Fearary warning: No drinking water.

Landing mountain areas below snow and ice is more common in European ski resorts that depend on artificial snow and become summer resorts instead of winter resorts.

The Swiss government says the number of skiers in the Alps has dropped by about 24 percent over the past ten years. By the end of the 21st century, the amount of snow on ski slopes is likely to fall to less than 50 percent of the current amount, and tracks below 1,500 feet [1,500 m] above sea level can be totally snowless, writes the magazine “Nature”.

Experts cite the most important mountain regions that have large amounts of water in the form of snow and ice. There are more in the mountain ranges than anywhere else in the world than in the Arctic and Antarctic, where over 200,000 glaciers and lakes are located.

As ice and snow melt, the water is gradually releasing and filling the water source of rivers and lakes essential to the life of some 1.9 billion people, which is about 20 percent of earth's present population.

The new study highlights the four largest systems on four continents in Asia, Europe, North America, and South America.

The largest, most important system, but even the most endangered, is the Asian water supply system from the area where the Himalaya, Karakorum, Hiduus, and Ladak are located. It directly affects more than 200 million people mainly in Afghanistan, China, India and Pakistan.

In Europe, these are the Alps and the basins associated with Rhoone, yes, Rhine and the Black Sea... about 70 million people depend on them. In North America there are the mountains of Cordilera, which supply many rivers and depend on some 14 million people.

In South America, there are Andes and Cordiers, from which some eight and a half million people depend. Mountains are warming twice as fast as the rest of the world.

Over the next 100 years, climate change will affect drinking water for people, electricity and agricultural water, climatelogists warn.