The glaciers in the Third Pole are melting at an alarming rate due to climate change, causing several environmental hazards that have led to human fatalities and ecological and infrastructure damage. In addition, black carbon particle emissions from wildfires in the region threaten to worsen this trend. Now, researchers from China bring to light how the concentration of these particles have been increasing in the Himalayas and the importance of monitoring them.
Spanning over 5 million square kilometers in Central, South, and East Asia, the Third Pole is a high-mountain region encompassing the Tibetan plateau and its surroundings. The region gets its name from the fact that it holds the third largest ice reserves in the world after the polar regions. As much of this ice supplies water to the major rivers of Asia, it has also been dubbed the “Water Tower of Asia.” Consisting of the world’s 14 highest peaks, this seemingly imposing and unchanging region is now under threat due to climate change, which is increasing the frequency of environmental hazards occurring in the area.
Warming temperatures and changing precipitation patterns have accelerated glacier-ice loss, leading to glacial lake outbursts, glacier collapse, and ice-rock avalanches that have damaged infrastructure, blocked rivers, and caused widespread human casualties. While climate change and the unstable nature of mountain landscapes are the main drivers for glacier-related hazards, a recent study shows that other factors have also contributed to the glacier melting.
In an article published in Nature Geoscience on 14 November 2022, and supported by the Second Tibetan Plateau Scientific Expedition and Research Program, Associate Professor Chao You from Chongqing University and Dr. Chao Xu from the CMA Earth System Modeling and Prediction Centre (CEMC), China Meteorological Administration in China highlighted the effect of black carbon emissions from wildfires on glacier melting in the Himalayas.
Black carbon particles contribute to glacier melting in two ways: by raising the surrounding temperatures through sunlight absorption, and by depositing on top of snow and ice and reducing the ability of these surfaces to reflect light. Consequently, black carbon has been one of the main reasons for the rising temperatures not just in the Third Pole but also in the Arctic.
However, the Himalayas have been particularly vulnerable to the effects of black carbon emissions. These mountains hold 30% of the glaciers in the Tibetan Plateau and receive a substantial amount of black carbon particles brought in by the Indian summer monsoon and the westerly winds. However, more than half of the black carbon particles deposited on the Himalayas during the non-monsoon months (March-May and October-November) have been attributed to emissions from vegetation fires.
“Black carbon concentration in glacier snow and ice has been reported to reach higher than 20 ng g–1 following wildfire events, suggesting that wildfires have contributed to substantial glacier melting in the Himalayas,” says Dr. You.
This is more than twice the concentration of black carbon particles required to reduce the reflective capabilities of snow and ice. “When the concentration of black carbon reaches 10 ng g–1, it can significantly reduce the albedo (the proportion of reflected light) of glacier snow and ice,” says Dr. You
The researchers have also brought to light how the black carbon emissions in the Himalayas are becoming more severe due to climate change and human activities. “Global climate warming is not only causing an earlier melting of glacier snow and ice and increased summer monsoon precipitation but also declining winter precipitation, prolonging the dry season, and prompting fire weathers,” says Dr. Xu. “Additionally, clearing the land for agriculture through slash and burn over India and Nepal Himalayas has promoted wildfires in recent years.”
The Himalayan glaciers are an important source of water resources during the non-monsoon seasons. However, since the 1990s, a significant amount of ice has been lost from the Himalayan glaciers owing to warming temperatures. The increased prevalence of black carbon particles in the Himalayas is likely to affect not only the water balance but also increase the likelihood of glacier-related hazards. Considering its risks to human life and various hydroelectric projects, the researchers stress the importance of a deeper look into the black carbon emissions from vegetation fires. “Serious attention must be given to better understand the growing wildfires over the Himalayas, not only to reduce property losses and casualties but to help reduce the risk of glacier-related hazards,” concludes Dr. You.
