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Riled Up is a journal of science, the environment, exploration, new technology, and related commentary.  Contributors include scientists, explorers, engineers, and others who provide perspectives and context not typically offered in general news circulation.  For interested readers, additional resources are included.

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Surging Glaciers, Climate Change, and Tibet

Surging Glaciers, Climate Change, and Tibet

Tibetan Glacial Surges, July to October, 2016 (credit: NASA Terra)

In an earlier post, this Journal shared satellite imagery of glaclial surges in Tibet. At that time, the rapid collapse of stationary ice was a puzzle to geologists and other researchers but climate change was suspected. It now has been correctly identified as the culprit with multiple climate related impacts to the high plateau of rural Tibet.

Publishing in Nature Geoscience, researchers from the University of Oslo and elsewhere conclude:

"the detachment of entire parts of two glaciers in western Tibet led to an unprecedented pair of giant, low-angle, ice avalanches in 2016. Using satellite remote sensing, numerical modelling, and field investigations, we find that the ice collapses were caused by climate-change and weather-driven external forces, acting on polythermal ice (ice temperatures mixed internally) and soft glacier-bed properties. These factors converged to produce surge-like driving stresses and reduced glacier base friction exceeding collapse thresholds of ice frozen to their bed. These catastrophic glacial instabilities can happen without historical precedent."

 

                     Tibetan Plateau Rotung glacier surge, Summer 2016 (credit: NASA)

As climate change increases atomospheric temperatures, air can physically carry more moisture. This hydrologic situation drives increasingly powerful storms. When monsoonal weather crosses the Tibetan Plateau (the Third Pole), the additional water is deposited as increased snow and rainfall in the highest mountains. The two glaciers in Tibet received both snow and rain at different seasons during the year. Snow increases the glacier's mass while the rain fell on its surface entering ice cracks (crevasse) sending water to its base. The water acted like a lubricant on the underlying bedrock consisting of sandstone, clay, and silts. The dual climate impacts produced a situation where the ice mass, bedrock lubrication, and slope angle created a 'tipping point' and the glacier's stability collapsed in a massive surge.

The new research provided important information for protection against avalanches but also for the future water situation in high mountains of the Tibetan Plateau.

WHB

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