Holocene alpine glaciation inferred from lacustrine sediments on northeastern Baffin Island, Arctic Canada

With accelerated melting of alpine glaciers, understanding the future state of the cryosphere is critical. Because the observational record of glacier response to climate change is short, palaeo-records of glacier change are needed. Using proglacial lake sediments, which contain continuous and datable records of past glacier activity, we investigate Holocene glacier fluctuations on northeastern Baffin Island. Basal radiocarbon ages from three lakes constrain Laurentide Ice Sheet retreat by ca. 10.5 ka. High sedimentation rates (0.03cm a ^-1) and continuous minerogenic sedimentation throughout the Holocene in proglacial lakes, in contrast to organic-rich sediments and low sedimentation rates (0.005cma ^-1) in neighbouring non-glacial lakes, suggest that glaciers may have persisted in proglacial lake catchments since regional deglaciation. The presence of varves and relatively high magnetic susceptibility from 10 to 6 ka and since 2ka in one proglacial lake suggest minimum Holocene glacier extent ca. 6-2ka. Moraine evidence and proglacial and threshold lake sediments indicate that the maximum Holocene glacier extent occurred during the Little Ice Age. The finding that glaciers likely persisted through the Holocene is surprising, given that regional proxy records reveal summer temperatures several degrees warmer than today, and may be due to shorter ablation seasons and greater accumulation-season precipitation.