PERTH: For years, scientists have documented the fast retreat of Arctic ice, from dissolving glaciers in Greenland to shrinking snow cover in far northern Eurasia. Now researchers have exposed one Arctic ice cap that appears to be literally sliding into the sea.
Ice is disappearing at a truly astonishing rate in Austfonna, an expanse of frozen rock far north of the Arctic Circle in Norway’s Svalbard island chain. Just since 2012, a portion of the ice cap covering the island has thinned by a whopping 160 feet, according to an analysis of satellite measurements by a team led by researchers at Britain’s University of Leeds.
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Put another way, the ice cap’s vertical expanse dropped in two years by a distance equivalent to the height of a 16-story building. As another comparison, consider that scientists were recently alarmed to discover that one of Western Antarctica’s ice sheets was losing vertical height at a rate of 30 feet a year.
“It is a very large signal,” said Mal McMillan, a geophysicist and one of two researchers at Leeds’ Center for Polar Observation and Modelling who worked on the study. “The ice cap has slumped out into the ocean with a substantial loss of ice.”
McMillan and colleague Andrew Shepherd analyzed changes in Austfonna’s ice using data from satellites that measure, among other things, changes in elevation. They found that the gradual melting of the island’s 1,550-cubic-mile ice cap recently shifted into overdrive, for reasons that aren’t fully understood. Small ice caps like the one over Austfonna are believed to be more vulnerable to climate change-related thawing because relatively more surface area is exposed to the air and sea.
