Glacial Lake Floods
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The world's tallest glaciers are fast melting which can cause glacial lakes to burst and flood. That's worrying news for residents in Nepal, Bhutan, Pakistan, India and Tibet-- the South Asian countries with most of the world's tallest mountains, glaciers and glacial lakes.

Hi I'm Bryan Yeaton and this is the Weather Notebook.

A research center in Nepal is gathering data on these lakes to gauge the melting and possible floods. Correspondent Manisha Aryal ("Ma-knee-shah Are-ee-ell") reports.

During the Little Ice Age, between 1550 and 1850, Himalayan glaciers were longer than they are today. Now, according to, ICIMOD, the Kathmandu-based mountain research institute, Global Warming is causing the glaciers to melt.

Glacial lakes develop when melt water from retreating and shrinking glaciers get trapped inside natural dams of ice or moraine. When the lakes break, large volumes of debris flow down, causing severe damage to life and property.

In the past, there was little research on this important phenomenon. Until now. ICIMOD has developed an inventory of the Glaciers and Glacial Lakes in the Himalayan region. Project coordinator Pradeep Mool shows how one lake in the area has grown.

Mool: You can see the size of the lake -- very small, scattered. But if you look at 1984, you see it's a continuous big mass already. And 1999 satellite image, you can see the length has increased. 1984, just 2 and half kilometers long; 1999 it is 3.3 kilometers long.

And the surface area of the lake has also increased -- to 8 times the size it was 50 years ago. Mool has identified over 18 thousand melting glaciers in the Himalayas. Nepal alone has over 3 thousand glaciers and 2 thousand dangerous glacial lakes.

Mool: Even the smaller lakes can have a devastating effect downstream.

20 lakes in Nepal, warns Mool, may burst at any time.

That's correspondent Manisha Aryal of Kathmandu, Nepal. The Weather Notebook is a production of the Mount Washington Observatory, supported by Subaru of America. Thanks today to engineer, Sean Doucette.