珠穆朗玛峰冰川或将发生巨大变化

If greenhouse-gas emissions continue to rise, glaciers in the Everest region of the Himalayas could experience dramatic change in the decades to come. A team of researchers in Nepal, France and the Netherlands have found Everest glaciers could be very sensitive to future warming, and that sustained ice loss through the 21st century is likely. The research is published today (27 May) in The Cryosphere, an open access journal of the European Geosciences Union (EGU). "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," says Joseph Shea, a glacier hydrologist at the International Centre for Integrated Mountain Development (ICIMOD), Kathmandu, Nepal, and leader of the study.

The glacier model used by Shea and his team shows that glacier volume could be reduced between 70% and 99% by 2100. The results depend on how much greenhouse-gas emissions continue to rise, 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," says Shea. Increased temperatures will not only increase 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 concentrated. Together, these act to reduce glacier growth and increase the area exposed to melt.

Glaciers in High Mountain Asia, a region that includes the Himalayas, contain the largest volume of ice outside the polar regions. The team studied glaciers in the Dudh Kosi basin in the Nepal Himalaya, which is home to some of the world's highest mountain peaks, including Mt Everest, and to over 400 square kilometres of glacier area. "Apart from the significance of the region, glaciers in the Dudh Kosi basin contribute meltwater to the Kosi River, and glacier changes will affect river flows downstream," says Shea.