With about the same minimum Arctic sea ice extent this season as 2008 and 2010, persistent claims of ‘rapid decline’ are looking more than threadbare, and polar bears don’t seem too bothered either, judging by the numbers. Climate scare merchants may have to look elsewhere to try and generate a headline.
We’ve hit the seasonal Arctic sea ice minimum for this year, called this morning by US NSIDC for 19th and 23rd of Septmeber: 4.59 mkm2, the same extent as 2008 and 2010. This is not a “ho-hum” year for polar bears: it means that since 2007, they have triumphed through 10 or 11 years1 with summer ice coverage below 5.0 mkm2 — levels that in 2007were expected to cause catastrophic declines in numbers.
Summer sea ice below 5.0 mkm2 were not expected to occur until about 2050, according to 2005/2006 sea ice models and polar bear specialists at the US Geological Survey (USGS). Polar bear survival models predicted 2/3 of the world’s polar bears would disappear when ice levels reached this threshold for 8 out of 10 years (Amstrup et al. 2007, 2008; Hunter 2007) but polar bears have been more resilientthan expected (Crockford 2017, 2018; Crockford…
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September 28, 2018 at 02:57AM