ATMOSPHERIC SCIENCE:
In Search of Balance
Robert J. Charlson, Francisco P. J. Valero, John H. Seinfeld
Emissions of gases such as carbon dioxide are responsible for an enhanced greenhouse effect, but human-made changes in Earth's reflectivity via changes in clouds and aerosols may partly counteract the resulting warming. In their Perspective, Charlson et al. discuss attempts to estimate the changes in reflectivity (or albedo) both via observations and through model studies. Papers in this issue by Wielicki et al., Pinker et al., and Wild et al. report such observational estimates. However, Charlson et al. conclude that the uncertainties are still large and that sustained, direct, and simultaneous observations of albedo with all methods at researchers' disposal are necessary to resolve this important question of how much albedo is changing as a result of human activities.
R. J. Charlson is in the Department of Atmospheric Sciences and Department of Chemistry, University of Washington, Seattle, WA 98195, USA. F. P. J. Valero is in the Center for Atmospheric Sciences, Scripps Institution of Oceanography, University of California at San Diego, La Jolla, CA 92093, USA. E-mail: fvalero{at}ucsd.edu J. H. Seinfeld is in the Department of Chemical Engineering and the Department of Environmental Science and Engineering, California Institute of Technology, Pasadena, CA 91125, USA. E-mail: seinfeld{at}caltech.edu
