The report, Caring for our Australian Alps Catchments, has found the Alps, which stretch from Victoria through New South Wales to the Australian Capital Territory, face an average temperature rise of between 0.6 and 2.9 degrees by 2050, depending on how much action the international community takes to combat climate change.

''The effects of climate change are predicted to be the single greatest threat to the natural condition values of the Australian Alps catchments,'' the report states.

Rain, snow and other precipitation will decrease up to 24 per cent over the next four decades, accompanied by more bushfires, droughts, severe storms and rapid runoff, causing heavy erosion.

Australia's major mountain range, which peaks with Mount Kosciuszko at 2228 metres, is vulnerable to climate change and faces a dramatic transformation unless serious efforts are made, the study concluded.

''The scenario that is most likely is that there will be less snow both in total and in area, and that we shift more to summer rainfall,'' said study co-author Roger Good, a retired botanist with the NSW government.

''There won't be snow that sits around and slowly melts as there has been in the past. There will be more storm events in summer and therefore faster run-off, which has a lot of potential impacts in terms of soil erosion and damage to vegetation. The worst-case scenario is that there will be no snow at all … only rainfall in both summer and winter.''

The study looked at the 235 Alps catchments, which provide about 29 per cent of the annual water flows into the Murray-Darling Basin. Towns and cities from Wagga Wagga to Mildura and all the way to Adelaide would be affected by global warming damage to the Alps, Mr Good said.

It was the first full health check on the Alpine catchments since 1957. Six out of 10 of the catchments are in ''poor to moderate'' condition. Less than a quarter are getting better.

Snow cover has already declined by more than 30 per cent since 1954. The spring thaw has happened two days earlier per decade.

Loss of vegetation and more severe storms meant that the catchments would hold less water, leading to more rapid run-off, the report states. This would erode soil and reduce water quality as well as causing dams to overflow.

''They would not be able to regulate the flows,'' Mr Good said. ''We would have less water to actually utilise in future, both for human use and for storing for environmental uses.''

Ski fields should continue to get reasonable natural snow cover if the international community sticks to its ambition of keeping global carbon dioxide levels to 450 parts per million (ppm), up from the present 385 ppm, the report states.

But if less action is taken, leading to a concentration of 550 ppm, cover lasting more than 60 days could be reduced by up to 96 per cent by 2050.