Part of this struggle involves a scientific clash about transparency in polar bear science. My close examination of recent research has revealed that serious inconsistencies exist within the polar bear literature and between that literature and public statements made by some researchers. For example, Canadian polar bear biologist Ian Stirling learned in the 1970s that spring sea ice in the southern Beaufort Sea periodically gets so thick that seals depart, depriving local polar bears of their prey and causing their numbers to plummet. But that fact, documented in more than a dozen scientific papers, is not discussed today as part of polar bear ecology. In these days of politicized science, neither Stirling nor his colleagues mention in public the devastating effects of thick spring ice in the Beaufort Sea; instead, they imply in recent papers that the starving bears they witnessed are victims of reduced summer sea ice, which they argued depleted the bears' prey. There are also strong indications that thick spring-ice conditions happened again in 2014-16, with the impacts on polar bears being similarly portrayed as effects of global warming.
The polar bear's resilience should have meant the end of its use as an icon of global warming doomOne reason that the 2007 predictions of future polar bear survival were so far off base is that the model developed by American biologist Steven Amstrup (now at Polar Bears International, an NGO) assumed any polar bear population decline would be caused by less summer ice, despite the Beaufort Sea experience. Moreover, Amstrup and fellow modelers were overly confident in their claim that summer ice was critical for the polar bear's survival and they had little data on which to base their assumption that less summer ice would devastate the polar bears' prey.
Consequently, many scientists were surprised when other researchers subsequently found that ringed and bearded seals (the primary prey of polar bears) north of the Bering Strait especially thrived with a longer open-water season, which is particularly conducive to fishing: These seals do most of their feeding in summer. More food for seals in summer means more fat seal pups for polar bears to eat the following spring, a result that's probably true throughout the Arctic.
As long as polar bears have lots of baby seals to eat in spring, they get fat enough to survive even a longer-than-usual summer fast. And while it's true that studies in some regions show polar bears are lighter in weight than they were in the 1980s, there is no evidence that more individuals are starving to death or becoming too thin to reproduce because of less summer ice.
Not all bears get enough to eat in the spring, of course. Starvation has always been the leading natural cause of death for polar bears, due to a number of factors including competition, injury, tooth decay and illness. Some cancers induce a muscle-wasting syndrome that leads to faster-than-usual weight loss. This is likely what happened to the emaciated Baffin Island bear captured on video in July 2017 and promoted by National Geographic late last year. The videographers claimed it showed what starvation due to sea-ice loss looked like - an implausible conclusion given the time of year, the isolated nature of the incident, and the fact that sea ice that year was no more reduced than previously.
That starving-bear video may have convinced a few more gullible people that only hundreds of polar bears are left in the world. But it also motivated others to locate the International Union for Conservation of Nature (IUCN) Red List report for 2015 that estimated global polar bear numbers at somewhere between 22,000-31,000, or about 26,000, up slightly from 20,000-25,000, or about 22,500, in 2005. Newer counts not included in the 2015 assessment potentially add another 2,500 or so to the total. This increase may not be statistically significant, but it is decidedly not the 67-per-cent decline that was predicted given the ice conditions that prevailed.
The failure of the 2007 polar bear survival model is a simple fact that explodes the myth that polar bears are on their way to extinction. Although starving-bear videos and scientifically insignificant research papers still make the news, they don't alter the facts: Polar bears are thriving, making them phony icons, and false idols, for global warming alarmists.
Susan Crockford, a zoologist and adjunct professor at the University of Victoria, is author of State of the Polar Bear Report 2017, released Tuesday. She will present her findings at Grounds for Thought in Toronto. www.susancrockford.com