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Ice sheets melting three times faster than in 1990s, new study says

Undated handout photo of an iceberg and its reflection in Disko Bay, Greenland. Photo: PA Wire

Ninety-nine per cent of the freshwater ice in the world is locked into two great ice-sheets covering Greenland and Antarctica. If the Greenland Ice sheet melted, sea levels would rise by 20 feet. If the Antarctic ice sheet melted, they'd rise by 200 feet.

So it's pretty important for scientists to know what's happening to these two giant sheets of frozen water. In general, they know global temperatures are rising, so you'd expect those ice-sheets to be melting.

With 1000 monitoring stations in Greenland, they know ice there is melting and glaciers are flowing more rapidly to the sea. But Antarctica has few monitoring stations and it's much more difficult to find out what's happening there.

Now an international group of scientists, backed by the European Space Agency and NASA, have painted a picture that they say is "concerning".

That's the word used by Dr Andrew Shepherd of Leeds University who led the research. What they did was to combine all the observations made by 10 different satellites over the last 20 years and map what's happening to the ice sheets.

They found that melting ice from Antarctica and Greenland has increased sea levels by 11 millimetres since 1992. Doesn't sound too frightening does it? Eleven millimetres is less than half an inch.

But there are two reasons for their concern. The first is Antarctica. No-one really knew how much ice in the Antarctic was melting - and whether it was being replaced by snowfall. Different scientists had different estimates. But now, they've all got together and agreed Antarctic ice is being lost.

The second is the pace of what's happening. In 1992, melting ice from the two ice sheets were responsible for 10 per cent of the rise in sea level that scientists observed. Today that figure is about 30 per cent. Ice in Greenland is being lost five times faster than it was 20 years ago.

OK, don't rush out and build your own Noah's Ark just yet. This group of scientists have plotted ice loss over 20 years - and that's too short a period on which to base predictions.

But governments the world over would be foolish to ignore their concerns of this group of scientists when making big decisions about how to cut the amount of carbon dioxide we put into the atmosphere - the gas that most scientists believe is driving global warming.