I am a glaciologist, geophysicist, and photographer.
My research is focused on glacier mechanics and dynamics, and particularly on the behavior of ocean-ending glaciers and glacier contributions to sea level. I have done field research for more than 30 years in glacier regions from Alaska to Antarctica to the summit of Mt. Kilimanjaro. For about a decade starting in the late 1990s, I led the long-term study of Columbia Glacier, on Alaska’s South Central Coast, a research program started by glaciology pioneers Mark Meier (also an INSTAAR Director, from 1985 to 1994) and Austin Post. Columbia Glacier is one the world’s most extensively studied and most rapidly changing glaciers, and has been the source of many crucial insights about glacier-ocean interaction. I have served as an advisor to the United Nations Environmental Program (UNEP), the Arctic Monitoring and Assessment Program (AMAP), and was a Lead Author for Chapter 13 (Sea Level Change) in the IPCC Fifth Assessment/Working Group I (2010-2014). I also operate WT Pfeffer Geophysical Consultants, LLC, providing consulting modeling, analysis, and assessments on sea level rise and glacier-related hazards.