Atmospheric Connections: Wildfire Aerosols and Their Role in Andean Tropical Glacier Dynamics

This research examines the relationship between wildfire aerosol deposition—primarily from Amazonian fires—and the accelerated retreat of tropical glaciers in the Andes. Covering approximately 1,409 km² and supplying water to over 30 million people, these glaciers have experienced significant shrinkage since the 1970s. This decline is driven by rising average temperatures (1–2 °C) and the deposition of light-absorbing particles (LAPs), notably black carbon (BC).
Black carbon deposition on glacier surfaces reduces albedo, increasing absorbed solar radiation and enhancing glacier melt rates. BC-induced albedo reductions range from 0.04% to 3.8%, contributing to a positive radiative forcing of up to +3.2 W/m². Annually, 5–20% of glacier mass loss can be attributed to this darkening effect. BC concentrations spike during El Niño events, when atmospheric conditions promote Amazonian wildfire activity and enhance aerosol transport to high-altitude glaciers.
Amazonian wildfires account for approximately 70% of BC emissions deposited in the Andes, peaking at 50 teragrams of BC per fire season due to agricultural expansion and slash-and-burn practices. Atmospheric transport models (e.g., WRF-CHEM) and field measurements highlight the role of meteorological systems such as the South American Monsoon System (SAMS), the Intertropical Convergence Zone (ITCZ), and the South American Low-Level Jet (SALLJ) in moving aerosols over 2,000 km during the dry season (July–October). This process leads to BC concentrations in glacier snowpacks reaching up to 1,092 ng/g.
The combined effects of albedo reduction and increased radiative forcing exacerbate glacier melting, with significant implications for water resources, food security, and ecosystem stability in regions reliant on seasonal glacier runoff. Observed melt rates range from 0.1 to 0.4 meters of ice thickness per year, with peaks during El Niño episodes.