October 25, 2020

African dust accelerates thaw in the Himalayas


Panoramic of Everest.

Panoramic of Everest.
Shutterstock

Dust from Africa and the Asian continent is causing a warming and accelerating snowmelt in the Himalayas -thousands of kilometers-, where one of the most important masses of ice on Earth accumulate.

And this scientific evidence published this Monday by a team of researchers is especially relevant because some 700 million people from Southeast Asia, as well as many areas of China and India, depend directly on the melting of snow and ice accumulated in the Himalaya for meet your fresh water needs in summer and fall.

Researchers from the National Laboratory of the Pacific Northwest of the United States and the Indian Institute of Technology in Madras (India) have published this Monday in Nature Climate Change the conclusions of an investigation that has shown that accumulation of large amounts of dust over the Himalayas absorbs sunlight and causes a warming of snow and ice

The study has been funded by NASA And scientists have been able to analyze some of the most detailed satellite images ever taken of the Himalayas to make calculations about the elevation of mountains, the presence of dust or contamination from snow.

Researchers have analyzed the “albedo effect” -the amount of solar radiation reflected by the Earth with respect to the incident solar radiation- and they have confirmed that the dirty snow due to the dust that is deposited on it absorbs more light, so it heats up and melts faster.

This effect is especially important at high altitudes – above 4,500 meters -, according to the researchers, who have warned that That snow is crucial to the livelihoods of millions of people who depend on snowmelt for their water.

In this case, the darkest “and dirtiest” snow melts faster than pure snow, which changes the timing and amount of snowmelt and has a very negative impact on agriculture and other aspects of life for millions of people.

The researchers found that dust plays a much bigger role in melting snow than soot and other forms of pollution, known as “black carbon, at altitudes above 4,500 meters. Dust reaches the western Himalayas from the west: from the Thar desert in northwestern India , from Saudi Arabia and even from the Sahara in Africa.

Although desert dust is natural, scientists have observed that its presence in the Himalayas has also a human influenceSince rising temperatures have changed atmospheric circulation and affected the winds that can carry dust thousands of kilometers.

The study was coordinated by researchers Yun Qian (from the US Department of Energy’s Pacific Northwest National Laboratory) and Chandan Sarangi (from the Indian Institute of Technology in Madras)

In their conclusions, published in Nature Climate Change, the scientists have pointed to the probability that these effects that they have verified in the Himalayas are also occurring in other large mountain ranges, such as the Rocky Mountains, the mountain ranges and waterfalls in North America and various mountain ranges in Asia, such as the Caucasus and the Urals.

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