The mountains have been the selling-point of Switzerland's successful tourist industry for more than 100 years. Without tourists, many Alpine areas would not be economically viable. In some places over 80 % of jobs depend on them. The Alpine area as a whole, spreading over eight countries, receives 100 million visitors every year.

But the influx of tourists puts the mountain areas under enormous pressure. The leisure industry could be in danger of killing the goose that lays the golden eggs.

For example, in the winter tourists come to ski - and they expect to find snow. But in recent years snow has been less dependable, which spells economic disaster, especially for lower level resorts. One controversial answer has been to use artificial snow cannons. These machines use huge amounts of water: about four liters per square meter per centimeter of snow cover, in other words about 800 tonnes to cover an area of 2.5 acres with snow 8 inches deep. They take the water from reservoirs and streams, and this at a time of year when the water is in any case running low. This water is effectively dumped elsewhere, harming both soil and plants. The cannons also consume huge amounts of energy. To make matters worse, artificial snow quickly forms a hard surface and needs frequent fresh snow to keep the pistes usable.

Despite the disadvantages, facilities are available to provide snow to a total of 16.7 km2, according to the 2001 report of the Swiss Federation of Cableways. The proportion of pistes with cannons available is more than five times what it was in 1990. Supporters of the procedure point out that they keep people away from danger areas, like slopes exposed to sun or wind, or glaciers. They also say that without the possibility of skiing down to the very bottom, people would stay away from upper slopes too, damaging their tourist industry.

Visitors inevitably put resorts as well as landscape under pressure. They think of the mountains as being a place where they can get back to nature; they don't want to see villages disfigured with new hotels and tourist villas, or huge car parks, and yet all these things are built for them. The locals have to cope with huge temporary influxes of visitors. The former lifestyle is being swept away.

It has been calculated that a family of four will consume ten times as much electricity in a two-week skiing holiday as they would if they stayed at home. And almost certainly they will come by car, polluting the air they have come to enjoy.