A continuous record of insect (Chironomidae) remains preserved in lake sediments is used to infer temperature changes at a small lake in Arctic Canada through the Holocene. Early Holocene summers at the study site were characterized by more thermophilous assemblages and warmer inferred temperatures than today, presumably in response to the positive anomaly in Northern Hemisphere summer insolation. Peak early Holocene warmth was interrupted by two cold reversals between 9.5 and 8 cal ka BP, during which multiple cold-stenothermous chironomid taxa appeared in the lake. The earlier reversal appears to correlate with widespread climate anomalies around 9.2 cal ka BP; the age of the younger reversal is equivocal but it may correlate with the 8.2 cal ka BP cold event documented elsewhere. Widespread, abrupt climate shifts in the early Holocene illustrate the susceptibility of the climate system to perturbations, even during periods of enhanced warmth in the Northern Hemisphere.
Bibliographical noteFunding Information:
E. Farris and E. Thomas helped with chironomid preparations. R. Coulthard, J. Hainnu, J. Qillaq and A. Wolfe assisted in the field. VECO Polar Resources provided logistical support of field work, and the Nunavut Research Institute (Nunavummi Qaujisaqtulirijikkut) helped with logistics in Iqaluit and granted access to the field site. Gratitude is extended to the people of Clyde River, Nunavut, for their hospitality and help with field work. J. Turnbull, C. Wolak (INSTAAR) and M. deMartino (University of Arizona) prepared 14 C samples. Thanks to D. Kaufman and C. Schiff (Northern Arizona University) and F.S. Hu and L. Roschen (University of Illinois) for BiSiO 2 measurements. C. Schiff also provided advice about age model development. This research was funded by Geological Society of America graduate student grants, the U.S. National Science Foundation, and University at Buffalo faculty start-up funds. A. Dyke, M. Kaplan, J. Knox, D. Porinchu and two anonymous reviewers provided helpful feedback on this manuscript.
Copyright 2011 Elsevier B.V., All rights reserved.
- Abrupt climate change