Glacier avalanches more common than thought
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#ESA; #Glaciers; #ClimateChange
New York/Canadian-Media: Glaciers are generally slow-flowing rivers of ice, under the force of gravity transporting snow that has turned to ice at the top of the mountain to locations lower down the valley — a gradual process of balancing their upper-region mass gain with their lower-elevation mass loss.
This process usually takes many decades. Since this is influenced by the climate, scientists use changes in the rate of glacier flow as an indicator of climate change.
For some glaciers around the world, this gradual flow can speed up, so that they advance several kilometres in just a few month or years, a process called glacier surging. After a surge, the glacier usually remains still and the displaced ice melts over a few decades.
However, a paper published recently in The Cryosphere describes how scientists working in ESA’s Climate Change Initiative Glaciers team has discovered, together with several colleagues, that these glacier detachments have happened much more often than had been known. Even more surprisingly, this is happening to glaciers resting on relatively flat beds.
Andreas Kääb, from the University of Oslo, explained, “We have known about debris flows originating from glaciers that break off at high elevations for several decades now, however, until relatively recently, we were extremely surprised to discover that glaciers resting on flatter beds can also detach as a whole.
“These events are reported only rarely. In fact, they only really came to light in 2002 after a huge chunk of the Kolka glacier, which sits in a gently sloping valley on the Russian–Georgian border, detached and thundered down the valley at about 80 metres a second, carrying around 130 million cubic metres of ice and rock that killed more than 100 people.
“Using satellite data, we have now discovered that such events are more common than we could have ever imagined, and this might be a consequence of a changing climate.”
The team of scientists from all over the world used data from different satellites including the Copernicus Sentinel-1 and Sentinel-2 missions and the US Landsat mission as well as digital elevation models to…
