Polar bears feel the effects of warming Arctic

International Polar Bear Day is Thursday to discuss the challenges facing the animals because of melting sea ice. Polar bears depend on the ice to hunt their main food source: seals.

Sage Smith

With the diminishing population of polar bears, future generations may only know polar bears as the ones on Coca-Cola cans and in zoos. Thursday is International Polar Bear Day to bring awareness to the challenges facing polar bears.

Polar bears are starving to death as the continuing warming of the Arctic, due to climate change, melts the sea ice. This leaves the bears without their main food source: seals.

Polar bears are listed as a vulnerable species by the International Union for Conservation of Nature. According to the most recent study (Hamilton and Derocher, 2018), there are about 23,000 polar bears worldwide.

Andrew Derocher, professor of biology at the University of Alberta, is a longtime scientific adviser for Polar Bears International. He has been studying polar bears for about 36 years, mainly in the Canadian Arctic, but he also worked in the Norwegian Arctic for seven years.

“The simplest way to look at the ecology of polar bears is it’s what we call a sea ice obligate species, so they’re only found where sea ice persists for most of the year,” Derocher said. “They’re highly adapted to be a predator from the surface of the sea ice. So sea ice is their preferred habitat. It’s where they travel, it’s where they hunt, it’s where they mate and even some parts of their distribution, such as often the north coast of Alaska, pregnant females will actually den out on the sea ice and give birth to their cubs there.”

These bears rely on sea ice for hunting, and with it disappearing, the bears’ ability and time to hunt for food is limited.

“The simplest summation for them is that the main threat to polar bears is habitat loss,” Derocher said. “And that is exactly the same threat that is putting many, many species around the world at risk.”

Stephen Dinsmore, department chair of the entomology department, is a professor of natural resource ecology and management. He is also a population biologist and avian ecologist.

“So the food supply that’s on the mainland is not as good, is not as nutritious, so they’re trying to make do with a secondary food supply, which causes the emaciated images [of polar bears] that you see on the news,” Dinsmore said. “That’s not sufficient for something like that. They’re a big animal. They need a lot of input of calories. And meat and fat and proteins and things like that are very, very important, so I think that’s kind of this phenological mismatch we call it.”

Derocher said the Arctic is warming somewhere between two to three times faster than areas of lower latitudes. He said in the 70s and 80s, studies about polar bears weren’t looking at monitoring climate change. Through those studies, though, they found monitoring information to look at things like reproductive rates and survival rates.

“In essence, with increasing greenhouse gas in the atmosphere, we’re getting rapid warming in the Arctic and essentially shortening the time period that sea ice is present but also doing some fundamental changes, like changing the thickness of the sea ice and its distribution,” Derocher said. “So in overview, there’s not a lot of things you can do from a conservation effort for polar bears without trying to at least address climate change, greenhouse gas emissions across the planet.”

James Colbert, associate professor of ecology, evolution and organismal biology, has been director for the undergraduate biology program for 15 years. He said a lot of people assume if a species doesn’t have a direct impact on humans that they don’t really view them as important.

“Every species has a role in the ecosystems that they live in,” Colbert said. “Because of limitations of time and effort and money and people to study these things, we often don’t know exactly what the role is, but they all have a role, whether we know what it is or not.”

The role that every species has is called a niche. They have their job and the goal to survive to pass on their genes to the next generation.

Michael Rentz, assistant teaching professor of natural resource ecology and management, grew up adventuring in nature and watching the “1970s versions of Animal Planet.” He said the more time he spends in his career, the more passion he has.

“The polar bear is a great example of an animal with a pretty narrow niche,” Rentz said. “It’s able to live off of seals and to hunt seals in the winter on the ice.”

Rentz relates the idea of niches to humans. There used to be a niche for blacksmiths and pager salesmen, and now it’s more about repairing iPhones. With polar bears though, he said they can’t evolve to have a different main food source or adapt to eating seals without the help of ice, considering the time scale.

“So they can’t necessarily swim [seals] down, and the seals don’t necessarily come to land reliably enough that they can hunt exclusively just on land,” Rentz said. “As the climate change is, an ice up comes later and ice out comes earlier. We’re shrinking that period of time where the bears can be effectively feeding.”

Not being able to effectively feed on seals and build up fat can be a challenge for mother polar bears when reproducing and feeding their young. They can lack the energy needed to go through the process and may be unable to give their cubs the proper nutrients and teach them skills needed for the wild once separated from their mother.

Rentz said the bears do eat for more than just themselves when pregnant, but it takes even more energy to produce milk for the young than it does to produce the cub itself.

Mother polar bears have one to three cubs at a time, twins being the most common, according to Polar Bears International. The newborns are fully dependent on their mother for warmth and food, as when first born, they can’t see, don’t have teeth and only have short fur. The cubs will nurse for at least 20 months using the milk, which is 31 percent fat to grow bigger and stronger.

“The other thing, because they eat mostly fat and they store lots and lots of fat, any chemicals that are fat soluble, that accumulate in the environment, there’s the chance for bioaccumulation in the bears,” Rentz said. “So I don’t think necessarily the way the ocean currents work that bears are seeing a lot of straws, but any of that pollution in the water or in the air that’s accumulating in the food chain — the fish eating the plankton, the seals eating the fish, the bear eating the seal.”

Getting educated not only about what can be done to address climate change but also what animals do can be helpful to people so they have a better understanding of why animals are important to their ecosystem.

Dinsmore said with polar bears, there has been the use of satellite tracking technology. Satellite tags track where the bears are and if they stick to the same routines year by year.

Understanding how polar bears use their environment can be helpful when looking at how to correct the problems the bears are facing.

“Well, certainly I hope that all the attention and research and images of polar bears that are suffering get enough attention so that we can deal with the Arctic ecosystem in a way that reverses those trends,” Dinsmore said. “So that we don’t have to have our children see the same images or not have the opportunity to see a wild polar bear. It’s a magnificent animal and it’s something that’s great to have the possibility that we can have those around for next generations.”

Polar Bears International will have special programming throughout Thursday including live chats on Facebook. There will be a range of experts from the U.S., Canada, Norway and Denmark on the live chats so people can ask them questions. The full schedule for International Polar Bear Day can be found on Polar Bears International’s website.

A Canada Goose short film called Bare Existence documents the work Polar Bears International has done to drive awareness and inspire action. The Polar Bears International website also has a large amount of information about polar bears, climate change and how people can get involved to help not only polar bears but all species.

“Personally, I think it’s a much sadder world if the only place you can see polar bears is a zoo,” Colbert said. “But not everybody would agree with me.”