Contributions to accelerating atmospheric CO2 growth from economic activity, carbon intensity, and efficiency of natural sinks
- Global Carbon Project, Commonwealth Scientific and Industrial Research Organisation Marine and Atmospheric Research, GPO Box 3023, Canberra ACT 2601 (Australia)
- School of Environment Sciences, University of East Anglia, Norwich NR4 7TJ (United Kingdom)
- Department of Global Ecology, Carnegie Institution of Washington, Stanford, CA 94305 (United States)
- fLaboratorie des Sciences du Climat et de l'Environnement, Commissariat a l'Energie Atomique, 91191 Gif sur Yvette (France)
- National Oceanic and Atmospheric Administration Earth System Research Laboratory, Boulder, CO 80305 (United States)
- hWoods Hole Research Center, Falmouth, MA 02540 (United States)
- Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States)
The growth rate of atmospheric carbon dioxide (CO2), the largest human contributor to human-induced climate change, is increasing rapidly. Three processes contribute to this rapid increase. Two of these processes concern emissions. Recent growth of the world economy combined with an increase in its carbon intensity have led to rapid growth in fossil fuel CO2 emissions since 2000: comparing the 1990s with 2000-2006, the emissions growth rate increased from 1.3% to 3.3%/y. The third process is indicated by increasing evidence (P 0.89) for a long-term (50-year) increase in the airborne fraction (AF) of CO2 emissions, implying a decline in the efficiency of CO2 sinks on land and oceans in absorbing anthropogenic emissions. Since 2000, the contributions of these three factors to the increase in the atmospheric CO2 growth rate have been {approx}65 {+-} 16% from increasing global economic activity, 17 {+-} 6% from the increasing carbon intensity of the global economy, and 18 {+-} 15% from the increase in AF. An increasing AF is consistent with results of climate-carbon cycle models, but the magnitude of the observed signal appears larger than that estimated by models. All of these changes characterize a carbon cycle that is generating stronger-than-expected and sooner-than-expected climate forcing. airborne fraction anthropogenic carbon emissions carbon-climate feedback terrestrial and ocean carbon emissions vulnerabilities of the carbon cycle.
- OSTI ID:
- 20962186
- Journal Information:
- Proceedings of the National Academy of Sciences of the United States of America, Journal Name: Proceedings of the National Academy of Sciences of the United States of America Journal Issue: 47 Vol. 104; ISSN PNASA6; ISSN 0027-8424
- Country of Publication:
- United States
- Language:
- English
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