Science

‘Wholly Unexpected’: These Polar Bears Can Survive With Less Sea Ice

Scientists have recognized a definite subpopulation of polar bears in southeastern Greenland that, in an space with little sea ice, survive by looking from ice that breaks off glaciers.

The discovery suggests a manner {that a} small variety of bears would possibly survive as warming continues and extra of the ocean ice that they usually rely on disappears. But the researchers and different polar consultants cautioned that critical dangers to the general polar bear inhabitants within the Arctic stay and can solely be lessened by chopping greenhouse gasoline emissions to curb international warming.

The subpopulation, believed to quantity a number of hundred animals, was recognized throughout a multiyear research of what was considered a single inhabitants of bears alongside Greenland’s complete 1,800-mile-long east coast. Through evaluation of satellite-tracked actions, tissue samples and different information, the bears within the southeast had been discovered to be remoted, each bodily and genetically, from the others.

“This was a completely sudden discovering,” stated Kristin Laidre, a biologist on the University of Washington who has studied marine mammal ecology in Greenland for 20 years. Dr. Laidre is the lead writer of a paper on the subpopulation revealed Thursday within the journal Science.

Southeastern Greenland is particularly distant, with slender fjords hemmed in by steep mountains. At the inland finish there are sometimes glaciers that terminate within the water; on the different finish is open ocean, with a robust south-flowing present. “These bears are very geographically remoted,” Dr. Laidre stated. “They’ve actually form of advanced to be residents as a result of that is the one method to dwell down there.” The researchers estimated that this subpopulation had been remoted for at the very least a number of hundred years.

Overall. there are an estimated 26,000 polar bears across the Arctic, in 19 formally designated subpopulations. The animals dwell on the seasonal sea ice, looking their main prey, seals, because the seals bask on the ice or come up for air via respiratory holes. But the fast warming of the Arctic linked to human-caused emissions of greenhouse gases has diminished the extent and length of sea-ice cowl.

Some subpopulations, notably one within the southern Beaufort Sea off Alaska and Canada, are already declining as a result of the ice doesn’t persist lengthy sufficient for the bears to hunt sufficient meals for themselves and their offspring. Polar bear consultants say that if the world continues to heat polar bears may develop into practically extinct by the tip of the century.

Southeastern Greenland is comparatively heat, and the fjords there have much less sea-ice cowl than many different areas with polar bears – on common, about 100 days a yr with sufficient ice for them to dwell and hunt on. “We know that that’s simply too few for a polar bear to outlive,” Dr. Laidre stated. Those are the sorts of situations that will develop into widespread elsewhere within the Arctic later this century.

Dr. Laidre and her colleagues discovered that the Southeastern Greenland bears hunt from sea ice whereas it’s round. But when it is gone, the bears produce other ice to hunt from: the freshwater ice that calves off from the glaciers into the fjords, as icebergs and progressively smaller chunks, and that persists many of the yr

The bears hunt from this floating mixture of ice, referred to as glacial mélange, in the identical manner they hunt from the ocean ice. “It provides them an additional and unusual ice platform that bears in lots of different locations haven’t got,” Dr. Laidre stated, permitting them to catch sufficient seals for them and their offspring to outlive and thrive.

But habitats like this are uncommon, stated Twila Moon, a scientist with the National Snow and Ice Data Center in Boulder, Colo., Who analyzed sea-ice and glacial-ice cowl within the fjords as a part of the analysis.

“There are restricted areas within the Arctic the place we see substantial and constant manufacturing of glacial melange,” Dr. Moon stated. In addition to some areas in Greenland, the Norwegian archipelago of Svalbard has glaciers that terminate within the water.

So whereas these particular situations might enable some bears to outlive as the ocean ice continues to shrink, general the animals will proceed to be threatened by local weather change.

“We predict to see giant declines of polar bears throughout the Arctic beneath present warming trajectories,” stated Dr. Laidre stated. “And this research does not change that.”

Steven Amstrup, chief scientist with the conservation group Polar Bears International, who was not concerned within the analysis, stated the research was “actually totally finished” and “factors to a really discreet group of bears.”

Whether it constitutes a twentieth official subpopulation is as much as a bunch of consultants to resolve, beneath the auspices of the International Union for Conservation of Nature. “It’s not clear to me whether or not that can profit this group of bears by way of their safety or their general welfare as we go into the long run,” Dr. Amstrup stated.

He stated he agreed with the researchers that, as he put it, “this isn’t some form of salvation for polar bears.” For one factor, he stated, warming is inflicting every kind of ice to retreat and disappear, together with glaciers. So the glaciers within the Greenland fjords is not going to proceed to terminate within the water and produce glacial combination ceaselessly. The research, he stated, “is displaying a transient profit for these bears.”

“They can survive now, though the ice-free days by way of sea ice are too nice,” stated Dr. Amstrup added. “But going into the long run, that can change until we arrest the rise of world greenhouse gases.”

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