Would Polar Bears Be Able to Adapt to a Warmer Climate?

As Arctic ice melts, polar bears are in increasing trouble.

The world is warming—swiftly. The last decade (2010-2019) was the hottest ever recorded, while Europe saw its hottest year in 2019, according to Climate Change Service. This has put an enormous strain on Earth’s regional ecosystems, not least of all, on its usually-frozen poles. In 2019, the sea ice cap in the Arctic shrank to 1.6 million square miles, down from 2.44 million square miles in 2010—with no sign that it will rebound, says NASA’s Earth Observatory. This has changed weather patterns and sea levels, and it has had devastating effects on wildlife, including polar bears. Of course, arctic ice isn’t the only thing that’s shrinking.

Why ice matters

Polar bears rely on sea ice in order to raise their pups and hunt their prey—mostly ring seals. Without it, and trapped on land, they’re going hungry and their numbers are dwindling. As National Geographic reported in 2015, they’re getting “creative” to stay alive. One strategy noticed by a team of researchers in Svalbard, Norway was that bears managed to trap a species of dolphin they don’t usually eat, that swam into their habitat (also thanks to the lack of ice), ate some of it, then buried the rest in snow to eat later—a behavior these animals don’t normally exhibit.

Alternate food sources

Polar bears in the western Hudson Bay have been eating another alternate and highly unusual food source, snow geese eggs; according to researchers 88 of which equal the calories that come from devouring a single seal. While this may be a most welcome snack alternative in the absence of anything else of substance to eat, it cannot sustain the bears longterm; additionally, bears eating eggs will have the secondary effect of decreasing snow geese populations. Warming weather is also driving polar bears, actually classified as marine mammals, south, to forage in human garbage. Find out 13 more polar bear facts you never knew.

On the menu

In 2014, an ecologist at New York’s American Museum of Natural History figured out what a polar bear might be able to eat during longer, ice-free summers. In addition to goose eggs, she included geese and goslings, caribou, and some berries on her menu, reports National Geographic. While that may sound like a good use of resources and a decent haul of food, another problem is that polar bears are waking up from winter slumbers earlier and earlier, which means they need more (unavailable) food than ever. And these smaller bits of sustenance require more energy to pursue and collect—energy a hungry bear has little of to spare.

Enough to matter?

This alternate menu might help stave off starvation temporarily, but in the long run, no one’s sure how effective it will be. Polar bear populations are getting skinnier and less healthy; fewer cubs are surviving and those that do are smaller, according to Carbon Brief. And their numbers are declining; some scientists predicted a few years back that polar bears could be extinct by 2020—yes, that’s this year. This hasn’t happened (yet). But whether it’s possible for polar bears, among the largest animals on our planet, to figure out how to live in a new ice-free world, quickly enough to rebound, remains to be seen. And the evidence we do have is grim.

The matter of disease

For example, a warming world means an increase in the number of diseases that species are being exposed to. As far back as 2015, Frontier Scientists reported that polar bears, with their “naive immune systems,” were encountering pathogens that were new—and dangerous—to them as they spent more time, uncustomarily, on land. They’re getting infected with more parasites, bacteria like Coxiella burnetii, viruses, and fungi. And they do not have the genetic capability to fight them off. In short, these “sentinels of ecosystem health” are suffering poor health themselves.

More scientists weigh in

As Canadian biologist Andrew Derocher told Carbon Brief, “Without sea ice, there is no sea ice ecosystem and losing that ecosystem includes losing polar bears” in all 19 of the polar regions they call home. That’s because, according to Polar Bear International, there’s only so much a polar bear can adapt to an ice-free life. They go without food for about 220 days, but more than that decreases their chances of survival. And while they can swim from (melting) ice floe to (melting) ice floe, they can’t go far, for long, and cubs have even less ability to swim distances.

Looking for good news in the wrong places

Some people have expressed optimism that polar bears would survive melting ice due to the fact that they evolved from their land-happy cousins, brown bears. But as NRDC points out, their adaption to ice took some 30,000 years; even if they could evolve back in the other direction, the world is warming faster than their ability to keep pace. Additionally, every physical feature of a polar bear—from ice-gripping claws to thick warm coats—is designed for a life of frigid cold and variations to their usual behavior can cause them to overheat and expend too many calories. And that white fur? In a non-white world, it stops acting as camouflage. Tragically, in a world without ice, polar bears will most likely cease to exist. These are 14 other animals that could disappear in your lifetime.

What you can do

Consider donating to Polar Bears International, a non-profit that works to preserve polar bears and their sea ice home. And share these 12 adorable polar bear pictures to raise awareness about their plight.

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Lela Nargi
Lela Nargi is a veteran journalist covering science, sustainability, climate, and agriculture for Readers Digest, Washington Post, Sierra, NPR, The Counter, JSTOR Daily, and many other outlets. She also writes about science for kids. You can follow her on Twitter @LelaNargi.