Arctic will be ice-free in a decade, according to Pen Hadow

The explorer trekked more than 269 miles towards the North Pole this winter in temperatures below -40 degrees C to measure the depth of the ice.

The average thickness of ice floes was 1.8 metres, suggesting the ice sheet is now largely made up of first year ice rather than "multiyear" ice that will have built up over time.

An analysis by Cambridge University has concluded that the Arctic is now melting at such a rate that it will be largely ice free within ten years, allowing ships to cross the Arctic Ocean.

Further analysis by the World Wildlife Fund (WWF) warned that the "irreversible trend" will cause dangerous feedback because water absorbs more heat from the sun than ice, therefore further speeding up the global warming process. The melting of the ice could also trigger extreme weather patterns as the ocean currents change and release even more greenhouse gases stored under the ice.

The results will be presented to a UN meeting this December in Copenhagen as further evidence that the world must reduce carbon emisisons in order to prevent the Arctic melting at an even faster rate.

The Catlin Arctic Survey, led by Mr Hadow, came in for criticism after the team only managed to get half way to the North Pole because of extreme weather conditions and the hi-tech radar equipment for measuring the ice failed in the first few days.

The seasoned Arctic Explorer, who was the first person to trek to the North Pole alone, was forced to continue with just a simple ice drill. During the 73 day trek he took 1,500 readings, often during pitch blackness and with windchill factors down to -70 degree C. The team also took thousands of visual observations to give an impression of how the shape of the ice sheet is changing.

Mr Hadow insisted the effort was worth it. He pointed out that no other readings of this year's winter sea ice was available to scientists and surface readings can pick up changes in the ice that were not being picked up by computer models.

"Our on-the-ice techniques are helping scientists to understand better what is going on in this fragile ecosystem," he said.

"To all intents and purposes the Arctic will be ice free in a decade. I do find the implications of this happening in my lifetime quite shocking."

Professor Peter Wadhams, of the Polar Ocean Physics Group at the University of Cambridge, said scientists rely on readings from submarines or satellite for data sea ice.

However the new data from the survey confirmed the wider evidence that the Arctic will be completely ice free within twenty years, with most of the ice gone within a decade.

"The Catlin Arctic Survey data supports the consensus view that the Arctic will be ice-free in summer within about 20 years and that much of that decrease will be happening within 10 years," he said.

"It will not be very long before we start to think of the Arctic as an open sea. We have taken the lid off the northern part of the planet and we cannot put it back on again."