Dramatic scenarios from man-made global warming can no longer be excluded, including the complete disappearance of glaciers from entire mountain ranges, states a new UN report.

Global warming is leading to processes "without precedent in the history of the earth", says a latest update of the 1995-2000 edition of the UN-supported World Glacier Monitoring Service's (WGMS) 'Fluctuations of Glaciers'.

"The last five years of the 20th century have been characterised by an overall tendency of continuous if not accelerated glacier melting," says the report compiled with the support of the UN Environment Programme (Unep).

"The period 1980-2000 shows a trend of increasingly negative balances with average annual ice thickness

losses of a few decimetres,"it adds.

"The observed trend of increasingly negative mass balances is consistent with accelerated global warming."

Analysis of repeated inventories shows that glaciers in the European Alps have lost more than 50 per cent of their volume since the middle of the 19th century.

A further loss of one-fourth the remaining volume is estimated to have occurred since the 1970s, the report states.

"With a realistic scenario of future atmospheric warming, almost complete deglaciation of many mountain ranges could occur within decades, leaving only some ice on the very highest peaks," the report warns.

The worldwide programme for collecting standardised information on glacier changes wasinitiatedin 1894.

"Due to the human impacts on the climate system (enhanced green-

house effect), dramatic scenarios of future developments - including complete deglaciation of entire mountain ranges - must be taken into consideration," the report says.

"Such scenarios may lead far beyond the range of histori-cal/holocene variability and most likely introduce processes (extent and rate of glacier vanishing, distance to equilibrium conditions) without precedence in the history of the earth."The report finds echo in several other global studies including that of the Intergovernmental Panel on Climate Change (IPCC), which has been urging developed and developing countries to undertake steps to reduce greenhouse gas emission.