Scientists alarmed at increase in melt rate of ice

4 August 2004 | The Scotsman


GREENLAND?S cover of ice is melting ten times quicker than previously thought, an increase that could lead to floods across the world, scientists have found.

Newly published research shows an alarming rise in the rate of collapse of the massive Greenland ice-sheet as a result of global warming. Scientists now believe the ice-sheet is shrinking at the rate of ten metres a year, not the one metre previously thought.

If the entire ice-sheet melts, the resulting flood waters would raise the level of global seas by seven metres, submerging large areas of land, including sea-level cities such as London.

Greenland has the biggest ice-sheet in the northern hemisphere: almost 772,000 square miles of ice which is up to 1.9 miles thick, the base of which is below sea level.

The new research was published by the Geological Survey of Greenland and Denmark, which has been monitoring the ice-sheet for several years. Icebergs from the ice-sheet crash into the sea regularly, but they have been doing so with increasing frequency over the past year.

The last major study of Greenland was by NASA, the US space agency, four years ago. That found that the surface of the ice was receding by one metre a year.

Carl Boggild, the lead scientist, said the ice had dropped by two or three metres in just the past few months.

“There is a high melt rate due to warm winters and warm summers,” he said.

Jonathan Gregory, of the Hadley Centre for Climate Prediction, at the University of Reading, along with colleagues from Brussels and Bremerhaven, has also found that an average annual warming in the region of 2.7C would mean that the rate of melting would outpace the annual snowfall.

The greater the warming, the faster the snow melts. The worst-case predictions for Greenland, made by an inter-governmental panel of scientists, now involve an average warming of 8C.

At those temperatures, oceans that have risen by 2.5mm (less than one-tenth of an inch) a year will start to rise by a steady 7mm a year.

One medium-term side-effect of the destruction of the Greenland ice-sheet could be the loss of the Gulf Stream, which keeps Europe warm and temperate. The fresh water from the ice mixes with the salt water in the sea, altering the salinity and changing the direction and behaviour of major currents.

The scientists on the Greenland survey admit they have no way of setting any kind of timetable to a rise in water levels or forms of climate change, and insist that further monitoring will have to take place over the next few years to get a clearer picture. But they do admit that their findings are worrying and suggest a much more serious picture for global sea levels than had been available up until now.

It is likely to take hundreds of years for the entire ice-sheet to melt but, as this year’s survey has shown, if the speed of the destruction increases, that timescale could be brought forward dramatically.

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