http://www.msnbc.msn.com/id/33538279/ns/us_news-environment/

OTTAWA - The multiyear sea ice covering the Arctic Ocean has effectively vanished, an Arctic expert says, a startling development that will make it easier to open up polar shipping routes.

Vast sheets of impenetrable multiyear ice, which can reach up to 260 feet thick, have for centuries blocked the path of ships seeking a quick short cut through the fabled Northwest Passage from the Atlantic to the Pacific. They also ruled out the idea of sailing across the top of the world.

But David Barber, the research chair in Arctic System Science at the University of Manitoba, said the ice, also known as old ice, was melting at an extraordinarily fast rate. . .