A chunk of ice is shown drifting after it separated from the Ward Hunt Ice Shelf off the north coast of Ellesmere Island in Canada's far north on Sunday July 27, 2008.

(CCTV.com 07-31-2008 09:18)--18 square kilometers chunk of ice has broken off Canada's largest remaining ice shelf.

The enormous icy plain broke free sometime last week and has started slowly drifting into the Arctic Ocean. The piece had been a part of the Ward Hunt shelf for 3,000 years.

A crack in the shelf was first spotted in 2002 and spread into an extensive network last year. Scientists say the disintegration of the ice chunk shows the ecosystem there is in danger.

Many scientists now believe the Arctic will have ice-free summers by 2013 instead of 2030 as predicted by the International Panel on Climate Change.