Sea ice in the Arctic is near its all-time minimum for the end of winter, increasing fears that summers in the polar region could be free of it within 20 or 30 years.
The area of the Arctic covered by floating sea ice is already the lowest for this time of year, according to the latest satellite data. It could fall below the record winter minimum if there is no improvement in the next two weeks.
Sea ice expands and contracts with the seasons but satellite data collected since the 1970s shows that it is now retreating further during the summer months. Sea ice in summer has shrunk by 30% on average over the past 30 years while average temperatures in the Arctic have risen by about 4C.
Satellite records show the area of the Arctic covered by sea ice in March has also fallen, although to a lesser extent than in summer when the natural minimum point is in September. Scientists at the US National Snow and Ice Data Centre said it was too early to say whether the record winter minimum was likely to be reached this year.
Mark Serreze, the director of the centre, said: "The low extent for the Arctic as a whole is mostly due to mild ice conditions in the Sea of Okhotsk and the Bering Sea, which even in an average year, will melt out anyway during summer.
"Looking towards September, a great deal will depend on the summer weather patterns, and we can't predict what they'll be."