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The natural world. Looking pretty for 3.5b years.

Surging Glaciers, Climate Change, and Tibet

Surging Glaciers, Climate Change, and Tibet

Author: Hugh Bollinger/Thursday, January 25, 2018/Categories: natural history, photography, space science, sustainability, environment, climate change

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

In a 2016 Journal post, Riled Up 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 impacts to the high landscapes 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 tongues frozen to their bed. These catastrophic instabilities of glaciers can happen without historical precedent."

                          Tibetan Plateau Glacial 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 crossed the Tibetan Plateau (the Third Pole), the additional water was deposited as increased snowfall and rainfall in the highest mountains. The two glaciers in Tibet received both snow and rain at different seasons in the year. The snow increased the glacier's mass while the rain fell on its surface and eroded cracks (crevasse) sending water to its base. the water acted like a lubricant on the underlying bedrocks 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 offer important consideration for protection against avalanche collapse but also for the future water situation in high mountains.

WHB

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