Why Do Polar Bears Need Ice to Survive?


It’s hard to imagine a polar bear without the backdrop of snow-covered, frozen tundra. Unlike any other land-loving bears, polar bears are actually considered marine mammals whose daily life is closely tied to the sea ice. “The name, polar bear in many languages even indicates this,” says Thea Bechshoft, PhD, staff scientist at Polar Bears International, a non-profit that works to preserve polar bears and their sea ice home, who points out that in Danish, her native language, polar bears are called ice bears (isbjørn). Read on to find how ice is critical to their everyday life, the survival of the species.

Icy travel

Polar bears are well-equipped to travel the icy landscape. Their paws are nearly a foot wide, with small bumps on the bottom, called papillae that help them grip the ice. Not to mention their claws, each nearly two inches long, that help them grip the ice—and their prey. In the icy waters, the front paws act as paddles and back as rudders. While polar bears are strong swimmers, sea ice is essential for travel, because it takes a lot of energy to move their bodies through the water. “Swimming has been found to be five times as energetically demanding for a polar bear than walking,” says Bechshoft. “Navigating the increasingly fragmented sea ice landscape can be energetically stressful, particularly for young cubs and for bears in poor body condition that are lacking a good layer of insulating fat. For them, swimming in the cold Arctic water carries with it the risk of hypothermia,” she says.

Cool naps

polar bear metling ice
Evgeny555/Getty ImagesYes, polar bears hunt, mate, and even sleep on sea ice, but it’s more than just a frozen platform. “Sea ice is absolutely essential for the day-to-day survival of polar bears,” says Kruger. “It is an entire ecosystem inhabited by plankton and micro-organisms, which support a rich food chain that nourishes seals, that in turn become prey for polar bears. It is the very foundation and defining characteristic of the Arctic marine ecosystem,” says Kruger. Yet, sea ice is vanishing at an alarming rate—especially in the Arctic. “Rapid loss of sea ice is the primary threat to the polar bears’ long-term survival. Our reliance on fossil fuels and the resulting climate change is causing a 13 percent decline per decade in the sea ice extent,” says Bechshoft. When polar bears spend longer periods searching forgoing food, their health and the health of their cubs suffer. “Unhealthy bears can mean lower reproduction rates, higher cub mortality—and eventually, local extinction. The main causes of death for cubs are lack of food or lack of fat on nursing mothers,” Kruger says. “We anticipate that polar bear populations will decline due to the loss of sea ice habitat.”

What can we do?

The decline in the polar bear population isn’t just as an estimate. It’s already happening. “Over the past 30 years, the western Hudson Bay has lost 30 percent of its bears, while the southern Beaufort Sea population has declined by 50 percent,” says Bechshoft. “Overall scientists predict that as the Arctic continues to warm, two-thirds of the world’s 20,000 to 25,000 polar bears could disappear within this century. Yet the future doesn’t have to be so grim for the polar bear. Dr. Bechshoft says reducing greenhouse gas emissions in the immediate future will help, but combatting climate change is the most important factor in protecting polar bears and ensuring their existence for generations to come. “The most important step anyone can take to do this is to vote and speak up, vote with the climate in mind, in each and every election, and let your representatives know you support bold climate action and a swift transition to clean energy sources,” urges Bechshoft. You can also donate to Polar Bears International and share these 12 adorable polar bear pictures to raise awareness about their plight.

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