The amount of sea ice covering the Arctic Ocean has declined sharply each decade since the 1980s, according to measurements taken each September when the ice is at its minimum. Older, thicker ice is disappearing as well. Scientists say global warming is largely responsible for the changes. Parts of the Arctic are warming twice as fast as elsewhere.
The changing conditions offer an opening to shipping companies. The Arctic is potentially a faster, more direct route between Asia and ports in Europe and eastern North America.