Analysis of satellite images by researchers at the University of Bristol has helped in the quest to make more accurate predictions for sea-level rises in the future.

University researchers in conjunction with the British Antarctic Survey analysed millions of NASA satellite measurements of the rapidly-thinning glaciers along the coastline of both the Antarctic and Greenland ice sheets. This has shown the most profound ice loss as a result of glaciers speeding up where they flow into the sea.

Laura Edwards from the University of Bristol said: "This study highlights just how important satellite measurements are for observing change on the scale of the Greenland and Antarctica ice sheets.

"There is realistically no other way of obtaining such comprehensive coverage, and what we see is that many more glaciers than we'd expected have speeded up. "We really need these measurements because we don't yet understand what the ice sheets are going to do in the future, but we know that they'll have a big effect on sea level."

Lead author Dr Hamish Pritchard from British Antarctic Survey (BAS) added: "We were surprised to see such a strong pattern of thinning glaciers across such large areas of coastline. We think warm ocean currents reaching the coast and melting the glacier front is the most likely cause of faster glacier flow. This ice loss is so poorly understood it's the most unpredictable part of future sea level rise."

In Greenland, for example, the scientists studied 111 fast-moving glaciers and found 81 thinning at rates twice that of slow-flowing ice at the same altitude.They found ice loss from many glaciers in Antarctica and Greenland is greater than the rate of snowfall further inland.

In Antarctica some of the fastest thinning glaciers are in West Antarctica where Pine Island Glacier and neighbouring Smith and Thwaites Glacier are thinning by up to nine metres every year.