generalspeaking

Friday, January 25, 2019

A Global Epidemic of Glacier Melt

"Things that normally happen in geologic time are happening during the span of a human lifetime. It's like watching the Statue of Liberty melt."
"This glacier used to be closer [since 1901, Sperry Glacier has shrunk from more than 800 acres (320 hectares) to 300 acres (120 hectares)]. That's out of date."
"It's now less than 250 acres (100 hectares)."
Daniel Fagre, research scientist, U.S. Geological Survey Global Change Research Program

Photo of a glacier in the Pamir Mountains

A glacier in the Pamir Mountains of Central Asia where some of the largest runoff changes are projected to occur Source: ‏Nozomu Takeuchi‏/Twitter

The Tuyuksu glacier in Kazakhstan is rapidly melting and rivulets of meltwater gush down the thin leading edge of the glacier. A warming climate is shrinking glaciers in Central Asia, as it is all around the world. Every year, ice is being lost at the Tuyuksu glacier as it does globally, and this will result in less available water for crops and people in future years. Tuyuksu is considered to be one of the longest-studied glaciers in the world, studies that help gauge the effect of climate change on the world's ice.

The snows acquired and accumulated over centuries become compressed as time wears on, becoming gradually flowing ice rivers up to around 300 metres of thickness in the Tien Shan range of Central Asia, though glaciers are known elsewhere to assume even thicker proportions, as for example in Antarctica. Glaciers never remain static, they are always moving as they accumulate new snow in winter, and lose ice in summer as melting occurs.

In Kazakhstan and elsewhere around the globe, with its 150,000 glaciers worldwide, melting is beginning to vastly outstrip accumulation, for a net loss of ice. Those glaciers worldwide cover roughly 520,000 square kilometres of the surface of this planet and during the past four decades they have been diminished by the equivalent of a layer of ice 21 metres of thickness. Along with the loss of thickness, smaller glaciers in the Andes and Rockies have disappeared where elsewhere many are losing length as well as thickness.

Cayoosh Glacier, Marriott Basin, British Columbia Photo: JSR

In lock-step with melting glaciers, where thousands of years of ice accumulation are calving off from the main glacier in Antarctica and Greenland, seas are rising as they absorb the melt and cradle the melting pieces that crack off. All of this has consequences seen in rapid-onset floods that bring catastrophe, in the alteration of river courses and ecosystems, impacting on the marine organisms that live within. Production of hydroelectricity is also affected. And looming into the future is the prospect of less available water for agriculture and for people.

The Tuyuksu, about two kilometres in length, is steadily decreasing in length as well. Its research station was positioned a few hundred metres from the Tuyuksu's edge when it was built in 1957. It needs the better part of an hour now, scrambling over boulders and till left as the glacier retreated, to reach the ice tongue, where in six decades the glacier has lost over 800 metres. As it melts, the rivulets become torrents, carving surface channels in its hurried wake.

The Little Almaty River, fed from the flow, services the capital city of the country, Almaty, supplying drinking water for two million people and irrigation for cornfields and other crops nearby. The fear is that in the next twenty years shortages of water will loom, threatening water deprivation. "At some point they cannot produce the water they are providing right now. It's really important for water managers to know when this tipping point is reached", explained Maatthias Huss, researcher at the Swiss Federal Institute of Technology, in Zurich.