Himalayan glaciers face soot threat beyond rising temperatures

Himalayan glaciers face a dual threat as black carbon and dust deposited on snow absorb solar heat, accelerating melt rates beyond the impact of rising temperatures alone, increasing risks of disasters like recent flash floods in Nepal. Soot from vehicles, coal plants, factories, brick kilns, and fires travels long distances to settle on glacier surfaces, reducing reflectivity and speeding up melting. Studies indicate black carbon from South Asia may account for up to one-third of Himalayan ice loss between 2007 and 2016. Unlike carbon dioxide, black carbon remains in the atmosphere for only days or weeks, meaning emission reductions could show rapid benefits. A 2023 study found that reduced pollution during the 2020 COVID lockdown made Himalayan snow brighter and cut melting rates by up to 40 percent.