Polar bears use summer pack ice to hunt seals, summer ice helps keep the arctic climate steady as open sea would absorb more solar heat.  Quite apart from the sea level rises should it melt the summer sea ice also keeps the natural mineral and oil resources that bit further out of reach of exploitation.

All the more worrying then that a recent study published in the Geophysical Research Letters journal and carried out by the US National Oceanic and Atmospheric Administration (NOAA) and the University of Washington predicts that the Arctic will be ice free during the summer by 2037 and possibly as soon as 2020; up to 80 years earlier than previously thought.  The research estimates that come 2037 compared to the 4.6 square kilometres of summer ice left in the arctic today after the summer melt period that the level will have dropped to 1 million square kilometres making much of the arctic navigable in the summer.  Most of the remaining ice will be blown by prevailing winds onto the noth coast of Canada and Greenland.

The models used in the research show that once the tipping point is reached and the level of sea ice falls below the 4.6 million square kilometre level then the pace of melt increases rapidly.  In 2007 the summer sea ice level was 4.3 million kilometres, in 2008 4.7 million kilometres.