"To make artificial snow all day long and during the whole season is just completely irresponsible for our climate, especially on such a large scale," said Carmen de Jong, professor and research manager at the Mountain Institute at the University of Savoie in France.

"That is insane, you cannot continue like this," de Jong told reporters during the annual meeting this week of the European Geosciences Union in Vienna.

Artificial snow is used on around 23,800 hectares -- the equivalent of some 35,000 soccer pitches or nearly 30 percent of all Alpine skiing slopes.

Some 95 million cubic metres of water -- the annual water consumption of a city of 1.5 million people -- are needed to produce one season's artificial snow for skiers and snowboarders in Italy, France, Germany, Austria, Switzerland and Slovenia.

Water used for the snow comes from surface streams, artificial reservoirs and increasingly from ground reserves.

De Jong said by keeping water in surface reservoirs instead of in the ground and by spraying it through the air to create the snow, around one third of the water evaporated, forming clouds that often travelled to other regions.

RIVERS RUNNING DRY?

Effects were already visible in some areas, like in parts of French skiing region Les Trois Vallees where water levels of some mountain rivers had dropped by 70 percent, she said.

Some Alpine villages, which previously got most of their drinking water from mountain streams, now needed to pump water out of the ground to ensure drinking supplies. Water taken out of the Alps would be missing for people and industry down the line.

"This could also have an enormous impact on the Mediterranean Sea if river discharges continue to fall," she said.

Ski resort operators argue there is no ecological impact from producing artificial snow.

"The water is not really used up, we simply extend the water cycle," said Albert Baier, managing director of the Planai ski lift operator in the Austrian resort of Schladming, where nearly all slopes are fitted with snow cannons.

"Everything comes from nature, and if I make snow now and then give it back to nature there is no problem with that," said Astrid Petri from the marketing department of Tyrolean ski resort Wilder Kaiser-Brixental.

De Jong recognised the economic role winter sports played for the region, but said snow sport enthusiasts and the tourism industry needed to come up with alternatives, like snow-shoe hiking.

"The tourism industry needs to realise that they cannot produce snow and have a skiing season at all costs," she said.