The total glacier area and ice reserves in the landlocked Himalayan country came down by 24 per cent and 29 per cent respectively between 1977 and 2010, according to a report released by the Kathmandu-based International Centre for Integrated Mountain Development (ICIMOD) on 16 May.
The glaciers receded on an average by 38 square kilometre (sq km) every year, and such a massive retreat could destabilise adjoining ice sheets, trigger frequent avalanches, and increase the risk of glacial lake outbursts, affecting communities downstream, say experts.
Nepal has a total of 3,808 glaciers covering 3,902 sq km.
The latest ICIMOD report comes a week after studies by the US National Aeronautics and Space Administration (NASA) and the University of Washington revealed that a large section of the Antarctica ice sheet was rapidly melting.
“The accelerated melting of glaciers in the last three decades is a key indicator of global warming, which threatens water flow in rivers fed by glaciers. The increased melting of ice also puts the local communities at risk of glacial lake outbursts,” says Samjwal Ratna Bajracharya, lead author of the report.
“Reduced precipitation and warmer temperatures will cause a short-term danger of too much water coming out of the Himalayas, and long-term danger of insufficient water,” Bajracharya tells SciDev.Net.
Nearly 1 billion people downstream in China, India, Pakistan and Southeast Asia depend on the Himalayas and the Tibetan plateau for water.
The study is based on an analysis of satellite images of the glaciers as well as field studies and is one of the most comprehensive surveys of Nepal’s glaciers. It found that the rate of glacial area loss between 1980 and 1990 was almost twice that recorded between 1990 and 2010.
“Reduced precipitation and warmer temperatures will cause a short-term danger of too much water coming out of the Himalayas, and long-term danger of insufficient water.”
Samjwal Bajracharya, ICIMOD
“The snow cover was higher in the 80s, which could explain the accelerated melting in that decade in comparison to the recent past,” says Bajracharya. Due to fragmentation caused by glacial melt, the number of glaciers in Nepal has gone up by 11 per cent in the last three decades.
ICIMOD also released 30 years (1980-2010) of glacier data from Bhutan, which showed a similar trend. Bhutan lost 23.3 per cent of its glacier area between 1980 and 2010 and the fragmentation of glaciers in the last three decades resulted in a 14.8 per cent increase in the number of glaciers.
Experts say a lot more needs to be done to map hazardous valleys, glacial lakes in Himalayan region that are in danger of bursting.
Melting of glaciers is a clear indicator of climate change which is already affecting weather, with erratic rainfall patterns, frequent cloudbursts, delayed onset of monsoons, says Rishi Ram Sharma, chief of Nepal’s department of hydrology and meteorology, which jointly prepared the report. “We need more studies and better science to understand vulnerable regions like the Himalaya,” he says.
> Link to the ICIMOD report
This article has been produced by SciDev.Net's South Asia desk.