A report warns the Antarctic ice shelf is melting and sea levels will rise by 1.4 metres this century.
The amount is more than double the previous estimate by the Inter-governmental Panel on Climate Change.
The report was authored by the Scientific Committee on Antarctic Research, which is part of the International Committee for Science, and coordinates research in Antarctica. The report is based on the work of 100 scientists in 13 countries.
The committee's executive director, Colin Summerhayes, says the main area of concern is west Antarctica - that part of the continent between New Zealand and South America.
Dr Summerhayes told Morning Report the same thing is happening on the coast of Greenland, exacerbating the problem.
"Warm water is getting in under the mouths of the Greenland coastal glaciers and causing them to carve icebergs much faster than usual.
"What we have is the unusual situation in which both this part of west Antarctica and Greenland are discharging about the same amount each of ice into the ocean and that's raising sea levels faster than anybody thought it would."
The report comes 50 years to the day that the Antarctic Treaty, regulating use of the territory, was opened for signing and a week before the United Nations' climate change summit in Copenhagen gets under way.