Abstract:

We investigate aerosol effects on climate for 1980 to 2030 using the NASA Goddard Institute for Space Studies climate model. The climate model is coupled to an on-line aerosol source and transport model with interactive oxidant and aerosol chemistry. Aerosols simulated include sulfates, organic carbon (OC), black carbon (BC), sea-salt and dust. The amount of tropospheric ozone is also calculated, thus allowing us to estimate both changes to air quality and climate for different time periods and emission amounts. We include both the direct and aerosol-cloud effects. Future changes for the 2030 A1B scenario are examined, focusing on Asia, since changes are pronounced in these regions. In particular, we examine the role of biofuel and transportation based emissions (for BC and OC) on regional climate over Asia. Prior simulations for present-day versus pre-industrial emissions indicate that the ratio of changes in surface temperature to the top of the atmosphere radiative fluxes for twice the amount of fossil- and biofuel BC is higher by over a factor of 10 (changes from 0.097 to 1.14 K W-1m2). Although these ranges cannot directly be compared to the climate sensitivity for 2xCO2, estimated as 0.66 K W-1m2, in the absence of a coupled ocean-atmosphere model, the wide range and magnitude for fossil- and biofuel related impacts suggest the potential role these emissions may play in mitigation efforts. Additionally, scenarios that include a projected increase in transport-based emissions over Asia and associated health effects will be investigated. Residential emissions over Asia are presently particularly large but uncertain. Some future projections suggest these will decline, however their present-day uncertainty suggests that future projections warrant particular scrutiny. We will address these issues, including climate change over Asia, for the past 20 years, for the 2030 A1B scenario, and for other alternate scenarios.

Presentation: http://www.cleanairnet.org/baq2006/1757/docs/SW20_2.ppt