Global Warming

Early Collapse of Arctic Sea Ice

Earth’s already-beleaguered northern icecap suffered another blow this month with the early collapse of a barrier that kept some of Arctic’s most durable ice in place.

The ice arch across the Nares Strait, which separates Greenland from Ellesmere Island in Canada’s far northeast, gave way two months earlier than usual, said Laurence Dyke, a paleoglaciologist at the Geological Survey of Denmark and Greenland.

“On May 10, this arch disintegrated, leaving the oldest and thickest sea ice in the Arctic vulnerable to being swept south where it will melt away,” Dyke told Seeker. “Over the last two weeks, the area of broken ice has expanded massively to the north, and lots of Arctic sea ice is flowing southwards through the Nares Strait.”

The channel and the Lincoln Sea, at the northern tip of Greenland, are normally covered by a sheet of ice several meters thick until around July, Dyke said. Usually, ice sheets that cover the strait are anchored to land and don’t move, blocking the passage of sea ice through the strait.

But as heat-trapping fossil-fuel emissions like carbon dioxide build up in the atmosphere, the Arctic is warming twice as fast as the rest of the globe. And this year, land-anchored ice in the strait failed to form amid the record warmth and record low sea ice coverage recorded across the Arctic. That left only an arch of ice at the northern end of the strait, where it joined the Lincoln Sea — the structure that gave way earlier this month.

“This is especially important as the Lincoln Sea contains the last bastion of old, thick multi-year sea ice,” Dyke said.

This image shows the boundary between permanent and seasonal sea ice in the Arctic Ocean, northwest of Greenland