It has been less than a month since the 2015 IUCN Red List assessment for polar bears was announced, which emphasized that the population trend for polar bears is unknown and that there is only a 70% chance that polar bear numbers could decline by 30% over the next 35 years.
Yet, in a press release announcing the Weston Family Prize for lifetime achievement in northern research (along with $50,000) to Ian Stirling for his work on polar bears (Newswire, December 9, 2015), Stirling is quoted repeating an out-of-date prediction:
“Dr. Stirling estimates that about half of the polar bear population around the circumpolar Arctic could disappear by 2050 to 2060, if climate warming continues as is currently projected…”
I’d have thought that if Stirling did not agree with the IUCN assessment prepared by his colleagues, he would have said so last month when the report was released to international fanfare. Instead, he seems to be deliberately ignoring the 2015 IUCN Red List assessment and pretending that the flawed predictions he had a hand in making are still plausible.
Not surprisingly, one of the “highlights” of Stirling’s career mentioned in the press release misrepresents his work on Southern Beaufort Sea bears and the devastating effects of thick spring ice because it leaves out the part about the thick spring ice.
“Another highlight was a long-term study of polar bears and seals in the Southern Beaufort Sea which was the first documentation of a distinct cycle in the ringed seal population. At intervals of roughly ten years, ringed seal reproduction and survival of their pups plummets and remains low for 2-3 years, as does the survival of young polar bears that rely on them for food. The populations then recover for a few years before the cycle repeats itself.”
Here’s the quote from (Stirling et al. 2008:21) that describes what actually happened:
“The 1960s, 1970s, and 1980s each experienced a two- to three-year decline in seal productivity in the eastern Beaufort Sea and Amundsen Gulf, associated with heavy ice conditions, around mid-decade. Each was followed by a decline in polar bear reproduction and condition, after which both seal and bear populations recovered (Smith, 1987; Harwood et al., 2000; Stirling, 2002). The beginning of each of those three periods was associated with heavy ice conditions through the winter before the reproductive decline of the seals, followed by a late spring breakup.“ [my bold]
As I pointed out earlier this week, thick spring ice due to natural causes is currently the single biggest threat to polar bears (Crockford 2015). Not declining summer sea ice – thick spring ice. That could change in the future but in recent years, thick spring ice has taken the largest toll on polar bear populations. Not just in the Southern Beaufort but in Hudson Bay as well.
Stirling has perpetuated the Arctic Fallacy that Arctic sea ice is a naturally stable habitat for the last half of his career – perhaps more vigorously than others – despite collecting and publishing strong evidence to the contrary. He knows the position he defends to this day [that the single biggest current threat to polar bears is declining summer sea ice] is not supported by the evidence because he collected that evidence.
In my opinion, Stirling may deserve an award for his dedicated early work in the Arctic but for his recent contributions, not so much.
References
Crockford, S.J. 2015. “The Arctic Fallacy: Sea ice stability and the polar bear.” GWPF Briefing 16. The Global Warming Policy Foundation, London. Pdf here.
Stirling, I., Richardson, E., Thiemann, G.W. and Derocher, A.E. 2008. Unusual predation attempts of polar bears on ringed seals in the southern Beaufort Sea: possible significance of changing spring ice conditions. Arctic 61: 14–22. http://arctic.journalhosting.ucalgary.ca/arctic/index.php/arctic/article/view/3
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