Polar bears are thriving despite global warming: this short essay explains why

This essay explains in simple terms why so many people still believe that polar bears are in peril when nothing could be further from the truth: it is an essential lesson that shatters the basis of the shameful indoctrination of young school children and undermines the baseless claims of activist protestors. It was written and translated into French for a special climate change feature issue (July) of the monthly French magazine Valeurs Actuelles (reviewed here) and reprinted by the French hunting magazine Chasses Internationales. It has also been translated into German for a dedicated climate change issue (11 July) of the Swiss weekly magazine Die Weltwoche.

Chukchi Sea polar bear Arctic_early August 2018_A Khan NSIDC

I have added a couple of figures to illustrate this English version of the essay.

There is a huge disconnect between public perception of the conservation status of polar bears and the present-day reality. That is because the polar bear was the first species to be classified as threatened with extinction based on predictions of future survival rather than current conditions of living populations. Polar bear conservation status is a special case.

By the late 1980s, studied populations of polar bears had more than doubled in size since international protection against over-hunting was provided in 1973. By 1993, the average size of the global population was estimated to be about 25,000 and in 1996, the species was removed from the IUCN Red List of Threatened and Endangered Species. Polar bears had been saved.

But in 2005, new concerns were raised about possible effects from predicted loss of Arctic sea ice due to human-caused global warming. In 2008, the United States Fish and Wildlife Service (USFWS) listed polar bears as threatened under the Endangered Species Act (ESA). For the first time ever, biologists used untested computer models of future polar bear survival that depended on untested predictions of summer sea ice loss over the 21st century.

These models concluded that the global polar bear population would decline 67% by mid-century. Out of nineteen designated subpopulations worldwide, ten subpopulations were expected to be wiped out when summer sea ice routinely fell to 42% or less of 1979 levels. From the global population estimate of 24,500 that these researchers used for their calculations, only 8,100 bears were predicted to remain by 2050 and by the end of the century, the species was expected to be near extinction.

USGS_pbear_ecoregions_sm

In 2007, US government biologists predicted that when summer sea ice declined by 42% from 1979 levels, all of the polar bears in the green and purple regions of the Arctic would be wiped out, leaving only about 8,100 remaining.

However, the dramatic decline in summer sea ice came much sooner than expected. By 2007, it was already underway. Sea ice levels not expected until 2050 have existed virtually every year since then.

Yet, the latest population assessment conducted by the IUCN Red List in 2015 generated an estimate of 26,000 bears (22,000-31,000). Surveys conducted since that time would bring the global total to about 28,500 – about a 16% increase. Because this increase since 2007 is not a statistically significant amount, the most conservative interpretation of this situation is that the population size has not changed despite the dramatic decline in summer ice. Moreover, against all expectations, in regions where sea ice has been the most pronounced (in the Barents and Chukchi Seas), bear are thriving: they are abundant, in good condition, and reproducing well.

Book graphic 1 for promotion

Only in the Southern Beaufort Sea off Alaska has a statistically significant decline in polar bear numbers been recorded since 2007. However, this region has unique sea ice characteristics: thick spring ice conditions develop for two or three years every ten years or so. The thick and compacted ice drives pregnant seals away before they give birth and creates spring food shortages for bears. Especially severe thick ice conditions were known to have happened in 1974-1976 and again in 2004-2006, causing short-term declines in polar bear numbers. The temporary effect of these events on the survival of polar bears and abundance of seals is well documented in the scientific literature.

However, the predictable and devastating effects of the thick ice conditions of 2004-2006 were not taken into account when population estimates were made for the Southern Beaufort in 2007 (or in 2015, when a revised count was done). Polar bear researchers in 2007 blamed the documented starvation and poor survival of bears in 2004-2006 on summer sea ice loss caused by global warming. To this day, these researchers and others continue to make such claims and falsely suggest that population numbers have remained at depleted levels since 2010.

In conclusion, the polar bear is thriving with almost 50% less sea ice than existed in 1979 with little evidence that catastrophe for the species awaits. On the contrary, many Arctic residents complain there are now too many bears for human safety.

Dr. Susan Crockford is a University of Victoria (British Columbia, Canada) zoologist who specializes in Holocene mammals, including polar bears and walrus. Her new book is The Polar Bear Catastrophe That Never Happened (Amazon).

via polarbearscience

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July 11, 2019 at 11:54AM

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