Scientists discover large rift in the Arctic's last bastion of thick sea
ice
The 3,000-square-kilometer gap in the ice may signal that the Last Ice
Area is not as resilient as previously thought.

Date:
October 14, 2021
Source:
American Geophysical Union
Summary:
In May 2020, a hole a little smaller than the state of
Rhode Island opened up for two weeks in the Last Ice Area, a
million-square-kilometer patch of sea ice north of Greenland and
Ellesmere Island that's expected to be the last refuge of ice in
a rapidly warming Arctic. The polynya is the first one that has
been identified in this part of the Last Ice Area.



FULL STORY ==========================================================================
A new study documents the formation of a 3,000-square-kilometer rift
in the oldest and thickest Arctic ice. The area of open water, called
a polynya, is the first to be identified in an area north of Ellesmere
Island, Canada's northernmost island, and is another sign of the rapid
changes taking place in the Arctic, according to researchers.


==========================================================================
In May 2020, a hole a little smaller than the state of Rhode Island opened
up for two weeks in the Last Ice Area, a million-square-kilometer patch
of sea ice north of Greenland and Ellesmere Island that's expected to
be the last refuge of ice in a rapidly warming Arctic.

The polynya is the first one that has been identified in this part of the
Last Ice Area, according to a new study detailing the findings in the
AGU journal Geophysical Research Letters, which publishes high-impact, short-format reports with immediate implications spanning all Earth and
space sciences.

The formation of the polynya was unusual because of its location, off
the coast of Ellesmere Island, where the ice is up to five meters thick.

"No one had seen a polynya in this area before. North of Ellesmere Island
it's hard to move the ice around or melt it just because it's thick,
and there's quite a bit of it. So, we generally haven't seen polynyas
form in that region before," said Kent Moore, an Arctic researcher at
the University of Toronto- Mississauga who was lead author on the study.

The surprise polynya formed during extreme wind conditions in a lingering
anti- cyclone, or a high-pressure storm with high winds that rotate
clockwise, Moore found. He combed through decades of sea-ice imagery
and atmospheric data and found that polynyas formed there at least twice before, under similar conditions in 2004 and 1988, but no one had noticed.



========================================================================== Extreme wind conditions created the gap by pushing ice aside, which
is common, said David Babb, a sea ice researcher at the University of
Manitoba who was not involved in the study. But it's unusual for sea ice
as thick as in the Last Ice Area to be blown around, especially far from
the coast where winds tend to be weaker than near the coast, he said.

The new study shows the region may not be as resilient to climate change
as previously thought.

"The formation of a polynya in the area is really interesting. 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," said Babb.

With Arctic ice getting thinner every year, polynyas could form more frequently, setting off a feedback loop of ice loss.

"The thing about thinning ice is that it's easier to move it around. As
the ice gets thinner, it's easier to create these polynyas with less
extreme forcing, so there is some evidence that these polynyas may
become more common, or become larger, than they were in the past,"
Moore said. And warmer temperatures mean that lost ice is not likely to
be replaced.



========================================================================== Crack in Arctic armor Polynyas form primarily through two ways: The
ice is either blown out of the region or melts, forming the hole. They
tend to form in the same locations year after year and typically grow
near the coast, where the landscape can channel winds along the shore,
blowing steadily in the same spot.

Polynyas are not necessarily bad for their local ecosystem on short
timescales.

Snow-covered ice doesn't let much light into the water beneath it,
limiting how much photosynthesis can occur, and that slows productivity
further up the food chain. When the ice parts, the ecosystem perks up.

"When sea ice is around, it's kind of like a desert. But when you get an
area of open water, suddenly, all kinds of activity can occur. Seabirds go there to feed, as do polar bears and seals. They're incredibly productive regions," said Moore. That food-web boost historically filtered up to
local Inuit populations who hunted in polynyas, according to Babb.

But the short-term boost for the local ecosystem doesn't outweigh the
long- term, and irreversible, damage of sea-ice loss.

"There's a transient time where if we start to lose ice, there might
be a net gain because it'd be more productive. But over the long term,
as ice melts and moves offshore and species like walruses and seabirds,
lose access to it, we lose that benefit. And eventually, it gets so warm
that species can't survive," Moore said.

========================================================================== Story Source: Materials provided by American_Geophysical_Union. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. G. W. K. Moore, S. E. L. Howell, M. Brady. First Observations of a
Transient Polynya in the Last Ice Area North of Ellesmere Island.

Geophysical Research Letters, 2021; 48 (17) DOI:
10.1029/2021GL095099 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/10/211014131158.htm

--- up 6 weeks, 8 hours, 25 minutes
* Origin: -=> Castle Rock BBS <=- Now Husky HPT Powered! (1:317/3)