Unveiling the large coverage of red snow algae blooms in antarctic coastal snowfields

Several locations across Antarctica are experiencing snow algal blooms on the surfaces of coastal snowfields, which significantly reduce surface albedo – by up to 20% – and consequently enhance the melting of snow and ice. Here we revealed the potential distribution of red snow algal blooms in the Antarctic South Shetland Islands between 2018 and 2024. A supervised machine learning approach was applied to 45 cloud-free Sentinel-2 images, using spectral information obtained from a drone-mounted hyperspectral sensor to monitor bloom extent across the entire archipelago. Our results provide clear evidence of the spatial distribution of red snow algae blooms in the South Shetland Islands, which covered up to 12% of the total surface area of a single island during the growth season. These findings offer valuable insights into the extent of red snow algae, supporting ongoing efforts to monitor their evolution and to understand their ecological implications under current climate change scenarios. Red snow algal blooms in the Antarctic South Shetland Islands can cover up to 12% of an island’s surface during the growth season, suggesting a possible influence on surface albedo and melt dynamics, based on a supervised machine-learning analysis of 45 cloud-free Sentinel-2 images