Dr. Richard B. Alley is Evan Pugh Professor of Geosciences and Associate of the EMS Environment Institute at The Pennsylvania State University, University Park, Pennsylvania. There he teaches and conducts research on the paleoclimatic records, dynamics, and sedimentary deposits of large ice sheets, as a means of understanding the climate system and its history, and projecting future changes in climate and sea level. Dr. Alley has spent three field seasons in Antarctica and five in Greenland. He is a Fellow of the American Geophysical Union, and has received many awards, including a Packard Fellowship, a Presidential Young Investigator Award, and the Horton Award of the American Geophysical Union Hydrology Section. His book on abrupt climate change, The Two-Mile Time Machine, was the national Phi Beta Kappa Science Award winner for 2001. Dr. Alley chaired a recent National Research Council study on Abrupt Climate Change, and serves, or has served, on many other advisory panels and steering committees. He has authored or coauthored more than 135 peer-reviewed publications.