AAAR 33rd Annual Conference
October 20 - October 24, 2014
Rosen Shingle Creek
Orlando, Florida, USA
Abstract View
Future Projections of Aerosol Optical Depth, Radiative Forcing, and Climate Response due to Diminishing Aerosol Emissions
DANIEL WESTERVELT, Larry Horowitz, Vaishali Naik, Denise Mauzerall, Princeton University
Abstract Number: 556 Working Group: Aerosols, Clouds, and Climate
Abstract It is widely expected that global emissions of atmospheric aerosols and their precursors will decrease strongly throughout the remainder of the 21st century, due to emission reduction policies enacted based on human health concerns. However, the resulting decrease in atmospheric aerosol burden will have unintended climate consequences. Since aerosols generally exert a net cooling influence on the climate, their removal will lead to an unmasking of global warming as well as other changes to the climate system. Aerosol and precursor global emissions decrease by as much as 80% by the year 2100, according to projections in four Representative Concentration Pathway (RCP) scenarios. We use the Geophysical Fluid Dynamics Laboratory Climate Model version 3 (GFDL CM3) to simulate future climate over the 21st century with and without aerosol emission changes projected by the RCPs in order to isolate the radiative forcing and climate response due to the aerosol reductions. We find that up to 1 W m$^(-2) of radiative forcing may be unmasked globally by 2100 due to reductions in aerosol and precursor emissions, leading to average global temperature increases up to 1 K and global precipitation rate increases up to 0.09 mm d$^(-1) (3%). Regionally and locally, climate impacts are much larger, as RCP8.5 projects a 2.1 K warming over China, Japan, and Korea due to reduced aerosol emissions. Our results highlight the importance of crafting emissions control policies with both climate and air pollution benefits in mind. The expected unmasking of additional global warming from aerosol reductions highlights the importance of robust greenhouse gas mitigation policies and may require more aggressive policies than anticipated.