About polar bears & science on the front lines of global warming

Summary: Today’s post reviews a book about applied climate science, discussing polar bears — poster animals for the effects of global warming. It tells the rest of the story, the good news. It’s well worth reading.

Polar Bear Science

Review of Susan Crockford’s new book:
Polar Bears: Outstanding Survivors of Climate Change.

For thirty years we have heard increasingly dire claims about the coming climate Armageddon, divorced from what the IPCC’s physical scientists tell us. We can’t test them. But sometimes we can test smaller predictions by scientists about the climate change and its effects. Such as the recent successful 10-year forecast of global temperatures.

Polar Bears: Outstanding Survivors of Climate Change
Available at Amazon.

Polar bears provide another test case, well-documented in Susan Crockford’s powerful 2017 book Polar Bears: Outstanding Survivors of Climate Change. It’s a classic example telling the rest of the story to about “doomed polar bears.” She describes the remarkable resilience of polar bears — top predators in one of Earth’s harshest environments — to climate change.

Polar bears survived the Last Glacial Maximum 26 thousand years ago, which probably slashed their numbers — creating the genetic bottleneck seen in modern polar bear DNA. Stories about their vulnerability to climate change seldom mention that polar bears more easily withstood periods roughly 1° warmer than today than much colder periods.

“Yet, polar bears apparently survived the Eemian and early Holocene warm periods with only a moderate drop in population size – nothing like the scourge wrought by the LGM.”

What brought polar bears to the brink of extinction was hunting. Whalers slaughtered uncounted numbers from 1880-1930 (there are no good estimates of their numbers before that). Widespread “sports” hunting after WWII reduced the survivors to just remnants. When hunting restrictions began to be applied in 1960, there were only 5 to 15 thousand. By 1996 there were 25,000. Now there are over 28 thousand, with numbers rising — despite the loss of sea ice (here’s a March 2017 table). These numbers are estimates, since little of the deep polar ice is surveyed.

What the public sees

Before we look at what Dr. Crockford says about polar bears, let’s look at some of what feeds the public’s fear for the survival of polar bears. See this famous, sad picture of a polar bear floating out to sea in Science, 7 May 2010. In fact, polar bears can swim long distances — and it was photoshopped.

Photoshopped polar bear in Science

We also see pitiful pictures of dead or dying polar bears — their fate attributed to global warming without actual evidence. It’s easy and cheap propaganda. Such as this story about the following photograph: “Global warming may have led to the death of this polar bear, researcher says” at Mashable.

Dead polar bear. Photo by Paul Nicklen.
Photo by Paul Nicklen.

Here is an unusually candid confession from a climate activist in 2015 about to make doomster claims about polar bears and climate change: “I do not have scientific data to proof my observations ….”

Starving Svalbard polar bear
Starving Svalbard polar bear. Photo by Kerstin Langenberger.

But the days are fortunately gone when scientists routinely let these claims go by. See this rebuttal by Elizabeth Newbern at Live Science.

“Wildlife photographer Kerstin Langenberger snapped the now-famous photo of the gaunt polar bear and wrote a concerned Facebook post questioning the health of polar bear populations. Though it was widely circulated online, the photograph is misleading, said Karyn Rode, a wildlife biologist at the U.S. Geological Survey in Anchorage, Alaska. ‘I think you are always going to have animals in any population [that are] in poor conditions,’ Rode said. This can be because they have an injury (as may be the case with the polar bear in the photo) or because the animal is old and has lost some of its canines, she said.

“Steven Amstrup, chief scientist at Polar Bears International, a nonprofit research organization dedicated to studying polar bears, agreed and added that seeing a skinny bear in the wild is not altogether uncommon. ‘We know that animals in the wild don’t live forever,’ he said. ‘Polar bears, they don’t have natural enemies, so when they die it’s of starvation.'”

Crawford makes the same point in her conclusion to a fascinating discussion of the “feasting/fasting life of polar bears.”

“Starvation is the leading cause of death for polar bears. Young subadult polar bears hunting alone for the first time (2-5 years old) are less experienced than older bears and often less successful hunters. But young males, especially, also face the challenge of having adult males steal the kills they do make, as do past-their-prime elderly and inured bears.”

The prediction and the results

The core of the book explains how biologists of the Polar Bear Specialist Group predicted in 2006 that shrinking polar sea ice would reduce the number of polar bears by 30% by 2050. In 2008 the US Geological Survey predicted that shrinking polar sea ice would reduce the number of polar bears by two-thirds by 2050.

But she says — in a fascinating but lightly documented chapter 5 — that sea ice levels collapsed much faster than they expected. We already have had years of the sea ice levels that they expected by 2040. Yet, for reasons she explains quite clearly, polar bear numbers have not declined as predicted. This is blockbuster news, a rare test of predictions about the effects of climate change. Let’s hope that there is more research about this.

If true, what does this tell us about those scientists? I believe it shows that they are passionate about their work — and about the animals they study. But they lack the kind of cool supervision that takes those emotions out the equation so that their work provides a reliable basis for making public policy. This is a pervasive problem in climate science, where many scientists believe their goal is to save the world.

About the book

This is a fascinating book about one of our fellow top predators in the age of global warming. It describes how we almost exterminated them, their slow recovery — and new role as poster animals in the debate about global warming. The author briefly and clearly describes how they survive in one of the harshest environments on Earth, and how each year the weather determines how many live or die. She brings the perspective of a zoologist to review the forecasts by specialists of these bears’ fate as the Earth warms.

It provides a brief on-the-ground look at the dynamics of one kind of climate change in a warming world. Crockford writes well. The photos of are excellent and the illustrations are clear. It needs better maps, discussing places not mentioned on them. Crockford says more in 50 pages than others in one hundred.

Update: see her paper

She documents her theory in “Testing the hypothesis that routine sea ice coverage of 3-5 mkm2 results in a greater than 30% decline in population size of polar bears (Ursus maritimus)”, posted at Peer J Preprints. Abstract:

“The polar bear (Ursus maritimus) was the first species to be classified as threatened with extinction based on predictions of future conditions rather than current status. These predictions were made using expert-opinion forecasts of population declines linked to modeled habitat loss – first by the International Union for the Conservation of Nature (IUCN)’s Red List in 2006, and then by the United States Fish and Wildlife Service (USFWS) in 2008 under the Endangered Species Act (ESA), based on data collected to 2005 and 2006, respectively. Both assessments predicted significant population declines of polar bears would result by mid-century as a consequence of summer sea ice extent rapidly reaching 3-5 mkm2 on a regular basis: the IUCN predicted a >30% decline in total population, while the USFWS predicted the global population would decline by 67% (including total extirpation of ten subpopulations within two vulnerable ecoregions).

“Biologists involved in these conservation assessments had to make several critical assumptions about how polar bears might be affected by future habitat loss, since sea ice conditions predicted to occur by 2050 had not occurred prior to 2006. However, summer sea ice declines have been much faster than expected: low ice levels not expected until mid-century (about 3-5 mkm2) have occurred regularly since 2007. Realization of predicted sea ice levels allows the ‘rapid sea ice decline = population decline’ assumption for polar bears to be treated as a testable hypothesis.

“Data collected between 2007 and 2015 reveal that polar bear numbers have not declined as predicted and no subpopulation has been extirpated. Several subpopulations expected to be at high risk of decline remained stable and five showed increases in population size. Another at-risk subpopulation was not counted but showed marked improvement in reproductive parameters and body condition with less summer ice. As a consequence, the hypothesis that repeated summer sea ice levels of below 5 mkm2 will cause significant population declines in polar bears is rejected, a result that indicates the ESA and IUCN judgments to list polar bears as threatened based on future risks of habitat loss were scientifically unfounded and that similar predictions for Arctic seals and walrus may be likewise flawed.

“The lack of a demonstrable ‘rapid sea ice decline = population decline’ relationship for polar bears also potentially invalidates updated survival model outputs that predict catastrophic population declines should the Arctic become ice-free in summer.”

It was ignored. Perhaps scientists are following ancient rule of silence means assent (“qui tacet consentire videtur”). More likely this is an exercise of power, using their role as “gatekeepers” to keep challenges out of the debate. We can speak out by circulating this paper and force their response.

Susan Crockford

About the author

Susan Crockford is a zoologist with more than 35 years of experience, including published work on the Holocene history of Arctic animals. She is an adjunct professor at the University of Victoria, British Columbia (a “non-remunerated professional zooarcheologist associate”) and co-owner of a private consulting company, Pacific Identifications Inc. See her publications here and her website Polar Bear Science.

She has also written a novel, Eaten — a polar bear attack thriller.

For More Information

See this review of her other book by Kip Hansen: “Polar Bear Facts and Myths – A Science Summary for All Ages”.

If you liked this post, like us on Facebook and follow us on Twitter. For more information about polar bears, about the keys to understanding climate change and these posts about the politics of climate change…

  1. Twenty stories of good news about polar bears!
  2. Are 30 thousand species going extinct every year?
  3. Good news about polar bears, thriving as the arctic warms!
The Rightful Place of Science: Disasters and Climate Change
Available at Amazon.

To learn more about the state of climate change…

… see The Rightful Place of Science: Disasters and Climate Change by Roger Pielke Jr. (Prof of Environmental Studies at U of CO-Boulder). From the publisher…

“In recent years the media, politicians, and activists have popularized the notion that climate change has made disasters worse. But what does the science actually say? Roger Pielke, Jr. takes a close look at the work of the Intergovernmental Panel on Climate Change, the underlying scientific research, and the data to give you the latest science on disasters and climate change. What he finds may surprise you and raise questions about the role of science in political debates.”

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