Where do polar bears live?
Polar bears live in Arctic regions around the North Pole and frozen coastal plains of Canada, Russia, Greenland, Norway, and the United States. They are not found in the South Pole. The places they live are determined by the distribution of arctic ice.
How large do polar bears get?
A polar bear cub weighs a little more than a pound when born. However, when fully grown, polar bears are 8 to 11 feet when standing on their back legs and 3.5 to 5 feet when on all four legs. On average, males weigh 775 to 1,200 pounds and females weigh 330 to 650 pounds.
What do polar bears eat?
Polar bears prefer a seal dinner over that of anything else. Polar bears travel great distances in search of prey, and can smell seals up to 20 miles (30 kilometers) away. Though polar bears can stay underwater for about two minutes, most sea animals are too fast for the bear to catch. In the fall, when ice is softer, seals cut holes in the ice so that they can come up for air when they need to. Polar bears find such breathing holes and wait, sometimes for several days, until a seal comes up for breath. Then they pounce! On average, it takes 43 ringed seals per year to feed one polar bear. Polar bears also eat walrus, whale carcasses, birds' eggs, and (rarely) plants/vegetation.
How do polar bears survive in the cold?
Polar bears are uniquely suited to life in icy habitats. Their fur is very thick and covers even their paws for warmth and traction on ice. Their front feet are large, flat and oar-like, making them excellent swimmers. A thick layer of blubber beneath their fur insulates them from the cold and provides buoyancy. A polar bear's fur is not white but rather, is transparent. It is made up of small, hollow tubes which reflect light and trap the sun’s heat to help keep the polar bear warm. Under the fur, the bear’s skin is black which also helps to retain heat.
Are polar bears disappearing?
Polar bears were listed as a threatened species in the US under the Endangered Species Act in May 2008. There are 20,000 to 25,000 polar bears in the world today. Without any intervention, scientists estimate that two-thirds of the world’s polar bears will be gone by 2050.
Why is the sea ice important to polar bears?
Sea ice is vital to polar bears because they travel across it to reach their prey: ringed and bearded seals. They also perch on top of sea ice, waiting to catch the seals and other prey. With less sea ice, polar bears must swim increasingly long distances from shore to reach the ice to hunt. When the distance is too far, polar bears drown. In addition, the remaining sea ice lies over deep waters which have fewer seals, leading to unproductive hunting. In areas which have less ice than in the past, polar bears must spend summer months on shores. As a result, they must fast for months. This leaves the bears with fewer fat deposits to sustain the long and frigid winter. In poor health, the bears also have fewer cubs, and cubs frequently don’t survive to adulthood.
Why else is arctic ice important?
Many species rely on arctic ice to maintain the balance in their ecosystem. Penguins, walrus, and sea gulls all depend on sea ice for resting and retreat. Sea ice provides a food source, as ice algae grow at the porous bottom, providing food for marine life. Many species use the sea ice to hunt. Also, changes in sea surface temperatures or currents could have a strong effect on Arctic marine fish stocks, which are an important food source for the world.
How quickly is arctic ice melting?
Arctic ice is melting at the rate of 1% per year. The polar ice caps have melted faster in last 20 years than in the last 10,000. However, the most profound impact of ice loss is that it becomes a “self-fulfilling prophecy.” Sea ice has a bright surface; 80 percent of the sunlight that strikes it is reflected back into space. As sea ice melts, it exposes the dark ocean surface. Instead of reflecting 80 percent of the sunlight, the ocean absorbs 90 percent of the sunlight. This causes further warming of the oceans, and Arctic temperatures rise even further. The more ice that melts, the more sunlight the ocean absorbs. The more sunlight the ocean absorbs, the warmer it gets, and the more ice melts. That self-reinforcing loop is the process that scientists refer to as “Arctic amplification”.