While melting glaciers are caused by global warming, glaciers melting can also impact the temperatures across the globe. According to Wikipedia, the albedo (a measure of the reflective ability of a surface) of snow is about 0.8 to 0.9. This means that snow-covered glaciers can reflect back about 80% to 90% of the energy from the sun’s rays.

     So when ice on glaciers melts, the reflective properties of the glaciers are lost. The earth beneath the ice sheets gets uncovered. The glacier then absorbs more heat, which in turn causes more of its ice sheets to melt away, resulting in further increase in the global temperatures. This phenomena is called ‘ice-albedo feedback’.

     Professor Peter Wadhams from Cambridge University, UK, is an expert on Arctic ice. He said white ice reflects more sunlight than open water, acting like a parasol. Melting of white Arctic ice, currently at its lowest level in recent history, is causing more absorption.

     Prof Wadhams calculates this absorption of the sun's rays is having an effect "the equivalent of about 20 years of additional CO2 being added by man".

   The Cambridge University expert says that the Arctic ice cap is "heading for oblivion".

   In 1980, the Arctic ice in summer made up some 2% of the Earth's surface. But since then the ice has roughly halved in area.

   "Thirty years ago there was typically about eight million square kilometres of ice left in the Arctic in the summer, and by 2007 that had halved, it had gone down to about four million, and this year it has gone down below that," Prof Wadhams said.

   And the volume of ice has dropped, with the ice getting thinner:

   "The volume of ice in the summer is only a quarter of what it was 30 years ago and that's really the prelude to this final collapse," Prof Wadhams said.

     Parts of the Arctic Ocean are now as warm in summer as the North Sea is in winter, Prof Wadhams said.