Carbon dioxide (Agricultural & Resource Economics)

Carbon dioxide bubbles in a carbonated beverage. Source: CC-BY-SA-3.0

Published: May 17, 2010, 12:00 am

Updated: March 28, 2018, 12:48 pm

Topics:

Physics & Chemistry (main) Environmental Chemistry (main) Environmental Monitoring (main) Greenhouse Gases (main) Petroleum (main) Climate Change (main)

Carbon dioxide (CO₂) is a linear chemical molecule consisting of one carbon atom covalently bonded to two oxygen atoms. At atmospheric pressure and temperature, carbon dioxide is a colorless, odorless gas that exists naturally as a trace gas in the Earth's atmosphere. In pure form its density is 1.45 grams per liter at 25 °C. It is a fundamental component of the Earth's carbon cycle, with a considerable number of sources, both natural and man-made; moreover, there are a significant number of large natural carbon sinks including oceans, peatlands, forests and other plant life. Plants, algae and cyanobacteria use sunlight energy to synthesize carbohydrates from carbon dioxide and water in photosynthesis, which produces oxygen as a product. Solubility of CO₂ in water is 1.45 grams per liter at 25 degrees C.

Carbon dioxide is a minor greenhouse gas produced by natural and human activities, primarily through animal, fungal and soil respiration and to a smaller extent combustion of fossil fuels; however, methane, chlorofluorocarbons, nitrogen trifluoride, and other gases are more potent greenhouse gases. Its concentration in the Earth's atmosphere has risen by more than 35% since the Industrial Revolution. Charles D. Keeling was a pioneer in the monitoring of carbon dioxide concentrations in the atmosphere. Atmospheric mixing ratios for carbon dioxide are now higher than at any time in at least the last 800,000 years, standing at 385 parts per million (ppm) compared to a pre-industrial high of 280 ppm. The current rate of increase is around two ppm per year (see Figure 1).

Sinks of Carbon Dioxide

Carbon dioxide is stored in a number of media including seawater, soils and addition to plant biomass via photosynthesis. While all of these processes have not been quantified in detail, they represent massive fluxes and sinks for sequestration of carbon. Forests are a major carbon sink; hence, deforestation and slash and burn practises are detrimental to atmospheric carbon stability.

Sources of Carbon Dioxide

Figure 1: The following graph illustrates the rise in atmospheric carbon dioxide from 1744 to 2005. Note that the increase in carbon dioxide's concentration in the atmosphere has been exponential during the period examined. An extrapolation into the immediate future would suggest continued increases. (Source: PhysicalGeography.net)

Over ninety percent of carbon dioxide is produced by living organism respiration; including soil fungi respiration. About five percent derives from deforestation and other land use change, including wildfires and slash and burn agriculture. Less than four percent derives from burning fossil fuels. Less than one percent derives from volcanic sources.

Respiration

Respiration, both on land and in the sea, is a key component of the global carbon cycle. On land, an estimated 60 Pg C (60 billion tonnes) is emitted to the atmosphere each year by autotrophic respiration. A similar amount, about 55 Pg C, is emitted as a result of heterotrophic respiration.

In the sea, autotrophic respiration is thought to account for about 58 Pg of the dissolved inorganic carbon in surface waters each year, with the contribution of heterotrophic respiration being 34 Pg C.

Although respiration is a large source of carbon dioxide, it is currently smaller than the amount of CO2 that is removed from the atmosphere annually by photosynthesis, the biochemical process by which plants and other autotrophic organisms convert carbon dioxide into biomass. However, the rapidly expanding human population is a major growth source in atmospheric emissions due to direct human respiration.

Vulcanism

Emissions of CO₂ due to volcanic activity, though sometimes large on a local scale, are relatively minor on a global scale, accounting for between 0.02 and 0.05 Pg C per year, or less than one percent of yearly human-generated carbon dioxide emissions.

Land-use Change

It is estimated that man-made changes in land-use have, until now, produced a cumulative global loss of carbon from the land of about 200 Pg. Widespread deforestation has been the main source of this loss, estimated to be responsible for nearly 90 percent of losses since the mid-nineteenth century. Losses primarily occur due to the relatively long-term carbon sinks of forests being replaced by agricultural land.

The conversion of land from forested to agricultural land can have a wide range of negative effects as far as greenhouse gas emission is concerned. Soil disturbance and increased rates of decomposition in converted soils can both lead to emission of carbon to the atmosphere, with increased soil erosion and leaching of soil nutrients further reducing the potential for the area to act as a sink for carbon. Wetland and peat disturbance also contribute to emission of methand, which is a much more potent greenhaous gas compared to carbon dioxide.

Current estimates suggest land-use changes lead to the emission of 1.7 Pg C per year in the tropics, mainly as a result of deforestation, and to a small amount of uptake (about 0.1 Pg C) in temperate and boreal areas - so producing a net source of around 1.6 Pg C per year.

Energy - Stationary Sources

Of the carbon dioxide emissions arising from fossil fuel combustion—up to 6.5 Pg C each year—around 40% is a result of electricity generation, with coal-fired generation being the leading sector. Other stationary sources include industrial (particularly iron and steel manufacture), emissions resulting from oil extraction, refinement and transportation, and domestic and commercial fossil fuel use.

Energy - Mobile Sources

Globally, transport-related emissions of carbon dioxide are growing rapidly. They currently consitute around 24% of anthropogenic CO₂ emissions. Road transport dominates these emissions, though off-road, air and marine transport emissions are aslo significant. The use of petroleum as a fossil fuel for transportation dominates carbon dioxide emissions from this source. In 1999, in the U. S., more than 30 percent of fossil fuel-related carbon dioxide emissions were a direct result of transportation. With about two-thirds of this being from gasoline consumption by motor vehicles and the remainder coming from diesel and jet fuel use in lorries and aircraft, respectively. Per mile driven, the least CO2 polluting vehicle is the hybrid vehicle, followed by fuel efficient internal combustion engine vehicles. Electric vehicles generate the highest CO2 emissions on a life cycle basis, due to the extremely high carbon emissions of electric vehicle battery production, most of which occurs in China from coal burning.(Dai et al, 2019)

Industry (non-energy-related)

Carbon dioxide is produced in lime and cement manufacture as a result of the heating of limestone. The final amount of CO₂ produced varies depending the type of cement being made. Globally, this source is estimated to amount to 0.2 Pg C emission to the atmosphere each year. Significant carbon dioxide emissions (around 0.25 PgC per year) also result from its use in chemical feedstocks.

Biomass Burning

Though responsible for large CO₂ emissions over short time-scales, the net CO₂ emissions due to biomass burning are difficult to quantify due to the subsequent uptake of CO₂ through regrowth of vegetation. An unsustainable (i.e., not off-set by regrowth) fraction equivalent to about 10% of total emissions is generally assumed biomass used in energy-generation, with this figure being incorporated into the total emissions resulting from land-use change.

Relationship to Climate Outcome Parameters

From tree ring studies (Cook, 2001), hurricane historic records, stalagmite studies (Jennings, 1957) and flooding historic records, there is no evidence that carbon dioxide increases starting in the Industrial Revolution has any effect on frequency of hurricanes, floods, droughts (Hughes, 1992) or wildfires. In fact most of these extreme events peaked hundreds of years before present.

See Also

• Deforestation
• Holocene Climate
• Groundwater
• Paleoclimate
• Respiration
• Radiative forcing
• Solar photovoltaic
• Solar power

References

• K. R. Briffa, P. D. Jones, T. S. Bartholin, D. Eckstein, F. H. Schweingruber, W. Karlén, P. Zetterberg, M. Eronen, Fennoscandian summers from A.D. 500: Temperature changes on short and long timescales. Clim. Dyn. 7, 111–119 (1992).
• U. Büntgen, W. Tegel, K. Nicolussi, M. McCormick, D. Frank, V. Trouet, J. O. Kaplan, F. Herzig, K.-U. Heussner, H. Wanner, J. Luterbacher, J. Esper, 2500 years of European climate variability and human susceptibility. Science 331, 578–582 (2011).
• Ed Cook. (2001) North American Drought Atlas. National Science Foundation, Division of Atmospheric Sciences, Paleoclimate Program, SGER Award ATM 03-22403
• R. J. Cooper, T. M. Melvin, I. Tyers, R. J. S. Wilson, K. R. Briffa, A tree-ring reconstruction of East Anglian (UK) hydroclimate variability over the last millennium. Clim. Dyn. 40, 1019–1039 (2013).wkins, E., and R. Sutton (2009) The potential to narrow uncertainty in regional climate predictions. Bull. Amer. Meteor. Soc., 90, 1095–1107
• Qiang Dai, Jarod Kelly, Linda Gaines and Michael Wang (2019) Life Cycle Analysis of Lithium-Ion Batteries for Automotive Applications. Systems Assessment Group, Energy Systems Division, Argonne National Laboratory, DuPage County, Argonne, IL 60439, USA. Batteries 2019, 5(2), 48; https://doi.org/10.3390/batteries5020048
• Malcolm K Hughes & Peter M Brown (1992) Drought frequency in central California since 101 B.C. recorded in giant sequoia tree rings. Climate Dynamics volume 6, pages161–167
• Jennings, Jesse (1957). Danger Cave. Salt Lake City: University of Utah Press Anthropological Papers, No. 27. ISBN 978-0874806120
• Zhenhao Duana and Rui Sun. 2003. An improved model calculating CO2 solubility in pure water and aqueous NaCl solutions from 273 to 533 K and from 0 to 2000 bar. Chemical Geology 193: 260–271.
• Carbon dioxide Capture and Storage. IPCC 2005 Full Text (Carbon dioxide) .
• Greenhouse Gas Sinks. Reay et al. (eds). CABI Publishing (in press).
• PhysicalGeography.net

Citation

Dave Reay, Michael Pidwirny and C. Michael Hogan. (2013). Carbon dioxide. ed. Sidney Draggan. Encyclopedia of Earth. National Council for Science and Environment. Washington DC. Retrieved from http://editors.eol.org/eoearth/wiki/Carbon_dioxide_(Agricultural_&_Resource_Economics)

1 Comment

Milton Beychok wrote: 09-12-2011 16:21:56

The title of this article should be revised to reflect the fact that it is entirely about carbon dioxide as a greenhouse gas. If the title is not changed, than readers should be provided at least some of the physical and chemical properties of the gaseous chemical compound named carbon dioxide. For example, the article should at least include the chemical compound's molecular weight, melting point, boiling point, color, odor, density, solubility in water, etc., etc.