EVIDENCE OF ABRUPT CLIMATE CHANGE AT 9.3 KA AND 8.2 KA IN THE CENTRAL CANADIAN ARCTIC: CONNECTION TO THE NORTH ATLANTIC AND ATLANTIC MERIDIONAL OVERTURNING CIRCULATION

The increase in temperature observed during the early Holocene in the high northern latitudes was perturbed by a series of abrupt climate events, the most pronounced of which occurred at ~ 9.3 ka and 8.2 ka. This study presents the results of a multi-proxy analysis of a Holocene lacustrine sediment sequence recovered from a small tundra lake in the central Canadian Arctic, an area known to be sensitive to climate forcing. Chironomid and pollen-based reconstructions of mean July air temperature (MJAT) document notable deviations at ~ 9.3 ka and ~ 8.2 ka. Midge-inferred July air temperature is depressed by ~ 1.1^oC at ~ 9.3 ka and 1.7^oC at ~ 8.2 ka relative to the long-term midge-inferred Holocene. The cooling that occurred at ~ 9.3 ka and ~ 8.2 ka corresponds to fluctuations in the ratio of algal chrysophycean stomatocysts to diatoms (C:D) and Gramineae (Poaceae) to Betula pollen, which likely reflect changes in ice cover and increased landscape instability, respectively. The paleoclimate data from Lake TK2 are compared to existing paleoenvironmental records from areas adjacent to the central Canadian Arctic to determine the geographic extent of environmental change associated with these events. Expression and timing of change evidenced at TK2 is consistent with abrupt climate events identified in the circum-North Atlantic and coincides with intervals of weakened Atlantic meridional overturning circulation (AMOC). Improving our understanding of the spatial extent, magnitude and seasonality of major climatic perturbations, such as the ~ 9.3 ka and ~ 8.2 ka events, will provide greater insight to the expression of abrupt climate change in the central Canadian Arctic, an area expected to be particularly impacted by anthropogenic warming, but also susceptible to perturbations in the AMOC projected to occur in the coming century.