High Arctic polar bears face starvation, reproductive failure: study

A polar bear walks over the ice near a floe edge in August. (PHOTO BY JANE GEORGE)

Arctic conditions may become “critical” for polar bears by end of 21st century, suggests a new study, which says shifts in ice cover may impact polar bear populations in the High Arctic islands.

The study links climate change and the future health of polar bears, stating that “under business-as-usual climate projections, polar bears may face starvation and reproductive failure across the entire [Canadian Arctic] Archipelago by the year 2100.”

Polar bears are “inextricably linked to Arctic sea ice and are sensitive to sea ice loss,” says the study, called Projected Polar Bear Sea Ice Habitat in the Canadian Arctic Archipelago, published this week in the open-access journal Plos One, by Stephen Hamilton of the University of Alberta and colleagues.

“We predict that nearly one-tenth of the world’s polar bear habitat, as much as one-quarter of their global population, may undergo significant habitat loss under business-as-usual climate projections,” Hamilton said in a news release about the study.

The study notes that polar bears rely on sea ice as a platform for hunting, migrating, and mating, but move to land in regions where sea ice does not seasonally persist.

The study’s simulation projects the sea ice habitat in all polar bear populations of the High Arctic islands may change from a multi-year to an annual ice system before the end of the century.

Primarily multi-year ice cover will shift to a primarily seasonally ice-free system by 2100, with the exception of Kane Basin and the Gulf of Boothia, the study says.

“In all cases, the final years of the simulation exhibit some proportion of year-round ice-free areas, where no such areas exist in most of the 21st century.”

“The remaining annual ice might not persist sufficiently long each year to allow hunting opportunities for polar bears as we currently understand them,” the study says.

The study’s modeling and population projections suggest that continued sea ice loss with climate warming “will negatively affect polar bear survival and reproduction potentially leading to population declines.”

Its modeling predicts that two to three per cent of adult polar bear males could starve when the ice-free period reach 120 days and up to 21 per cent could starve at 180 days of ice-free period “with other age and sex classes even more vulnerable.”

The modeling also shows early break-up of sea ice could result in reproductive failure in 55 per cent to 100 per cent of pregnant females

Moreover, of the ice that survives the melt season,” insufficient snow cover may limit its viability as habitat for ringed seals,” the primary prey species of polar bears, the study says.

Money for the project came from WWF (Canada), ArcticNet, the Canadian Association of Zoos and Aquariums, Canadian Wildlife Federation, Environment Canada, Hauser Bears, Natural Sciences and Engineering Research Council of Canada, Office of Naval Research grant, Pittsburgh Zoo, Polar Continental Shelf Project, Polar Bears International, and Quark Expeditions.

Another study published earlier this month by researchers from Canada and the United States suggested that the southern Beaufort Sea polar bear population had already experienced a decline of about 40 cent during the early 2000s.