ARCTIC WARMING: EFFECTS ON LAKES NEAR RESOLUTE BAY, NUNAVUT, CANADA

The average annual air temperature at Resolute Bay is cold (-16.4˚C), but summers are getting warmer. Year 2011 provided an extreme example: 37 days during June, July, and August had temperatures that exceeded 10˚C, with an all-time recorded high of 18.7˚C on July 9^th. The warm temperatures extended to local lakes. Ice break-up occurred during the first two weeks of July, and water temperatures peaked soon thereafter – exceeding 10˚C in all lakes measured. Shallow lakes were isothermal, and deep lakes exhibited thermal stratification for a brief period. To put these observations into perspective, during 1969-1972 only 15 days during June, July, and August (avg. per year) had air temperatures that exceeded 10˚C, ice break-up occurred during late July or mid-August or not at all, and water temperatures rarely exceeded 4˚C [Schindler et al. 1974 J. Fish. Res. Board Can. 31:585-607]. The physical environments of these lakes are thus being pushed by climate warming into new steady states (from amictic or monomictic to polymictic or dimictic). We have begun research to understand resulting effects on lake chemistry and biology.