Simulations of aerosol indirect effect for IPCC emission scenarios

The potential effects of atmospheric aerosols from anthropogenic emissions on global climate changes have received a considerable amount of attention recently. Concerns are expressed regarding a possible change in the global energy budget as a result of variations in the clear sky albedo (direct effect) as well as variations in the cloud optical properties (indirect effect). In this paper, we used a coupled climate/chemistry model with cloud nucleation parameterization to simulate present and future projections of aerosol indirect radiative effects associated with model scenarios for the IPCC Third Assessment Report. These model scenarios include computations of the “Base Group A2 scenario for 2000, 2030 and 2100” and B1 2100 with all the major sulfur species, organic, black carbon, dust and sea salt aerosols. We will present global distributions of the simulated cloud drop number concentrations, effective radii as well as the magnitude of aerosol indirect forcing to address issues on the aerosol/cloud/climate interactions.

* Work performed under the auspices of the U.S. Department of Energy by the Lawrence Livermore National Laboratory under contract No. W-7405-Eng-48.