COLLABORATIVE RESEARCH: CONSTRAINING THE TIMING AND RATE OF SOUTHEASTERN LAURENTIDE ICE SHEET THINNING DURING THE LAST DEGLACIATION WITH COSMOGENIC NUCLIDE DIPSTICKS

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Global sea level is rising and this rise is accelerating, with implications for global economics, geopolitics, and security. The largest, but also most uncertain, control on the pace and magnitude of future sea level rise is how the Greenland and Antarctic Ice Sheets will respond to continued warming. The end of the last Ice Age provides an outstanding opportunity to probe this question since it featured the collapse of major ice sheets and abrupt mult-meter jumps in sea level that remain to be fully explained. This project will focus on reconstructing the three-dimensional collapse of the New England sector of the Laurentide Ice Sheet, the largest of the Ice Age ice masses. This research will first constrain the timing and rate of ice sheet thinning in New England by measuring surface exposure ages of glacial boulders down the sides of a dozen large mountains -- revealing when the ice sheet surface lowered below various elevations, much like rings in a bathtub. These vertical datapoints will then be combined with the well-constrained horizontal ice margin retreat history in the region to produce three-dimensional reconstructions of the ice sheet collapse through time. These reconstructions will enable an assessment of this region's contribution to deglacial sea level rise, freshwater input to the ocean and possible impacts on its circulation, and how the ice sheet responded to the abrupt climate changes of the last deglaciation -- all critical for testing computer models used to predict the future.