81-2 Bedrock geology impacts dissolved inorganic carbon availability to snow algae blooms across the Western US

Abstract:

Snow algae are globally distributed photosynthetic microorganisms that contribute to snowmelt by lowering albedo. As photoautotrophs, snow algae require inorganic carbon, which is typically limited in snow. Here, we examined the role of carbonate bedrock in supplying inorganic carbon to snow algae by comparing biomass and snow from sites in the Rocky Mountains in the US with and without carbonate bedrock to sites in the Cascade Range where silicic rocks are devoid of carbonates. Snow algae were more abundant in sites with carbonates where dissolved inorganic carbon concentrations were higher due to carbonate dissolution and biomass degradation (heterotrophy). Both internal carbon cycling and allochthonous inputs, including carbonate bedrock, were important for snow algae abundance. Increasing atmospheric CO₂ is a positive feedback on snow algae bloom abundance and thus their impact on albedo, but additional sources of CO₂ can lead to bigger blooms that could impact melt and water resources.

© Copyright 2026 The Geological Society of America (GSA), all rights reserved.