explain me the effects and causes of glacier lake outbrust
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Will Climate Change Cause More Glacial Lake Outburst Floods?
BY GUEST BLOGGER|MAY 21, 2018
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By Natalie Belew for GlacierHub
glacial lake
Glacial lakes, dammed by rocks and/or ice jams, can burst suddenly and cause catastrophic damage in nearby communities. Photo: National Park Service
A glacial lake outburst flood (GLOF) occurs when the dam containing a glacial lake fails—the sudden and intense flooding that results can be catastrophic for nearby communities.
How certain is it that climate change will increase the frequency and severity of these GLOFs? The answer is complicated and the subject of a new study published in The Cryosphere. Although previous research has examined the nature and characteristics of GLOF events in mountain ranges across the world, this recent study provides the first global assessment of the problems involved in developing a robust attribution argument for climate change and GLOF events.
GlacierHub has covered GLOFs throughout the years, including major milestones in understanding their characteristics and interviewing a Peruvian farmer who is suing a German energy firm over the disasters caused by the rapidly melting glaciers. However, the GLOFs in this study refer specifically to ones caused by the failure of moraine dams. The formation of these moraine-dammed lakes and resulting GLOFs involve the process of thinning, flow stagnation, and glacier recession. Such moraines often contain a melting ice core built from transported rock debris. And, as stated in the study, “when they fail, large volumes of stored water can be released, producing glacial lake outburst floods.” These floods have already caused hundreds of fatalities across the world, destroying downstream communities and stunting the socio-ecological integrity in their wake.
This study presents an unprecedented global GLOF inventory related to the failure of moraine dams. The motivation behind the focus on this type of GLOF is the clear diagnostic evidence left behind by moraine-dam failures, as well as the conventional link between climate change and moraine-dammed lake formation.
Dan Shugar, one of the authors of the study and a geoscientist at the University of Washington Tacoma, explained that these particular glacial lakes don’t tend to re-form once they burst, which allows for clear diagnostic evidence. “With ice-dammed lakes that burst, the glacier typically ‘heals’ the breach, and so they can reform and burst again and again,” he said.
Adam Emmer, a co-author from CzechGlobe, told GlacierHub that the research is the first attempt to link climate change with GLOF patterns on a global level. Christian Huggel, another co-author and geographer from the University of Zurich, added that this is no trivial task.
“It is reasonable to assume that glacier hazards will increase as the climate warms, and we were somewhat surprised to see that over the past century or so, there has not been a monotonic rise in outburst floods,” Shugar told GlacierHub. “The reality, as usual, is a bit more complicated.”
As simple as it might seem to link warming climate to the increased frequency and severity of GLOFs, a number of factors go into a GLOF event. Differences in ground thermal conditions, for example, plus presence or absence of ground ice or permafrost all influence extreme weather. Seismic processes, topography, and glacial history also vary across mountain ranges.
However, as the study states, “although we know that GLOFs involve a complex set of dynamics… there must be a relationship here to climatic warming.” The scientists did conclude a lagged time response when it comes to glacial lake outburst floods and climate change, with outburst flood frequency actually decreasing in recent decades since 1970.
“We suggest that outburst floods will become more frequent in response to contemporary warming, but that there is a lag built into the system,” Shugar explained. Thus, although an attribution of glacial lake outburst floods to climate change is possible, a suite of factors influencing GLOF occurrence means scientists cannot adequately quantify the attribution as many might hope.
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