Global warming could wipe out three-quarters of New Zealand's glaciers by 2100, a study by scientists at the University of Alaska says.
The research looked at how climate change will affect glaciers on which millions depend for their water and the problems faced by generations in the far distant future.
Some regions will be far worse hit than others because of the altitude of their glaciers, the nature of the terrain and their susceptibility to localised warming.
New Zealand could lose 65-79% of its glaciers, while Europe's Alps could experience glacier loss of 60-90%.
At the other end of the scale, Greenland is predicted to lose about 8% of its glaciers and a 10% loss is predicted for high-mountain Asia.
The study, published in the journal Nature Geoscience on Sunday, predicts mountain glaciers and icecaps will shrink by 15-27% in volume terms on average by 2100.
Geophysicists Valentina Radic and Regine Hock, of the University of Alaska, based their calculations on a computer model derived from records for more than 300 glaciers between 1961 and 2004.
The model factors in a "middle of the road" scenario for greenhouse-gas emissions, by which the earth's mean surface temperature would rise by 2.8°C during the 21st century.
But it does not include the icesheets of Antarctica and Greenland, where 99% of earth's fresh water is locked up.
If either of these icesheets were to melt significantly, the scientists say sea levels could rise by an order of metres, drowning coastal cities.