Canadian Arctic glacier melt accelerating, irreversible

Ongoing glacier loss in the Canadian high Arctic is accelerating and probably irreversible, new model projections by Lenaerts et al. suggest. The Canadian high Arctic is home to the largest clustering of glacier ice outside of Greenland and Antarctica—146,000 square kilometers (about 60,000 square miles) of glacier ice spread across 36,000 islands. In the past few years, the mass of the glaciers in the Canadian Arctic archipelago has begun to plummet. 

The rate of ice loss in Canada’s Arctic sharply increased between 2004 and 2009, with ice loss increasing to as much as 93 cubic kilometres a year [Credit: Credit: NASA/ESA]

Observations from NASA's Gravity Recovery and Climate Experiment (GRACE) satellites suggest that from 2004 to 2011 the region's glaciers shed approximately 580 gigatons of ice. Aside from glacier calving, which plays only a small role in Canadian glacier mass loss, the drop is due largely to a shift in the surface-mass balance, with warming-induced meltwater runoff outpacing the accumulation of new snowfall.

Using a coupled atmosphere-snow climate model, the authors reproduced the observed changes in glacier mass and sought to forecast projected changes given a future of continued warming. Driving the model with a climate reanalysis dataset for the period 1960 to 2011 and with a potential future warming pathway, the authors find that their model accurately reproduces observed glacier mass losses, including a recent up-tick in the rate of the ice's decline.

The authors calculate that by 2100, when the Arctic archipelago is 6.5 Kelvin (14 degrees Fahrenheit) warmer, the rate of glacier mass loss will be roughly 144 gigatons per year, up from the present rate of 92 gigatons per year. In total, the researchers expect Canadian Arctic archipelago glaciers to lose around 18 percent of their mass by the end of the century. Given current warming trends, they suggest that the ongoing glacier loss is effectively irreversible.

Source: American Geophysical Union via EurekAlert! [March 12, 2013]