In the 1980s, the polar bear biologist Andrew Derocher never see the weak, gaunt bear cub wandering along the coast of Canada’s frigid Hudson Bay. Then, beginning around 2000, he had sometimes found malnourished polar bear cub”in a Walking Dead State.”
“They’re just walking skeletons,”Derocher,Professor, University of Alberta, said. Since the nineties, the Western Hudson Bay polar bear population, one of 19 subpopulations, decreased by 30%.
The current decline in the polar bear population in some, although not the Arctic region is straightforward: the Arctic sea ice is rapidly declining, and Bears need the sea ice to skillfully hunt the SEALs. Polar bears can’t catch seals open water. Now, a study published Monday in the journal Nature Climate Change Identify how long the Bears can fast in different Arctic regions before their people began to decline, perhaps rapidly.
“It has been clear for a long time, polar bears will suffer huge underground climate change, but it is unclear when we should start to see refused,”said Peter Molnar, an ecologist at the University of Toronto and lead author of the study.
This study concluded range between bad and dire. The researchers tested how the population of polar bears will fare how to by measuring the length of the bear is possible to quickly under two different carbon emission scenarios of the present century, both of which will be further depletion of Arctic sea ice. The study showed the importance of substantial reductions in heat-trapping carbon emissions, even if the human can not meet the extremely ambitious reductions agreed to by countries around the world in 2015-year history of the Paris climate Convention. ACE the government has abandoned this agreement.
As the Earth warmed, in the next ten years and beyond, researchers found that in a warm solution, in which the greenhouse gas emissions, a modest decline(from the beginning around mid-century), 10 of the 19 polar bear subpopulations is still Possible Or Very likely Suffer from”reproductive failure”by 2080. Reproductive point of failure for the survival of the Cubs is dramatically reduced, mainly because their mother ran out of energy to nurse her helpless cub.
This intermediate emissions case(labeled as”moderate mitigation”and officially known as the RPC4. 5)the need of civilization bring the discharge into a slow decline and ultimately stabilize the climate in some of the 2. 4 degrees Celsius(4.3 degrees Fahrenheit)above pre-industrial levels. In such a future, the polar bear experts still expect many bears to death.
“You’ll still lose some of the Southern people,”explained Molnar. “So it’s not all great news.”
In the most extreme(although more unlikely)warming of the situation—in which our civilization is rising global demand for energy increases coal combustion Five times This century almost all the population of polar bears may experience reproductive failure. For two people, it would be all but guaranteed. (This case is often labeled”business as usual”or BAU, but many climate scientists now say this Still catastrophicAlthough not so extreme, emissions scenario better describes the BAU).
The decline of the polar bear is not a simple story. Things will play out in different ways in different places. That’s because the Arctic is a diverse, sprawling place, with Islands, bays, Straits, and beyond.
“The polar bear, occur across the globe,”said Steven Amstrup, a research collaborator and chief scientist for polar bears international conservation organization based in Churchill, Canada actively studying polar bears. “Ecological and sea-ice conditions have great differences, so we hope that different groups respond in different ways at different times,”noting that the Amstrup, who previously led polar bear research for the U.S. Geological Survey in Alaska for 30 years.
Scientists have a good understanding of how long polar bears may the quick before their fat stores depleted, they cannot survive or support of the Cubs. Bears usually by fasting during each of the summer sea-ice reduction and the search for food becomes difficult.
“The polar bear is amazing, and in fasting to say,”Molnár, noting that the Bears can fast for a few months. “But, ultimately, every creature is limited.”
“Our goal is to use physiology to explore the limits of what bears can do,”he said.
“Every creature is limited.”
For example, researchers know that a healthy female bears with newborn cubs can be faster for 117 days before her cubs survival begins to decrease, with each passing day(the researchers used the body condition of polar bears in the study of the Western Hudson Bay subpopulation in the early 1990s as a reference point). To determine how the bear population will fare, Molnár and his team a pair of these survival expectations, with the survival of the desired bear on both thin and high country, how the ice is expected to disappear, in the different regions in the coming decades.
In some polar bear populations-like in the Barents Sea, Davis Strait, Western Hudson Bay, and the Chukchi Sea—it will become difficult for the Bears to continue to exist: with more ice days, the mother must go beyond the Come on. they can support the Cubs, or yourself, cause the people can not endure.
“We want people to mouth the polar bear is not self-sustaining then again,”bear biologist Derocher, who had no role in the study. It relates to a physical energy limit. “They can only get so fat, they can only use that fat for so long,”he said.
Polar bear cubs may still be born in a struggling people, but if they can’t survive, the population will decrease, perhaps disappear. It is already beginning to happen. In Western Hudson Bay, the home of the”polar bear capital of the world,”the proportion of Cubs in their second year of life, is called one year old, is in decline, said Amstrup.
But serious, these polar bear population prediction is,Amstrup emphasizes that they may be”too optimistic.” This is because as the Arctic continues warming and sea ice decline, polar bears are more likely to lean when the low-ice summer begins. “If the bear the weight of the lighter, they cannot fast long,”Amstrup said. So bear through their fasting threshold value earlier than these new forecasts show. This is probably why the population of polar bears in the southern Beaufort Sea decreased significantly About 40% of the From 2001 to 2010.
More importantly, if the human is difficult to reduce carbon emissions, the Earth will need at least several decades of stability(whether it is temperature rise of 2C, 2.5 C, 3C,or more pre-industrial levels or more), because there is still a fertile heat retention in the climate system. Stable Arctic sea ice, even in levels much lower than today, not going to happen in addition a quarter of a century later, the earth stopped warming. Protect the polar bear’s habitat, then, requires much foresight.
“If we wait until the expected event is upon us, it will be too late,”said Amstrup.
Although many of the polar bear population may still save the depletion, if humans significantly reduce carbon emissions—that is, the data of the spell a dark future. Arctic sea ice is plummeting.
“This is not a good news story for the polar bears,”said Derocher.