Spatially consistent microbial biomass and future cellular carbon release from melting Northern Hemisphere glacier surfaces

Abstract Melting glacier ice surfaces host active microbial communities that enhance glacial melt, contribute to biogeochemical cycling, and nourish downstream ecosystems; but these remain poorly characterised. Over the coming decades, forecast ‘peak melt’ of Earth’s glaciers necessitates an improvement in understanding state fate supraglacial ecosystems better predict effects climate change upon catchment biogeochemistry. Here we show a regionally consistent mean abundance 10 4 cells mL −1 surface meltwaters from eight across Europe North America, two sites western Greenland. Microbial is correlated with suspended sediment concentration, not hydraulic properties. We release microbes under medium carbon emission scenario (RCP 4.5) will deliver 2.9 × 22 yr , equivalent 0.65 million tonnes cellular carbon, over next ~80 years.