Reduced Black Carbon Emissions with Covid-19 Slowed Himalayan Melt and Increased Water Security

Proceedings of the National Academy of Sciences, April 18

Research into the impact of black carbon has long noted the potential of emissions reductions to slow snow and ice loss. With Covid-19, this appears to have been borne out in a real-world scenario, when corona virus lockdowns in South Asia last year reduced emissions of particle pollution, including black carbon by 30% compared with the 20-year average. This improvement in air quality (allowing Everest to be visible from Kathmandu for the first time in many decades) also appears to have decreased black carbon (soot) deposition on ice and snow supplying the Indus River basin. The cleaner snow and ice reflects sunlight, and this effect slowed the summer and springtime melt by an estimated 1.5 cubic miles of runoff water. The slowing in melt was significant enough to increase reservoir levels, allowing managers to maintain a more steady flow in serving the 300 million people dependent on Indus water resources. This unanticipated Covid-19 impact indicates how decreases in black carbon emissions can benefit regional cryosphere and related water resources, in addition to the immediate health impacts of decreased particle pollution, which WHO estimates caused 8 million excess deaths annually.

https://tc.copernicus.org/articles/15/1501/2021/

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