Collaborative Research: Constraining the timing and rate of southeastern Laurentide Ice Sheet thinning during the last deglaciation with cosmogenic nuclide dipsticks

全球海平面正在上升，而且还在加速上升，这对全球经济、地缘政治和安全都有影响。关于未来海平面上升的速度和幅度，最大但也是最不确定的控制因素是格陵兰和南极冰盖将如何应对持续变暖。上一次冰河时代的结束为探索这一问题提供了一个绝佳的机会，因为它以主要冰盖的崩溃和海平面的突然数米跃升为特征，这些都有待充分解释。该项目将专注于重建冰川时代最大的冰盖劳伦蒂德冰盖新英格兰部分的三维坍塌。这项研究将首先通过测量十几座大山两侧冰川巨石的表面暴露年龄来限制新英格兰冰盖变薄的时间和速度--揭示冰盖表面何时低于不同的海拔，就像浴缸里的环一样。然后，这些垂直数据点将与该地区受良好约束的水平冰缘退缩历史相结合，产生随时间推移的冰盖坍塌的三维重建。这些重建将能够评估该地区对消冰期海平面上升的贡献、对海洋的淡水输入及其对其循环的可能影响，以及冰盖如何应对上次冰川消融的突然气候变化--所有这些都对测试用于预测未来的计算机模型至关重要。

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.