Decadal-scale sea ice changes in the Canadian Arctic and their impacts on humans during the past 4,000 years

Climate warming of >1.5°C over three decades has diminished Arctic sea ice and forced drastic changes on Inuit people of the Canadian Arctic. Discontinuities in archaeological records also suggest that climatic changes may have caused site abandonment and life style shifts in Paleo- and Neo-eskimo societies. We therefore examine the decadal-scale palaeoclimatic changes recorded by quantitative palynological data in marine records from Coburg Polynya, near Palaeo- and Neo-eskimo settlements on the North Devon Lowlands, and from the North Water Polynya between Canada and Northwest Greenland. Palaeotransfer functions from dinoflagellate cyst assemblages provide quantitative estimates of changes in sea surface temperature (SST) and sea ice cover (SIC) with the accuracy of historical measurements.Both sites record temperature variations of 2–4°C corresponding to changes in hunting modes and occupation-abandonment cycles on Devon and Ellesmere Islands. Our data show that from ∼6500 to 2600 BP, there were large oscillations in summer SST from 2–4°C cooler than present to 6°C warmer and SIC ranged from 2 months more sea ice to 4 months more open water. The warmer interval corresponds to the period of pre-Dorset cultures that hunted muskox and caribou. Subsequent marine-based Dorset and Neo-eskimo cultures correspond to progressively cooler intervals with expanded sea ice cover. The warming took ∼50–100 years and lasted ∼300 years before replacement by colder intervals lasting ∼200–500 years. These climate oscillations are more rapid than the archaeological cultural changes, but are of similar length to successive Palaeoeskimo occupations in the Nares Strait region.