What they found was that the annual ice loss by this date would be running at about 145 billion tonnes, with the north of the archipelago, on and around the likes of Ellesmere Island, experiencing the greatest retreat.

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The area is now more likely to become open water each summer, bringing forward the potential date when the summer sea ice will be completely gone.

CNN: Arctic ice to vanish in summer, report says

With 102 holes drilled so far, hundreds of measurements have been made of ice thickness and snow cover over the 243km covered to date.

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They carbon-date back to millennia after the end of the ice age, about 9-10 thousand years ago.

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But the research, conducted by the U.S.-based National Center for Atmospheric Research (NCAR) and the University of Colorado's National Snow and Ice Data Center (NSIDC), demonstrates that the 18 models on which the IPCC has based its current recommendations could already be out of date -- and that the retreat of the ice could already be 30 years ahead of the IPCC's worst case scenario.

CNN: Arctic melt worse than predictions

To address these outstanding questions, the team will collect samples of rock to date their exposure to cosmic radiation and analyse how glaciers and ice have retreated since the last ice age, around 20, 000 years ago.

BBC: Polar expedition to study Antarctica's climate history