2024-2025: Cryosphere: Eric Steig

Eric Steig

University of Washington

Biography

Eric Steig is the Rabinowitz Professor in the Department of Earth and Space Sciences, and Adjunct Professor in Atmospheric Sciences, University of Washington. He served as Department Chair from 2020 to 2024. 
Eric holds a BA from Hampshire College, and M.S. and Ph.D. degrees from the University of Washington in Seattle. He did postdoctoral work University of Colorado and taught at the University of Pennsylvania before returning to Seattle in 2001. He has held visiting appointments at the University of Copenhagen, University Aix-Marseille, and University of Edinburgh.
For most of his career, Eric’s work has focused on the acquisition of alpine and polar ice-core records, and the development of methods and instrumentation for their analysis. He also contributed to the development of cosmogenic isotope methods used for dating landscape features and determining rates of geomorphic change. His primary current interest is role of atmosphere-ocean forcing in driving Antarctic and Greenland ice sheet change.
Eric teaches about climate, glaciology, and isotope geochemistry, and the history of earth sciences. He has advised a diverse group of more than two dozen postdocs and graduate students, all of whom have gone on to successful careers in science in academia and the private sector.
 
Eric was elected a Fellow of the American Association for the Advancement of Science in 2019 in part for his "innovation in science communication". He was elected an AGU Fellow in 2023 for "fundamental contributions in ice core, paleoclimate, and climate dynamics research". He was awarded a Guggenheim Fellowship in 2024.


Abstract: The past and future of the polar ice sheets.

It is well known that the Greenland and Antarctic ice sheets are melting and contributing to sea level rise.  Perhaps less well known is that the reasons this is happening are quite different in each region, and are not entirely well understood. In Greenland, and throughout the Arctic, it is largely (though not entirely) a matter of warmer air temperatures: warmer air, more ice melt. In Antarctica, air temperatures remain well below freezing all year and are not a particularly important factor except in but the most northerly parts of Antarctica. Instead, Antarctica is primarily melting from below, where relatively warm ocean water melts the underside of ice shelves (the floating part of a glacier where it reaches the sea). For both regions, the connection between climate change and ice melt is more complicated than it might appear at first glance.
This talk will review our current understanding of the relationship between climate change and melting ice sheets, with an emphasis on the role that geological records from ice and sediment cores have played in advancing our knowledge. Such records are especially important in Antarctica, where direct climate observations from modern instruments began only in the last 1950s, and where most observations of ice sheet change begin only in the 1990s.
We now know that West Antarctic ice sheet collapsed during the last interglacial period, about 125,000 years ago, raising sea level by as much a 3 meters. The Greenland ice sheet, too, was much smaller at that time, contributing about 1.5 meters. We also know that the beginning of melting that we observe today in Antarctica probably began in the 1940s, much earlier than once thought. These observations, combined with modern observations and numerical climate and ice-sheet models, show that a complex interplay between winds, sea ice, ocean currents, and the geometry of the melting ice itself, all influence the efficiency with which warm air or warm water reaches and melts the ice. Remarkably, the distant tropical Pacific Ocean may play an important role, both in Greenland and in Antarctica. This new understanding has important implications for how the ice sheets will evolve in the future, and how rapidly they will change.