Scientists predict warmer and wetter Himalayas

Plateau glacier

A neat plateau glacier with an icefall terminus, just below the Morimoto Peak seen at the centre of the photo at an altitude of 5990m. Photo: Evan Miles

By Arun Bhakta ShresthaICIMOD

Water levels of the critical rivers that originate in the Himalayan glaciers will not drop over the next century, say scientists.

The latest research led by Dr Walter Immerzeel, a scientist from Utrecht University in the Netherlands and visiting scientist at the International Centre for Integrated Mountain Development (ICIMOD) in Nepal, indicates that increasing rains would prevent rivers from drying up. His earlier works, published in Science in June 2010,   indicated worrisome drop in the levels of the same rivers by 2050.

Details of the new study have now been published in an article, titled ‘Rising river flows throughout the twenty-first century in two Himalayan glacierized watersheds’,  in Nature Geoscience on 4 August 2013, authored by  Immerzeel, Dr Francesca Pellicciotti, and Prof M.F.P. Bierkens.

New results from Dr Immerzeel’s research indicate that water levels of the rivers will not drop over the next century due to an increase in monsoon rains in the region. However, climate change will result in smaller glaciers and less meltwater in the Himalayas. The research shows that although the size of the glaciers in the basins of the Indus and the Ganges will decrease in the 21st century, water discharge will however increase.

“The research concerns two basins, and while the models are representative they only relate to a small area of the Himalayas,” says Pellicciotti, a glaciologist of ETH Zürich, a science and technology university in Switzerland and also a visiting scientist at ICIMOD. “Furthermore, we concentrated on the impact on average discharge, rather than extremes.”

The results very much depend on the climate scenarios used for the analysis and available scenarios have high uncertainties in projecting monsoon precipitation but do provide scope for improvement in the future.

Director General of ICIMOD, Dr David Molden, says this important research challenges perception of the impact on climate change on water resources. “However much work remains, including better understanding of changes in monsoon patterns and snowmelt, and resulting variability in river flows, including low flows and flood peaks.”

Dr Immerzeel conducted his study in collaboration with ETH Zürich and Deltares, an independent institute for applied research in the field of water, subsurface, and infrastructure based in the Netherlands. ICIMOD is collaborating with Immerzeel and Pellicciotti under its Cryosphere Monitoring Programme and some of the research results are the outputs of this collaboration.