Extreme water shortages predicted for tropical Andes

A new scientific study says that climate change in the tropical Andes will lead to water shortages and impact on socioeconomic activity in the region, writes Paula Leighton from SciDev, part of the Guardian Environment Network

guardian.co.uk, Wednesday 11 February 2009 14.08 GMT

Climate change will seriously affect the tropical Andes by the end of this century and could lead to water shortages, say scientists.
Their study — a first attempt at determining future climate change in the region — concludes that increases in temperature "will likely lead to severe impacts on socioeconomic activity" and biodiversity.
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.
This, she says, will reduce water supplies during the dry season, "affecting human consumption, agricultural irrigation and hydroelectric power generation" mainly in the Ancash region of Peru, where nearly one million people live today.
"Considering alternative sources of energy, a more efficient use of water and better technology to manage its supply", are some of the initiatives to reduce the impact of the predicted scenarios, says Urrutia.
The authors stress that comparisons across a range of regional climate models are required to put their findings into perspective.
The study was published in the Journal of Geophysical Research last month (23 January)
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