. The Khumbu Glacier has retreated 5 km since the first ascent of Mt Everest 50 years ago.
. 44 glacial lakes in Nepal and Bhutan are growing so fast, they are in danger of bursting their banks in the near future.
. A few small ponds on the Imja Glacier have grown in the past decade into a huge lake 2 km long.

All these are effects of global warming. Aside from the polar ice caps, it is in our mountains that the effects of atmospheric warming are most dramatic.

Temperatures records started being kept in Nepal only 40 years ago, but even in that time, there is already a discernibale warming trend. "Our high altitude monitoring sites indicate that temperatures have been increasing in Nepal," says Arun B Shrestha, a government hydrologist with the Snow and Glacier Hydrology Unit, which is trying to siphon water off the Tsho Rolpa glacial lake in the Rolwaling. In some parts of the country, the average annual temperature has risen by 0.1 Celsius a year, and research shows the warming trend is faster in the trans-Himalayan regions of northwestern Nepal.

"It is clear that global warming is emerging as one, if not the, biggest threat to mountain areas," says Roger Payne, a member of a United Nations Environment Programme (UNEP) sponsored expedition to Island Peak near Lhotse.

When temperatures rise even by a fraction of a degree, snow cover begins to melt and lakes start forming on glaciers. These expanding lakes eventually burst through and tumble down narrow Himalayan valleys.

Says Surendra Shrestha, the Nepali regional coordinator for UNEP's Divison of Early Warning and Assessment in Bangkok: "Our findings indicate that 20 glacial lakes in Nepal and 24 in Bhutan have become potentially dangerous as a result of climate change. We have evidence that anyone of these could, unless urgent action is taken, burst its banks in five to 10 years time with potentially catastrophic results."

The only long-term solution is to reduce emissions of carbon dioxide and other greenhouse gases. But an international treaty on cutting emissions is bogged down because of opposition mainly from the US, and disagreements over reduction quotas for developing countries like India and China.

Satellite images show that Bhutan has more glacial lakes that are in danger of bursting, mainly because of the higher precipitation there. In Nepal, the Tradkarding glacier which feeds Tsho Rolpa is retreating at 20 metres a year. In some years within the last decade, the retreat even reached 100 metres.

Shrestha stresses the need for more ground and on-site studies to analyse actual threats. He cites the example of the Tulagi lake in Manang, once considered an extreme danger, which later proved to be exaggerated. While ice fields in the Everest region have seen rapid changes in the last 20 years, including the retreat of the Khumbu glacier, experts say the threat of Imja lake below Lhotse bursting has been reduced.

Meanwhile, Nepal is carrying out an inventory of its own greenhouse emissions to identify measures to reduce them. But the real worry is about when richer and more populous countries will do the
same.