DUBAI, United Arab Emirates - Nearly 60 million people living around the Himalayas will suffer food shortages in the coming decades as glaciers shrink and the water sources for crops dry up, a study said Thursday.
But Dutch scientists writing in the journal Science concluded the impact would be much less than previously estimated a few years ago by the U.N. Intergovernmental Panel on Climate Change. The U.N. report in 2007 warned that hundreds of millions of people were at risk from disappearing glaciers.
The reason for the discrepancy, scientists said, is that some basins surrounding the Himalayas depend more on rainfall than melting glaciers for their water sources.
Those that do count heavily on glaciers, like the Indus, Ganges, and Brahamaputra basins in South Asia, could see their water supplies decline by as much as 19.6 percent by 2050. China's Yellow River basin, in contrast, would see a 9.5 percent rise in precipitation as monsoon patterns shift due to the changing climate.
"We show that it's only certain areas that will be affected," said Utrecht University hydrology professor Marc Bierkens, who along with Walter Immerzee and Ludovicus van Beek conducted the study. "The amount of people affected is still large. Every person is one too many, but it's much less than was first anticipated."
The study is one of the first to examine the impact of shrinking glaciers on the Himalayan river basins. It will likely further fuel the debate on the degree that climate change will devastate the river basins that are mostly in India, Pakistan, Nepal, Bangladesh, Bhutan, and China.
Scientists for the most part agree glaciers are melting at an accelerated rate as temperatures increase. Most scientists tie that warming directly to higher atmospheric concentrations of greenhouse gases such as carbon dioxide.
Some glaciers, such as in the Himalayas, could hold out for centuries in a warmer world. But more than 90 percent of glaciers worldwide are in retreat, with major losses already seen across much of Alaska, the Alps, the Andes, and many other ranges, according to researchers in the United States and Europe.
Some scientists have come under fire for the 2007 U.N. report, which includes several errors that suggested the Himalayan glaciers could disappear by 2035, hundreds of years earlier than data actual indicates.