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

一组研究人员建议调查劳伦泰德和格陵兰冰盖对9300年和8200年前发生的两次短期冷却事件（持续时间为几十年到几个世纪）的反应。评估冰盖对短期气候变化的敏感性是科学界和公众利益的最前沿，因为短期冰盖变化将推动21世纪海平面上升。因此，拟议工作的一个中心问题是冰盖是否突然对气候强迫作出反应，或者需要多千年尺度的气候趋势来引起大规模的冰盖反应？研究人员提出了一项密集的基于实地的研究计划，利用他们新发表的工作，使用高精度铍-10测年法重建冰盖变化，以测试以下假设：标志着西格陵兰岛和巴芬岛前冰范围的突出冰碛系统记录了9300年和8200年前突然冷却事件驱动的格陵兰岛和Laurentide冰盖的同步推进。试验数据显示，与周围海洋接触的冰盖边缘部分能够对短期气候扰动迅速作出反应。为了测试这些记录的变化是否仅限于最敏感的海洋终端冰盖部门，或者冰盖是否能够对百年尺度的气候变化做出更大规模的反应，需要其他地区的冰盖变化年表。研究人员的研究目标是：1）确定冰盖的陆地终止区域（更能代表更广泛的冰盖边缘）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反应中所起的作用，3）重建全新世早期山地冰川系统的行为（夏季温度的替代物）以评估是什么气候条件影响了冰盖。调查人员将努力使公众容易获得结果。这项工作是由一个早期的职业调查员领导，并将支持两个研究生和几个本科生。

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.