The image of Canada’s great Arctic expanses covered with snow and ice and stretching for thousands of kilometers into the distance is changing, or rather melting.

Canadian scientists are reporting with some alarm the break up of some Canada’s largest ice shelves.

In August the Markham Ice Shelf, a 50 kilometer square area of fresh water ice, collapsed and broke up into smaller pieces which melted and opened up large new expanses of open water.

Scientists say that Arctic temperatures have risen much faster than the global average over the last two decades and its effect is rapidly changing the Canadian Arctic landscape.

“The changes….were massive and disturbing,” said Warwick Vincent, Director of the Center for Northern Studies at Laval University in Quebec.

“These changes are irreversible under the present climate and indicate that the environmental conditions that have kept these ice shelves in balance for thousand of years are no longer present,” said David Mueller, an Arctic ice shelf specialist at Trent University in Ontario.

Ellesmere Island off the northern east coast of Canada was once surrounded by a single enormous ice shelf of just under 6 thousand square kilometers. What is left today of the giant shelf now barely covers less than 5 hundred square kilometers.

More than 90 percent of Canada’s ice shelves have been lost over the last hundred years. The ice suffered significant loss during a warm period in the 1930s and 1940s. Today’s temperatures are even warmer than those in the past.

The loss of the traditional ice cover and the opening of new areas of water has the Canadian Government worried about sovereignty issues.

Canadian Prime Minister Stephen Harper wants to toughen regulations for ships that are planning to venture into Canada’s newly formed Arctic waters. Many nations, including the United States, Denmark and Russia, are disputing Canadian claims to Arctic territories.