Collaborative Research: Arctic Sensitivity to Climate Perturbations and a Millenial Perspective on Current Warming Derived from Shrinking Ice Caps

这项提议的目标是为目前的气候变暖提供一个千年背景，并更好地限制过去5000年北极北大西洋地区气候突然变化的性质。这一目标将通过强大的数据集来实现，这些数据集来自保存在冰盖下数百年至数千年的放射性碳年代植被，但现在加拿大东北部和西格陵兰岛目前的冰缘撤退每年都会暴露出来。这些年表定义了最近夏季突然降温的模式和时间，并将当前的变暖置于千禧年的背景下。植被的14C测年将通过在最近裸露的岩石表面现场测量14C库存来补充，这对整个全新世有冰和无冰条件的持续时间提供了基本的时间限制。这两个数据集结合在一起，将通过明确测定该地区上一次像现在一样温暖的时间，为当前夏季变暖的特征提供最可靠的证据。将我们的气候重建与欧洲西北部正在进行的研究进行比较，将有助于区分非强迫变化和半球对称强迫作为气候突然变化的原因所起的作用。这一奖项下的研究活动将通过将目标和最终成果翻译成因努基特语、张贴描述研究的海报以及在努纳武特首府伊卡卢伊特和研训所长期存在的奇基克塔尔华克举办公开讲座，向土著人民提供。该研究项目将培养一名博士和硕士研究生，并为本科生提供参与研究的机会，延续前几年的成功传统。

The goal of this proposal is to provide a millennial context for current warming and to better constrain the nature of abrupt climate changes over the past 5000 years in the North Atlantic sector of the Arctic. This goal will be addressed with the powerful datasets derived from radiocarbon-dated vegetation preserved beneath ice caps for centuries to millennia, but now being exposed annually by current ice-margin retreat across northeastern Canada and West Greenland. These chronologies define the pattern and timing of abrupt summer coolings in the recent past and place current warming in a millennial context. 14C dating of vegetation will be complemented by measuring in situ 14C inventories in recently exposed rock surfaces, providing essential temporal constraints on the duration of ice-covered and ice-free conditions throughout the Holocene. Combined, these two datasets will provide the most secure evidence for the character of current summer warming by explicitly dating when the region was last as warm as present. Comparing our climate reconstructions with on-going studies in NW Europe will help to separate the roles of unforced variability from hemispherically symmetric forcing as causes for abrupt climate change. Research activities under this award will be made accessible to indigenous peoples by translating the goals and eventual results into Inuktitut, through posters that describe the research, and by offering public lectures in Iqaluit, the capital of Nunavut, and at Qikiqtarjuaq, where INSTAAR has long had a presence. This research program will train a PhD and MSc student, and provides opportunities for undergraduate students to become involved with research, building on successful traditions from previous years.