Tag Archives: summer sea ice minimum

Paris climate change deal will not stop polar bears dying due to thick ice in spring

Thick spring ice due to natural causes is currently the single biggest threat to polar bears. Not declining summer sea ice – thick spring ice. That could change in the future but right now, the evidence supports that statement.

polar_bear with collar_USGS

Polar bear deaths due to cyclical changes in Arctic sea ice thickness in the spring have continued despite rising CO2 emissions and declining summer sea ice extent (last major incident, 2004-2006): there is no reason to expect this will not continue. Unwarranted attention on summer ice extent has deflected attention from this major cause of local polar bear population decline.

Sea ice models do not address past or future changes in spring ice thickness and predictive models of polar bear survival blame all population declines on summer sea ice declines despite strong evidence to the contrary (Crockford 2015: The Arctic Fallacy). Continue reading

Summer sea ice melt and polar bear maternity dens

The yearly sea ice minimum extent is almost upon us, which has recently been the seasonal signal for excitable biologists and their activist groupies to resume their breathless rants about what sea ice loss could mean for polar bears.

Polar bear den_CreditUSFWS_labeled

Never mind that the summer minimum extent reached in September, no matter how low it goes, is pretty much irrelevant to polar bear health and survival. As I’ve discussed before, what’s really important is the presence of not-too-thick ice during the spring, so they can catch lots of young seals and put on lots of fat.

But to a lesser degree, the extent at mid-to-late summer is important because this is when pregnant females that prefer to make their maternity dens on shore are looking for good places to spend the winter.

So the topic for today is this: how much does the extent of ice at the height of summer dictate where polar bear females make their winter dens?
Continue reading

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