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Atmospheric chemistry-climate feedbacks

Raes, Frank and Liao, Hong and Chen, Wei-Ting and Seinfeld, John H. (2010) Atmospheric chemistry-climate feedbacks. Journal of Geophysical Research B, 115 . Art. No. D12121. ISSN 0148-0227.

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We extend the theory of climate feedbacks to include atmospheric chemistry. A change in temperature caused by a radiative forcing will include, in general, a contribution from the chemical change that is fed back into the climate system; likewise, the change in atmospheric burdens caused by a chemical forcing will include a contribution from the associated climate change that is fed back into the chemical system. The theory includes two feedback gains, G_(che) and G_(cli). G_(che) is defined as the ratio of the change in equilibrium global mean temperature owing to long-lived greenhouse gas radiative forcing, under full climate-chemistry coupling, to that in the absence of coupling. G_(cli) is defined as the ratio of the change in equilibrium mean aerosol or gas-phase burdens owing to chemical forcing under full coupling, to that in the absence of coupling. We employ a climate-atmospheric chemistry model based on the Goddard Institute for Space Studies (GISS) GCM II', including tropospheric gas-phase chemistry, sulfate, nitrate, ammonium, black carbon, and organic carbon. While the model describes many essential couplings between climate and atmospheric chemistry, not all couplings are accounted for, such as indirect aerosol forcing and the role of natural dust and sea salt aerosols. Guided by the feedback theory, we perform perturbation experiments to quantify G_(che) and G_(cli). We find that G_(che) for surface air temperature is essentially equal to 1.00 on a planetary scale. Regionally, G_(che) is estimated to be 0.80–1.30. The gains are small compared to those of the physical feedbacks in the climate system (e.g., water vapor, and cloud feedbacks). These values for G_(che) are robust for the specific model used, but may change when using more comprehensive climate-atmospheric chemistry models. Our perturbation experiments do not allow one to obtain robust values for G_(cli). Globally averaged, the values range from 0.99 to 1.28, depending on the chemical species, while, in areas of high pollution, G_(cli) can be up to 1.15 for ozone, and as large as 1.40 for total aerosol. These preliminary values indicate a significant role of climate feedbacks in the atmospheric chemistry system.

Item Type:Article
Related URLs:
URLURL TypeDescription DOIArticle
Chen, Wei-Ting0000-0002-9292-0933
Seinfeld, John H.0000-0003-1344-4068
Additional Information:© 2010 American Geophysical Union. Received 29 September 2009; revised 2 February 2010; accepted 24 February 2010; published 26 June 2010. This work was supported by the U.S. Environmental Protection Agency STAR Program (grant RD‐83337001). Hong Liao acknowledges support from the National Science Foundation of China (grant 40775083). Frank Raes acknowledges support by the JRC Director General Sabbatical Programme.
Funding AgencyGrant Number
Environmental Protection Agency (EPA)RD‐83337001
National Natural Science Foundation of China40775083
Joint Research CentreUNSPECIFIED
Record Number:CaltechAUTHORS:20100719-112033490
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Official Citation:Raes, F., H. Liao, W.-T. Chen, and J. H. Seinfeld (2010), Atmospheric chemistry‐climate feedbacks, J. Geophys. Res., 115, D12121, doi:10.1029/2009JD013300.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:19105
Deposited By: Jason Perez
Deposited On:30 Jul 2010 22:06
Last Modified:09 Mar 2020 13:18

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