December 12th, 2012 by Joshua S Hill
Here’s one of those science stories that seem to make no sense on the surface: according to new research Potsdam Institute for Climate Impact Research (PIK) increased snowfall over Antarctica as a result of climate change is actually countered by an increase in ice-flow to the ocean, up to three times.
Thus, Antarctica’s contribution to global sea-level increase is much greater than previously estimated.
On the surface of it, this makes no sense. But here’s the catch: Antarctica will receive more snow in a warming world. That snow, however, is heavy, and exerts pressure on the ice it falls upon.
Because additional snowfall elevates the grounded ice-sheet but less so the floating ice shelves, it flows more rapidly towards the coast of Antarctica where it eventually breaks off into icebergs and elevates sea level.
“Between 30 and 65 percent of the ice gain due to enhanced snowfall in Antarctica is countervailed by enhanced ice loss along the coastline,” says lead-author Ricarda Winkelmann. “The effect exceeds that of surface warming as well as that of basal ice-shelf melting.”
“The one certainty we have about Antarctica under global warming is that snowfall will increase,” Winkelmann explains. “Since surface melt might remain comparably small even under strong global warming, because Antarctica will still be a pretty chilly place, the big question is: How much more mass within the ice sheet will slowly but inexorably flow off Antarctica and contribute to sea-level rise, which is one of the major impacts of climate change.”
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