A new assessment of climate change in the Arctic shows the region’s ice and snow are melting faster than previously thought and sharply raises projections of global sea level rise this century.

The report – Snow, Water, Ice and Permafrost in the Arctic – by the international Arctic Monitoring and Assessment Programme (Amap) is one of the most comprehensive updates on climate change in the Arctic, and builds on a similar assessment in 2005.

The full report will be delivered to foreign ministers of the eight Arctic nations next week, but an executive summary including the key findings has been obtained by reporters.

It says Arctic temperatures in the past six years were the highest since measurements began in 1880, and that feedback mechanisms believed to accelerate warming in the climate system have now started kicking in.

It also shatters some of the forecasts made in 2007 by the UN’s expert panel on climate change.

The cover of sea ice on the Arctic Ocean, for example, is shrinking faster than projected by the UN panel. The level of summer ice coverage has been at or near record lows every year since 2001, Amap said, predicting that the Arctic Ocean will be nearly ice free in summer within 30-40 years.

Amap also said the UN panel was too conservative in estimating how much sea levels will rise - one of the most closely watched aspects of global warming because of the potentially catastrophic impact on coastal cities and island nations.

The melting of Arctic glaciers and ice caps, including Greenland’s massive ice sheet, are projected to help raise global sea levels by 35 to 63 inches by 2100, Amap said, though it noted that the estimate was highly uncertain.

That’s up from a 2007 projection of 7 to 23 inches by the UN panel, which did not consider the dynamics of ice caps in the Arctic and Antarctica.