The North Pole has become an island for the first time in human history, with fears the melting ice cap has entered a "death spiral".

The historic development was revealed in satellite images that show melting ice has produced an opening in the famed Northwest and Northeast Passages, with water stretching all the way round the Arctic.

Until recently, both passages had been blocked by ice since the start of the last Ice Age. It is feared by some scientists that the ice cap will completely disappear in summer within five years as global warming continues to take its toll.

Shipping companies are already planning to exploit the first simultaneous opening of the routes since the beginning of the last Ice Age 125,000 years ago. The Beluga Group in Germany said it will send the first ship through the Northeast Passage, around Russia, next year - cutting 4000 miles off the voyage from Germany to Japan.

The pictures, taken two days ago and gathered using microwave sensors that penetrate clouds, were published on a website by scientists at the University of Bremen in Germany. They show the Northwest Passage around Canada opened last weekend and the Northeast Passage was free from ice a few days later.

Prof Mark Serreze, a sea ice specialist at the National Snow and Ice Data Centre in the US, said the images suggested the Arctic may have entered a "death spiral". He warned that official bodies would be reluctant to confirm the passages were open, however, for fear of lawsuits if ships hit ice.

Stephen Harper, Canada's PM, has already said ships entering the Northwest Passage should first report to his government.