Northwest Territories lake is about to fall off a cliff
Undated photo from the University of Alberta
Digital Reporter
Thursday, July 23, 2015, 5:27 PM - Melting permafrost brought about by climate change is helping push a small lake in the Northwest Territories over the edge of a cliff. Expert say it still has a long way to go before toppling, but they suspect it will happen sometime in the next few months.
The unnamed lake sits near the community of Fort McPherson, and is situated on top of a slope about 600 feet above the Mackenzie Valley.
Much of N.W.T's melting permafrost is contained in ice headwalls that can be up to 30 metres thick, and has been in the area for 20,000 years.
Parts of the headwalls have become exposed from wind and rain erosion. That causes it to melt, and forces the soil and rock that's on top of it to collapse.
That exposes even more ice, and the cycle starts again. The collapsed debris then moves down a slope, eroding the land.
“[the ice] thaws in the summertime and will continue to work its way back upslope until you run out of ice or the headwall gets covered by sediment,” Steve Kokelj of the Northwest Territories Geological Survey told the Canadian Press.
Slumps are mass movements of debris that move a short distance either up or down an elevation. Experts say slumps are getting bigger in the area due to an increase in rainfall and warming temperatures.
Some are more than a kilomtere long and as large as 40 hectares.
The lake that's about to topple over the cliff is on top of a slump that's been wasting away for about a decade.
Experts say when it falls, tens of thousands of cubic metres of water will come crashing down. Researchers have installed cameras to capture its eventual collapse.
There are no communities in the anticipated flood path.
Source: The Canadian Press
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