Polar Bears and Climate Change

A friend of mine, JP, started all of this when writing:

If you were to ask me 2 years ago what my key understandings were about climate change, I would have said the following:

Sea ice is rapidly shrinking (summer arctic sea ice to be gone by 2015)

Sea levels are rising and accelerating

Polar bear populations are under stress (have increased in the last 20 years)

The levels of glacial retreat around the world are unprecedented (similar retreats have been seen in the last century)

97% of scientists agree that global warming is real and an urgent problem

Any scientist who is skeptical about the claims made about climate change is a "denier" and is funded by oil/resource companies

We are seeing an increase in extreme weather events (they are actually getting less common)

Climate models are accurate in their predictions 

Every one of those things is either totally false, or a largely exaggerated claim.

This is the third in a series based on my response, which itself was split over a few emails.  The first was Ice Extent Challenge (in which I provided a little more context about JP) and the second was Sea Levels Rising.  Some of the issues may also be touched on in a series of articles on the nature of climate denialism.  Please also note the caveat.

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JP’s Claim: The statement “polar bear populations are under stress” is either totally false or largely exaggerated and “(the population size has) increased in the last 20 years”

(Kerstin Langenberger)

(National Geographic)

For some reason, there don’t seem to be any photos of starving polar bears, or polar bears on ice-free islands, or polar bears stranded on ice floes or ice bergs before 2007.  Here are a couple from 2007:

(Arctic Meltdown, October 2007)

(Photographer of the Year, 2007)

While I am not sure that polar bear populations are under stress, there does appear to be some stress being experienced by individual polar bears.  They will have to adapt as a species (and as individuals) if the amount of Arctic ice in summer continues to decrease.

Like many of these topics, there is a level of complexity to the issue.  According the WWF, based on figures from the Polar Bear Specialist Group, there are two regions where numbers are increasing (population 200-500 individuals in each region), four where there’s a decline (population 500-1000 individuals in each region), five regions where the population is stable (1500-2000 in two, 2000-2500 in three) and eight regions where there is insufficient data.

The latest estimate, according to the IUCN Red List (see the population section and Table 3 in the supplementary information for details), of the total polar bear population in 2015 was 22-31000 (with a 90% confidence interval).

There has been an increase in the population of polar bears since the 1973 International Agreement on the Conservation of Polar Bears when the estimates for the number of individuals across the Arctic ranged from 5000 (USSR) to 20000 (Canada).  According to the Wikipedia page (based on figures from Ian Stirling although in documents that I have not been able to access) there were as many as 40000 individuals in the 1980s.

So, it’s true that, due to conservation efforts and limits on hunting of polar bears (and their prey), there has been an increase in their numbers over what they might otherwise be.  However, the simplistic cherry picked numbers are misleading: “5000 bears in the 1970s to 31000 today” or “10000 or fewer in the 1960s to easily more than 40000 today” is not telling the whole story.

As Ian Stirling reports, there’s more to it, even aside from the questionable numbers, which seem to have declined from the 1980s.  Polar bears were trending towards being thinner in the mid-2000s (a 2018 report indicated that weight loss is still a problem):

And it wasn’t just starvation that female polar bears needed to worry about.  Melting ice is not strong ice, so ice dens can collapse:

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JP’s claim was that polar bear populations are not under stress and that number were increasing over the last 20 years.  Finding evidence on this, in either direction, that is not from originally from Susan Crockford or one of her reradiators (ie the Foundation for Economic Education), is hard.  There is this, for a subset of the global population:

(Demography and Population Status of Polar Bears in the Western Hudson Bay)

That can be compared to denialist data which they present as:

If Hudson Bay numbers are representative of global numbers then, since there was a slight increase in numbers between 2000 and 2005 and a 10% to 20% increase between 2005 and 2015, then it’s not unreasonable to say that there’s been an increase in polar bear numbers over the past 20 years.  They might be having a miserable life, but at least there are more of them.  There is one estimate (by Susan Crockford) that the current polar bear estimate (March 2019) is as in the range 26000 to 58000, implying the possibility of a near doubling of the population since 2015.  In 2017, Crockford was calling for the endangered species listing for the polar bear to be lifted.  It should be noted that Crockford has been criticised for not having any of her claims regarding polar bears peer reviewed and basically for being a denialist mouthpiece (with connections to denialist blogs and the Heartland Institute).  Put it this way, I’d prefer to wait on more reliable data on current polar bear numbers.

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So, was JP right?  If the meaning intended was “there is no incontrovertible proof at the moment that the reduction in summer ice extent will wipe out polar bears and in fact the numbers appear to be increasing” then JP is probably right.  However, to say that polar bears are not under pressure is misleading.  They are having all sorts of problems with their hunting range being reduced, their body mass decreasing on average and interactions with humans increasing (which will increase the number of them that are shot and will distort the perception with regard to numbers).  Nevertheless, climate activists are going to cause problems for themselves if they continue to promote the simplistic claim that polar bear numbers are decreasing due to climate change – unless someone can crunch the numbers to show that numbers would have increased significantly more as a result of preservation agreements, if it weren’t for climate change.  I’m not sure that that is anyone’s highest priority though.

I’ll give JP a caveated tick of approval for this one.

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Sadly, the major casualty of this research is a joke that I’ve always liked.

A family of polar bears are walking along the ice one day, pappa bear, mamma bear, big brother bear and little baby bear.  Little baby bear pipes up and asks his big brother; “Am I a polar bear?”

His big brother says, “Yes, pappa is a polar bear, mamma is a polar bear, I’m a polar bear, so you are a polar bear.”

After a while of trudging along the ice, little baby bear scoots past his big brother and asks his mum, “Mamma, am I polar bear?”

Mamma bear laughs and says, “Yes, your pappa is a polar bear, I am a polar bear, your brother is a polar bear, we’re all polar bears, so you are a polar bear.”

Little baby bear falls silent again and they continue walking along the ice but after a while, he runs forward to his father and asks: “Dad, am I really a polar bear?”

Pappa bear stops, turns around and glares at his youngest son.  “Look here son, I am a polar bear, your mother is a polar bear, your brother is a polar bear and you are a polar bear.  That’s how it works.  So, what’s all this about?”

Little baby bear looks up as his father, with a tear in his eye, and says: “I’m really f^<#ing cold!”

Not so cold now!  (Note also total absence of pappa bear.)