Black Carbon Accelerates Melting of South Andean Snowpack

Environmental Research Letters, 25 March 2022

Concentrations of black carbon (BC) in the snow near Santiago, one of the most populated cities in South America, are more than five times higher than elsewhere in the southern Andes and Patagonia. This study provides the first comprehensive assessment of the impacts of black carbon on seasonal snow in this region. The greatest amount of black carbon was found in snow in the mountainous La Parva and Valle Nevado, forty kilometers east of Santiago. Black carbon primarily arises in this region from poor combustion in diesel engines; coal and residential wood burning; and set agricultural fires and related wildfires. Strong winds flowing from the valleys west of the Andes transport these BC particles toward the mountains, where they accumulate on top of the snow. This darkens the surface and increases the amount of sunlight absorbed, which accelerates melting. The Andes snowpack provides an essential source of water for many South American communities, and supports everything from generation of hydroelectric power to local agriculture. Authors underscore the importance of developing environmental policies that reduce the black carbon footprint of major cities in nearby cryosphere.