Geoff York stands on the platform of Buggy One, near Churchill, Manitoba. A camera is mounted on the front of the vehicle, streaming footage to the public through the educational website Explore.org.

An inquisitive bear shows some “buggy love.” Bears would occasionally get close enough to fog the photographer’s camera lens. (Neil Ever Osborne)

The polar bear has become perhaps the pre-eminent symbol of the consequences of climate change because it needs sea ice to survive. From November, when the ice fastens to shore, to May, when it breaks up, the ice is polar bear territory across the Arctic. The pregnant females can even hibernate there during the winter. Males and non-pregnant females stay active through the winter days, and the ice is their hunting ground. Laying ambush behind a pressure ridge of ice fragments, the bears stalk seals. “On the ice, they’re slow,” York says of the seals. “The bears are explosive as they run them down.”

Polar bears are ferocious hunters, but they spend much of their time at rest and play. They can sleep as long as eight hours at a time, but unlike humans, they sleep more during the day than at night. (Neil Ever Osborne)

Frequent wrestling matches help polar bears develop hunting and fighting skills. Compared with omnivorous brown bears, from which they evolved more than 100,000 years ago, carnivorous polar bears have more jagged cheek teeth and larger, sharper canines. Their feet have papillae: small bumps that give them traction on ice. (Neil Ever Osborne)

There are between 16,000 and 31,000 polar bears in the world today, congregating in 19 populations across the Arctic. In some areas where the bears were heavily impacted by hunting, bans helped their numbers resurge. But the shrinking of their Arctic habitat is making the species more and more fragile worldwide. In Greenland and Norway, the World Wildlife Foundation lists polar bears as vulnerable. In Russia, they’re rare or recovering, depending on the location, and in Alaska (the only place in the United States where they’re found), polar bears are threatened. In Canada, where 60 to 80 percent of polar bears live, they’re a species of special concern, a click of the dial below threatened or endangered.

Polar bears are hardy creatures—they can fast for upward of 180 days and swim hundreds of miles without a break—but consensus among scientists is the animals won’t be able to find new food sources once they can no longer hunt seals. If a warming climate shrinks sea ice at projected rates, most polar bear populations will be too nutrient-starved to reproduce by the end of the 21st century.

Adult female polar bears commonly give birth to twins. They nurse for as long as two and a half years—at which point, either the mother herself or an adult male chases her offspring away. A healthy female delivers about five litters in her lifetime.

https://www.smithsonianmag.com/science-nature/polar-bears-live-cliate-change-crisis-180976995/