Scientific Symposium Presentation Abstracts
September 19
Dr. Robert Bindschadler: Why Predicting West Antarctic Ice Sheet Behavior is So Hard: What We Know, What We Don’t Know, and How We Will Find Out
One million years of paleoclimate data are consistent—a warmer Earth contains less ice. What these data do not indicate is how the ice shrinks, although the period of recovery from the last glacial maximum about 20,000 years ago includes periods when rapid ice loss forced sea level upward at rates modern civilization has never experienced.
Warmer temperatures encourage ice flow and increased discharge into the ocean. This is seen in recent observations of the Greenland Ice Sheet, where surface melting is often suggested to be the agent responsible for these changes. Similar behavior is seen for the equally large West Antarctic Ice Sheet, but this is occurring where surface melting is extremely rare. Rather than seek a separate explanation for these changes in the Southern Hemisphere, warmer ocean temperatures may explain the behaviors of both ice sheets.
The sudden awakening of the ice at the margins of both ice sheets has destroyed the expectation that a precise quantification of today’s ice sheet mass balance (the rate of growth or shrinkage) can serve as a valid predictor of tomorrow’s behavior. Models of a more flexible ice sheet are being constructed, but are challenged by new observations of a highly active subglacial water system. New methods are leading to discovery of more subglacial lakes, with the surprising finding that large volumes of water are moving rapidly beneath the ice sheets. This subglacial activity of the primary lubricant of ice flow and will need to be included in models of the ice sheets before credible predictions of ice sheet behavior are possible.
