Welcome to the new version of CaltechAUTHORS. Login is currently restricted to library staff. If you notice any issues, please email coda@library.caltech.edu
Published April 10, 2012 | Published
Journal Article Open

Climatic effects of 1950-2050 changes in US anthropogenic aerosols - Part 2: Climate response


We investigate the climate response to changing US anthropogenic aerosol sources over the 1950–2050 period by using the NASA GISS general circulation model (GCM) and comparing to observed US temperature trends. Time-dependent aerosol distributions are generated from the GEOS-Chem chemical transport model applied to historical emission inventories and future projections. Radiative forcing from US anthropogenic aerosols peaked in 1970–1990 and has strongly declined since due to air quality regulations. We find that the regional radiative forcing from US anthropogenic aerosols elicits a strong regional climate response, cooling the central and eastern US by 0.5–1.0 °C on average during 1970–1990, with the strongest effects on maximum daytime temperatures in summer and autumn. Aerosol cooling reflects comparable contributions from direct and indirect (cloud-mediated) radiative effects. Absorbing aerosol (mainly black carbon) has negligible warming effect. Aerosol cooling reduces surface evaporation and thus decreases precipitation along the US east coast, but also increases the southerly flow of moisture from the Gulf of Mexico resulting in increased cloud cover and precipitation in the central US. Observations over the eastern US show a lack of warming in 1960–1980 followed by very rapid warming since, which we reproduce in the GCM and attribute to trends in US anthropogenic aerosol sources. Present US aerosol concentrations are sufficiently low that future air quality improvements are projected to cause little further warming in the US (0.1 °C over 2010–2050). We find that most of the warming from aerosol source controls in the US has already been realized over the 1980–2010 period.

Additional Information

© Author(s) 2012. This work is distributed under the Creative Commons Attribution 3.0 License. Received: 20 May 2011 – Discussion started: 29 Aug 2011 – Revised: 14 Dec 2011 – Accepted: 22 Feb 2012 – Published: 10 Apr 2012. This work was funded by the Electric Power Research Institute (EPRI) and by an EPA Science to Achieve Results (STAR) Graduate Research Fellowship to Eric Leibensperger. The EPRI and EPA have not officially endorsed this publication and the views expressed herein may not reflect those of the EPRI and EPA. This work utilized resources and technical support offered by the Harvard University School of Engineering and Applied Science (SEAS) Instructional and Research Computing Services (IRCS). We would like to thank Jeff Jonas and Mark Chandler of NASA GISS for help with ocean heat flux calculations and Jack Yatteau for computational assistance. We also thank three anonymous referees. Edited by: E. Highwood.

Attached Files

Published - acp-12-3349-2012.pdf


Files (1.4 MB)
Name Size Download all
1.4 MB Preview Download

Additional details

August 19, 2023
October 20, 2023