primary reductions in waste generation through recycling, reuse,and waste minimization can provide substantial benefitsfor the conservation of raw materials and energy. Over the longterm, because landfills continue to produce CH4 for decades,landfill gas recovery will be required at existing landfills even asmany countries change to non-landfilling technologies such asincineration, industrial co-combustion, mechanical-biologicaltreatment, large-scale composting and anaerobic digestion. Inaddition, the ‘back-up’ landfill will continue to be a criticalcomponent of municipal solid waste planning. In developingcountries, investment in improved waste and wastewatermanagement confers significant co-benefits for public health andsafety, environmental protection and infrastructure development.
11 Mitigation from a cross-sectoral perspective Mitigation options across sectors While many of the technological, behavioural and policyoptions mentioned in Chapters 4–10 concern specific sectors,some technologies and policies reach across many sectors; for example, the use of biomass and the switch from high-carbonfuels to gas affect energy supply, transport, industry andbuildings. Apart from potentials for common technologies, theseexamples also highlight possible competition for resources,such as finance and R&D support [11.2.1]. The bottom:up compilation of mitigation potentials bysector is complicated by interactions and spill-overs betweensectors, over time and over regions and markets. A series of formal procedures has been used to remove potentialdouble counting, such as reduction of the capacity neededin the power sector due to electricity saving in industryand the buildings sector. An integration of sector potentialsin this way is required to summarize the sectoral assessmentsof Chapters 4–10. The uncertainty of the outcome is influenced by issues of comparability of sector calculations, difference incoverage between the sectors (e.g., the transport sector) and the aggregation itself, in which only the main and direct sectorinteractions have been taken into account [11.3.1]. The top-down estimates were derived from stabilizationscenarios, i.e., runs towards long-term stabilization ofatmospheric GHG concentration [3.6]. Figure TS.26A and Table TS.15 show that the bottom:upassessments emphasize the opportunities for no-regrets optionsin many sectors, with a bottom:up estimate for all sectors by2030 of about 6 GtCO2-eq at negative costs; that is, net benefits.A large share of the no-regrets options is in the building sector.The total for bottom:up low cost options (no-regrets and otheroptions costing less than 20 US$/tCO2-eq) is around 13 GtCO2-eq (ranges are discussed below). There are additional bottomuppotentials of around 6 and 4 GtCO2-eq at additional costsof <50 and 100 US$/tCO2-eq respectively (medium agreement,medium evidence) [11.3.1].
Figure TS.26B (right): Global economic mitigation potential in 2030 estimated from top-down studies. Data from Table TS.16. 11.3.
| Carbon price (US$/tCO2-eq) | Economic potential (GtCO2-eq/yr) | Reduction relative to SRES A1 B (68 GtCO2-eq/yr) (%) | Reduction relative to SRES B2 (49 GtCO2-eq/yr) (%) |
|---|---|---|---|
| 0 | 5-7 | 7-10 | 10-14 |
| 20 | 9-17 | 14-25 | 19-35 |
| 50 | 13-26 | 20-38 | 27-52 |
| 100 | 16-31 | 23-46 | 32-63 |
| Carbon price (US$/tCO2-eq) | Economic potential (GtCO2-eq/yr) | Reduction relative to SRES A1 B (68 GtCO2-eq/yr) (%) | Reduction relative to SRES B2 (49 GtCO2-eq/yr) (%) |
|---|---|---|---|
| 20 | 9-18 | 13-27 | 18-37 |
| 50 | 14-23 | 21-34 | 29-47 |
| 100 | 17-26 | 25-38 | 35-53 |
| Chapter of report | Sectors | Sector-based (‘bottom:up’) potential by 2030 (GtCO2-eq/yr) ! class="theadcent t1011" style="background-color: rgb(255, 204, 153)" colspan="2" | Economy-wide model (‘top-down’) snapshot of mitigation by 2030 (GtCO2-eq/yr) |- ! class="theadcent t1111" style="background-color: rgb(255, 204, 153)" colspan="2" | End-use sector allocation (allocation of electricity savings to end-use sectors) ! class="theadcent t1011" style="background-color: rgb(255, 204, 153)" colspan="4" | Point-of-emissions allocation (emission reductions from end-use electricity savings allocated to energy supply sector) |- ! class="theadcent t1011" style="background-color: rgb(255, 204, 153)" colspan="6" | Carbon price <20 US$/tCO2-eq |- ! class="theadcent t1111" style="background-color: rgb(255, 204, 153)" | Low ! class="theadcent t1111" style="background-color: rgb(255, 204, 153)" | High ! class="theadcent t1111" style="background-color: rgb(255, 204, 153)" | Low ! class="theadcent t1111" style="background-color: rgb(255, 204, 153)" | High ! class="theadcent t1111" style="background-color: rgb(255, 204, 153)" | Low ! class="theadcent t1011" style="background-color: rgb(255, 204, 153)" | High |- | 4 | Energy supply & conversion | 1.2 | 2.4 | 4.4 | 6.4 | 3.9 | 9.7 |- | 5 | Transport | 1.3 | 2.1 | 1.3 | 2.1 | 0.1 | 1.6 |- | 6 | Buildings | 4.9 | 6.1 | 1.9 | 2.3 | 0.3 | 1.1 |- | 7 | Industry | 0.7 | 1.5 | 0.5 | 1.3 | 1.2 | 3.2 |- | 8 | Agriculture | 0.3 | 2.4 | 0.3 | 2.4 | 0..6 | 1.2 |- | 9 | Forestry | 0.6 | 1.9 | 0.6 | 1.9 | 0.2 | 0.8 |- | 10 | Waste | 0.3 | 0.8 | 0.3 | 0.8 | 0.7 | 0.9 |- | 11 | Total | 9.3 | 17.1 | 9.1 | 17.9 | 8.7 | 17.9 |- ! class="theadcent t1110" | ! class="theadcent t1111" | ! class="theadcent t1011" colspan="6" | Carbon price <50 US$/tCO2-eq |- | 4 | Energy supply & conversion | 2.2 | 4.2 | 5.6 | 8.4 | 6.7 | 12.4 |- | 5 | Transport | 1.5 | 2.3 | 1.5 | 2.3 | 0.5 | 1.9 |- | 6 | Buildings | 4.9 | 6.1 | 1.9 | 2.3 | 0.4 | 1.3 |- | 7 | Industry | 2.2 | 4.7 | 1.6 | 4.5 | 2.2 | 4.3 |- | 8 | Agriculture | 1.4 | 3.9 | 1.4 | 3.9 | 0.8 | 1.4 |- | 9 | Forestry | 1.0 | 3.2 | 1.0 | 3.2 | 0.2 | 0.8 |- | 10 | Waste | 0.4 | 1.0 | 0.4 | 1.0 | 0.8 | 1.0 |- | 11 | Total | 13.3 | 25.7 | 13.2 | 25.8 | 13.7 | 22.6 |- ! class="theadcent t1110" | ! class="theadcent t1111" | ! class="theadcent t1011" colspan="6" | Carbon price <100 US$/tCO2-eq |- | 4 | Energy supply & conversion | 2.4 | 4.7 | 6.3 | 9.3 | 8.7 | 14.5 |- | 5 | Transport | 1.6 | 2.5 | 1.6 | 2.5 | 0.8 | 2.5 |- | 6 | Buildings | 5.4 | 6.7 | 2.3 | 2.9 | 0.6 | 1.5 |- | 7 | Industry | 2.5 | 5.5 | 1.7 | 4.7 | 3.0 | 5.0 |- | 8 | Agriculture | 2.3 | 6.4 | 2.3 | 6.4 | 0.9 | 1.5 |- | 9 | Forestry | 1.3 | 4.2 | 1.3 | 4.2 | 0.2 | 0.8 |- | 10 | Waste | 0.4 | 1.0 | 0.4 | 1.0 | 0.9 | 1.1 | |||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 11 | Total | 15.8 | 31.1 | 15.8 | 31.1 | 16.8 | 26.2 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
See notes to Tables 3.16, 3.17 and 11.3, and Annex 11.1.
1. The ranges for global economic potentials as assessed in each sector are shown by vertical lines. The ranges are based on end-use allocations of emissions, meaning that emissions of electricity use are counted towards the end-use sectors and not to the energy supply sector.
2. The estimated potentials have been constrained by the availability of studies particularly at high carbon price levels.
3. Sectors used different baselines. For industry the SRES B2 baseline was taken, for energy supply and transport the WEO 2004 baseline was used; the building sector is based on a baseline in between SRES B2 and A1B; for waste, SRES A1B driving forces were used to construct a waste specific baseline, agriculture and forestry used baselines that mostly used B2 driving forces.
4. Only global totals for transport are shown because international aviation is included [5.4].
5. Categories excluded are: non-CO2 emissions in buildings and transport, part of material efficiency options, heat production and cogeneration in energy supply, heavy duty vehicles, shipping and high-occupancy passenger transport, most high-cost options for buildings, wastewater treatment, emission reduction from coal mines and gas pipelines, fluorinated gases from energy supply and transport. The underestimation of the total economic potential from these emissions is of the order of 10-15%.
CO2 concentration and global temperature could have beneficialconsequences, for example, in increasing the productivityof agriculture and forestry (in as far as CO2 fertilization is
effective), but they do not mitigate or address other impactssuch as further acidification of the oceans. Detailed costestimates for these options have not been published and they
are without a clear institutional framework for implementation(medium agreement, limited evidence) [11.2.2]. Mitigation costs across sectors andmacro-economic costs The costs of implementing the Kyoto Protocol are estimatedto be much lower than the TAR estimates due to US rejection ofthe Protocol. With full use of the Kyoto flexible mechanisms,costs are estimated at less than 0.05% of Annex B (without US)GDP (TAR Annex B: 0.1–1.1%). Without flexible mechanisms,costs are now estimated at less than 0.1% (TAR 0.2–2%) (highagreement, much evidence) [11.4]. Modelling studies of post-2012 mitigation have beenassessed in relation to their global effects on CO2 abatementby 2030, the carbon prices required and their effects on GDP or GNP (for the long-term effects of stabilization after 2030 seeChapter 3). For Category IV[19] pathways (stabilization around650 ppm CO2-eq) with CO2 abatement less than 20% belowbaseline and up to 25 US$/tCO2 carbon prices, studies suggestthat gross world product would be, at worst, some 0.7% belowbaseline by 2030, consistent with the median of 0.2% andthe 10–90 percentile range of –0.6 to 1.2% for the full set ofscenarios given in Chapter 3. Effects are more uncertain for the more stringent CategoryIII pathways (stabilization around 550 ppm CO2-eq) with CO2abatement less than 40% and up to 50 US$/tCO2 carbon prices,with most studies suggesting costs less than 1% of global grossworld product, consistent with the median of 0.6% and the10–90 percentile range of 0 to 2.5% for the full set in Chapter3. Again, the estimates are heavily dependent on approachesand assumptions. The few studies with baselines that requirehigher CO2 reductions to achieve the targets require highercarbon prices and most report higher GDP costs. For categoryI and II studies (stabilization between 445 and 535 ppm CO2-eq) costs are less than 3% GDP loss, but the number of studiesis relatively small and they generally use low baselines. Thelower estimates of the studies assessed here, compared with thefull set of studies reported in Chapter 3, are caused mainly bya larger share of studies that allow for enhanced technologicalinnovation triggered by policies, particularly for more stringent
mitigation scenarios (high agreement, medium evidence) [11.4]. All approaches indicate that no single sector or technologywill be able to address the mitigation challenge successfully onits own, suggesting the need for a diversified portfolio basedon a variety of criteria. Top-down assessments agree with thebottom:up results in suggesting that carbon prices around 20-50 US$/tCO2-eq (73-183 US$/tC-eq) are sufficient to drivelarge-scale fuel-switching and make both CCS and low-carbonpower sources economic as technologies mature. Incentivesof this order might also play an important role in avoidingdeforestation. The various short- and long-term models comeup with differing estimates, the variation of which can beexplained mainly by approaches and assumptions regardingthe use of revenues from carbon taxes or permits, treatmentof technological change, degree of substitutability betweeninternationally traded products, and the disaggregation ofproduct and regional markets (high agreement, much evidence)11.5, 11.6. The development of the carbon price and the correspondingemission reductions will determine the level at whichatmospheric GHG concentrations can be stabilized. Models suggest that a predictable and ongoing gradual increase in thecarbon price that would reach 20–50 $US/tCO2-eq by 2020–2030 corresponds with Category III stabilization (550 ppm
CO2-eq). For Category IV (650 ppm CO2-eq), such a pricelevel could be reached after 2030. For stabilization at levelsbetween 450 and 550 ppm CO2-eq, carbon prices of up to 100 US$/tCO2-eq need to be reached by around 2030 (mediumagreement, medium evidence) 11.5, 11.6. In all cases, short-term pathways towards lower stabilizationlevels, particularly for Category III and below, would requiremany additional measures around energy efficiency, low-carbonenergy supply, other mitigation actions and avoidanceof investment in very long-lived carbon-intensive capital stock.Studies of decision-making under uncertainty emphasize theneed for stronger early action, particularly on long-livedinfrastructure and other capital stock. Energy sectorinfrastructure (including power stations) alone is projected torequire at least US$ 20 trillion investment to 2030 and the optionsfor stabilization will be heavily constrained by the nature andcarbon intensity of this investment. Initial estimates for lowercarbon scenarios show a large redirection of investment, withnet additional investments ranging from negligible to less than5% (high agreement, much evidence) [11.6]. As regards portfolio analysis of government actions, ageneral finding is that a portfolio of options that attempts tobalance emission reductions across sectors in a manner that appears equitable (e.g., by equal percentage reduction), islikely to be more costly than an approach primarily guidedby cost-effectiveness. Portfolios of energy options across sectors that include low-carbon technologies will reduce risksand costs, because fossil fuel prices are expected to be morevolatile relative to the costs of alternatives, in addition to theusual benefits from diversification. A second general finding isthat costs will be reduced if options that correct the two marketfailures of climate change damages and technological innovationbenefits are combined, for example, by recycling revenues frompermit auctions to support energy-efficiency and low-carboninnovations (high agreement, medium evidence) [11.4]. Technological change across sectors A major development since the TAR has been the inclusionin many top-down models of endogenous technological change.Using different approaches, modelling studies suggest that allowing for endogenous technological change may lead tosubstantial reductions in carbon prices as well as GDP costs,compared with most of the models in use at the time of the TAR (when technological change was assumed to be includedin the baseline and largely independent of mitigation policiesand action). Studies without induced technological change show that carbon prices rising to 20 to 80 US$/tCO2-eq by2030 and 30 to 155 US$/tCO2-eq by 2050 are consistent withstabilization at around 550 ppm CO2-eq by 2100. For the samestabilization level, studies since TAR that take into accountinduced technological change lower these price ranges to 5 to65 US$/tCO2eq in 2030 and 15 to 130 US$/tCO2-eq in 2050.The degree to which costs are reduced hinges critically on theassumptions about the returns from climate change mitigationR&D expenditures, spill-overs between sectors and regions,crowding-out of other R&D, and, in models including learning-by-doing, learning rates (high agreement, much evidence) [11.5]. Major technological shifts like carbon capture and storage,advanced renewables, advanced nuclear and hydrogen requirea long transition as learning-by-doing accumulates and marketsexpand. Improvement of end-use efficiency therefore offersmore important opportunities in the short term. This is illustratedby the relatively high share of the buildings and industry sectorin the 2030 potentials (Table TS.17). Other options and sectorsmay play a more significant role in the second half of the century(see Chapter 3) (high agreement, much evidence) [11.6]. Spill-over effects from mitigation in Annex Icountries on Non-Annex I countries Spill-over effects of mitigation from a cross-sectoralperspective are the effects of mitigation policies and measuresin one country or group of countries on sectors in other countries. One aspect of spill-over is so-called ‘carbon leakage’:the increase in CO2 emissions outside the countries takingdomestic measures divided by the emission reductions withinthese countries. The simple indicator of carbon leakage doesnot cover the complexity and range of effects, which includechanges in the pattern and magnitude of global emissions.Modelling studies provide wide-ranging outcomes on carbonleakages depending on their assumptions regarding returnsto scale, behaviour in the energy-intensive industry, tradeelasticities and other factors. As in the TAR, the estimates ofcarbon leakage from implementation of the Kyoto Protocol aregenerally in the range of 5–20% by 2010. Empirical studieson the energy-intensive industries with exemptions under theEU Emission Trading Scheme (ETS) highlight that transportcosts, local market conditions, product variety and incompleteinformation favour local production, and conclude that carbonleakage is unlikely to be substantial (medium agreement,medium evidence) [11.7]. Effects of existing mitigation actions on competitivenesshave been studied. The empirical evidence seems to indicatethat losses of competitiveness in countries implementing Kyoto are not significant, confirming a finding in the TAR. Thepotential beneficial effect of technology transfer to developingcountries arising from technological development broughtabout by Annex I action may be substantial for energy-intensiveindustries, but has not so far been quantified in a reliable manner(medium agreement, low evidence) [11.7]. Perhaps one of the most important ways in which spill-oversfrom mitigation actions in one region affect others is throughthe effect on world fossil fuel prices. When a region reduces itsfossil fuel demand because of mitigation policy, it will reducethe world demand for that commodity and so put downwardpressure on the prices. Depending on the response of the fossilfuel producers, oil, gas or coal prices may fall, leading to lossof revenues by the producers, and lower costs of imports forthe consumers. As in the TAR, nearly all modelling studies thathave been reviewed show more pronounced adverse effects onoil-producing countries than on most Annex I countries that aretaking the abatement measures. Oil-price protection strategiesmay limit income losses in the oil-producing countries (highagreement, limited evidence) [11.7]. Co-benefits of mitigation Many recent studies have demonstrated significant benefitsof carbon-mitigation strategies on human health, mainlybecause they also reduce other airborne emissions, for example,SO2, NOx and particulate matter. This is projected to result inthe prevention of tens of thousands of premature deaths inAsian and Latin American countries annually, and severalthousands in Europe. However, monetization of mortalityrisks remains controversial, and hence a large range ofbenefit estimates can be found in the literature. However, all studies agree that the monetized health benefits may offset asubstantial fraction of the mitigation costs (high agreement,much evidence) [11.8]. In addition, the benefits of avoided emissions of air pollutantshave been estimated for agricultural production and the impactof acid precipitation on natural ecosystems. Such near-termbenefits provide the basis for a no-regrets GHG-reductionpolicy, in which substantial advantages accrue even if the impactof human-induced climate change turns out to be less thancurrent projections show. Including co-benefits other than thosefor human health and agricultural productivity (e.g., increasedenergy security and employment) would further enhance the costsavings (high agreement, limited evidence) [11.8]. A wealth of new literature has pointed out that addressingclimate change and air pollution simultaneously through a singleset of measures and policies offers potentially large reductions inthe costs of air-pollution control. An integrated approach is neededto address those pollutants and processes for which trade-offsexist. This is, for instance, the case for NOx controls for vehiclesand nitric acid plants, which may increase N2O emissions, orthe increased use of energy-efficient diesel vehicles, whichemit relatively more fine particulate matter than their gasolineequivalents (high agreement, much evidence) [11.8]. Adaptation and mitigation There can be synergies or trade-offs between policy options thatcan support adaptation and mitigation. The synergy potential ishigh for biomass energy options, land-use management and otherland-management approaches. Synergies between mitigationand adaptation could provide a unique contribution to ruraldevelopment, particularly in least-developed countries: manyactions focusing on sustainable natural resource managementcould provide both significant adaptation benefits and mitigationbenefits, mostly in the form of carbon sequestration. However,in other cases there may be trade-offs, such as the growth ofenergy crops that may affect food supply and forestry cover,thereby increasing vulnerability to the impacts of climate change(medium agreement, limited evidence) [11.9]. 12 Sustainable developmentand mitigation Relationship between sustainable developmentand climate change mitigation The concept of sustainable development was adopted bythe World Commission on Environment and Developmentand there is agreement that sustainable development involves a comprehensive and integrated approach to economic, socialand environmental processes. Discussions on sustainabledevelopment, however, have focused primarily on the environmental and economic dimensions. The importanceof social, political and cultural factors is only now gettingmore recognition. Integration is essential in order to articulatedevelopment trajectories that are sustainable, includingaddressing the climate change problem [12.1]. Although still in the early stages, there is growing useof indicators to measure and manage the sustainability ofdevelopment at the macro and sectoral levels, which is driven in part by the increasing emphasis on accountability in the contextof governance and strategy initiatives. At the sectoral level,progress towards sustainable development is beginning to bemeasured and reported by industry and governments using,inter alia, green certification, monitoring tools or emissionsregistries. Review of the indicators shows, however, that fewmacro-indicators include measures of progress with respect toclimate change (high agreement, much evidence) [12.1.3]. Climate change is influenced not only by the climate-specificpolicies that are put in place (the ‘climate first approach’), butalso by the mix of development choices that are made and thedevelopment trajectories that these policies lead to (the ‘developmentfirst approach’) - a point reinforced by global scenario analysispublished since the TAR. Making development more sustainableby changing development paths can thus make a significantcontribution to climate goals. It is important to note, however, thatchanging development pathways is not about choosing a mapped outpath, but rather about navigating through an uncharted andevolving landscape (high agreement, much evidence) [12.1.1]. It has further been argued that sustainable development mightdecrease the vulnerability of all countries, and particularly ofdeveloping countries, to climate change impacts. Framing thedebate as a development problem rather than an environmentalone may better address the immediate goals of all countries,particularly developing countries and their special vulnerabilityto climate change, while at the same time addressing thedriving forces for emissions that are linked to the underlyingdevelopment path [12.1.2]. Making development more sustainable Decision-making on sustainable development and climatechange mitigation is no longer solely the purview of governments.The literature recognizes the shift to a more inclusive conceptof governance, which includes the contributions of variouslevels of government, the private sector, non-governmentalactors and civil society. The more that climate change issuesare mainstreamed as part of the planning perspective at theappropriate level of implementation, and the more all theserelevant parties are involved in the decision-making processin a meaningful way, the more likely are they to achieve thedesired goals (high agreement, medium evidence) [12.2.1]. Regarding governments, a substantial body of politicaltheory identifies and explains the existence of national policystyles or political cultures. The underlying assumption of this work is that individual countries tend to process problemsin a specific manner, regardless of the distinctiveness orspecific features of any specific problem; a national ‘way of doing things’. Furthermore, the choice of policy instrumentsis affected by the institutional capacity of governments toimplement the instrument. This implies that the preferred mix ofpolicy decisions and their effectiveness in terms of sustainabledevelopment and climate change mitigation depend stronglyon national characteristics (high agreement, much evidence).However, our understanding of which types of policies willwork best in countries with particular national characteristicsremains sketchy [12.2.3]. The private sector is a central player in ecological andsustainability stewardship. Over the past 25 years, there hasbeen a progressive increase in the number of companies that are taking steps to address sustainability issues at either the firmor industry level. Although there has been progress, the privatesector has the capacity to play a much greater role in makingdevelopment more sustainable if awareness that this willprobably benefit its performance grows (medium agreement,medium evidence) [12.2.3]. Citizen groups play a significant role in stimulating sustainabledevelopment and are critical actors in implementing sustainabledevelopment policy. Apart from implementing sustainabledevelopment projects themselves, they can push for policyreform by awareness-raising, advocacy and agitation. They canalso pull policy action by filling the gaps and providing policyservices, including in the areas of policy innovation, monitoringand research. Interactions can take the form of partnerships or bethrough stakeholder dialogues that can provide citizens’ groupswith a lever for increasing pressure on both governments andindustry (high agreement, medium evidence) [12.2.3]. Deliberative public-private partnerships work mosteffectively when investors, local governments and citizen groupsare willing to work together to implement new technologies, and provide arenas to discuss such technologies that are locallyinclusive (high agreement, medium evidence) [12.2.3]. Implications of development choices for climatechange mitigation In a heterogeneous world, an understanding of differentregional conditions and priorities is essential for mainstreamingclimate change policies into sustainable-development strategies.Region- and country-specific case studies demonstrate thatdifferent development paths and policies can achieve notableemissions reductions, depending on the capacity to realizesustainability and climate change objectives [12.3]. In industrialized countries, climate change continues tobe regarded mainly as a separate, environmental problemto be addressed through specific climate change policies. A fundamental and broad discussion in society on the implicationsof development pathways for climate change in general andclimate change mitigation in particular in the industrializedcountries has not been seriously initiated. Priority mitigationareas for countries in this group may be in energy efficiency,renewable energy, CCS, etc. However, low-emission pathwaysapply not only to energy choices. In some regions, land-usedevelopment, particularly infrastructure expansion, is identifiedas a key variable determining future GHG emissions [12.2.1;12.3.1]. Economies in transition as a single group no longer exist.Nevertheless, Central and Eastern Europe and the countries ofEastern Europe, the Caucasus and Central Asia (EECCA) doshare some common features in socio-economic developmentand in climate change mitigation and sustainable development.Measures to decouple economic and emission growth would beespecially important for this group 12.3.1. Some large developing countries are projected to increasetheir emissions at a faster rate than the industrialized world andthe rest of developing nations as they are in the stage of rapidindustrialization. For these countries, climate change mitigationand sustainable-development policies can complement oneanother; however, additional financial and technologicalresources would enhance their capacity to pursue a low-carbonpath of development 12.3.1. For most other developing countries, adaptive and mitigativecapacities are low and development aid can help to reduce theirvulnerability to climate change. It can also help to reduce theiremissions growth while addressing energy-security and energy-accessproblems. CDM can provide financial resources for suchdevelopments. Members of the Organization of the Petroleum-Exporting Countries (OPEC) are unique in the sense that theymay be adversely affected by development paths that reducethe demand for fossil fuels. Diversification of their economiesis high on their agenda 12.3.1. Some general conclusions emerge from the case studiesreviewed in this chapter on how changes in developmentpathways at the sectoral level have (or could) lower emissions (high agreement, medium evidence) [12.2.4]: * GHG emissions are influenced by, but not rigidly linked to,economic growth: policy choices can make a difference. * Sectors where effective production is far below the maximumfeasible production with the same amount of inputs – thatis, sectors that are far from their production frontier – haveopportunities to adopt ‘win-win-win’ policies, that is,policies that free up resources and bolster growth, meetother sustainable-development goals and also reduce GHG emissions relative to baseline. * Sectors where production is close to the optimal givenavailable inputs – i.e., sectors that are closer to the productionfrontier – also have opportunities to reduce emissions by meeting other sustainable development goals. However, thecloser one gets to the production frontier, the more tradeoffsare likely to appear. * What matters is not only that a ‘good’ choice is made ata certain point in time, but also that the initial policy issustained for a long time – sometimes several decades – to really have effects. * It is often not one policy decision, but an array of decisionsthat are needed to influence emissions. This raises the issueof coordination between policies in several sectors and at various scales. Mainstreaming requires that non-climate policies, programmesand/or individual actions take climate change mitigation intoconsideration, in both developing and developed countries.However, merely piggybacking climate change on to an existingpolitical agenda is unlikely to succeed. The ease or difficultywith which mainstreaming is accomplished will depend onboth mitigation technologies or practices, and the underlyingdevelopment path. Weighing other development benefits againstclimate benefits will be a key basis for choosing developmentsectors for mainstreaming. Decisions about macro-economicpolicy, agricultural policy, multilateral development banklending, insurance practices, electricity market reform, energysecurity, and forest conservation, for example, which are oftentreated as being apart from climate policy, can have profoundimpacts on emissions, the extent of mitigation required, and thecosts and benefits that result. However, in some cases, such asshifting from biomass cooking to liquid petroleum gas (LPG)in rural areas in developing countries, it may be rational todisregard climate change considerations because of the smallincrease in emissions when compared with its developmentbenefits (see Table TS.18) (high agreement, medium evidence)[12.2.4]. In general terms, there is a high level of agreement on thequalitative findings in this chapter about the linkages betweenmitigation and sustainable development: the two are linked, and synergies and trade-offs can be identified. However, theliterature about the links and more particularly, about howthese links can be put into action in order to capture synergiesand avoid trade-offs, is as yet sparse. The same applies to goodpractice guidance for integrating climate change considerationsinto relevant non-climate policies, including analysis of theroles of different actors. Elaborating possible developmentpaths that nations and regions can pursue – beyond morenarrowly conceived GHG emissions scenarios or scenariosthat ignore climate change – can provide the context for newanalysis of the links, but may require new methodological tools(high agreement, limited evidence) [12.2.4].
| class="tbody t1110" | Macro economy | class="tbody t1111" | Implement non-climate taxes/ subsidies and/or other fiscal and regulatory policies that promote SD | class="tbody t1111" | State (governments at all levels) | class="tbody t1111" | 100 | class="tbody t1111" | Total global GHG emissions | class="tbody t1011" | Combination of economic, regulatory, and infrastructure non-climate policies could be used to address total global emissions. |- | class="tbody t1110" | Forestry | class="tbody t1111" | Adoption of forest conservation and sustainable management practices | class="tbody t1111" | State (governments at all levels) and civil society (NGOs) | class="tbody t1111" | 7 | class="tbody t1111" | GHG emissions from deforestation | class="tbody t1011" | Legislation/regulations to halt deforestation, improve forest management, and provide alternative livelihoods can reduce GHG emissions and provide other environmental benefits. |- | class="tbody t1110" | Electricity | class="tbody t1111" | Adoption of cost-effective renewables, demand-side management programmes, and reduction of transmission and distribution losses | class="tbody t1111" | State (regulatory commissions), market (utility companies) and, civil society (NGOs, consumer groups) | class="tbody t1111" | 20b | class="tbody t1111" | Electricity sector CO2 emissions (excluding auto producers) | class="tbody t1011" | Rising share of GHG-intensive electricity generation is a global concern that can be addressed through non-climate policies. |- | class="tbody t1110" | Petroleum imports | class="tbody t1111" | Diversifying imported and domestic fuel mix and reducing economy’s energy intensity to improve energy security | class="tbody t1111" | State and market (fossil fuel industry) | class="tbody t1111" | 20b | class="tbody t1111" | CO2 emissions associated with global crude oil and product imports | class="tbody t1011" | Diversification of energy sources to address oil security concerns could be achieved such that GHG emissions are not increased. |- | class="tbody t1110" | Rural energy in developing countries | class="tbody t1111" | Policies to promote rural LPG, kerosene and electricity for cooking | class="tbody t1111" | State and market (utilities and petroleum companies), civil society (NGOs) | class="tbody t1111" | <2c | class="tbody t1111" | GHG emissions from biomass fuel use, not including aerosols | class="tbody t1011" | Biomass used for rural cooking causes health impacts due to indoor air pollution, and releases aerosols that add to global warming. Displacing all biomass used for rural cooking in developing countries with LPG would emit 0.70 GtCO2-eq., a relatively modest amount compared with 2004 total global GHG emissions. |- | class="tbody t1110" | Insurance for building and transport sectors | class="tbody t1111" | Differentiated premiums, liability insurance exclusions, improved terms for green products | class="tbody t1111" | State and market (insurance companies) | class="tbody t1111" | 20 | class="tbody t1111" | Transport and building sector GHG emissions | class="tbody t1011" | Escalating damages due to climate change are a source of concern to insurance industry. Insurance industry could address these through the types of policies noted here. |- | class="tbody t1110" | International finance | class="tbody t1111" | Country and sector strategies and project lending that reduces emissions | class="tbody t1111" | State (international) financial institutions) and market (commercial banks) | class="tbody t1111" | 25b | class="tbody t1111" | CO2 emissions from developing countries (non-Annex I) | class="tbody t1011" | International financial institutions can adopt practices so that loans for GHG-intensive projects in developing countries that lock-in future emissions are avoided. |}
a) Data from Chapter 1 (IPCC Fourth Assessment Report, Working Group III: Technical Summary) unless noted otherwise.
b) CO2 emissions from fossil fuel combustion only; IEA (2006).
c) CO2 emissions only. Authors estimate, see text.
d) Emissions indicate the relative importance of sectors in 2004. Sectoral emissions are not mutually exclusive, may overlap, and hence sum up to more than total global emissions, which are shown in the Macro economy row.
| Sector and mitigation options | Potential SD synergies and conditions for implementation | Potential SD trade-offs | ||||||
|---|---|---|---|---|---|---|---|---|
| Energy supply and use: Chapters 4-7 | ||||||||
| Energy efficiency improvement in all sectors (buildings, transportation, industry, and energy supply) (Chapters 4-7) | - Almost always cost-effective, reduces or eliminates local pollutant emissions and consequent health impacts, improves indoor comfort and reduces indoor noise levels, creates business opportunities and jobs and improves energy security - Government and industry programmes can help overcome lack of information and principal agent problems - Programmes can be implemented at all levels of government and industry - Important to ensure that low-income household energy needs are given due consideration, and that the process and consequences of implementing mitigation options are, or the result is, gender-neutral | - Indoor air pollution and health impacts of improving the thermal efficiency of biomass cooking stoves in developing country rural areas are uncertain |- | Fuel switching and other options in the transportation and buildings sectors (Chapters 5 and 6) | - CO2 reduction costs may be offset by increased health benefits - Promotion of public transport and non-motorized transport has large and consistent social benefits - Switching from solid fuels to modern fuels for cooking and heating indoors can reduce indoor air pollution and increase free time for women in developing countries - Institutionalizing planning systems for CO2 reduction through coordination between national and local governments is important for drawing up common strategies for sustainable transportation systems | - Diesel engines are generally more fuel-efficient than gasoline engines and thus have lower CO2 emissions, but increase particle emissions. - Other measures (CNG buses, hybrid diesel-electric buses and taxi renovation) may provide little climate benefit. |- | Replacing imported fossil fuels with domestic alternative energy sources (DAES) (Chapter 4) | - Important to ensure that DAES is cost-effective - Reduces local air pollutant emissions. - Can create new indigenous industries (e.g., Brazil ethanol programme) and hence generate employment | - Balance of trade improvement is traded off against increased capital required for investment - Fossil fuel-exporting countries may face reduced exports - Hydropower plants may displace local populations and cause environmental damage to water bodies and biodiversity |
| Replacing domestic fossil fuel with imported alternative energy sources (IAES) (Chapter 4) | - Almost always reduces local pollutant emissions - Implementation may be more rapid than DAES - Important to ensure that IAES is cost-effective - Economies and societies of energy-exporting countries would benefit | - Could reduce energy security - Balance of trade may worsen but capital needs may decline | ||||||
| Forestry sector: Chapter 9 | ||||||||
| Afforestation | - Can reduce wasteland, arrest soil degradation, and manage water runoff - Can retain soil carbon stocks if soil disturbance at planting and harvesting is minimized - Can be implemented as agroforestry plantations that enhance food production - Can generate rural employment and create rural industry - Clear delineation of property rights would expedite implementation of forestation programmes | - Use of scarce land could compete with agricultural land and diminish food security while increasing food costs - Monoculture plantations can reduce biodiversity and are more vulnerable to disease - Conversion of floodplain and wetland could hamper ecological functions |- | Avoided deforestation | - Can retain biodiversity, water and soil management benefits, and local rainfall patterns - Reduce local haze and air pollution from forest fires - If suitably managed, it can bring revenue from ecotourism and from sustainably harvested timber sales - Successful implementation requires involving local dwellers in land management and/or providing them alternative livelihoods, enforcing laws to prevent migrants from encroaching on forest land. | - Can result in loss of economic welfare for certain stakeholders in forest exploitation (land owners, migrant workers) - Reduced timber supply may lead to reduced timber exports and increased use of GHG-intensive construction materials - Can result in deforestation with consequent SD implications elsewhere | |||
| Forest Management | - See afforestation | - Fertilizer application can increase N2O production and nitrate runoff degrading local (ground)water quality - Prevention of fires and pests has short term benefits but can increase fuel stock for later fires unless managed properly | ||||||
| Sector and mitigation options | Potential SD synergies and conditions for implementation | Potential SD trade-offs | ||||||
|---|---|---|---|---|---|---|---|---|
| Bio-energy (chapter 8 en 9) | ||||||||
| Bio-energy production | - Mostly positive when practised with crop residues (shells, husks, bagasse and/or tree trimmings). - Creates rural employment. - Planting crops/trees exclusively for bio-energy requires that adequate agricultural land and labour is available to avoid competition with food production | - Can have negative environmental consequences if practised unsustainably - biodiversity loss, water resource competition, increased use of fertilizer and pesticides. - Potential problem with food security (location-specific) and increased food costs. |- | Agriculture: Chapter 8 |- | Cropland management (management of nutrients, tillage, residues, and agroforestry; water, rice, and set-aside) | - Improved nutrient management can improve groundwater quality and environmental health of the cultivated ecosystem | - Changes in water policies could lead to clash of interests and threaten social cohesiveness - Could lead to water overuse | ||
| Grazing land management | - Improves livestock productivity, reduces desertification, and provide social security for the poor - Requires laws and enforcement to ban free grazing | |- | Livestock management | - Mix of traditional rice cultivation and livestock management would enhance incomes even in semi-arid and arid regions | |- | Waste management: Chapter 10 | ||
| Engineered sanitary landfilling with landfill gas recovery to capture methane gas | - Can eliminate uncontrolled dumping and open burning of waste, improving health and safety for workers and residents. - Sites can provide local energy benefits and public spaces for recreation and other social purposes within the urban infrastructure. | - When done unsustainably can cause leaching that leads to soil and groundwater contamination with potentially negative health impacts | ||||||
| Biological processes for waste and wastewater (composting, anaerobic digestion, aerobic and anaerobic wastewater processes) | - Can destroy pathogens and provide useful soil amendments if properly implemented using source-separated organic waste or collected wastewater. - Can generate employment - Anaerobic processes can provide energy benefits from CH4 recovery and use. | - A source of odours and water pollution if not properly controlled and monitored. |- | Incineration and other thermal processes | - Obtain the most energy benefit from waste. | - Expensive relative to controlled landfilling and composting. - Unsustainable in developing countries if technical infrastructure not present. - Additional investment for air pollution controls and source separation needed to prevent emissions of heavy metals and other air toxics. | |||
| Recycling, re-use, and waste minimization | - Provide local employment as well as reductions in energy and raw materials for recycled products. - Can be aided by NGO efforts, private capital for recycling industries, enforcement of environmental regulations, and urban planning to segregate waste treatment and disposal activities from community life. | - Uncontrolled waste scavenging results in severe health and safety problems for those who make their living from waste - Development of local recycling industries requires capital. | ||||||
| Sector and mitigation options | Potential SD synergies and conditions for implementation | Potential SD trade-offs | |||
|---|---|---|---|---|---|
| Energy supply and use: Chapters 4-7 | |||||
| Energy efficiency improvement in all sectors (buildings, transportation, industry, and energy supply) (Chapters 4-7) | - Almost always cost-effective, reduces or eliminates local pollutant emissions and consequent health impacts, improves indoor comfort and reduces indoor noise levels, creates business opportunities and jobs and improves energy security - Government and industry programmes can help overcome lack of information and principal agent problems - Programmes can be implemented at all levels of government and industry - Important to ensure that low-income household energy needs are given due consideration, and that the process and consequences of implementing mitigation options are, or the result is, gender-neutral | - Indoor air pollution and health impacts of improving the thermal efficiency of biomass cooking stoves in developing country rural areas are uncertain | |||
| Fuel switching and other options in the transportation and buildings sectors (Chaptes 5 and 6) | - CO2 reduction costs may be offset by increased health benefits - Promotion of public transport and non-motorized transport has large and consistent social benefits - Switching from solid fuels to modern fuels for cooking and heating indoors can reduce indoor air pollution and increase free time for women in developing countries - Institutionalizing planning systems for CO2 reduction through coordination between national and local governments is important for drawing up common strategies for sustainable transportation systems | - Diesel engines are generally more fuel-efficient than gasoline engines and thus have lower CO2 emissions, but increase particle emissions. - Other measures (CNG buses, hybrid diesel-electric buses and taxi renovation) may provide little climate benefit. | |||
| Replacing imported fossil fuels with domestic alternative energy sources (DAES) (Chapter 4) | - Important to ensure that DAES is cost-effective - Reduces local air pollutant emissions. - Can create new indigenous industries (e.g., Brazil ethanol programme) and hence generate employment | - Balance of trade improvement is traded off against increased capital required for investment - Fossil fuel-exporting countries may face reduced exports - Hydropower plants may displace local populations and cause environmental damage to water bodies and biodiversity | |||
| Replacing domestic fossil fuel with imported alternative energy sources (IAES) (Chapter 4) | - Almost always reduces local pollutant emissions - Implementation may be more rapid than DAES - Important to ensure that IAES is cost-effective - Economies and societies of energy-exporting countries would benefit | - Could reduce energy security - Balance of trade may worsen but capital needs may decline | |||
| Forestry sector: Chapter 9 | |||||
| Afforestation | - Can reduce wasteland, arrest soil degradation, and manage water runoff - Can retain soil carbon stocks if soil disturbance at planting and harvesting is minimized - Can be implemented as agroforestry plantations that enhance food production - Can generate rural employment and create rural industry - Clear delineation of property rights would expedite implementation of forestation programmes | - Use of scarce land could compete with agricultural land and diminish food security while increasing food costs - Monoculture plantations can reduce biodiversity and are more vulnerable to disease - Conversion of floodplain and wetland could hamper ecological functions |- | Avoided deforestation | - Can retain biodiversity, water and soil management benefits, and local rainfall patterns - Reduce local haze and air pollution from forest fires - If suitably managed, it can bring revenue from ecotourism and from sustainably harvested timber sales - Successful implementation requires involving local dwellers in land management and/or providing them alternative livelihoods, enforcing laws to prevent migrants from encroaching on forest land. | - Can result in loss of economic welfare for certain stakeholders in forest exploitation (land owners, migrant workers) - Reduced timber supply may lead to reduced timber exports and increased use of GHG-intensive construction materials - Can result in deforestation with consequent SD implications elsewhere |
| Forest Management | - See afforestation | - Fertilizer application can increase N2O production and nitrate runoff degrading local (ground)water quality - Prevention of fires and pests has short term benefits but can increase fuel stock for later fires unless managed properly | |||
| Sector and mitigation options | Potential SD synergies and conditions for implementation | Potential SD trade-offs | |||
|---|---|---|---|---|---|
| Bio-energy (chapter 8 and 9) |- | Bio-energy production | - Mostly positive when practised with crop residues (shells, husks, bagasse and/or tree trimmings). - Creates rural employment. - Planting crops/trees exclusively for bio-energy requires that adequate agricultural land and labour is available to avoid competition with food production | - Can have negative environmental consequences if practised unsustainably - biodiversity loss, water resource competition, increased use of fertilizer and pesticides. - Potential problem with food security (location-specific) and increased food costs. | ||
| Agriculture: Chapter 8 | |||||
| Cropland management (management of nutrients, tillage, residues, and agroforestry; water, rice, and set-aside) | - Improved nutrient management can improve groundwater quality and environmental health of the cultivated ecosystem | - Changes in water policies could lead to clash of interests and threaten social cohesiveness - Could lead to water overuse | |||
| Grazing land management | - Improves livestock productivity, reduces desertification, and provide social security for the poor - Requires laws and enforcement to ban free grazing | ||||
| Livestock management | - Mix of traditional rice cultivation and livestock management would enhance incomes even in semi-arid and arid regions | ||||
| Waste management: Chapter 10 | |||||
| Engineered sanitary landfilling with landfill gas recovery to capture methane gas | - Can eliminate uncontrolled dumping and open burning of waste, improving health and safety for workers and residents. - Sites can provide local energy benefits and public spaces for recreation and other social purposes within the urban infrastructure. | - When done unsustainably can cause leaching that leads to soil and groundwater contamination with potentially negative health impacts | |||
| Biological processes for waste and wastewater (composting, anaerobic digestion, aerobic and anaerobic wastewater processes) | - Can destroy pathogens and provide useful soil amendments if properly implemented using source-separated organic waste or collected wastewater. - Can generate employment - Anaerobic processes can provide energy benefits from CH4 recovery and use. | - A source of odours and water pollution if not properly controlled and monitored. |- | Incineration and other thermal processes | - Obtain the most energy benefit from waste. | - Expensive relative to controlled landfilling and composting. - Unsustainable in developing countries if technical infrastructure not present. - Additional investment for air pollution controls and source separation needed to prevent emissions of heavy metals and other air toxics. |
| Recycling, re-use, and waste minimization | - Provide local employment as well as reductions in energy and raw materials for recycled products. - Can be aided by NGO efforts, private capital for recycling industries, enforcement of environmental regulations, and urban planning to segregate waste treatment and disposal activities from community life. | - Uncontrolled waste scavenging results in severe health and safety problems for those who make their living from waste - Development of local recycling industries requires capital. | |||
13 Policies, instruments andco-operative agreements
Introduction This chapter discusses national policy instruments andtheir implementation, initiatives of the private sector, localgovernments and non-governmental organizations, andcooperative international agreements. Wherever feasible,national policies and international agreements are discussedin the context of four principle criteria by which they canbe evaluated; that is, environmental effectiveness, cost-effectiveness,distributional considerations and institutionalfeasibility. There are a number of additional criteriathat could also be explicitly considered, such as effectson competitiveness and administrative costs. Criteria maybe applied by governments in making ex-ante choicesamong instruments and in ex-post evaluation of the performanceof instruments [13.1]. (IPCC Fourth Assessment Report, Working Group III: Technical Summary)
National policy instruments, their implementation andinteractions
The literature continues to reflect that a wide variety ofnational policies and measures are available to governmentsto limit or reduce GHG emissions. These include: regulations and standards, taxes and charges, tradable permits, voluntaryagreements, phasing out subsidies and providing financialincentives, research and development and information instruments. Other policies, such as those affecting trade,foreign direct investments and social development goals canalso affect GHG emissions. In general, climate change policies,if integrated with other government polices, can contribute tosustainable development in both developed and developingcountries (see Chapter 12) [13.1]. Reducing emissions across all sectors and gases requires aportfolio of policies tailored to fit specific national circumstances.While the literature identifies advantages and disadvantages forany given instrument, the above-mentioned criteria are widelyused by policy makers to select and evaluate policies.All instruments can be designed well or poorly, stringent orlax. Instruments need to be adjusted over time and supplementedwith a workable system of monitoring and enforcement.Furthermore, instruments may interact with existing institutionsand regulations in other sectors of society (high agreement,much evidence) [13.1].
| Instrument | Criteria |- | Environmental effectiveness ! class="thead t1111" | Cost-effectiveness | Meets distributional considerations | Institutional feasibility | |||
|---|---|---|---|---|---|---|---|
| Regulations and standards | Emission levels set directly, though subject to exceptions Depends on deferrals and compliance | Depends on design; uniform application often leads to higher overall compliance costs | Depends on level playing field; small/new actors may be disadvantaged | Depends on technical capacity; popular with regulators, in countries with weak functioning markets | |||
| Taxes and charges | Depends on ability to set tax at a level that induces behavioural change | Better with broad application; higher administrative costs where institutions are weak | Regressive; can be improved with revenue recycling | Often politically unpopular; may be difficult to enforce with underdeveloped institutions | |||
| Tradable permits | Depends on emissions cap, participation and compliance | Decreases with limited participation and fewer sectors | Depends on initial permit allocation, may pose difficulties for small emitters | Requires well-functioning markets and complementary institutions | |||
| Voluntary agreements | Depends on programme design, including clear targets, a baseline scenario, third-party involvement in design and review, and monitoring provisions | Depends on flexibility and extent of government incentives, rewards and penalties | Benefits accrue only to participants | Often politically popular; requires significant number of administrative staff | |||
| Subsidies and other incentives | Depends on programme design; less certain than regulations/ standards. | Depends on level and programme design; can be market-distorting | Benefits selected participants; possibly some that do not need it | Popular with recipients; potential resistance from vested interests. Can be difficult to phase out | |||
| Research and development | Depends on consistent funding, when technologies are developed, and polices for diffusion. May have high benefits in long-term | Depends on programme design and the degree of risk | Initially benefits selected participants, Potentially easy for funds to be misallocated | Requires many separate decisions; Depends on research capacity and long-term funding | |||
| Information policies | Depends on how consumers use the information; most effective in combination with other policies | Potentially low cost, but depends on programme design | May be less effective for groups (e.g., low-income) that lack access to information | Depends on cooperation from special interest groups | |||
Initiatives of sub-national governments, corporationsand non-governmental organizations
The preponderance of the literature reviews nationally basedgovernmental instruments, but corporations, local- and regionalauthorities, NGOs and civil groups can also play a key role and areadopting a wide variety of actions, independent of governmentauthorities, to reduce emissions of GHGs. Corporate actionsrange from voluntary initiatives to emissions targets and, in afew cases, internal trading systems. The reasons corporationsundertake independent actions include the desire to influenceor pre-empt government action, to create financial value, and todifferentiate a company and its products. Actions by regional,state, provincial and local governments include renewableportfolio standards, energy-efficiency programmes, emissionregistries and sectoral cap-and-trade mechanisms. Theseactions are undertaken to influence national policies, addressstakeholder concerns, create incentives for new industries, orcreate environmental co-benefits. NGOs promote programmesto reduce emissions through public advocacy, litigation andstakeholder dialogue. Many of the above actions may limitGHG emissions, stimulate innovative policies, encourage thedeployment of new technologies and spur experimentationwith new institutions, but by themselves generally have limitedimpact. To achieve significant emission reductions, these actionsmust lead to changes in national policies (high agreement, muchevidence) [13.4].
International agreements (climate changeagreements and other arrangements)
The UNFCCC and its Kyoto Protocol have set a significantprecedent as a means of solving a long-term internationalenvironmental problem, but are only the first steps towards implementation of an international response strategy to combatclimate change. The Kyoto Protocol’s most notable achievementsare the stimulation of an array of national policies, the creationof an international carbon market and the establishment ofnew institutional mechanisms. Its economic impacts on theparticipating countries are yet to be demonstrated. The CDM,in particular, has created a large project pipeline and mobilizedsubstantial financial resources, but it has faced methodologicalchallenges regarding the determination of baselines andadditionality. The protocol has also stimulated the developmentof emissions trading systems, but a fully global system has notbeen implemented. The Kyoto Protocol is currently constrainedby the modest emission limits and will have a limited effect onatmospheric concentrations. It would be more effective if thefirst commitment period were to be followed up by measuresto achieve deeper reductions and the implementation of policyinstruments covering a higher share of global emissions (high agreement, much evidence) [13.3]. Many options are identified in the literature for achievingemission reductions both under and outside the Conventionand its Kyoto Protocol, for example: revising the formand stringency of emission targets; expanding the scope ofsectoral and sub-national agreements; developing and adoptingcommon policies; enhancing international RD&D technology programmes; implementing development-oriented actions,and expanding financing instruments (high agreement, muchevidence). Integrating diverse elements such as international R&D cooperation and cap-and-trade programmes within anagreement is possible, but comparing the efforts made bydifferent countries would be complex and resource-intensive (medium agreement, medium evidence) [13.3]. There is a broad consensus in the literature that a successfulagreement will have to be environmentally effective, cost-effective,incorporate distributional considerations and equity,and be institutionally feasible (high agreement, much evidence)[13.3]. A great deal of new literature is available on potentialstructures for and the substance of future internationalagreements. As has been noted in previous IPCC reports, because climate change is a globally common problem, any approachthat does not include a larger share of global emissions will bemore costly or less environmentally effective. (high agreement,much evidence) (See Chapter 3) [13.3]. Most proposals for future agreements in the literature includea discussion of goals, specific actions, timetables, participation,institutional arrangements, reporting and compliance provisions.Other elements address incentives, non-participation and noncompliancepenalties (high agreement, much evidence) [13.3]. Goals The specification of clear goals is an important elementof any climate agreement. They can both provide a commonvision about the near-term direction and offer longer-term certainty, which is called for by business. Goal-setting alsohelps structure commitments and institutions, provides anincentive to stimulate action and helps establish criteria againstwhich to measure the success in implementing measures (highagreement, much evidence) [13.3]. The choice of the long-term ambition significantly influencesthe necessary short-term action and therefore the design of theinternational regime. Abatement costs depend on the goal, varywith region and depend on the allocation of emission allowancesamong regions and the level of participation (high agreement,much evidence) [13.3]. Options for the design of international regimes canincorporate goals for the short, medium and long term. Oneoption is to set a goal for long-term GHG concentrations ora temperature stabilization goal. Such a goal might be basedon physical impacts to be avoided or conceptually on the basisof the monetary and non-monetary damages to be avoided.An alternative to agreeing on specific CO2 concentration ortemperature levels is an agreement on specific long-term actionssuch as a technology R&D and diffusion target – for example,‘eliminating carbon emissions from the energy sector by 2060’.An advantage of such a goal is that it might be linked to specificactions (high agreement, much evidence) [13.3]. Another option would be to adopt a ‘hedging strategy’,defined as a shorter-term goal on global emissions, from whichit is still possible to reach a range of desirable long-term goals. Once the short-term goal is reached, decisions on next stepscan be made in light of new knowledge and decreased levels ofuncertainty (medium agreement, medium evidence) [13.3]. Participation Participation of states in international agreements canvary from very modest to extensive. Actions to be taken byparticipating countries can be differentiated both in terms of when such action is undertaken, who takes the action and whatthe action will be. States participating in the same ‘tier’ wouldhave the same (or broadly similar) types of commitments.Decisions on how to allocate states to tiers can be based onformalized quantitative or qualitative criteria, or be ‘ad hoc’.Under the principle of sovereignty, states may choose the tierinto which they are grouped (high agreement, much evidence)[13.3]. An agreement can have static participation or may changeover time. In the latter case, states can ‘graduate’ from onetier of commitments to another. Graduation can be linked to passing of quantitative thresholds for certain parameters (orcombinations of parameters) that have been predefined in theagreement, such as emissions, cumulative emissions, GDP percapita, relative contribution to temperature increase or othermeasures of development, such as the human developmentindex (HDI) (high agreement, much evidence) [13.3]. Some argue that an international agreement needs toinclude only the major emitters to be effective, since thelargest 15 countries (including the EU-25 as one) make up80% of global GHG emissions. Others assert that those withhistorical responsibility must act first. Still another viewholds that technology development is the critical factor for aglobal solution to climate change, and thus agreements mustspecifically target technology development in Annex I countries– which in turn could offset some or all emissions leakage in Non-Annex I countries. Others suggest that a climate regimeis not exclusively about mitigation, but also encompassesadaptation – and that a far wider array of countries is vulnerableto climate change and must be included in any agreement (highagreement, much evidence) [13.3]. Regime stringency: linking goals, participation and timing Under most equity interpretations, developed countries as agroup would need to reduce their emissions significantly by 2020(10–40% below 1990 levels) and to still lower levels by 2050(40–95% below 1990 levels) for low to medium stabilizationlevels (450–550ppm CO2-eq) (see also Chapter 3). Under mostof the regime designs considered for such stabilization levels,developing-country emissions need to deviate below theirprojected baseline emissions within the next few decades (highagreement, much evidence). For most countries, the choice ofthe long-term ambition level will be more important than thedesign of the emission-reduction regime [13.3]. The total global costs are highly dependent on the baselinescenario, marginal abatement cost estimates, the assumedconcentration stabilization level (see also Chapters 3 and 11) and the level (size of the coalition) and degree of participation(how and when allowances are allocated). If, for example somemajor emitting regions do not participate in the reductionsimmediately, the global costs of the participating regions will behigher if the goal is maintained (see also Chapter 3). Regionalabatement costs are dependent on the allocation of emissionallowances to regions, particularly the timing. However, theassumed stabilization level and baseline scenario are moreimportant in determining regional costs 13.3. Commitments, timetables and actions There is a significant body of new literature that identifiesand evaluates a diverse set of options for commitments thatcould be taken by different groups. The most frequently evaluated type of commitment is the binding absolute emissionreduction cap as included in the Kyoto Protocol for Annex Icountries. The broad conclusion from the literature is that suchregimes provide certainty about future emission levels of theparticipating countries (assuming caps are met). Many authorspropose that caps be reached using a variety of ‘flexibility’approaches, incorporating multiple GHGs and sectors as wellas multiple countries through emission trading and/or projectbasedmechanisms (high agreement, much evidence) [13.3]. While a variety of authors propose that absolute caps beapplied to all countries in the future, many have raised concernsthat the rigidity of such an approach may unreasonably restricteconomic growth. While no consensus approach has emerged,the literature provides multiple alternatives to address thisproblem, including ‘dynamic targets’ (where the obligationevolves over time), and limits on prices (capping the costs ofcompliance at a given level – which while limiting costs, wouldalso lead to exceeding the environmental target). These optionsaim at maintaining the advantages of international emissionstrading while providing more flexibility in compliance (highagreement, much evidence). However, there is a trade-offbetween costs and certainty in achieving an emissions level.[13.3] Market mechanisms International market-based approaches can offer a cost-effectivemeans of addressing climate change if they incorporatea broad coverage of countries and sectors. So far, only a fewdomestic emissions-trading systems are in place, the EU ETSbeing by far the largest effort to establish such a scheme, withover 11,500 plants allocated and authorized to buy and sellallowances (high agreement, high evidence) [13.2]. Although the Clean Development Mechanism is developingrapidly, the total financial flows for technology transfer have sofar been limited. Governments, multilateral organizations andprivate firms have established nearly 6 billion US$ in carbonfunds for carbon-reduction projects, mainly through the CDM.Financial flows to developing countries through CDM projectsare reaching levels in the order of several billion US$/yr.This is higher than the flows through the Global EnvironmentFacility (GEF), comparable to the energy-oriented developmentassistance flows, but at least an order of magnitude lower thanall foreign direct investment (FDI) flows (high agreement,much evidence) [13.3]. Many have asserted that a key element of a successfulclimate change agreement will be its ability to stimulate thedevelopment and transfer of technology – without which it may be difficult to achieve emission reductions on a significant scale.Transfer of technology to developing countries depends mainlyon investments. Creating enabling conditions for investmentsand technology uptake and international technology agreementsare important. One mechanism for technology transfer is toestablish innovative ways of mobilizing investments to coverthe incremental cost of mitigating and adapting to climatechange. International technology agreements could strengthenthe knowledge infrastructure (high agreement, much evidence)[13.3]. A number of researchers have suggested that sectoralapproaches may provide an appropriate framework for post-Kyoto agreements. Under such a system, specified targets could be set, starting with particular sectors or industries thatare particularly important, politically easier to address, globallyhomogeneous or relatively insulated from competition withother sectors. Sectoral agreement may provide an additionaldegree of policy flexibility and make comparing efforts within asector between countries easier, but may be less cost-effective,since trading within a single sector will be inherently morecostly than trading across all sectors (high agreement, muchevidence) [13.3]. Coordination/harmonization of policies Coordinated policies and measures could be an alternativeto or complement internationally agreed targets for emissionreductions. A number of policies have been discussed in the literature that would achieve this goal, including taxes (suchas carbon or energy taxes); trade coordination/liberalization;R&D; sectoral policies and policies that modify foreign directinvestment. Under one proposal, all participating nations– industrialized and developing alike – would tax theirdomestic carbon usage at a common rate, thereby achieving cost-effectiveness. Others note that while an equal carbonprice across countries is economically efficient, it may not bepolitically feasible in the context of existing tax distortions (high agreement, much evidence) [13.3]. Non-climate policies and links to sustainable development There is considerable interaction between policies andmeasures taken at the national and sub-national level withactions taken by the private sector and between climate change mitigation and adaptation policies and policies in other areas.There are a number of non-climate national policies that canhave an important influence on GHG emissions (see Chapter12) (high agreement, much evidence). New research on futureinternational agreements could focus on understanding the interlinkagesbetween climate policies, non-climate policies andsustainable development, and how to accelerate the adoption ofexisting technology and policy tools [13.3]. An overview of how various approaches to internationalclimate change agreements, as discussed above, performagainst the criteria, given in the introduction, is presented inTable TS.21. Future international agreements would havestronger support if they meet these criteria (high agreement,much evidence) [13.3]. Table TS.21: Assessment of international agreements on climate changea 13.3.| Approach | Environmental effectiveness | Cost effectiveness | Meets distributional considerations | Institutional feasibility | |||||
|---|---|---|---|---|---|---|---|---|---|
| National emission targets and international emission trading (including offsets) | Depends on participation, and compliance | Decreases with limited participation and reduced gas and sector coverage | Depends on initial allocation | Depends on capacity to prepare inventories and compliance. Defections weaken regime stability | |||||
| Sectoral agreements | Not all sectors amenable to such agreements, limiting overall effectiveness. Effectiveness depends on whether agreement is binding or non-binding | Lack of trading across sectors increases overall costs, although may be cost-effective within individual sectors. Competitive concerns reduced within each sector | Depends on participation. Within-sector competitiveness concerns alleviated if treated equally at global level | Requires many separate decisions and technical capacity. Each sector may require cross-country institutions to manage agreements | |||||
| Coordinated policies and measures | Individual measures can be effective; emission levels may be uncertain; success will be a function of compliance | Depends on policy design | Extent of coordination could limit national flexibility; but may increase equity | Depends on number of countries; (easier among smaller groups of countries than at the global level) | |||||
| Cooperation on Technology RD & Db | Depends on funding, when technologies are developed and policies for diffusion | Varies with degree of R&D risk Cooperation reduces individual national risk | Intellectual property concerns may negate the benefits of cooperation | Requires many separate decisions. Depends on research capacity and long-term funding |- | Development-oriented actions | Depends on national policies and design to create synergies | Depends on the extent of synergies with other development objectives | Depends on distributional effects of development policies | Depends on priority given to sustainable development in national policies and goals of national institutions |
| Financial mechanisms | Depends on funding | Depends on country and project type | Depends on project and country selection criteria | Depends on national institutions |- | Capacity building | Varies over time and depends on critical mass | Depends on programme design | Depends on selection of recipient group | Depends on country and institutional frameworks |
b) Research, Development and Demonstration
14 Gaps in knowledge
Gaps in knowledge refer to two aspects of climate changemitigation: * Where additional data collection, modelling and analysiscould narrow knowledge gaps, and the resulting improvedknowledge and empirical experience could assist decision-making on climate change mitigation measures andpolicies; to some extent, these gaps are reflected in theuncertainty statements in this report. * Where research and development could improve mitigationtechnologies and/or reduce their costs. This importantaspect is not treated in this section, but is addressed in the chapters where relevant. Emission data sets and projections Despite a wide variety of data sources and databasesunderlying this report, there are still gaps in accurate and reliableemission data by sector and specific processes, especially withregard to non-CO2 GHGs, organic or black carbon, and CO2from various sources, such as deforestation, decay of biomassand peat fires. Consistent treatment of non-CO2 GHGs in themethodologies underlying scenarios for future GHG emissionsis often lacking 1 and 3. Links between climate change and other policies A key innovation of this report is the integrated approachbetween the assessment of climate change mitigation andwider development choices, such as the impacts of (sustainable)development policies on GHG-emission levels andvice versa. However, there is still a lack of empirical evidence on themagnitude and direction of the interdependence and interactionof sustainable development and climate change, of mitigationand adaptation relationships in relation to development aspects,and the equity implications of both. The literature on the linkagesbetween mitigation and sustainable development and, moreparticularly, on how to capture synergies and minimize tradeoffs,taking into account state, market and civil society’s role, isstill sparse. New research is required into the linkages betweenclimate change and national and local policies (including but notlimited to energy security, water, health, air pollution, forestry,agriculture) that might lead to politically feasible, economicallyattractive and environmentally beneficial outcomes. It wouldalso be helpful to elaborate potential development pathsthat nations and regions can pursue, which would providelinks between climate protection and development issues.Inclusion of macro-indicators for sustainable developmentthat can track progress could support such analysis 12 and 13. Studies of costs and potentials The available studies of mitigation potentials and costsdiffer in their methodological treatment and do not cover allsectors, GHGs or countries. Because of different assumptions, for example, with respect to the baseline and definitions ofpotentials and costs, their comparability is often limited. Also,the number of studies on mitigation costs, potentials and instruments for countries belonging to Economies in Transitionand most developing regions is smaller than for developed andselected (major) developing countries. This report compares costs and mitigation potentials based onbottom:up data from sectoral analyses with top-down costs andpotential data from integrated models. The match at the sectorallevel is still limited, partly because of lack of or incomplete datafrom bottom:up studies and differences in sector definitions andbaseline assumptions. There is a need for integrated studies thatcombine top-down and bottom:up elements 3, 4, 5,6, 7, 8, 9 and 10. Another important gap is the knowledge on spill-overeffects (the effects of domestic or sectoral mitigation measureson other countries or sectors). Studies indicate a large range (leakage effects[21] from implementation of the Kyoto Protocolof between 5 and 20% by 2010), but are lacking an empiricalbasis. More empirical studies would be helpful 11. The understanding of future mitigation potentials andcosts depends not only on the expected impact of RD&D ontechnology performance characteristics but also on ‘technology learning’, technology diffusion and transfer which are oftennot taken into account in mitigation studies. The studies on theinfluence of technological change on mitigation costs mostlyhave a weak empirical basis and are often conflicting. Implementation of a mitigation potential may compete withother activities. For instance, the biomass potentials are large,but there may be trade-offs with food production, forestry ornature conservation. The extent to which the biomass potentialcan be deployed over time is still poorly understood. In general, there is a continued need for a better understandingof how rates of adoption of climate-mitigation technologiesare related to national and regional climate and non-climatepolicies, market mechanisms (investments, changing consumerpreferences), human behaviour and technology evolution,change in production systems, trade and finance and institutionalarrangements.
Endnotes
- ^The GDPppp metric is used for illustrative purposes only for this report.
- ^SRES refers to scenarios described in the IPCC Special Report on Emission Scenarios (IPCC, 2000b). The A1 family of scenarios describes a future with very rapid economic growth, low population growth and rapid introduction of new and more efficient technologies. B1 describes a convergent world, with the same global population that peaks in mid century and declines thereafter, with rapid changes in economic structures. B2 describes a world ‘in which emphasis is on local solutions to economic, social, and environmental sustainability’. It features moderate population growth, intermediate levels of economic development, and less rapid and more diverse technological change than the A1B scenario.
- ^The Conference of the Parties (COP) is the supreme body of the Convention also serves as the Meeting of the Parties (MOP) for the Protocol. CMP1 is the first meeting of the Conference of the Parties acting as the Meeting of the Parties of the Kyoto Protocol.
- ^IPCC rules permit the use of both peer-reviewed literature and non-peer-reviewed literature that the authors deem to be of equivalent quality.
- ^‘Evidence’ in this report is defined as: Information or signs indicating whether a belief or proposition is true or valid. See Glossary.
- ^Private costs and discount rates reflect the perspective of private consumers and companies; see Glossary for a fuller description.
- ^Social costs and discount rates reflect the perspective of society. Social discount rates are lower than those used by private investors; see Glossary for a fuller description.
- ^This is the 5th to 95th percentile of the full distribution
- ^Studies on mitigation portfolios and macro-economic costs assessed in this report are based on a global least-cost approach, with optimal mitigation portfolios and without allocation of emission allowances to regions. If regions are excluded or non-optimal portfolios are chosen, global costs will go up. The variation in mitigation portfolios and their costs for a given stabilization level is caused by different assumptions, such as on baselines (lower baselines give lower costs), GHGs and mitigation options considered (more gases and mitigation options give lower costs), cost curves for mitigation options and rate of technological change.
- ^The median and the 10th–90th percentile range of the analysed data are given.
- ^Loss of GDP of 4% in 2050 is equivalent to a reduction of the annual GDP growth rate of about 0.1 percentage points.
- ^The equilibrium climate sensitivity is a measure of the climate system response to sustained radiative forcing. It is not a projection but is defined as the global average surface warming following a doubling of carbon dioxide concentrations WGI SPM.
- ^This counts all forms of energy use in buildings, including electricity.
- ^The term ‘thermal envelope’ refers to the shell of a building as a barrier to unwanted heat or mass transfer between the interior of the building and outside.
- ^The baseline CO2 emission projections were calculated on the basis of the 17 studies used for deriving the global potential (if a study did not contain a baseline, projections from another national mitigation report were used).
- ^Advanced control systems need to be created that permit the integration of all energy service functions in the design and subsequent operation of commercial buildings (‘intelligent control’).
- ^See IPCC Special Report on CO2 Capture and Storage
- ^In a point-of-emission analysis, emissions from electricity use are allocated to the energy-supply sector. In an end-use sector analysis, emissions from electricity are allocated to the respective end-use sector (particularly relevant for industry and buildings).
- ^See Chapter 3 for the definition of Category III and IV pathways.
- ^Carbon leakage is an aspect of spill-overs and is the increase in CO2 emissions outside countries taking domestic measures divided by the emission reductions in these countries.
Contributors Contribution of Working Group III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change Technical Summary Authors: Terry Barker (UK), Igor Bashmakov (Russia), Lenny Bernstein (USA), Jean E. Bogner (USA), Peter Bosch (The Netherlands), Rutu Dave (The Netherlands), Ogunlade Davidson (Sierra Leone), Brian S. Fisher (Australia), Sujata Gupta (India),Kirsten Halsnæs (Denmark), BertJan Heij (The Netherlands), Suzana Kahn Ribeiro (Brazil), Shigeki Kobayashi (Japan),Mark D. Levine (USA), Daniel L. Martino (Uruguay), Omar Masera (Mexico), Bert Metz (The Netherlands), Leo Meyer (The Netherlands),Gert-Jan Nabuurs (The Netherlands), Adil Najam (Pakistan), Nebojsa Nakicenovic (Austria/Montenegro), Hans-Holger Rogner (Germany),Joyashree Roy (India), Jayant Sathaye (USA), Robert Schock (USA), Priayadarshi Shukla (India), Ralph E. H. Sims (New Zealand),Pete Smith (UK), Dennis A. Tirpak (USA), Diana Urge-Vorsatz (Hungary), Dadi Zhou (PR China) Review Editor: Mukiri wa Githendu (Kenya) Terms of Use Unless otherwise stated, the information available on any page of the EoE that identifies the IPCC as Content Partner is the propriety of the IPCC and is protected by intellectual and industrial property laws. Click here (IPCC Fourth Assessment Report, Working Group III: Technical Summary) for the terms of use of IPCC material. Print Version Print versions of the IPCC Fourth Assessment Reports are available from Cambridge University Press (IPCC Fourth Assessment Report, Working Group III: Technical Summary) .
| This is a chapter from IPCC Fourth Assessment Report Working Group III. Previous: Summary for Policymakers (IPCC Fourth Assessment Report, Working Group III: Technical Summary) |Table of Contents (IPCC Fourth Assessment Report, Working Group III: Technical Summary)|Next: Chapter 1: Introduction (IPCC Fourth Assessment Report, Working Group III: Technical Summary) |} |
