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Why does aerosol forcing control historical global-mean surface temperature change in CMIP5 models?

Publication ,  Journal Article
Rotstayn, LD; Collier, MA; Shindell, DT; Boucher, O
Published in: Journal of Climate
January 1, 2015

Linear regression is used to examine the relationship between simulated changes in historical global-mean surface temperature (GMST) and global-mean aerosol effective radiative forcing (ERF) in 14 climate models from CMIP5. The models have global-mean aerosol ERF that ranges from -0.35 to -1.60 W m-2 for 2000 relative to 1850. It is shown that aerosol ERF is the dominant factor that determines intermodel variations in simulated GMST change: correlations between aerosol ERF and simulated changes in GMST exceed 0.9 for linear trends in GMST over all periods that begin between 1860 and 1950 and end between 1995 and 2005. Comparison of modeled and observed GMST trends for these time periods gives an inferred global-mean aerosol ERF of -0.92 W m-2. On average, transient climate sensitivity is roughly 40% larger with respect to historical forcing from aerosols than well-mixed greenhouse gases. This enhanced sensitivity explains the dominant effect of aerosol forcing on simulated changes in GMST: it is estimated that 85% of the intermodel variance of simulated GMST change is explained by variations in aerosol ERF, but without the enhanced sensitivity less than half would be explained. Physically, the enhanced sensitivity is caused by a combination of 1) the larger concentration of aerosol forcing in the midlatitudes of the Northern Hemisphere, where positive feedbacks are stronger and transient warming is faster than in the Southern Hemisphere, and 2) the time evolution of aerosol forcing, which levels out earlier than forcing from well-mixed greenhouse gases.

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Published In

Journal of Climate

DOI

ISSN

0894-8755

Publication Date

January 1, 2015

Volume

28

Issue

17

Start / End Page

6608 / 6625

Related Subject Headings

  • Meteorology & Atmospheric Sciences
  • 3708 Oceanography
  • 3702 Climate change science
  • 3701 Atmospheric sciences
  • 0909 Geomatic Engineering
  • 0405 Oceanography
  • 0401 Atmospheric Sciences
 

Citation

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Rotstayn, L. D., Collier, M. A., Shindell, D. T., & Boucher, O. (2015). Why does aerosol forcing control historical global-mean surface temperature change in CMIP5 models? Journal of Climate, 28(17), 6608–6625. https://doi.org/10.1175/JCLI-D-14-00712.1
Rotstayn, L. D., M. A. Collier, D. T. Shindell, and O. Boucher. “Why does aerosol forcing control historical global-mean surface temperature change in CMIP5 models?Journal of Climate 28, no. 17 (January 1, 2015): 6608–25. https://doi.org/10.1175/JCLI-D-14-00712.1.
Rotstayn LD, Collier MA, Shindell DT, Boucher O. Why does aerosol forcing control historical global-mean surface temperature change in CMIP5 models? Journal of Climate. 2015 Jan 1;28(17):6608–25.
Rotstayn, L. D., et al. “Why does aerosol forcing control historical global-mean surface temperature change in CMIP5 models?Journal of Climate, vol. 28, no. 17, Jan. 2015, pp. 6608–25. Scopus, doi:10.1175/JCLI-D-14-00712.1.
Rotstayn LD, Collier MA, Shindell DT, Boucher O. Why does aerosol forcing control historical global-mean surface temperature change in CMIP5 models? Journal of Climate. 2015 Jan 1;28(17):6608–6625.

Published In

Journal of Climate

DOI

ISSN

0894-8755

Publication Date

January 1, 2015

Volume

28

Issue

17

Start / End Page

6608 / 6625

Related Subject Headings

  • Meteorology & Atmospheric Sciences
  • 3708 Oceanography
  • 3702 Climate change science
  • 3701 Atmospheric sciences
  • 0909 Geomatic Engineering
  • 0405 Oceanography
  • 0401 Atmospheric Sciences