Tag Archives: annual summer minimum

Ian Stirling now says the polar bear that “died of climate change” last year was “in his prime”

With Barents Sea ice way above average this summer, Polar Bear Specialist Group biologist Ian Stirling now claims the old polar bear that he said died of climate change last year on Svalbard was “in his prime” and still blames the bear’s death on lack of sea ice — despite all evidence to the contrary.

UPDATE Sept. 19, 2014 typo fixed in Fig. 1 caption [sea ice low for 2012 was 3.41 m2km, not 4.1, see here.]

Figure 1. The National Snow and Ice Data Center (NSIDC) says the September minimum for 2014 is “imminent” and suggests the low may come in at 5.1 million square kilometers (far short of the 4.1 m2km low reached in 2012. About the much larger than average amount of ice around Svalbard and Franz Josef Land, they said only: “As was the case for the beginning of the month, extent remains below average in all sectors of the Arctic except for a region in the Barents Sea, east of Svalbard.”

Figure 1. The National Snow and Ice Data Center (NSIDC) says the September minimum for 2014 is “imminent” and suggests the low may come in at 5.1 million square kilometers (far short of the 4.1 3.41 m2km low reached in 2012. About the much larger than average amount of ice around Svalbard and Franz Josef Land, they said only: “As was the case for the beginning of the month, extent remains below average in all sectors of the Arctic except for a region in the Barents Sea, east of Svalbard.”

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Record sea ice loss in 2007 had no effect on polar bears, Chukchi study confirms

One aspect of the recently published study on Chukchi Sea polar bears (Rode et al.2014 [now in print] 2013; see here and here) has not been stressed enough: their finding that the differences in overall condition between bears in the Chukchi and Southern Beaufort Seas came down to disparities in spring feeding opportunities and therefore, the condition of spring sea ice.

The fact that spring — not summer — is the most critical period for polar bears is something I’ve pointed out before (see here and here, for example) but it’s worth repeating at this time of year, when all eyes are on the annual ice minimum. It is often treated as a given that the decline in extent of summer sea ice in the Arctic since 1979 has been detrimental to polar bears. However, this is an assumption that we can now say is not supported by scientific evidence (see summary of that evidence here).

The results published by Rode et al. (2014 2013) not only add further support to the conclusion that declines in summer sea ice have not harmed polar bears, but should put the matter to rest – unless new evidence to the contrary is produced.

Chukchi bears, the report tells us, had more food available in the spring than Southern Beaufort bears (see map below) and this was the primary reason that bears were doing very well in the Chukchi and not quite as well in the Southern Beaufort. And because the polar bears for this study were captured and measured in mid-March to early May, from 2008 to 2011, they reflect spring-time conditions for 2008-2011 as well as year-round conditions from 2007 through 2010.

This means that the annual low ice extent for 2007 (record-breaking at the time), in the fall before this study began, had no discernible negative effect on either Chukchi or Southern Beaufort polar bears – and neither did similarly low annual minimums in two of the three remaining years of the study (Fig 1).

Figure 1. Sea ice extent at August 27, 2007 – the lowest extent that year (downloaded September 15, 2013 from IARC-JAXA, Arctic Sea-ice Monitor). At the time, it was the lowest extent recorded since 1979 (2012 broke that record). This (2007) was the fall before the Rode & Regehr study on Chukchi/Southern Beaufort polar bears began (2008-2011). The ice was almost as low in September 2008 and 2010, while 2009 was more like 2013.

Figure 1. Sea ice extent at August 27, 2007 – the lowest extent that year (downloaded September 15, 2013 from IARC-JAXA, Arctic Sea-ice Monitor). At the time, it was the lowest extent recorded since 1979 (2012 broke that record). This (2007) was the fall before the Rode & Regehr study on Chukchi/Southern Beaufort polar bears began (2008-2011). The ice was almost as low in 2008 and 2010, while 2009 was more like 2013.

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