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Peru Floods
Tue Jun 29, 2004
Listen in RealAudio 
On December 13, 1941, a glacial lake high in the Cordillera Blanca Mountains of Peru
burst its banks, triggering a flood that killed an estimated 5,000 people. But this
appears to be just a warning sign of worse things to come. Hi, I’m Bryan Yeaton, and
this is The Weather Notebook.
In the years that followed the 1941 deluge, a series of so-called outburst floods and
avalanches would claim thousands more lives among the half million people who live
below these towering mountains. Now scientists believe that what’s really
responsible for these disasters may be global warming.
Peru’s Cordillera Blanca Mountains are especially sensitive to rising temperatures
because they are so heavily glaciated – in fact, they have more glaciers than any other
tropical mountain range in the world. As global temperatures rise, these glaciers have
been melting rapidly, and as they melt, they feed the water into scores of new and
extremely unstable lakes. Ice chunks from retreating glaciers topple into these lakes,
sending up massive waves that rip through the fragile banks. In minutes, the water of
an entire lake can come roaring down onto the villages below. Altogether some
30,000 people have died in the shadow of these mountains as a result of avalanches
and outburst floods.
In recent years, the Peruvian government has been working to contain the most
dangerous of these lakes by lowering water levels and reinforcing shore banks. But if
global temperatures continue to rise, as they’re expected to, new lakes will certainly
form in the craggy basins of the Cordillera Blanca Mountains – posing the risk for even
more catastrophic flooding in the years to come.
David Laskin sent in today’s story. The Weather Notebook is a program of the Mount
Washington Observatory, and is supported by Subaru of America and the National
Science Foundation.
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