Saturday, November 14, 2009

Melting glaciers threaten water supply for millions

Snow and ice in the Andes Mountains, high above the tropical regions of Bolivia, Peru, Ecuador and Colombia, supply the drinking water for 30 million people. That ice has been dwindling in recent years due to rising temperatures, threatening the region’s water supply, agriculture and power generation. Scientists are stepping in to help, using monitoring data to improve understanding of the region’s water cycle and better plan for future needs.
The high Andes Cordillera is home to 70 percent of the world’s so-called tropical glaciers.
During the winter, the glaciers accumulate and store rain and snow that then melts off in the summer, providing a freshwater source. Quito, Ecuador, draws 50 percent of its water from the glacial basin, while this source accounts for 30 percent of the water used in La Paz, Bolivia. This water supply is now in jeopardy, with warmer temperatures changing the timing of the glacial melt and the amount of precipitation over the mountains; warmer temperatures cause the clouds that cover the Andes to condense at higher altitudes and release even more heat along the way.
Since 1970, the Andean glaciers have lost 20 percent of their volume, according to Peru’s National Meteorology and Hydrology Service. Some models project that many of the lower-altitude glaciers could disappear entirely in the next 10 to 20 years. Because these glaciers are the major regulators of the water supply for the region, a global effort is under way to help the region cope with increased local climate variability and global climate change.
WMO Members are contributing to a multi-disciplinary project, led by the World Bank and the Global Environment Facility, to address the situation in the Andes. Several WMO Members are monitoring changes in the glaciers with the use of high-resolution satellite images.
Improved observation and assessment practices enable the region to better map out the vulnerable areas and develop adaptation strategies. Adaptation measures include the development of alternative water sources, diversification of the energy supply and shifting to alternative crops and advanced irrigation systems.
The Colombian Government has adopted an Integrated National Adaptation Plan that includes pilot projects to regulate water in the high-altitude moorlands and to compensate for loss of available water in the insular areas. In all of these efforts, climate information plays a keyrole. Effective water management requires advance warning of dramatic changes in the hydrological cycle. The ultimate goal is for climate scientists to be able to provide the necessary forecasts to water managers everywhere. Courtesy: World Meteorological Organization.

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