Polar bears are relatives of brown bears that have adapted to life on sea ice. Now, habitat loss and environmental pollution threaten their survival. How do these mysterious creatures survive? Check it out here with Scientific American's survey.

In fact, polar bears have become the voice of the fight against climate change, they have become a reflection of the wildness of human beings, how helpless they are now, and what people can do is to study their evolution, habitat, and what threat they face now and in the future.

The ancestors of polar bears were carnivores that lived 22 million years ago. The animal, called the Dawn Bear, is a close relative of the red panda and is about the size of a raccoon.

The polar bears that have evolved to today have already possessed unique skills.

First, they developed a unique way of hunting—catching seals on sea ice. In addition, they will not miss any opportunity to obtain food: such as robbing bird nests or searching for plants with high nutritional value. These adaptive behaviors surprise humans. People have even witnessed polar bears preying on dolphins.

At present, polar bears are distributed on more than 21 million square kilometers of land, and the existing number may range from 16,000 to 31,000. (2015 data), scientific expeditions in recent years are still limited by logistics or secrets, but the five countries in the polar bear ecosystem (Denmark, Norway, Canada, and the United States) have jointly formulated documents to protect polar bears.

It is currently believed that the only effective protection measures for polar bears are to stabilize carbon dioxide emissions, coupled with the protection of local people, these measures will hopefully save polar bears from extinction within a few decades.

Another threat to polar bears, however, is pollution in the Arctic, where pollutants accumulate at the top of the food chain, in polar bears. The record for this is growing.

While polar bears have made adaptive behaviors in response to environmental changes, humans themselves should still take steps. A documentary shows that the photographer caught a polar bear that was about to starve to death, but was not allowed to feed it for ecological reasons and could only witness its death, which shocked people.

Some scientists say polar bears may learn to survive on other types of food, such as snow geese, or they may learn to catch seals in seawater without relying on ice as a platform.

But most researchers say that's not possible.

This evolution typically takes thousands of years, USGS wildlife expert David Douglas told the panel. The shrinking of sea ice extent, he said, "could happen within a very narrow time frame, and it may be too late for generations of polar bears to learn new ways of living."

In the small town of Kaktovik, whales provide another food source for polar bears, at least for now. But dead whales aren't the polar bear's go-to meal.

"Polar bears don't come here because people hunt whales. They come here because their habitat has disappeared and it's hundreds of miles of open water," Thompson said.