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The threat to millions of people, as glaciers in Central Asia melt

Melting glaciers spell trouble for millions in Asia, SMH, By Henry Fountain,19 January 2019  On a summer day in the mountains high above Almaty, Kazakhstan’s largest city, the Tuyuksu glacier is melting like mad. Rivulets of water stream down the glacier’s thin leading edge.

In Central Asia, a warming climate is shrinking many glaciers. The Tuyuksu is losing ice every year. Around the world, vanishing glaciers will mean less water for people and crops in the future. Here, the people need to prepare sooner.

As she has for nearly two decades, Maria Shahgedanova, a glaciologist at the University of Reading in England, has come here to check on the Tuyuksu. As one of the longest-studied glaciers anywhere, the Tuyuksu helps gauge the effect of climate change on the world’s ice.

Glaciers represent the snows of centuries, compressed over time into slowly flowing rivers of ice, up to about 300 metres thick here in the Tien Shan range of Central Asia and even thicker elsewhere. They are never static, accumulating snow in winter and losing ice to melting in summer.

But in a warming climate melting outstrips accumulation, resulting in a net loss of ice. That is what is happening in Kazakhstan and all over the globe.

The world’s roughly 150,000 glaciers, not including the large ice sheets of Greenland and Antarctica, cover about 500,000 square kilometres of the Earth’s surface. During the last four decades they have lost the equivalent of a layer of ice 20 metres thick.

Most are getting shorter, too. Small ones in places like the Rockies and Andes have disappeared. And researchers say that even if greenhouse gas emissions were sharply curtailed immediately, there has already been enough warming to continue shrinking glaciers around the world.

This great global melting contributes to sea level rise. It affects production of hydroelectricity. It leads to disasters like rapid, catastrophic floods and debris flows. It alters rivers and ecosystems, affecting the organisms that inhabit them.

But here in the Tien Shan, the biggest effect may be on the supply of water for people and agriculture. ……..The researchers analyse samples from streams to determine the mix of water sources, which is important for forecasting how the rivers will fare over time. A melting glacier can at first increase stream flow, but eventually the glacier reaches a tipping point, called peak flow, and meltwater begins to taper.

“At some point they cannot produce the water they are providing right now,” said Matthias Huss, a researcher at the Swiss Federal Institute of Technology in Zurich. “It’s really important for water managers to know when this tipping point is reached.”

Glaciers elsewhere in Central Asia – in China to the east, and Kyrgyzstan and Tajikistan to the south – will eventually decline as well. But the biggest effect will be further south, where countless glaciers feed the great river basins of Asia.

Across the Tibetan Plateau and in the Himalayan and Karakoram ranges, the glaciers number in the thousands and the people who rely on them in the hundreds of millions, along rivers like the Indus in Pakistan, the Ganges and Brahmaputra in India, the Yellow and Yangtze in China and the Mekong in south-east Asia……… https://www.smh.com.au/environment/climate-change/melting-glaciers-spell-trouble-for-millions-in-asia-20190118-p50sb6.html 

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January 21, 2019 - Posted by | ASIA, climate change

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