Students at Centre Wellington District High School took a virtual trip to the Arctic on Oct. 29 with Dr. Andrew Derocher, a scientist and professor at the University of Alberta.
Derocher spoke to a crowded room about his vocation, polar bears, and more specifically how they are linked to climate change.
“It is one of the most recognizable species in the world… there’s something about polar bears that draws people in,” he said.
Derocher explained polar bears have long been connected to the Inuit people that live in the Canadian Arctic, but also to cultures around the world.
He showed the students photographs of statues and paintings of polar bears from many European cultures, stamps from countries all over the world that depict polar bears, and advertisements that use the polar bear image.
But more recently, he explained, polar bears are now linked to the changing climate.
“Polar bears have become the poster species for climate change and it’s because … it’s really just a simple story of habitat loss,” he said.
Derocher asked, “What is it about the species that makes them so vulnerable to climate change?”
For the answer, he said one has to look into the development of the species.
The ancestor of the polar bear was in fact a grizzly bear, he explained. Grizzlies are brown, terrestrial, omnivorous mammals and with one to six million years of divergence, polar bears developed into white, marine carnivores.
“A vastly different organism, totally adapted to a different way of life,” said Derocher.
While hybrids of the two species can be found, differences between the two species are ample.
The home range of a polar bear is 300,000 to 600,000 square kilometres, compared to grizzly bear’s range of 1,000km2 in a single year, which emphasizes the importance of sea ice.
Derocher explained that polar bears will not become more terrestrial.
“There’s nothing on land that can replace the energy that the polar bears get from hunting out on the sea ice … the sea ice has to persist for most of the year for them to ever be able to make a living. It comes down to: this is their primary habitat,” he said.
Ice, especially ice closer to land, is everything to the bear. While other species are migrating north to adapt to the warming climate, Derocher said polar bears cannot move north.
“You can’t push polar bears farther north, because their food source is not up there and the Arctic Ocean is about 2,000 to 3,000 metres deep. It’s not a productive area for them,” he said.
Derocher added, “If you look at the climate change models, the Arctic Ocean is predicted to be ice free certainly by mid-century at least in the summer.”
Derocher said there was a breakdown of the distributions of polar bears into 19 different populations and because warming is occurring at different rates in different areas, “we’re going to see 19 different scenarios play out over time in terms of climate change.”
With the population of polar bears around 21,000 to 25,000, Derocher sees a bleak future for the animal.
“The best work that we’ve got that was done by the US Fish and Wildlife Service suggests that globally … we’ll lose about two thirds of the world’s polar bears by about mid-century,” he said.
Derocher said he worries about ice loss, oil exploration and the increased shipping in the Northwest Passage, which could bring in invasive species, oil spills and broken ice.
Climate change also puts the bears in closer proximately to humans, where they normally would not roam.
The loss of ice gives the bears less of a chance to fatten up to survive. Bears range up to 800 kilograms in size. According to Derocher, the fattest bear is the fittest bear.
“Now with climate change we are seeing … there’s a warming period where the bears are on land … The problem we’re running into is the feeding period is getting smaller, we’re starting to cut into it in the spring time, we’re starting to bump into this fall feeding period because the ice is not forming for as long in a year,” he said.
Derocher said it is a chain effect. Climate change leads to a change in sea ice which causes less food to be available and increased movement. That causes bears to have poor body conditions, resulting in fewer or smaller cubs. These cubs have less of a chance for survival because their mother is unable to provide the required nutrition.
This all equals population decline.
“We’ve seen this chain happen across the Arctic in various places and various times,” he said.
When asked about the infamous skinny polar bear photo taken by Kerstin Langenberger in Svalbard, Norway this summer, Derocher admitted the bear was skinny, but he has seen skinny bears throughout his career.
He reminded the crowd that one bear does not determine everything.
“In science we deal with data … what’s the important thing? Your sample size,” he said.
“One bear will not tell us anything, but what we have seen is there is a trend in Svalbard on the west coast to see more and more skinny bears. That is a trend but the data is not very robust.”
He reminded students not to lose hope, but suggested habits need to change.
“I don’t want to be a natural historian on an extinct species,” he added.
Derocher told students the best thing they can do is to learn more about the issue of climate change, be politically active, and express their views by voting.
He encouraged students to run with every opportunity they get and suggested the harder they work the more opportunities they will get.
