Happy International Polar Bear Day! Thriving polar bear populations have exposed the hubris behind global warming’s most beloved icon.
In 2005, international polar bear specialists decided that future sea ice loss due to human-caused global warming had replaced wanton over-hunting as the primary threat to polar bear survival.
It was the first time that such future risks were used to decide a species conservation status.
In 2007, American government biologists insisted that by 2050, when summer sea ice would cover 42% less of the Arctic than it did in 1979, polar bears in ten populations most at risk would be wiped out.
Almost 20,000 bears would be gone by mid-century and by 2100, the species would be on the brink of extinction.
The process had already begun, the experts said, and it would only get worse.
Polar bears became a global warming icon, the preferred symbol of the consequences of burning fossil fuels.
The media, with the help of polar bear specialists and conservation organizations, made sure we were aware of each incident that signaled the dying of the species.
A few polar bears were reported to have drowned in a storm – expect more and more bears to drown during long swims across open water, we were told.
Photographers filmed a bear or two breaking through thin ice, and suggested yet another way drowning deaths could occur.
A few photos of starving bears made headlines, usually accompanied by the suggestion that perhaps hundreds more were in the same condition.
A few incidents of cannibalism also made headlines, again with the implication that dozens more were going unreported across the Arctic, as polar bears became desperate with hunger.
This frenzy of dire news went on unchecked until 2007, when the first reports on polar bear studies undertaken since 2004 were made public.
Surprisingly, the news from a new Davis Strait study wasn’t grim but encouraging.
Not until about 2013, however, as more studies were completed, did it become clear that polar bears really were thriving.
Unfortunately, the media weren’t so keen on good news: if positive results were reported at all, the encouraging aspects were downplayed or dismissed, often using quotes from polar bear specialists themselves.
It was as if polar bear scientists and their government funders wanted the public in the dark about the good news.
What was going on?
Summer sea ice had indeed declined – more than expected, in fact.
By 2016, it was apparent that potentially devastating ice levels had come decades sooner than experts predicted.
By September 2007 sea ice extent was about 43% less than it had been in 1979 – a magnitude of decline not expected until mid-century, and every year after was almost as low, or lower.
Polar bears had been living through their dire sea ice future since 2007.
Yet no more drowned polar bears were documented, no more bears than normal starved to death, no unusual spikes in cannibalism occurred, and not a single polar bear population was wiped out.
Polar bear photos still led media stories about starving bears, sea ice loss, and the threats of global warming but they were photos of fat, healthy bears.
By 2015, new studies showed that several populations once thought to be declining had increased in size or remained stable.
In 2005, the official global polar bear estimate was about 22,500.
By 2015, it had risen to about 26,500 but only part of that was a real increase.
However, by early 2017, the results of two studies of bears in high-risk regions were made public: they never made the mainstream papers, but they changed the picture.
Polar bear numbers in one half of the Barents Sea, had increased by 42% between 2004 and 2015, suggesting the entire population grew, by about 1100 – an increase not included in the official global estimate.
A survey of Baffin Bay bears, completed in 2013, showed that the population had not declined by 25% as expected but increased by 36% – adding about 750 more bears to the global total.
The formerly small population in Kane Basin more than doubled.
Now we know that between 2005 and 2015, the estimated size of polar bear populations in the two ecoregions that experts thought would be wiped out by years of low summer sea ice had grown by more than 3100.
The global average had risen to about thirty thousand bears, far and away the highest estimate in more than 50 years.
So why did the models devised by polar bear experts get it so wrong?
First, it appears that sea ice conditions and food abundance in early spring have been very good for polar bears despite the decline in summer ice extent.
Polar bears consume 8 months worth of food during early spring, which makes it the critical feeding period.
Second, it appears the experts assumed that when summer sea ice was present, polar bears ate more seals than they actually do.
Adult bearded and harp seals are virtually the only seals that rest on the ice from about mid-May to October because most ringed seals (the primary prey species of polar bears) have left the ice to feed.
Broken pack ice in summer leaves these adult seals many escape routes, which means most polar bears eat very little over the summer whether they spend those months on the sea ice or on shore.
It turns out summer is not a critical feeding season for polar bears.
Lastly, seal pups in many areas are more abundant than they were in the 1980s.
Less summer ice in the Chukchi Sea, for example, has meant more ringed seal pups in spring for polar bears to eat because these seals do most of their feeding in open water.
In short, the claim that summer sea ice is essential habitat for polar bears has been scuttled by their continued health through years of low ice coverage.
Evidence does not support the claim that loss of summer sea ice, regardless of the cause, is a major risk for polar bear survival.
Polar bear specialists vastly underestimated the resilience of polar bears when they modeled future survival and many of the assumptions they made were wrong.
Thriving polar bear populations have exposed the hubris behind global warming’s most beloved icon and “the plight of the polar bear” has become an international joke.
Humpback whales were recently taken off the US Endangered Species List because their population size indicated a strong recovery from past over-hunting.
Polar bears have done the same and are not currently threatened with extinction.
A thorough external review of the polar bear status issue is now required – not only because it’s the right thing to do but because it may help restore public support for science and conservation.