Aerosol Forcing of Climate: Environmental Sciences Research Report 17(No 17 Dahlem Workshop Reports)

Global climate change as a consequence of anthropogenic changes in the chemical composition of the atmosphere poses scientific questions of a nature and interdisciplinary scope that are unprecedented. Uncertainties in the climate forecast are large and thus far have hampered the establishment of a clear world plan for preventing or mitigating against unacceptable effects. The forecast of global and regional climate changes depends upon the development of a sound understanding of the factors that change the global heat balance and thus influence the climate. Changes in heat balance due to anthropogenic or externally imposed changes in the chemical composition of the atmosphere are referred to as forcings. While the uncertainties in the global mean greenhouse-gas forcing are not negligible ( 15 per cent), uncertainties in forcings by changes in the atmospheric aerosol and in clouds are much larger, and in some cases even include uncertainty in the sign of the forcing. Reductionist science, with its compartmentalized disciplines, has not coped effectively with the scientific problems of aerosols and their effects, largely because of a need for simultaneous consideration of chemical processes, chemical properties, physical properties, and a wide variety of physical processes and consequences. In the case of natural aerosols and their effects on clouds, it is even necessary to include studies of microbiology and of biochemistry. This volume the record of intense, interdisciplinary debate between atmospheric chemists, meteorologists, physicists, and biogeochemists - considers the subset of climate forcings due to atmospheric aerosols, with particular emphasis on integrating the necessary disciplinary components. It is truly unique in its interdisciplinary approach. The information contained in the overview papers and summary reports will be of interest to policymakers and scientists alike. Goal of this Dahlem Workshop to assess the controlling factors, geographic and temporal variations of the radiative properties of atmospheric aerosols, and to examine the extent to which their forcing through direct and indirect effects counteracts greenhouse-gas forcing on regional and global climate.

Table of Contents:
Partial table of contents: GENERAL BACKGROUND PAPERS. Climate Forcing, Climate Sensitivity, and Climate Response: A Radiative Modeling Perspective on Atmospheric Aerosols (A. Lacis & M. Mishchenko). Sulfate Aerosols and Their Atmospheric Precursors (D. Muller). DISCUSSION GROUP 1. Mechanisms of Direct and Indirect Climate Forcing by Aerosols in the Arctic Region (J.-P. Blanchet). Aerosol Dynamics and Its Implication for the Global Aerosol Climatology (F. Raes, et al.). Projection of Trends in Anthropogenic Aerosol Sources (G. Hidy & M. Wolf). DISCUSSION GROUP 2. A Systematic Approach to In Situ Observations of Aerosol Properties (J. Ogren). DISCUSSION GROUP 3. Modeling Geographical and Seasonal Forcing Due to Aerosols (J. Kiehl & H. Rodhe). Remote Sensing of Direct and Indirect Aerosol Forcing (Y. Kaufman). DISCUSSION GROUP 4. Evidence for Radiative Effects of Anthropogenic Sulfate Aerosols in the Observed Climate Record (T. Karl, et al.). Glossary of Terms and Acronyms. Indexes.