Massive Rift Detected in Arctic’s ‘Last Refuge of Ice’

Massive Rift Detected in Arctic’s ‘Last Refuge of Ice’

During spring 2020, a temporary gap the size of Rhode Island appeared in the sea ice to the north of Canada’s northernmost island. Troublingly, this rift is located in the so-called “Last Ice Area” — a frozen expanse that’s expected to host the last remnants of Arctic sea ice as our world gets continually warmer.

For a period of two weeks in May 2020, a giant hole in the sea ice known as a polynya appeared in a region where these sorts of gaps are not supposed to form. Polynyas are natural gaps that form in places normally covered in ice, but this particular rift was spotted in a region north of Canada’s Ellesmere Island — a place thought to be immune to this sort of occurrence.

At its peak, the polynya measured 60 miles (100 kilometers) long and 19 miles (30 kilometers) wide. It formed in a location to the north of Ellesmere Island and Greenland that’s “predicted to be the last region to lose its multi-year ice,” according to the new paper, published in Geophysical Research Letters. The Last Ice Area hosts the thickest and oldest ice in the Arctic, which can reach over 16 feet (5 meters) thick in some places. It stands in stark contrast to the rest of the Arctic, where old, thick sea ice has been all but obliterated by warmer temperatures. That a polynya could form here came as a complete surprise to the researchers, led by Arctic researcher Kent Moore from the University of Toronto-Mississauga.

Animation showing the emergence of the polynya.  (Gif: NASA EOSDIS Worldview)
Animation showing the emergence of the polynya. (Gif: NASA EOSDIS Worldview)

“Polynyas are common in the Arctic,” Moore explained in an email. “However most of them form along the coast and are known. This polynya formed in a region where the ice is quite thick and old and where there have been no previous sightings,” he said, adding that it’s “also unique in that it formed over the open ocean.”

Moore and his colleagues used remote sensing equipment to spot the transient polynya, including true-colour satellite images from MODIS, radar satellite imagery from RADARSAT-1, and high-resolution satellite imagery from Sentinel-1. The gap was open from May 14 to May 28, 2020.

A host of animals, like polar bears, walruses, and seals, are reliant on year-long ice. The absence of these perpetual frozen refuges could wipe out entire species. Recognising the importance of the Last Ice Area, the government of Canada recently established the Tuvaijuittuq — meaning the “place where ice never melts” in Inuktut — as a Marine Protected Area to assist with conservation efforts.

It needs to be said that polynyas aren’t completely terrible, and can even have ecological benefits. These occasional gaps in the ice allow for photosynthesis, which increases food production in the water. The rifts attract all sorts of wildlife, including seabirds, polar bears, and seals. These boosts to the ecosystem are good, but the concern is that we’ll start to get too much of a good thing, as the lack of sea ice could prove existentially detrimental to many ice-dependent species, and also result in the demise of an entire ecosystem.

As the new paper points out, the polynya formed during an episode of extreme winds. A high-pressure weather system, with winds moving in a counterclockwise direction, moved through the area pushing the ice aside, creating the gap. Moore said the polynya formed as a result of winds that accelerated the ice on the western side of the polynya but not on the east,” and as a result of this divergent motion “the polynya opened up.”

Diving into the archives, the scientists discovered that similar conditions were present in the region in 1998 and again in 2004. Polynyas formed as a result, but these historic holes went unnoticed.

In an American Geophysical Union press release, David Babb, a sea ice scientist from the University of Manitoba who wasn’t involved in the new study, said the process that formed the polynya is fairly routine, but it’s not common to see it occur in a region where the ice is so thick, and in an area so far from the coast where winds tend to be weaker. Ultimately, Babb said this is not a great sign.

“The formation of a polynya in the area is really interesting,” he told the AGU. “It’s sort of like a crack in the shield of this solid ice cover that typically exists in that area. So that this is happening is also really, really highlighting how the Arctic is changing.”

The fear is that this will become a recurring thing. Regular polynyas at the Last Ice Area could kickstart a feedback loop, in which the presence of thinner ice will make it increasingly easier for polynyas to form, and for them to get larger over time. This, combined with increasingly warmer temperatures, means the lost ice may never return. It’s another worrying sign that dramatic, and possibly irrevocable, changes are happening in the high Arctic as a result of human-caused climate change.

“This work and others suggests that the ice in this region is more dynamic and the ice in the region may not be as resilient as previously thought,” said Moore.

More: So Much Ice Has Melted, That the Earth’s Crust Is Shifting in Weird, New Ways.

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