Polar bears: what story to consider?

Initially revealed on Might 1, 2019 within the column Pacifica Tribune's What a Pure by Jim Steele, republished right here on the request of the creator.

When the polar bear knowledgeable Mitch Taylor modeled populations within the Baffin Bay space (West Greenland) within the 1980s, he estimated between 300 and 600 bears. Inuit hunters protested that his estimates had been far too low and that the searching quotas for Baffin Bay had been far too low. For instance, Taylor and Inuit hunters sat collectively in "kappiananngittuq" to debate their disagreements. The Inuit identified that he had investigated at a time and in a spot that ignored a big a part of the inhabitants. After all, fashions primarily based on dangerous information at all times fail to mannequin actuality.

To Taylor's credit score, he reshaped his investigations primarily based on hunter suggestions. The brand new survey has tripled the estimated inhabitants to over 2000 bears. Though a development of the bear inhabitants has not been decided, it has been universally acknowledged that for the reason that 1974 Worldwide Polar Bear Conservation Settlement, populations Polar bears had been rising thanks to raised regulation of the hunt.

Of the 5 polar bear populations thought of to be in decline by Canadian researchers, three had been brought on by overhunting. Solely two declines, such because the west of Hudson Bay, had been in all probability brought on by international warming. Fashions have recommended that bears from western Hudson Bay had been in decline as a result of warming was decreasing sea ice. In 2013, extremist researchers corresponding to Andrew Derocher proclaimed: "All indications are that this inhabitants may collapse within the subsequent yr or two if situations are sufficiently degraded," the media mentioned. "The bears had been about to break down." As a substitute, this bear inhabitants has now elevated. It’s value noting that Hudson Bay is completely freed from ice each summer time. So, is much less sea ice in summer time actually hurting polar bears?

The declare that much less sea ice will result in the extinction of polar bears is just one story, a science untested. Traditionally, Derocher's declare that two-thirds of all polar bears may disappear by 2030 is laughable. Many researchers have reported that the common temperature within the Arctic was about three levels greater than at the moment between 10,000 and 6,000 years in the past and that the extent of the Sea ice was a lot much less for hundreds of years. Clearly, polar bears haven’t disappeared, and historical past doesn’t assist Derocher's narrative.

Extra importantly, research on the Arctic present that much less sea ice promotes photosynthesis. After sea ice was not too long ago down 9%, Stanford scientists decided that productiveness elevated by 30%. Extra photosynthesis gives extra meals for the fish. Extra fish feed extra seals and bigger seals feed polar bears.

Inversely, there’s sturdy proof that thick ice is detrimental to seals and bears. Regardless of the abundance of sea ice, all polar bears reduce weight every winter. The principle prey of the polar bear is the ringed seal, however its success price may be very low when it hunts seals at their respiration gap. Polar bears feed with the best success from March to Might when ringed seals convey their younger on the ice. By feasting on seal pups, bears can shortly quadruple their weight. After childbirth and moult, ringed seals depart the ice and migrate offshore to feed and develop into very inaccessible to bears for the summer time. Latest ice pack reductions from July to September should not related to the success of the summer time bear hunt. However open waters profit seals and fish.

To remain within the Arctic, all winter-ringed seals should create a number of respiration holes. When a brand new skinny ice is fashioned, they make a number of respiration holes utilizing their heads. As they strategy the winter, they gnaw and scratch to maintain their holes open. Wherever sea ice survives for a few years, it turns into too thick to create respiration holes. For instance, within the Arctic, areas of thick ice include the least quantity of seals and bears. Then again, in Hudson Bay the place new ice has to kind every year, seals and bears are plentiful!

Researchers report rings of ringed seals confused by ice within the spring. Pure cycles change the course of the wind, trapping ice in opposition to numerous coasts. Because the layers of ice overlap, the brand new ice thickens. A thicker ice prevents seals from reaching open water for feeding in the summertime, leading to weight reduction. Low weights stop seals from breeding the next yr, decreasing the bear's meals provide.

As a result of native ice situations change incessantly, polar bears don’t defend the territories. As a substitute, bears are versatile and journey nice distances searching for areas with extra seals. A radio collared bear was noticed shifting from Alaska to Greenland throughout a summer time.

When the winds dissipate, a thick sea ice could be blown into the comparatively heat Atlantic. This enables new ice to kind which may then assist extra seals and extra bears. Primarily based on this fundamental biology, the Inuit story, "It's the time for probably the most polar bears," is best supported by scientific proof.

Jim Steele is the retired director of the Sierra Nevada Discipline Campus at San Francisco State College and the creator of Landscapes and Cycles: Local weather Skepticism in an Environmentalist.

Contact: naturalclimatechange@earthlink.internet

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