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The researchers simulated two different climate change scenarios for 2071–2100: a low-emission scenario with reduced population growth, and a medium-high emission scenario with high population growth, using regional climate models. The models predict temperature increases of 2–7 degrees Celsius, depending on location and scenario, for the entire tropical South America region.
Most strongly affected will be the tropical Andes, home to 99 per cent of the world's tropical glaciers. These provide the surrounding region with a steady supply of water, retaining much of the precipitation falling at high elevation and eventually — when the snow melts — releasing it to feed river streams. The largest temperature rise at high elevation is projected for the Cordillera Blanca in northern Peru (see Peru mountain glaciers 'receding rapidly'), the highest and most extensively glaciated tropical mountain range in the world.
"A higher temperature in Cordillera Blanca may cause a larger surface of glaciers receiving rain instead of snow, therefore reducing ice accumulation," says co-author Rocío Urrutia, of the University Austral of Chile. "On the other hand, a weakening of the winds providing humidity from the Amazon might also decrease precipitation, reducing even more the water supply for glaciers," she told SciDev.Net….
The Cordillera Blanca and the Cordillera Negra, shot by Ed Pax, Wikimedia Commons, under the terms of the GNU Free Documentation License, Version 1.2
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