Majestic, more and more hungry and threatened with extinction, the polar bear depends on one thing that’s melting on our warming planet: the ocean ice.
Within the harsh and unforgiving Arctic, the place freezing chilly isn’t just a lifestyle however a necessity, the polar bear stands out. However the place it lives, the place it hunts, the place it eats – it disappears below your ft within the essential summer season.
“They’ve at all times been a human species that goes again a whole lot and a whole lot of years,” stated the federal government’s longtime polar bear researcher Steve Amstrup, now chief scientist at Polar Bear Worldwide. “Polar bears simply have one thing particular.”
Scientists and advocates level to polar bears, marked “Endangered” on the Endangered Species listing, as a glowing purple flag for the remainder of the planet – “the canary within the cryosphere”. As world leaders meet in Glasgow, Scotland, to step up efforts to curb local weather change, the specter of polar bears looms over them.
Inger Andersen, head of the United Nations Atmosphere Program, beforehand headed the Worldwide Union for Conservation of Nature, which displays and classifies species in misery. She asks, “Do we actually wish to be the technology that noticed the tip of the viability of one thing as majestic because the polar bear?”
THE STATE OF SEA ICE
Arctic sea ice – frozen sea water – shrinks in summer season when it will get hotter, after which types once more within the lengthy winter. How a lot it shrinks is the place international warming begins, scientists say. The extra the ocean ice shrinks in summer season, the thinner the ice total, as a result of the ice is weaker first yr ice.
Julienne Stroeve, a College of Manitoba researcher, says summers with out sea ice are inevitable. Many different consultants agree.
One in every of them is former NASA chief scientist Waleed Abdalati, now a senior environmental researcher on the College of Colorado.
“Human civilization has by no means recognized that,” stated Abdalati. “It is like taking a sledgehammer to the local weather system and doing one thing huge about it.”
Warming is already engaged within the oceans and within the air – like a freight practice in movement. So the earth will quickly see a summer season through which lower than 1 million sq. kilometers of sea ice are scattered in tiny items throughout the Arctic.
The large query is when will the Arctic “seem like a blue ocean,” stated Mark Serreze, director of the Nationwide Snow and Ice Knowledge Heart.
Perhaps as early because the 2030s, most definitely within the 2040s, and nearly definitely within the 2050s, consultants say.
The Arctic is warming twice as quick as the remainder of the world. In some seasons of the yr it has warmed up 3 times quicker than the remainder of the world, stated College of Alaska scientist John Walsh.
This is because of one thing referred to as “arctic reinforcement”. Basically, white ice within the Arctic displays warmth. When it melts, the darkish sea absorbs much more warmth, which makes the oceans heat even quicker, scientists say.
THE POLAR BEAR CONNECTION
There are 19 completely different subpopulations of polar bears within the Arctic. Everyone seems to be somewhat completely different. Some are actually in bother, particularly the southernmost ones, whereas others are fairly steady. However their place-to-place survival is closely linked to sea ice.
“Whenever you go to the Arctic and see what’s occurring with your individual eyes … it is miserable,” stated College of Washington marine biologist Kristin Laidre, who studied polar bears in Baffin Bay.
Shrinking sea ice actually means shrinking polar bears.
In summer season, polar bears exit on the ice to hunt and eat, feast and achieve weight to hold them by the winter. They like areas which might be greater than half lined in ice as a result of these are the best looking and feeding grounds, Amstrup stated. The extra ice, the extra they will transfer and the extra they will eat.
As not too long ago as 30 or 40 years in the past, the bears feasted on a buffet with seals and walruses on the ice.
Within the Nineteen Eighties, “the males have been large, the females reproduced recurrently, and the younger survived effectively,” stated Amstrup. “The inhabitants appeared good.”
The bears weren’t doing so effectively with the ice loss, Amstrup stated. One signal: a better proportion of boys die earlier than their first birthday.
Polar bears are land mammals tailored to the ocean. The animals they eat – primarily seals and walruses – are aquatic animals.
The bears do finest once they can hunt in shallow water, which is often close to land.
“If there may be sea ice over these coastal waters, polar bears could make hay,” stated Amstrup.
However in recent times the ocean ice has retreated effectively offshore for a lot of the summers. That has compelled the bears to float into deep waters on the ice – typically practically a mile deep – which might be emptied of their prey, Amstrup stated.
Off Alaska, the polar bears Beaufort Sea and Chukchi Sea provide an instructive distinction.
Drive 30 to 40 miles off the coast of Prudhoe Bay within the Beaufort Sea “and you’re in very unproductive waters,” Amstrup stated.
Additional south within the Chukchi it’s shallower, which permits soil-eating walruses to thrive. That gives meals for polar bears, he stated.
“The bears within the Chukchi appear to be doing fairly effectively due to this additional productiveness,” stated Amstrup. However the Beaufort bears “give us a extremely good early warning of the place that is all going.”
THE FUTURE
As world leaders meet in Scotland to step up efforts to comprise local weather change, the scientists who monitor the ocean ice and watch the polar bears know that a lot warming is already underway.
If the negotiations are profitable and all goes effectively, there’s a likelihood the world will see an Arctic with important sea ice once more in the summertime of this century and within the twenty second century, consultants stated. However till then, “that door is closed,” stated Twila Moon, a scientist with the Nationwide Snow and Ice Knowledge Heart.
So hope is melting too.
“It’s nearly inconceivable for us to see a spot the place we can not attain a considerably sea-ice-free Arctic, even when we’re capable of produce a lot, a lot decrease emissions of heat-storing gases,” stated Moon. “Sea ice is likely one of the issues that may hit fairly devastating lows alongside the best way. And we are able to already see these influences for polar bears. “
—Seth Borenstein, Camille Fassett, and Kati Perry, The Related Press
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