It has been installed on the longest Himalayan glacier, in the Everest region of Nepal.

There have been numerous reports of glacial retreats in the Himalayas over the years, but this weather station will be able to quantify changes to the local climate.

One part of it has been set up on the Nguzumpa Glacier to record solar radiation, relative humidity, air and soil temperature, wind speed and direction, and precipitation.

The other part has been placed in the river fed by the 35km-long glacier, to measure changes in flow caused by glacial melt.

Officials with Nepal's Department of Hydrology and Metrology will climb up the Cho Oyu Mountain to the Nguzumpa Glacier in March to collect data from the unmanned station.

"Once we get to see the figures in March, we will learn the extent of glacial retreat caused by global warming," said the department's chief glaciologist, Om Ratna Bajracharya.

Temperatures rising

Previous studies have shown temperatures in the Himalayas have been rising at a rate of 0.06C per year, fuelling fears that melting glaciers have been filling glacial lakes more rapidly.

There are 3,250 glaciers in the Nepalese Himalayas, and 2,315 of them contain glacial lakes that are increasing in size at varying rates.

"While we do know that there is a lot of glacier melting due to global warming, we still need to know the exact causes and dynamics of such melting," said Chandra Prasad Gurung, Nepal representative of the environmental group WWF which provided the weather station equipment.

"Therefore, having the weather station installed will help us understand more of the weather patterns and enable us to monitor the issue clearly."

Globally, glaciers have lost an average 6m in height in 20 years

Before the station, scientists either visited the glaciers themselves or studied satellite images to see any changes.

Most of the scientific reports have shown that glacial retreat and increases in lake size are occurring at a rapid rate.

Between 1970 and 1989, Japanese researchers discovered most glaciers in the Everest region had retreated 30-60m (100-200ft). To the west, in the Dhaulagiri region, field studies carried out before 1994 showed the same trend.

Nepal's most studied glacier in Tsorong Himal underwent a 10m (33ft) retreat between 1978 and 1989.

However, the Himalayan glacial system is not the only one under threat.

The World Glacier Monitoring Service, supported by the United Nations Environment Programme (Unep), collated records from across the globe and concluded that 30 major glaciers - assessed as being a representative global sample - had thinned by an average of 6m (20ft) between 1980 and 2001.

Flooding lakes

Two years ago Unep and the Kathmandu-based International Centre for Integrated Mountain Development found that 20 glacial lakes in Nepal and 24 in Bhutan were filling up so rapidly that their walls could breach by 2009.

The report was based on satellite images, but there have been no follow-up studies even though glaciologists have called for urgent further investigation.

Their worries are triggered by both the short- and long-term problems that retreating glaciers can pose.

A short-term problem is Glacial Lake Outburst Flood (Glof), the result of shrinking glaciers and melting ice that causes lakes to grow and breach loose moraine walls, sending huge floods of water, mud and boulders downstream.

In 1985 a glacial lake burst in Khumbu in the Everest region, killing at least 20 people and washing away a hydropower station, the trekking trail to Everest base camp and numerous bridges.

Part of the new station will record river flow

Researchers say the worst-case scenario would be a major Himalayan earthquake, which could cause dozens of glacial lakes to burst simultaneously.

In Peru, experts say about 30,000 people have died in Glof-related incidents.

In the long-term, computer simulations suggest that global warming will affect the flow of Himalayan rivers over the 21st Century.

They indicate spring flow in these rivers will increase over the next five decades, but the time will come when there will be so little snow in the Himalayas that the rivers could run dry in the dry season.

"In some rivers, the flow may go down by as much as 90%," said hydrologist Syed Iqbal Hosnain, of the University of Calicut, India, who modelled what would happen in snow-fed regional rivers.

But the depletion in water level in Himalayan rivers will not just affect the lives of people in the mountains, but also the hundreds of millions of people who live downstream.

Nearly 70% of discharge to the River Ganges comes from Nepalese snow-fed rivers, which means that if Himalayan glaciers dry up, so could the Ganges.

This could also apply to other major rivers in South Asia like the Brahmaputra and Indus, the lifelines for millions.