Huge hole discovered in Arctic’s ‘last ice’
Ahuge hole opened in the Arctic’s oldest, thickest ice in May 2020. Scientists previously thought that this area of ice was the Arctic’s most stable, but the giant rift signals that the ancient ice is vulnerable to melt. The polynya, or area of open water, is the first to be observed north of Ellesmere Island. But researchers deduced from old satellite data that similar polynyas may have opened in 1988 and 2004.
“North of Ellesmere Island it’s hard to move the ice around or melt it because it’s thick, and there’s quite a bit of it,” said Kent Moore, an Arctic researcher at the University of Toronto-mississauga. “We generally haven’t seen polynyas form in that region before.” The sea ice off the northern coast is typically more than four metres thick and has an average age of five years. But this ‘last ice’ is proving vulnerable to the rapid warming occurring in northern latitudes. In summer
2020, the Wandel Sea, or the eastern reaches of the ‘last-ice’ region, lost half of its overlying ice. A 2021 study showed that the ice arches that connect the stable sea ice to Greenland are forming later and melting faster each year.
Now, researchers say that the last-ice area may melt completely each summer by the end of
the century, spelling the end for animals that depend on year-round sea ice, such as polar bears. The polynya is another bad sign for the last ice. Polynyas are cracks in the sea ice that often open up during storms, when strong winds move the ice. There was a powerful storm north of Ellesmere Island in May 2020, and satellite imagery showed that a long narrow crack, or lead, formed on 14 May. By 15 May the lead had evolved into an elliptical polynya about 62 miles long and 18.6 miles wide. On 26 May the polynya rapidly closed.
“The formation of a polynya in the area is really interesting,” said David Babb, a sea ice researcher at the University of Manitoba in Canada. “It’s sort of like a crack in the shield of this solid ice cover that typically exists in that area. That this is happening is also really highlighting how the Arctic is changing.” In the future, polynyas might open up more frequently as the Arctic’s last ice melts, Moore said.
In the short term, these areas can be oases for life: sunlight hits the ocean water, allowing for more algal photosynthesis, which attracts fish and crustaceans. These animals attract seabirds, seals and polar bears, he added. But this explosion of life is only temporary.