Shaky oasis for some polar bears discovered, however not for species

An grownup feminine polar bear, left, and two 1-year-old cubs stroll over snow-covered freshwater glacier ice in Southeast Greenland in March 2015. With restricted sea ice, these Southeast Greenland polar bears use freshwater icebergs spawned from the shrinking Greenland ice sheet as makeshift looking grounds, in line with a research in journal Science launched Thursday, June 16. Credit: Kristin Laidre through AP

With the polar bear species in a battle for survival due to disappearing Arctic sea ice, a brand new distinct group of Greenland bears appear to have came upon an icy oasis that may enable a small distant inhabitants to “cling on.”

But it is from “a life raft” for the endangered species that has lengthy been an emblem of local weather change, scientists mentioned.
A workforce of scientists tracked a gaggle of some hundred polar bears in Southeast Greenland that they present are genetically distinct and geographically separate from others, one thing not thought-about earlier than. But what’s actually distinct is that these bears handle to outlive regardless of solely having 100 days a 12 months when there’s sea ice to hunt seals from. Elsewhere on this planet, polar bears want at the very least 180 days, often extra, of sea ice for them to make use of as their looking base. When there is no sea ice bears typically do not eat for months.
With restricted sea ice, which is frozen ocean water, these Southeast Greenland polar bears use freshwater icebergs spawned from the shrinking Greenland ice sheet as makeshift looking grounds, in line with a research in Thursday’s journal Science. However, scientists aren’t certain if they’re thriving as a result of they’re smaller and have fewer cubs than different polar bear populations.
“These polar bears are tailored to residing in an setting that appears like the longer term,” mentioned research lead writer Kristin Laidre, a polar bear biologist on the University of Washington, who over 9 years tracked, collared and examined the all-white bears often from a helicopter hovering the white snow and ice backdrop. “But most bears within the Arctic do not have glacial ice. They do not have entry to this. So it could actually’t be taken out of context like one way or the other this is sort of a life raft for polar bears across the Arctic. It’s not. Greenland is exclusive.”
“We challenge giant declines of polar bears throughout the Arctic and this research doesn’t change that crucial message,” Laidre mentioned. “What this research does is present that we discover this remoted group residing on this distinctive place… We’re the place within the Arctic polar bears can as a species cling on, the place they may persist.”
The freshwater ice will preserve coming off the ice sheet for hundreds of years giving restricted hope that that is “a spot that polar bears would possibly proceed to outlive” however it’s separate from an general development of sea ice loss in the summertime due to emissions of heat-trapping gases from the burning of coal, oil and pure gasoline, mentioned National Snow and Ice Data Center deputy lead scientist Twila Moon, a research co-author.

These bears hunt on the recent glacial ice that has extra peaks and valleys than the flatter sea ice, typically in house- or car-sized bergs, known as bergy bits, Moon mentioned.
This inhabitants of polar bears are on the southeast tip of the large island, the place there aren’t any cities. For years scientists figured these bears had been a part of the identical inhabitants in Northeast Greenland, simply roaming up and down the large coast. But they do not, Laidre mentioned. An uncommon arrange of winds, currents and geographical options round 64 levels North make it subsequent to unattainable for bears to maneuver north of that time, the present sends them south quick, she mentioned.

Three grownup polar bears stroll in Southeast Greenland in April 2015 over sea ice through the restricted time when it’s obtainable. With restricted sea ice, these Southeast Greenland polar bears use freshwater icebergs spawned from the shrinking Greenland ice sheet as makeshift looking grounds, in line with a research in journal Science launched Thursday, June 16. Credit: Kristin Laidre through AP

While most bears journey 25 miles (40 kilometers) over 4 days, the Southeast Greenland bears go about 6 miles (10 kilometers) in the identical time, the research mentioned.
“They simply keep in the identical place for years and years,” Laidre mentioned.
Genetic testing Laidre and colleagues did confirmed they’re extra completely different from the neighboring populations than every other pair of polar bear populations on Earth, mentioned research co-author Beth Shapiro, a University of California Santa Cruz evolutionary geneticist.
Occasionally, a bear from elsewhere breeds with the southeast bear, however Shapiro mentioned it is rare and solely one-way with no bear heading north and breeding with that inhabitants.
In basic these bears are thinner than different Arctic bears, with females weighing about 400 kilos (185 kilograms), in comparison with 440 to 560 kilos (199 to 255 kilograms) elsewhere within the North American Arctic, Laidre mentioned. And in addition they are inclined to have fewer cubs, which might be as a result of they’re so remoted and do not get as many mating alternatives, she mentioned.
Because this group hadn’t been studied earlier than, Laidre mentioned it’s unattainable to inform if the Southeast Greenland polar bear inhabitants has simply tailored to be smaller and have fewer cubs or whether or not these are indicators of a harassed inhabitants and never a great signal for survival. Shapiro and others do not assume it appears good.
“They’re not reproducing as a lot as different people,” Shapiro mentioned. “They’re not as wholesome as different people who’re in a greater habitat. So it is form of an oasis perhaps, however it’s not a cheerful oasis. It’s a I’m-struggling-to-get-by-but-just-making-it form of oasis.”
Long-time polar bear scientist Steve Amstrup of Polar Bear International, who wasn’t a part of the research, mentioned he worries that folks will wrongly take this analysis to imply polar bears can adapt to local weather change, when it is about one small group that’s prolonging their capability to persist, including that this “doesn’t supply salvation.” While this group is distinct he mentioned he fears that calling consideration to it “might in truth diminish the pure isolation they at the moment get pleasure from.”
This reveals “that we are able to nonetheless actually have surprises,” Moon mentioned. “And I’m continually reminded that there is not ever a degree the place we throw within the towel.”

Newly documented inhabitants of polar bears in Southeast Greenland sheds gentle on the species’ future in a warming Arctic

More data:
Kristin L. Laidre, Glacial ice helps a definite and undocumented polar bear subpopulation persisting in late Twenty first-century sea-ice situations, Science (2022). DOI: 10.1126/science.abk2793. www.science.org/doi/10.1126/science.abk2793

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Shaky oasis for some polar bears discovered, however not for species (2022, June 19)
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