Experts say the Scottish ski industry is just one of the many that could be crippled by rising temperatures worldwide.

On Friday, the country's biggest resort, Glenshee, and neighbouring Glencoe were put up for sale. "Basically, we've lost half a million pounds each of the last two seasons, and it's down to lack of snow," said a Glenshee spokesman.

Temperatures have risen to the point where artificial snow is melting faster than the snow machines can churn it out, Bill Wright of the Cairngorms Campaign environmental group told Reuters. "The Scottish skiing situation is verging on crisis," he said. "It's hard to resist the conclusion that global warming is a factor."

Global temperatures are expected to rise up to three degrees Celsius in the next 50 years, said a recent U.N. report, and Europe's lower Alpine resorts are already suffering.

In Switzerland, for example, banks have stopped lending to resorts below 1,500 metres (4,900 ft) worried that they will never get their money back.

Tens of millions of pounds have been invested in Scotland's pistes, which host over 300,000 visitors each winter. But February snowfall has been sparse this year and mild temperatures in the rugged Highlands have thawed all but the most shadowed northern slopes.

Add several thousand holidaying schoolchildren and the result is a melange of slush, mud and bruised buttocks.

"This is traditionally the busiest time," said Bruce Crawford of Snowsport Scotland. "On a busy day at Glenshee or Cairngorm resorts you'd get about 3,000 people. They'll be shoe-horned into a small area this holiday."

But he argued against global warming as a factor: "The industry's always had its ups and downs," he said.

Experts debate the subtle nuances of climate change in mountain regions, especially ones close to the sea like Scotland, but the longer term prognosis is not good.

"The UK climate scenario up to 2080 certainly shows a significant decrease in winter snowfall," said Asher Minns of climate researchers the Tyndall Centre.

Scottish tourism has responded to the crisis by trying to diversify. "Ski breaks" are now being marketed as "Winter breaks": Mountain biking, hill walking, whisky tasting - with perhaps a little skiing thrown in.