Earlier this week, the Guardian newspaper ran a headline claiming that the ‘polar bear population in frozen sea north of Alaska falls 40% in 10 years’ – a claim repeated today by the AFP news agency.
Dr Susan Crockford, a Canadian zoologist and professor with more than 35 years experience, has been highly critical of these stories, claiming that they are misleading the public.
A study by US Geological Survey researchers and scientists did find that polar bear survival rates were particularly low from 2004 to 2006. However, the study also found that polar bear populations in the area had largely recovered by 2010.
Indeed, the US Fish & Wildlife Service reported earlier this year that “the number of polar bears observed in 2012 was high relative to similar surveys conducted over the past decade.”
Furthermore, some newspaper columns attributed the low survival rates in 2004- 2006 to thinning ice despite an acknowledgement by the authors that the population decline happened in thick spring ice conditions. In fact, the recovery in polar bear numbers from 2007 onwards occurred when summer sea ice was remarkably low, according to Dr Crockford.
Figure 1. This is Fig. 1 from Bromaghin et al. 2014 in press, showing the study area. Note about half of the Southern Beaufort Sea subpopulation is in the USA and the other half is in Canada. Canada has recently moved the eastern boundary to ~ Tuktoyaktuk.
Responding to the claims in the media, Dr Crockford said:
“The main story of this study is the remarkable recovery of the polar bear population by 2010 which has likely continued since then. To suggest that polar bear populations have been declining is hugely misleading.
“The authors have also acknowledged that the cause of the 2004-2006 decline was heavy spring ice conditions. They found no correlation for the decline with summer sea ice conditions.”