By Imogen Foulkes
BBC News, Berne
Some of Switzerland's most famous ski resorts have published a report looking at the consequences of global warming on their winter tourist business.
The report advises resorts to pitch for more summer visitors
The resorts, among them Wengen, Muerren, Grindelwald and Gstaad, are the first in the Alps to start planning for a future that is likely to contain less snow.
Climate change experts have already predicted a global temperature rise of one to two degrees Centigrade over the next 50 years.
In December, the Organisation for Economic Co-operation and Development (OECD) warned that the consequent rise in the snow line could make some ski resorts unviable.
Winter sports bring millions of tourists and dollars to the Alps every year, and many resorts now rely on the ski season for 70% to 80% of their income.
But the new report says that in future, resorts under 1,500 metres should not focus on skiing as their main attraction.
And it warns that without reliable winter sports, hotels stand to lose 25% of their overnight stays, while cable car companies will sell 35% fewer lift passes.
"Skiing will have to become just a side attraction, and not the main attraction anymore," said the report's author Hansruedi Muller, who is professor of leisure and tourism at the University of Berne.
"You'll come here [to the Alps] for nice walks, for wellness, and besides you'll do a little bit of skiing, but skiing will disappear as a main attraction," Prof Muller said.
Diversify or die
Already some resorts are starting to diversify in the hope of attracting tourists who have other interests than skiing.
Winter sports bring millions of tourists and dollars to the Alps
Gstaad has many vulnerable lower lying ski slopes, but it is also a wealthy town that has started to invest heavily in luxury spa facilities.
"Many resorts still offer only skiing and snowboarding", said Roger Seifritz, Gstaad's director of tourism.
"And that's a big trap they need to get out of. If they don't, it could be the end for them."
Gstaad believes it is preparing well for the future.
"Already a third of our winter guests don't ski," said Mr Seifritz.
"They like to walk, they like our good restaurants, they go to concerts. So, I'm confident we will find lots of ways to keep tourists coming."
But Mr Siefritz said it may not be so easy for everyone.
"Skiing has become mass tourism in many parts of the Alps. And there is no single activity which could replace the income it generates."
The report advises resorts to stop focusing solely on winter and start pitching for more summer visitors too.
"This could be a real opportunity for the Alps," said Prof Muller.
"As the climate gets warmer, many people may want to escape hot humid cities for cool mountain air."
There is already some evidence that the Alps could benefit from warmer temperatures.
In the wake of Europe's heat wave in 2003, mountain resorts saw an increase in tourists who had decided that a beach in Greece or Spain would be simply too hot.
But a decrease in snow cover is not the only negative consequence of global warming.
Some resorts are already trying to diversify to also attract non-skiers
Alpine regions will also have to deal with melting glaciers and thawing permafrost.
That will mean possible future water shortages and an increased risk of rock and mud slides.
The report says resorts need to invest more in preparing for possible natural disasters, particularly if they are at the same time campaigning for more tourists all year round.
Preparing for the future will be costly, especially since resorts are being asked to spend money developing new activities - just as they are losing money on traditional winter sports.
But the report warns that failure to act will be even more expensive - refusing to adapt to climate change could means losses of $100m (£52m) a year for the eight ski regions in the Bernese Alps alone.
"It's a huge challenge for us," admits Casimir Platzer, president of the Bernese Hoteliers Association.
"And it will be painful, that's for sure. But at least we are acting on the challenges ahead of us, instead of just reacting to them."