Collaborative Research: Testing Arctic Ice Sheet Sensitivity to Abrupt Climate Change

一组研究人员提议调查劳伦泰德冰原和格陵兰冰原对93000年前和82000年前发生的两次短期降温事件（持续时间从几十年到几个世纪不等）的反应。评估冰盖对短期气候变率的敏感性是科学界和公众最关心的问题，因为短期冰盖变化将推动21世纪海平面上升。因此，提出的工作的一个中心问题是，冰盖是否会突然对气候强迫作出反应，或者是否需要几千年尺度的气候趋势来引发大规模的冰盖反应？研究人员提出了一个密集的实地研究计划，利用他们最新发表的工作，利用高精度的铍-10测年法重建冰盖的变化，来验证一个假设，即标志着西格陵兰岛和巴芬岛以前冰范围的突出冰碛系统记录了93000年前和82000年前突然冷却事件驱动的格陵兰岛和劳伦泰德冰盖的同步推进。试点数据显示，与周围海洋接触的部分冰盖边缘能够对短暂的气候扰动作出迅速反应。为了检验这些记录的变化是否仅仅局限于最敏感的海洋终端化冰原部门，或者冰原是否能够对百年尺度的气候变化做出更大规模的响应，需要从其他地区获得约束良好的冰原变化年表。研究人员的研究目标是：1)确定更能代表更广泛冰盖边缘的冰盖陆地末端区域如何应对气候突变；2)进一步评估海洋强迫在调节冰盖对短期气候扰动的响应中所起的作用；3)重建全新世早期山地冰川系统的行为（夏季温度的代表），以评估气候条件对冰盖的影响。调查人员将努力使公众容易获得调查结果。这项工作由一位早期职业研究者领导，将支持两名研究生和几名本科生。

A team of investigators proposes to investigate the response of the Laurentide and Greenland Ice Sheets to two short term cooling events (several decades to a few centuries in duration) that occurred 9.3 and 8.2 thousand years ago. Assessing the sensitivity of ice sheets to short term climate variability is at the forefront of the scientific community's and the public's interest because short term ice sheet change will drive 21st century sea level rise. Thus a central question of the proposed work is whether ice sheets react abruptly to climate forcings, or are multi-millennial-scale trends in climate required to elicit a large-scale ice sheet response?The investigators propose an intensive field-based research program capitalizing on their newly published work reconstructing ice sheet change using high-precision beryllium-10 dating to test the hypothesis that prominent moraine systems marking former ice extents in West Greenland and Baffin Island record the synchronous advance of the Greenland and Laurentide ice sheets driven by the abrupt cooling events 9.3 and 8.2 thousand years ago. Pilot data reveal that portions of the ice sheet margin that are in contact with the surrounding ocean are able to respond rapidly to a short-lived climate perturbation. To test whether these documented changes were restricted to solely the most sensitive marine-terminating ice sheet sectors, or whether ice sheets are capable of a larger scale response to centennial-scale climate change, well-constrained chronologies of ice sheet change are needed from other regions. The investigators' research objectives are to 1) establish how land-terminating regions of ice sheets, which are more representative of broader ice sheet margins, respond to abrupt climate change, 2) further evaluate the role that oceanic forcing plays in modulating ice sheet response to short-lived climate perturbations, and 3) reconstruct the early Holocene behavior of mountain glacier systems (a proxy for summertime temperature) to evaluate what climatic conditions influenced the ice sheets. The investigators will work to make results easily accessible to the public. The work is led by an early career investigator and will support two graduate and several undergraduate students.