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Mount Everest's Glaciers Shrank by Hundreds of Feet in the Past 50 Years

In the same time period, the end of glaciers have retreated, on average, by 1300 feet.
Photo: Göran Höglund/Flickr

Here's another piece of the picture of the Himalayan glaciers melting: Researchers from the University of Milan have documented the extent of glacier retreat on Mount Everest and in the surrounding Sagarmatha National Park, showing that in the past fifty years glaciers in the vicinity of world's highest mountain have decreased in size overall by 13 percent. In the same time period, the end of glaciers have retreated 400 meters (roughly 1300 feet) on average.

This amount of melting is roughly similar to other glaciers in the eastern and central Himalaya—and if Everest is similar to other glaciers in the region much of this melting has taken place in the past decade and a half or so.

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That 13 percent average figure hides some far more dramatic declines in snow and ice cover though. The survey found that glaciers smaller than one square kilometer (247 acres) in size have melted back 43 percent.

Accompanying the glacier melting, the snow line on Everest has ascended 180 meters (590 feet) since 1962.

As for the causes of this, the researchers note that in since the early 1990s the region has experienced both a decrease in precipitation and an increase in temperature. Since 1992 the region on the Nepal-China border has experienced a 0.6°C temperature rise. Precipitation outside of the monsoon season and in winter has decreased by 100 millimeters (3.9").

Though lead researcher Sudeep Thakuri was careful to point out that they have yet to establish a firm connection between climate change and the glacier melting in the Everest region, it appears to be scientific caution. Plenty of other researchers have made this firm connection, as well as a connection with the effects of black carbon pollution on the region of the world often called the world's Third Pole, due to the massive amount of ice and snow stored there.

On the black carbon connection with glacier melting first: Research carried out by the Lawrence Berkeley National Laboratory in 2010 found that roughly 90 percent of glacier melting is being caused by aerosol pollution, with at least 30 percent caused by black carbon pollution. When black carbon (that is, soot from cooking stoves and diesel engines) falls on the glaciers it changes the reflectivity of the snow and ice, allowing it to absorb more sunlight, causing it to melt more quickly. Black soot is also contributes to warming more broadly.

The US Geological Survey places the blame for Himalayan glacier melting squarely on climate change, noting that though some glaciers in the western Himalayas are actually advancing (due to highly localized conditions), many are in retreat, impacting "water supplies to millions of people, [increasing] the likelihood of outburst floods that threaten the life and property in nearby areas, and [contributing] to sea level rise."

Thakuri hits a similar point: "The Himalayan glaciers and ice caps are considered a water tower for Asia since they store and supply water downstream during the dry season. Downstream populations are dependent on the melt water for agriculture, drinking, and power production."

Two of the main rivers of South Asia, the Indus and the Ganges, get about 40 percent of their water from glacial runoff. As glaciers continue to melt there will be an initial increase in water flow, but over time this will decrease markedly, potentially to the point that many rivers would become seasonal, dependent on monsoon rains for their flow.