Early Collapse of Arctic Sea Ice Is Another Ominous Sign of Rapid Warming
This image from 2010 shows the boundary between permanent and seasonal sea ice in the Arctic Ocean, northwest of Greenland. / Credit: NASA
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.
The Nares Strait is the smaller of two passages that can funnel ice from that area toward the Atlantic.
The Fram Strait, on the east side of Greenland, carries “significantly more,” said Twila Moon, a glaciologist at the National Snow and Ice Data Center in Colorado — “But every little bit counts.”
And the loss of multi-year ice is already a chronic problem in the Arctic. It forms the heart of next year’s sea ice and provides habitat for whales, seals, and birds.
“It’s also playing a role to reduce the amount of heat the ocean can take in during the summer,” Moon said. If less ice is floating on the surface of the Arctic ocean, the dark-colored sea will absorb more of the Sun’s energy — “and of course, more heat in the ocean reduces our sea ice further, and we get a runaway effect.”
“Each of these small events adds up, and they’re not good news,” she added.