Quantifying the role of biomass burning in black carbon deposition on Andean glaciers.

Abstract:

Andean glaciers are rapidly melting, with for example 50% of total glacial surface area lost in Peru since the 1960s. While some of the melting may likely be traced to anthropogenic climate change, deposition of black carbon (BC) particles, a major component in smoke, may also play a role. Smoke from fires in the Amazon Basin and elsewhere can be transported to the Andes and deposited on snow, reducing the surface albedo and inducing further glacial melting. Quantifying the potential impact of smoke BC on the Andean glaciers is however challenging, and few studies to date have addressed this issue. Here we combine atmospheric chemical modeling with BC observations from two sites in the Peruvian Andes – a snow pit in Quelccaya and an ice core in Huascarán. Preliminary results from the Stochastic Time-Inverted Lagrangian Transport (STILT) model suggest that fires across a broad region including the Amazon may contribute to the BC flux observed at Quelccaya. We also use the 3-D chemical model GEOS-Chem to simulate the wet and dry deposition of smoke BC across the Andes from 2014-2019. Results from GEOS-Chem show that the simulated BC fluxes are consistent with those observed at both Quelccaya and Huascarán, with smoke from fires accounting for most of that flux. Our work suggests that smoke from biomass burning across the Amazon Basin can reach locations as remote as the Andean glaciers in Peru and could contribute to the observed rapid melting of the glaciers.