Tag Archives: ice-free Arctic

Polar bears are not in peril due to recent sea ice changes

To counter the misleading ploy used by the Sunday Times — of implying polar bears are in peril because of recent changes in Arctic sea ice (Sunday Times & The Australian, 21/22 Sept. 2014 Arctic ice cap in a ‘death spiral’) — I’ll go over again why the polar bear as a species is not threatened by declines in summer sea ice or even winter ice that is predominantly “thin” (first year) ice.

Polar Peril_Arctic ice cap in a death spiral_SundayTimes_Sept 21 2014_21_NWS_20_POLAR_1096592k
Graphic above from the Sunday Times, September 21, 2014
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Sea ice experts make astonishing admissions to polar bear specialists

Climate scientists specializing in future sea ice predictions made some remarkable statements to polar bear scientists at their last meeting – admissions that may really surprise you.

USFWS_PolarBearNews2013_pg5 labeled

Back on June 26 (reported here), the IUCN Polar Bear Specialist Group (PBSG) posted a summary of its last meeting. So, I was very surprised to find (while there looking for something else), that on 18 July 2014 they had added minutes from the meeting to that summary.

These minutes are a bonanza because among the juicy nuggets of information is a summary of what the three invited climate scientists from Colorado (Jennifer Kay, Mark Serreze, and Marika Holland) had to say and what questions were asked. While real transparency would have involved posting copies of the sea ice presentations and transcripts of the question and answer sessions, this is certainly better than nothing.
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What about the polar bears? Disconnect between predictions and observations

With all the talk this week about future climate – the global warming imagined by IPCC crystal ball models, that is – the focus for many is rightly on the gulf between predictions and observations that have taken place so far. This follows on reminders a few weeks ago of the many failed predictions that we would have seen an “ice-free Arctic” by now.

[by “ice-free” they mean “nearly ice-free,” or “when ice coverage is less than 1 million square kilometers, or about 386,000 square miles.”]

But what about the polar bears? Is there a similar disconnect between predictions and observations for polar bear survival? Yes, indeed.

Many Arctic biologists insist that polar bears are not just threatened by future global warming and a “melting ice cap.” They contend polar bears are already being harmed by declines in summer sea ice coverage, or will be shortly.

The problem is, the results of scientific studies show otherwise. Virtually all of the evidence generated by polar bear researchers shows that polar bears are not being harmed by declines in summer sea ice, and in some cases, they are doing very well indeed. In other words, they are not responding as expected.

A few weeks ago, I summarized these studies, which reveal that:

Less summer ice ≠ few bears (evidence from Davis Strait; S. Hudson Bay; Barents Sea; S. Beaufort; W. Hudson Bay).

Less summer ice ≠ “skinnier” bears (evidence from Chukchi Sea; S. Hudson Bay).

“Skinnier” bears ≠ fewer bears (evidence from S. Hudson Bay; S. Beaufort; Davis Strait).

Less summer ice ≠  lower cub survival (evidence from S. Hudson Bay; Chukchi Sea).

Less summer ice ≠ more cannibalism & hybridization

Have a look if you missed it (August 18, 2013, with pdf copies to download), “Polar bears have not been harmed by sea ice declines in summer – the evidence.”

[Update Sunday Sept 29 2013: these two stories (on the temperature pause and polar bears thriving (in which I get a mention), just out in the Mail on Sunday (UK)]

Mail on Sunday_Temp pause and polar bears_Sept 29 2013

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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