TWIG - The ice in the Arctic Sea is dramatically thinner in some places than six years ago, German scientists said on Thursday (Sept. 13), but cautioned that they did not know if this was caused by global warming.

The findings come from a summer trip to the area by the German research icebreaker Polarstern. Measurements showed some ice on the eastern-hemisphere side of the North Pole was only 1 meter (3.28 feet) thick, compared to 2 meters (6.56 feet) the last time it was checked, the Alfred Wegener Polar Research Institute (AWI) said in Bremerhaven.

AWI deputy chief Heinrich Miller said the change was not consistent, with the ice thicker elsewhere.

A Danish icebreaker on a similar expedition had been unable to break its way through and ice off the north shore of Spitzbergen was thicker than in the past.

Scientists did not know if the changes were part of a normal cycle or were caused by the greenhouse effect.

Miller said the measurements were basically consistent with a long-term reduction in the sea's ice cover, but they were only samples. The ice thickness varied greatly over time.

Polarstern scientists found that at present, warm Atlantic water was flowing into the Arctic basin, whereas in previous years those currents had been getting colder.

Credible scientific models suggest the Arctic Sea could be entirely free of ice in the summertime within 50 years.

The University of Hamburg's Marine and Atmospheric Research Center calculated the summer ice area this year at 3 million square kilometers (1.16 million square miles). The North-West Passage off Canada and the East Siberian Sea are largely free of ice.

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