Dr. Kevin E. Trenberth is an atmospheric scientist and Head of the Climate Analysis Section at the National Center for Atmospheric Research* in Boulder, Colorado. He is a fellow of the American Meteorological Society and the American Association for the Advancement of Science, an honorary fellow of the Royal Society of New Zealand, and the Co-Chairman of the Scientific Steering Group for the World Climate Research Programme's Climate Variability and Predictability (CLIVAR) program. E-mail: trenbert@ucar.edu

*NCAR is sponsored by the National Science Foundation.