| Summary: | 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.
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