Driven by Ice: Microbial Processes and Seasonal Dynamics in a Changing Cryosphere (2024-09-13)

Abstract

Throughout Earth�s history, the planet has experienced expansions and contractions of its ice-covered surfaces, which profoundly influenced the distribution and diversity of life. Today, the cryosphere, which includes regions where it is cold enough for water to transition to ice for at least one month out of the year, comprises about one-fifth of the planet�s surface. This vast area spans northern and southern high latitudes and high elevations globally, but it is shrinking, threatened by rising global temperatures. The cryosphere contains some of Earth�s most famously threatened environments � glaciers, ice sheets, permafrost � whose loss has significant consequences for habitat, biogeochemical cycling, and human cultural and water resources. Numerous aquatic ecosystems spanning the latitude and altitude gradients of the cryosphere are equally threatened by climate change. The microbial life in these environments governs the biogeochemical cycling necessary to sustain these aquatic ecosystems, in some cases as the only or dominant form of life present. At the same time, they exist at an unprecedented interface of change, facing the combined effects of rising temperatures, ice loss, changes in ice thickness and duration, and changing snowpack. Using microbial ecosystems spanning from the polar regions to the upper midwestern U.S., my work focuses on developing a coherent understanding of the fundamental biotic and abiotic interactions that result in observable patterns in microbial community composition and function across the cryosphere�s aquatic ecosystems.