Polar bear numbers to plunge a third as sea ice melts: study

There is a 70% chance that the global polar bear population, estimated at 26,000, will decline by more than 30% over the next 35
There is a 70% chance that the global polar bear population, estimated at 26,000, will decline by more than 30% over the next 35 years, according to the latest assessment

Polar bear numbers could drop a third by mid-century, according to the first systematic assessment, released on Wednesday, of how dwindling Arctic sea ice affects the world's largest bear.

There is a 70 percent chance that the global polar bear population –- estimated at 26,000 -– will decline by more than 30 percent over the next 35 years, a period corresponding to three generations, the study found.

Other assessments have reached similar conclusions, notably a recent review by the International Union for the Conservation of Nature (IUCN), which tracks endangered species on its Red List.

The IUCN classified the sea-faring polar bear—a.k.a. Ursus maritimus—as "vulnerable", or at high risk of extinction in the wild.

But the new study, published in the Royal Society's Biology Letters, is the most comprehensive to date, combining 35 years of satellite data on Arctic sea ice with all known shifts in 19 distinct polar bears groupings scattered across four ecological zones in the Arctic.

"Polar bears depend on sea ice for most aspects of their life history," the study notes.

Most importantly, they use it as a floating platform to hunt seals, which can outswim them in open water.

Researchers led by Eric Regehr of the US Fish and Wildlife Service in Anchorage, Alaska projected three population scenarios out to mid-century, and all of them were bad news for the snow-white carnivores.

the International Union for the Conservation of Nature (IUCN) has classified the sea-faring polar bear, a.k.a. Ursus maritimus,
the International Union for the Conservation of Nature (IUCN) has classified the sea-faring polar bear, a.k.a. Ursus maritimus, as 'vulnerable', or at high risk of extinction in the wild

The first assumed a proportional decline in sea ice and polar bears.

Despite year-to-year fluctuations, long-term trends are unmistakable: the ten lowest Arctic ice extents over the satellite record have all occurred since 2007.

The record low of 3.41 million square kilometres (1.32 million square miles) in 2012 was 44 percent below the 1981-2010 average.

This week, the US National Snow and Ice Data Center reported that in October and November was the lowest ever registered for both months.

Ice-free summers

The culprit is global warming, which has raised the region's surface temperatures by more than two degrees Celsius (3.6 degrees Fahrenheit) compared to the pre-industrial era level, twice the global average.

On current trends, The Arctic could see its first ice-free summers sometime in the 2030s, according to climate scientists.

In the second and third scenarios, the same sea ice projections were matched with available data about changes in specific polar bear populations spanning at least a decade, in small areas in one case, and across the four larger "eco-zones" in the second.

On current trends, The Arctic could see its first ice-free summers sometime in the 2030s, according to climate scientists
On current trends, The Arctic could see its first ice-free summers sometime in the 2030s, according to climate scientists

Averaging all three scenarios, the probability that polar bear numbers would drop by a third in 35 to 41 years is more than 70 percent, the study concluded.

Unfortunately, face other threats besides a habitat radically altered by the release of heat-trapping greenhouse gases.

In the 1980s and 1990s, females and pups were found to have accumulated high levels of toxic PCPs in their tissue and organs.

The manmade chemicals—used for decades and banned in many countries in the late 1970s—worked their way up through the food chain, becoming more concentrated along the way.

But a new study, published last week in the Royal Society's Proceedings B, suggested that declines in some polar bear populations stemmed from contaminated males rendered sterile by the chemicals.

"PCB concentrations in the Arctic have levelled off," said lead author Viola Pavlova, a scientist at the Institute of Hydrobiology in the Czech Republic.

"Unfortunately, many other manmade chemicals that are also endocrine disruptors occur in the Arctic and could act similarly," she told AFP.


Explore further

Polar bears losing crucial sea ice: study

More information: Conservation status of polar bears (Ursus maritimus) in relation to projected sea-ice declines, Biology Letters, rsbl.royalsocietypublishing.or … .1098/rsbl.2016.0556
Journal information: Biology Letters

© 2016 AFP

Citation: Polar bear numbers to plunge a third as sea ice melts: study (2016, December 7) retrieved 26 April 2019 from https://phys.org/news/2016-12-polar-plunge-sea-ice.html
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Dec 07, 2016
As per usual, the researchers will be surprised when within the next 7 years, the numbers drop off to their predicted value. Not the 35 years they were expecting.
They are most probably underestimating the speed at which the snow melt is ACCELERATING!

Then of course there will be the mounting awareness of the problems the rising and churning sea levels are causing:
"On the earth, nations will be in anguish and perplexity at the roaring and tossing of the sea."
Luke 21:25.

Dec 07, 2016
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Dec 07, 2016
Sea ice summer lows have little effect on polar bears. They need good ice conditions in the spring when their main food source (seal pups) is appearing. How did they survive through these millions of years when no ice at all in the North Pole was frequently occurring? Google Susan Crockford to get less hysterical analyses.

Dec 07, 2016
Hey, it's okay, because this guy says so. Forget the opinions of real scientists who have studied this their professional lives, this guy is another Trump.

Dug
Dec 07, 2016
No mention of the El Nino (just ending - maybe) and the coming La Nina cycle's effect on Arctic melt predictions. Which at a minimum should make a readers at least skeptical of such predictions. A La Nina of equal strength to the current ending EL Nino would play havoc with any predictions that didn't make accurate forecasts of the coming La Nina. Seeing how the this current El Nino length forecast was totally off, not much hope for the La Nina forecast ability either. Conclusion - computer aided speculation at best.

Dec 07, 2016
Wait..... there is still ice in the Arctic!
Quick! No one tell False "Profit" Al.
http://dailycalle...ictions/

Dec 07, 2016
USGS scientist emeritus Steven Armstrup says " (W)hether polar bears survived one or two warming periods of the past, they never have faced the kind of warming we will see in the next century." And "(I)f we continue on our current greenhouse-warming path, it will be far warmer in 50 years than at anytime in the existence of polar bears. That is, by the latter half of this century, polar bears will be off the charts of anything they have experienced during their evolutionary history."

Brendan Kelly, an evolutionary biologist at the University of Alaska, says "(T)he kind of adaptation that's necessary is a change toward genes that fit the new climatic environment better than the old genes. Individuals don't adapt genetically. Populations do. That requires generations, which requires time. Bears, seals, whales -- these are long-lived animals. They need decades and centuries to adapt. But we're talking about losing the Arctic summer sea ice in a matter of a few decades."

Dec 07, 2016
The world polar-bear population is at a modern high — and growing. Mitch Taylor, a polar-bear biologist with Canada's Federal Provincial Polar Bear Technical Committee, notes that the bears now number about 24,000 — up about 40 percent from 1974....

http://www.sej.or...going-an

And so the AGW Cult keeps regurgitating the same old lies for their hungry ignorant Chicken Littles. Gobble up.

Dec 09, 2016
70 million Americans live on food stamps.

Dec 15, 2016
I've never met a denier that didn't have serious issues with autoerotic fixations. And erection control.

Hmm.... sounds so angry and disappointed, must have been the way you bent over.
LOL.

Dec 15, 2016
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