According to the US National Snow and Ice Data Center (NSIDC), Arctic sea-ice covered 4.5 million sq km (1.7 million sq miles) at its lowest point on 12 September last year.

BBC: Arctic team targets key ice data

Today, US military weather satellites return daily data on the state of the sea-ice at both poles, but the NSIDC team is keen to retrieve as much information as possible from the early, experimental Nasa Earth-observers.

BBC: Earliest satellite maps of Antarctic and Arctic sea-ice

"This suggests that current model projections may in fact provide a conservative estimate of future Arctic change, and that the summer Arctic sea ice may disappear considerably earlier than IPCC projections, " said NSIDC's Julienne Stroeve who led the study.

CNN: Arctic melt worse than predictions

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(NSIDC), demonstrates that the 18 models on which the IPCC has based its current recommendations could already be out of date -- and that the retreat of the ice could already be 30 years ahead of the IPCC's worst case scenario.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