The mystery of Antarctica's speeding glacier
With the possible exception of the ice that covers Greenland, the West Antarctic ice shelf is the most important body of water in the world. If it thaws, the results will be disastrous for millions, raising sea levels and flooding coastal cities such as London, New York, Tokyo and Calcutta. So it is understandable that scientists are alarmed as to why one particular section of it - Pine Island Glacier - is melting so much faster than the rest.
Pine Island, which contains around 30 trillion litres of water, is slipping into the sea at an ever accelerating rate, a development that alone could raise sea levels by as much as 10cm over the next century. Starting at an altitude of 2,500m, the glacier is 95 miles long and 18 miles wide, reaching the sea as an ice wall 750m high. Even before it began to speed up, it was one of the fastest-flowing glaciers in the world, at nine yards a day.
Scientists believe that the thinning of the glacier, and its acceleration, are due to unusual melting under the base as it enters the ocean. This is caused by either global warming or a hitherto unknown factor, such as an underwater volcano.
Finding proof of either, however, has been problematic. The mountain glaciers in the west of the Antarctic have the worst blizzards and some of the harshest temperatures on the planet. The zone is too hostile for any research station, so scientists have to base information on satellite studies and aerial surveys.
Now, though, a team of British scientists plans to attack the continent's "weak underbelly" â€“ the watery realms below the massive glaciers. Using a robot submarine nicknamed "Autosub", researchers from the British Antarctic Survey (BAS) hope to explore this previously inaccessible part of the glacier, to discover what is happening.