Polar bears in the Arctic use the sea ice that covers the North Pole as a platform for hunting seals, their primary prey. Recent data suggest that Arctic sea ice may have thinned as much as 40% over the past 50 years. If polar ice continues to melt, it is likely that the polar bear will become extinct. Many scientists believe that the melting of the Arctic sea ice is due primarily to human activities.

Question

Polar bears in the Arctic use the sea ice that covers the North Pole as a platform for hunting seals, their primary prey. Recent data suggest that Arctic sea ice may have thinned as much as 40% over the past 50 years. If polar ice continues to melt, it is likely that the polar bear will become extinct. Many scientists believe that the melting of the Arctic sea ice is due primarily to human activities.

Which of the following human activities is most likely to have the greatest effect on the thickness of the polar ice cap?
burning of fossil fuels
human population size
fishing in the Arctic Ocean
nuclear energy production

Answer 1

The burning of fossil fuels is most likely to have the greatest effect on the thickness of the polar ice cap. Burning fossil fuels releases greenhouse gases, such as carbon dioxide, into the atmosphere, which leads to global warming. This global warming is a primary cause of the melting of the Arctic sea ice.