Climate Solutions: Chapter 1
Summary of the IPCC Assessment Reports*
The Kyoto treaty would have wrecked our economy, if I can be blunt.
—George W. Bush, President, United States, 2005 While the Kyoto Protocol is a crucial step forward, that step is far too small. And as we consider how to go further still, there remains a frightening lack of leadership.
—Kofi Annan, Secretary-General, United Nations, 2006 Global warming has felt like breaking news a few times in recent years. But the first big pulse of coverage and public attention came in 1988, when the Amazon rain forest and Yellowstone were ablaze, a searing drought had farmers kicking dusty fields in frustration, and global temperatures had seen enough of a rise that a NASA climate expert, James Hansen, asserted before a Senate panel that statistics showed “the greenhouse effect has been detected and is changing our climate now.” [7]
—Andrew Revkin, 2008
- This content is adapted from summaries in the UNFCCC 10th Anniversary Brochure, and the IPCC Web site.
The World Meteorological Organization held the first ever World Climate Conference in 1979 to address concerns that human activities were interfering with regional and global climate patterns. In 1985, WMO, UNEP, and the International Council for Science (ICSU) held a joint conference on the Assessment of the Role of Carbon Dioxide and of Other Greenhouse Gases in Climate Variations and Associated Impacts and established the Advisory Group on Greenhouse Gases (AGGG) as follow-up. Two years later at the 10th Congress of the WMO came the call for an “objective, balanced and internationally coordinated scientific assessment of the understanding on the effects of increasing concentrations of greenhouse gases on the earth’s climate and on ways in which these changes may impact socio-economic patterns.” The WMO Executive Council asked the secretary-general of the WMO, in coordination with the executive director of UNEP, to create an “ad-hoc international mechanism” to do this. In November 1988, the WMO and UNEP collaborated to form a new panel with a long name and charged it to report back within 2 years. They called it the Intergovernmental Panel on Climate Change (IPCC).
The Panel’s First Assessment Report in 1990 was a landmark synthesis of global climate information. Working Group I experts concluded they were “certain that emissions from human activities are substantially increasing the atmospheric concentrations of greenhouse gases and that this will enhance the greenhouse effect and result in an additional warming of the Earth’s surface.” [4] Working Group II “highlighted important uncertainties with regard to timing, magnitude and regional patterns of climate change, but noted that impacts will be felt most severely in regions already under stress, mainly in developing countries.” [4] Working Group III “presented a flexible and progressive approach comprising shorter-term mitigation and adaptation measures and proposals for more intensive action over the longer-term. The group developed also possible elements for inclusion in a framework convention on climate change.” [4] It was this last piece from Working Group III that contained the ideas around which UN diplomats formulated the UN Framework Convention of Climate Change that became law in 1994.
The Second Assessment Report, completed in late 1995, included a new area, namely the socioeconomic aspects of climate change, and the scope of the reporting from working groups adjusted to meet this new requirement. The membership of the Panel expanded to include all the member nations of the WMO and UNEP. The 1995 Working Group I concluded that the basic science showed the following:
- Greenhouse gas concentrations had continued to increase.
- Anthropogenic aerosols tended to produce negative radiative forcing.
- Climate had changed over the past century.
- The balance of evidence suggested a discernible human influence on global climate.
- Climate was expected to continue to change in the future; and there remained still many uncertainties.
The 1995 Working Group II concluded, in parallel findings:
- Human-induced climate change added an important new stress.
- Most systems were sensitive to climate change.
- Impacts were difficult to quantify, and existing studies were limited in scope.
- Successful adaptation depended upon technological advances, institutional arrangements, availability of financing, and information exchange.
- Vulnerability increased as adaptive capacity decreased.
- Detection would be difficult, and unexpected changes could not be ruled out; further research and monitoring were essential.
The 1995 Working Group III highlighted a number of insights for policymakers, such as the following:
- A prudent way to deal with climate change would be through a portfolio of actions aimed at mitigation, adaptation, and improvement of knowledge.
- Earlier mitigation action might increase flexibility in moving toward stabilization of atmospheric concentrations of greenhouse gases.
- Significant "no-regrets" opportunities were available in most countries, and the risk of aggregate net damage due to climate change, consideration of risk aversion, and application of the precautionary principle provided rationales for action beyond no regrets.
The Group also stressed the value of obtaining better information about climate processes, their impacts and responses, and the need for more research and analysis of economic and social issues related to climate change.
By 2001, the Panel’s Third Assessment Report extended the earlier work and took advantage of increasingly sophisticated observation tools and modeling methods that allowed greater resolution in the findings. The key findings of 2001 Working Group I included these:
- An increasing body of observations gave a collective picture of a warming world and other changes in the climate system.
- Emissions of greenhouse gases and aerosols due to human activities continued to alter the atmosphere in ways that were expected to affect the climate.
- Confidence in the ability of models to project future climate had increased; there was new and stronger evidence that most of the warming over the last 50 years was attributable to human activities.
- Human influences would continue to change atmospheric composition throughout the 21st century.
- Global average temperature and sea level were expected to rise under all IPCC emissons scenarios; atmospheric climate change would persist for many centuries.
- Further action was required to address remaining gaps in information and understanding.
The 2001 findings of Working Group II included these:
- Recent regional climate changes, particularly temperature increases, had already affected many physical and biological systems.
- There were preliminary indications that some human systems had been affected by recent increases in floods and droughts.
- Natural systems were vulnerable to climate change, and some would be irreversibly damaged.
- Many human systems were sensitive to climate change, and some were vulnerable.
- Projected changes in climate extremes could have major consequences; the potential for large-scale and possibly irreversible impacts posed risks that had yet to be reliably quantified.
- Adaptation was a necessary strategy at all scales to complement climate change mitigation efforts.
- Those with the fewest resources had the least capacity to adapt and were the most vulnerable; and adaptation, sustainable development, and enhancement of equity could be mutually reinforcing.
The 2001 Working Group III on adaptation and mitigation reported that the desired mix of options to reduce human-induced climate change varied with time and place. Some other key findings included these:
- Near- and long-term implications of stabilizing atmospheric concentrations of greenhouse gases were determined.
- Technologies, policies, and costs of near- and long-term mitigation were identified.
- Alternative development paths could result in very different greenhouse gas emissions.
- Interactions between climate change and other environmental issues and development were xxxxx ,
- Climate change mitigation would both be affected by, and have impacts on, broader socioeconomic policies and trends, such as those relating to development, sustainability, and equity.
- Significant progress relevant to greenhouse gas emissions reduction had been made since the Second Assessment Report in 1995 and had been faster than anticipated.
- Forests, agricultural lands, and other terrestrial ecosystems offered significant carbon mitigation potential.
- Although not necessarily permanent, conservation and sequestration of carbon might allow time for other options to be further developed and implemented.
- Most model results indicated that known technological options could achieve a broad range of atmospheric CO2 stabilization levels, such as 550 ppmv , 450 ppmv, or below over the next 100 years or more, but implementation would require associated socioeconomic and institutional changes.
- Some sources of greenhouse gas emissions could be limited at no or negative social costs to the extent that policies could exploit no-regrets opportunities.
- Emission constraints in Annex I (industrialized) countries had been well established, though there had been varied “spillover” effects on non–Annex I countries.
- The effectiveness of climate change mitigation could be enhanced when climate policies were integrated with the non-climate objectives of national and sectoral policy development.
By 2007, the Panel’s Fourth Assessment Report, titled Climate Change 2007, reached stronger consensus on both the rapidity with which climate has been changing and the significance of the human contribution to climate disruption. Dan Perlman and James Morris of Brandeis University sum up the key new findings of the 2007 working groups on the science, adaptation and mitigation options, and policymaking insights in a few sentences, adapted below from their “What the IPCC Said” booklet:
- Warming of the climate system is unequivocal, and it is greater than what was found in the IPCC’s Third Assessment Report in 2001.
- Human activities, in particular the burning of fossil fuels and changes in land use, have resulted in warming of the planet; other changes in climate; and effects on natural ecosystems.
- The climate will continue to change in the 21st century. Specifically, we will see continued increases in temperature, increases in global greenhouse gas emissions, and changes in other aspects of climate, such as wind patterns and precipitation (Working Group II).
- We can respond to climate change in two ways. Adaptation involves developing ways to protect ourselves from climate impacts, such as building sea walls to protect communities from rising sea levels. Mitigation involves slowing the process of climate change by lowering the concentration of greenhouse gases in the atmosphere, for example, by reducing emissions or planting trees.
- While such strategies have begun, more extensive adaptation and mitigation efforts are required to reduce our vulnerability to climate change. In addition, there are barriers, limits, and costs associated with any of these strategies.
In the long term, there are many reasons to be concerned about climate change, ranging from increased risk of extinctions to rising sea levels. Adaptation (adjusting our environment to avoid climate impacts) and mitigation (such as decreasing our output of greenhouse gases) are both necessary to reduce adverse impacts of climate change. It will probably be possible to stabilize greenhouse gas concentrations in the atmosphere using technologies that are or will soon be available. We need to carefully evaluate both (1) the up-front economic costs of mitigation and (2) the noneconomic and economic costs of the impacts of climate change.
On the topic of whether and to what extent human activities influence greenhouse gases and climate, the Panel has made the following statements, summarized in Table 1.2, that show a steady march toward near certainty. This rise in certainty is due to both more information from more locations over time and higher-resolution modeling over time based on that information.
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Table 1.2 The Progression of Confidence by the IPCC in Its Findings |
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Over the course of 17 years and four assessment reports, the IPCC has made the following statements about whether the data show the Earth is warming and whether human activities are part of the warming: |
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1990: “Earth has been warming, and continued warming is likely.” (First Assessment Report) |
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1995: “Balance of evidence suggests discernible human influence.” (Second Assessment Report) |
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2001: “Most of warming of past 50 years [is] likely (odds 2 out of 3) due to human activities.” (Third Assessment Report) |
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2007: “Most of warming [is] very likely (odds 9 out of 10) due to greenhouse gases.” (Fourth Assessment Report) |
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Table Source: The IPCC’s First, Second, Third, and Fourth Assesment Reports, respectively. See www.ipcc.ch/ipccreports/assessments-reports.htm. |
Online figures
 Figure 1.1 (a) Onscreen edition of the Panel’s Summary for Policymakers in Brussels in 2007. The language being approved as amended in the screen now appears in the Summary for Policymakers of Working Group II in Climate Change 2007 (in section 1.3): “Effects of temperature increases have been documented in the following (medium confidence): ... effects on agricultural and forestry management at Northern Hemisphere higher latitudes, such as earlier spring planting of crops, and alterations in disturbance regimes of forests due to fires and pests.” Photos courtesy of Stephen Schneider |
 Figure 1.1 (b) Scientists in the back rows carefully tracking the language being approved. The scientists seated in the back, monitoring the debate over this Summary’s language, include from, left to right, {TK} Photos courtesy of Stephen Schneider |
 Figure 1.3 Three leading indicators: Temperature, sea level, and snow. The summary graph from the Climate Change 2007 report tracks three different indicators since 1900: Average global temperature is rising, average sea level is rising, and average area of winter snow cover in the northern hemisphere is falling. The baseline is the average for the period 1961 to 1990, for which the instrumental records are exceedingly good. Source: [1] | |
Bibliography
- Bernstein L, Bosch P, Canziani O, Chen Z, Christ R, Davidson O, Hare W, Huq S, Karoly D, Kattsov V, et al. (2007) Synthesis Report. (in Climate Change 2007: Fourth Assessment Report of the Intergovernmental Panel on Climate Change, 74 pp, eds Allali A, Bojariu R, Diaz S, Elgizouli I, Griggs D, Hawkins D, Hohmeyer O, Pateh Jallow BP, Kajfez?-Bogataj L, Leary N, Lee H, Wratt D) ar4_syr.pdf: http://www.ipcc.ch
- European Commission (EC) (2008) Emission Trading Scheme. Europa. European Commission (read August 24, 2008). http://ec.europa.eu/environment/climat/emission/index_en.htm
- IPCC (2007) Assesment Report Archive. UNFCCC IPCC (read August 24, 2008). http://www.ipcc.ch/ipccreports/index.htm
- IPCC (2004) About IPCC. UNFCCC, Geneva (read August 24, 2008). http://www.ipcc.ch/about/index.htm
- Parry ML, Canziani O, Palutikof JP, van der Linden PJ, Hanson CE (2007) Technical Summary: Working Group II (in Climate Change 2007: Impacts, Adaptation and Vulnerability. Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change 23?– 78). ar4-wg2-ts.pdf: http://www.ipcc.ch
- Regional Greenhouse Gas Initiative (RGGI) (2008) Home Page (read September 23, 2008). http://www.rggi.org
- Revkin A (2008) “1988?– 2008: Climate Then and Now.” New York Times, June 23, 2008 (read October 15, 2008). http://dotearth.blogs.nytimes.com/2008/06/23/1988-2008-climate-then-and-now
- UNFCCC (2008) Essential Background (read August 24, 2008). http://unfccc.int/essential_back-ground/items/2877.php
- UNFCCC (2008) Kyoto Protocol (read August 24, 2008). http://unfccc.int/kyoto_protocol/items/2830.php
Online resources
- Kyoto Protocol
- Kyoto Protocol and the United States
- Global Climate Change: Major Scientific and Policy Issues
- Intergovernmental Panel on Climate Change (IPCC)
- The Intergovernmental Panel on Climate Change
- The Kyoto Protocol
Instructor resources
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