4/10/2013 6:29:01 PM
Setting the Record Straight on Polar Bears
We suggest that Christopher Booker's recent article in the Telegraph (March 16, 2013) "Sir David Attenborough should check his facts on polar bears," should be re-titled, "Christopher Booker should check his facts."
As long time polar bear researchers, and long-standing members and former chairs of the IUCN Polar Bear Specialist Group (PBSG), we are disturbed by Mr. Booker's apparently deliberate publication of misinformation about polar bears. It would have been so simple to check the facts for himself.
Mr. Booker states that the PBSG believes all but one of the world's 19 polar bear populations were "significantly increasing in numbers." In fact, the most recent PBSG report, in 2009, concluded that eight polar bear populations were declining, three were stable, and only one was increasing. This compares negatively with the PBSG's 2005 report, where only three populations were thought to be in decline and the 2001 report when only two were thought to be declining.
Mr. Booker also incorrectly reported that the recent sea ice extent was the greatest it had been for 30 years. In fact, the summer sea ice extent has been declining for over three decades, and reached a record low in 2012 when it was 49% below the average for 1979-2000. These facts easily can be found with a simple Internet search.
Mr. Booker's erroneous statements continued when he said that the PBSG has found "not a shred of evidence of any threat to the bears from climate change." Nothing could be farther from the truth. Polar bears depend upon sea ice for reaching their seal prey. Declining sea ice leads to reduced access to prey, and has been statistically linked to reduced physical condition and stature in polar bears, declining survival rates, and population declines. Ultimately, no sea ice means no polar bears. It's not a complicated concept.
Fortunately, all polar bears are not being affected simultaneously. Because some populations will be affected later than others, there is still time to save the species. We must act fast, however, because the laws of physics require that with rising atmospheric greenhouse gas concentrations, temperatures can only get warmer and the bear's sea ice habitat more scarce.
Decades of data collection in Hudson Bay have shown that breakup of the sea ice is now a full three weeks earlier than it was only 30 years ago. Polar bears there are coming ashore in progressively poorer body condition and have to survive on smaller fat reserves for longer periods while waiting for sea ice to return in autumn. Polar bears in northern Alaska are already showing reduced condition and survival rates, and there is no reason to think they could do well if their sea ice disappears. The brown bears living along the northern Alaskan coast, adjacent to the sea-ice dwelling polar bears, are the smallest of all brown bears worldwide and live at the lowest densities because of the low amount of nutrition in the terrestrial environment. What logic would lead us to believe a whole population of the largest bears in the world could survive on a landscape that currently supports only small numbers of such small bears?
Mr. Booker cites Susan Crockford, who he labels "an experienced Canadian polar bear expert" as the source for some of his assertions that polar bears are fine. As far as we are aware, she has never done any research on polar bears, so we are not clear how she became an expert. She is, however, listed as a writer on the payroll of the Heartland Institute, an organization with a history of using misinformation to deny human caused climate change (see table 3).
Unless we take action to reduce greenhouse gas emissions and stop global warming, all polar bear populations eventually will disappear.
These are the facts, plain and simple. Sir David Attenborough's assessment is right on target. It is Mr. Booker who needs to check the facts.