Polar Bears Are Not Increasing

There are 20 populations across the Arctic with 20 different stories, but the worldwide average is not increasing. Some populations have experienced steep declines while others have rebounded a little after unregulated hunting was banned in 1973, but that increase is likely to be reversed as the sea ice melts.

One of the most frequent myths we hear about polar bears is that their numbers are increasing. Tales about how many polar bears there used to be (with claims as low as 5,000 in the 1960s) are undocumented, but cited over and over again.

Accurate polar bear counts are relatively new

“A common thread with misinformation about polar bears is omitting really crucial pieces of context for interpreting population numbers”, says Dr. John Whiteman. “In the 1950s and 60s, right after World War II, new technology really led to an explosion in hunting of polar bears. This overharvesting certainly drove numbers of polar bears down. We don't know by how much because there were not good population counts back then.”

One Russian extrapolation presented in 1956 suggested a number of 5,000 to 8,000*, but that figure was never accepted by scientists. The fact is that in the 1960s we had no idea how many polar bears there were. Even now, some of our population estimates are only educated guesses, especially in Russia. Back then, the best we had over most of the polar bear's range were uneducated guesses. Polar bear science has come a long way since then.

1970s success was temporary

We do know that some polar bear populations grew after harvest management systems were implemented in Canada, Alaska and Greenland, aerial sport hunting ceased in Alaska, and commercial trapping and hunting was banned across the Arctic. All of these events occurred in the late 1960s or early 1970s, and we know some populations responded as you would expect. Some populations were not being heavily hunted back then and those were probably unaffected by these actions.

“At the time, this was definitely a conservation success story, but that story ended by the 80s”, says Whiteman. “When we talk about polar bear population numbers now we're no longer talking about the consequence of this improvement in regulation and the success story that happened almost 50 years ago.”

Now climate change is the greatest threat

Across recent history, the sea ice was generally stable, thick and not noticeably in retreat. With stable habitat, polar bears were a renewable resource that could be harvested on a sustainable basis.

However, what happened in the past is increasingly irrelevant. Polar bear habitat is both changing (thinning) and disappearing (loss of sea ice extent) due to global warming at a rate that has never been seen before. Even the most careful on-the-ground management will ultimately fail if polar bears don't have the required habitat.

Polar bears depend on the sea ice surface to efficiently catch their seal prey. A shorter duration of ice cover over their productive hunting areas means less opportunity to hunt. A reduction in sea ice has been statistically linked to reduced stature and weight in polar bears and to lower survival rates of cubs. So, it doesn't really matter that hunting is now largely under control or that we know a lot about other impacts people might have on bears. Without habitat, polar bears will disappear no matter what else we do. 

If a farmer has 100 cows out in a pasture, and every year he goes out and paves over some of his pasture, pretty soon he won't have enough habitat to support 100 cows. And, each time he paves over a little more land, his remaining land will hold fewer cattle. There may be some short-term enhancements of the remaining habitat that will forestall the inevitable. But, when his whole pasture is paved there will be no cows. 

Declining habitat now and the assurance it will decline in the future is why polar bears were listed as a threatened species. Discussions about how many bears may have lived in the past before and after hunting quotas have little bearing on the current situation.

Planetary physics requires the world to warm as greenhouse gas concentrations rise, so without greenhouse gas mitigation, the ice will continue to melt. For an animal dependent on sea ice to survive, the prospects are not good. As the ice decline continues, the situation for polar bears can only worsen.

* For a fascinating look at where this widely repeated myth comes from, read "Magic Number: A sketchy 'fact' about polar bears keeps going … and going .. and going" by Peter Dykstra, published in the Society of Environmental Journalists' SEJournal.

With contributions from Geoff York and Dr. John Whiteman