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
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 and links climatic variations there to the North Atlantic. Chironomid and pollen-based reconstructions of mean July air temperature (MJAT) document notable deviations at 9.3 ka and 8.2 ka. Chironomid-inferred July air temperature is depressed by 1.4 degrees C at 9.3 ka and 1.7 degrees C at 8.2 ka relative to the long-term chironomid-inferred Holocene average of 9.4 degrees C. These cooling events also correspond to an increase in Gramineae (Poaceae) and a decrease in Betula pollen, reflecting a decrease in the density of dwarf birch cover. Concurrent, abrupt increases in several diatom taxa, including aerophilic epiphytes, and Sphagnum indicate an expansion of moss habitats as a result of wetter conditions. The expression and timing of the cooling evidenced at TK2 during the early Holocene is consistent with abrupt climate events identified in the North Atlantic and coincides with intervals of North Atlantic cooling and weakened Atlantic Meridional Overturning Circulation (AMOC). This research, which improves our understanding of the spatial extent and magnitude of the 9.3 ka and 8.2 ka events in the central Canadian Arctic, serves as a benchmark for coupled-ocean atmosphere climate models simulating the response of the climate system to abrupt climate events and provides insight in marine-atmosphere teleconnections in the circum-North Atlantic region. (C) 2019 Elsevier Ltd. All rights reserved.
1.Univ Georgia, Dept Geog, Athens, GA 30602 USA 2.Univ Calif Los Angeles, Dept Geog, Los Angeles, CA 90095 USA 3.Univ Calif Los Angeles, Dept EEB, Los Angeles, CA 90095 USA 4.Univ Western Ontario, Dept Geog, London, ON N6A 5C2, Canada 5.Fisheries & Oceans Canada, Moncton, NB E1C 5K4, Canada 6.Univ Helsinki, Dept Geosci & Geog, Helsinki, Finland 7.Queens Univ, Dept Biol, PEARL, Kingston, ON K7L 3N6, Canada
Recommended Citation:
Porinchu, David F.,MacDonald, Glen M.,Moser, Katrina A.,et al. 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[J]. QUATERNARY SCIENCE REVIEWS,2019-01-01,219:204-217