In case you haven't been paying attention the extent and thickness of Arctic sea ice in summer has been on a serious downward trajectory, even if not setting a new record year after year. Now, Prof Peter Wadhams from Cambridge University is predicting that, due to recent precipitous and unexpected declines, it's looking likely that Arctic sea ice may collapse entirely as soon as 2016.
Prof Wadhams, quoted in The Guardian:
The main cause is simply global warming: As the climate has warmed there has been less ice growth during the winter and more ice melt during the summer. At first this didn't get noticed. The summer ice limits slowly shrank back, at a rate which suggested that the ice would last another 50 years or so. But in the end the summer melt overtook the winter growth such that the entire ice sheet melts or breaks up during the summer months.
As for the consequences of this, though there may be some benefits in terms of shorter shipping routes, Arctic summers without ice will accelerate global warming, due to changing reflectivity of the region as well as increasing the melting of permafrost inland, in turn releasing stored greenhouse gases.