beecee Posted March 30, 2018 Posted March 30, 2018 https://phys.org/news/2018-03-reveals-startling-evidence-effects-climate.html New research led by U of T Mississauga geographer Igor Lehnherr provides startling evidence that remote areas in Canada's Arctic region—once thought to be beyond the reach of human impact—are responding rapidly to warming global temperatures. The study, published in Nature Communications, is the first to aggregate and analyze massive data sets on Lake Hazen, the world's largest lake by volume located north of the Arctic Circle. "Even in a place so far north, it's no longer cold enough to prevent the glaciers from shrinking," says Lehnherr, lead author on the study. "If this place is no longer conducive for glaciers to grow, there are not many other refuges left on the planet." Read more at: https://phys.org/news/2018-03-reveals-startling-evidence-effects-climate.html#jCp the paper: https://www.nature.com/articles/s41467-018-03685-z The world’s largest High Arctic lake responds rapidly to climate warming Abstract Using a whole-watershed approach and a combination of historical, contemporary, modeled and paleolimnological datasets, we show that the High Arctic’s largest lake by volume (Lake Hazen) has succumbed to climate warming with only a ~1 °C relative increase in summer air temperatures. This warming deepened the soil active layer and triggered large mass losses from the watershed’s glaciers, resulting in a ~10 times increase in delivery of glacial meltwaters, sediment, organic carbon and legacy contaminants to Lake Hazen, a >70% decrease in lake water residence time, and near certainty of summer ice-free conditions. Concomitantly, the community assemblage of diatom primary producers in the lake shifted dramatically with declining ice cover, from shoreline benthic to open-water planktonic species, and the physiological condition of the only fish species in the lake, Arctic Char, declined significantly. Collectively, these changes place Lake Hazen in a biogeochemical, limnological and ecological regime unprecedented within the past ~300 years. 1
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