No more polar bear?

We all know that the Earth is growing warmer and warmer. This problem is called “global warming”. We also know that global warming is causing a lot of problems. Ocean levels are getting higher and higher. Because ocean levels are getting higher, storms are getting stronger and stronger. This list of problems goes on and on.

Animals are suffering a lot because of global warming. Polar bears are suffering more than most animals. This is because polar bears live in the North Pole. In the North Pole, global warming is making ice melt. Polar bears hunt from large pieces of floating ice. They jump off the ice and hunt for food. Polar bears have to swim and find these floating pieces of ice. These days, they have to swim farther to find the floating ice. Many of them don’t have enough energy. They get too tired, and they die in the water.

Polar bears are suffering because of other problems, too. Pollution makes their water dirty. Many countries go to the North Pole to look for oil and gas, and they damage the environment of the bears. In addition, when ships sail through the North Pole, they cause a lot of damage. Finally, people hunt and kill too many polar bears. However, melting ice is definitely the biggest problem.

Right now, there are about 25,000 polar bears in the world. If global warming continues, there may be only about 12,000 in the year 2050. By the year 2080, that number might be much smaller.

It is important to study polar bears. When we learn about polar bears, we also learn about the health of the North Pole. If polar bears are doing well, then the environment in the North Pole is probably healthy. If polar bears are suffering then there are probably serious problems in the North Pole.

Right now, governments around the world are working to help polar bears. There are new laws that protect polar bears. However, if global warming continues to get worse, polar bears may disappear forever.

The word “this” in paragraph 2 refers to ____.