Mount Everest's glaciers may disappear almost entirely by the year 2100 if greenhouse gas emissions continue to rise, a new study warns.
"The signal of future glacier change in the region is clear: continued and possibly accelerated mass loss from glaciers is likely given the projected increase in temperatures," Joseph Shea, a glacier hydrologist at the International Centre for Integrated Mountain Development (ICIMOD), Kathmandu, Nepal, who led the study, said in a statement.
Specifically, glaciers in the Everest region of the Himalayas could lose between 70 percent and 99 percent of their volume through the 21st century. Though, researchers are quick to point out that this bleak future depends on how much greenhouse gas emissions continue to increase, and on how this will affect temperature, snowfall and rainfall in the area.
"Our results indicate that these glaciers may be highly sensitive to changes in temperature, and that increases in precipitation are not enough to offset the increased melt," Shea explained.
Increased temperatures will not only hasten the rates of snow and ice melt, but can also result in a change of precipitation from snow to rain at critical elevations, where glaciers are abundant. Together, these factors will reduce glacier growth as well as increase the area exposed to melt.
To better understand the climate's impact on glaciers in the future, a team of researchers in Nepal, France and the Netherlands studied glaciers in the Dudh Kosi basin in the Himalayas, which is home to some of the world's highest mountain peaks, including Mount Everest. They used a combination of field observations and data from local weather stations to test a model of glacier change over the past 50 years.
Glacier response, at least in part, is due to changes in the freezing level - the elevation where mean monthly temperatures are 0 degrees Celsius (32 degrees Fahrenheit).
"The freezing level currently varies between 3200 m in January and 5500 m in August. Based on historical temperature measurements and projected warming to the year 2100, this could increase by 800-1200m," explained co-author Walter Immerzeel of Utrecht University in the Netherlands. "Such an increase would not only reduce snow accumulations over the glaciers, but would also expose over 90% of the current glaciered area to melt in the warmer months."
The researchers caution, however, that their results are only a preliminary estimate of how Himalayan glaciers will react to increasing temperatures in the region. More research is needed to draw a definitive conclusion, but their study does strongly indicate that rising greenhouse gas emissions could make Mount Everest's glaciers all but disappear by 2100.
This, in turn, could impact the availability of water and thus prove detrimental to agriculture and hydropower generation in the region. Not to mention that ongoing glacial melt may negatively impact local populations as well as cause catastrophic floods.
The findings were published in the journal The Cryosphere, an open access journal of the European Geosciences Union (EGU).
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