Glacial Outburst

Browsing around the web this morning I was thinking about a comment in Al Gore's documentary "An Inconvenient Truth" about the number of people dependent for fresh water on meltwater from the Himalayas. I came across this report into the Himalaya Glaciers which suggested that around a half of humanity is dependent on freshwater which comes from mountains. I'm still looking for some better figures, but at the moment I'm under the impression that about 25% of humanity depends on meltwater from the Himalayan icefields which are expected to disappear by 2100.

But there's another problem: ever heard of a GLOF? Glacial Lake Outburst Flood. Apparently as the glaciers melt they form lakes of fresh water which are held back by dams of ice. Eventually the ice melts and the lake bursts out with the inevitable consequences for anybody or anything in its path. Apparently in 2005 26 glacial lakes were identified as being in a dangerous state in the Himalayan region out of 226 known glacial lakes.

Anybody who thinks that a bit of freshwater isn't a problem - think again. Around 70% of the world's freshwater is currently locked up as ice somewhere or other. If it melts then it end up in the sea and reduces its density. That affects the ocean currents and hence the way heat is distributed around the globe. The last ice age in Europe occured when the meltwater in Hudson Bay was released into the North Atlantic stopping the Gulf Stream.

We are looking, as Al Gore puts it, at a canary in a coalmine....