2. Arctic glaciers

As the Earth continues to warm, glaciers are melting and polar bears are treading on thin ice. Sea ice is not as barren as it seems and it is actually the source of life in the Arctic. It sustains the unique Arctic food web including the polar bears. In recent years, scientists have found out that sea ice are melting faster in the summer with the winter freeze coming later and later. Some 40 years ago, a polar bear can accumulate a thick layer of body fat before the winter sets in as they have stuffed themselves full in the abundance of spring and summer. Today, although the population is stable, polar bears are getting thinner.