Solving the microbial temperature problem in Earth system science

Earth system models (ESMs) represent the pinnacle of our ability to understand and predict Earth system dynamics, and are constructed from submodels that should capture the processes and process interactions occurring in the atmosphere, oceans, on land. One microbial parameter that defines key feedbacks in the Earth system is the microbial temperature dependence, e.g. for decomposition. Submodules within past (e.g. CENTURY, Roth-C) and future (Millennial, MEMS) ESMs represent this with one intrinsic temperature dependence for decomposition, and extending this static temperature dependence (i.e., unchanging) to all microbial processes (organic matter formation or destruction, etc.) and assuming no differences among climates across the globe.

 

Global microbial diversity has been mapped with -omics, revealing incredibly diverse, versatile and biogeochemically active microbes. However, the central challenge stubbornly persists – translating microbial diversity into quantitative representations that capture ecosystem processes. This inability forms a barrier for integration of microbial ecology into ESMs.

 

We use instantaneous measurements of microbial processes to estimate microbial intrinsic temperature dependences as “trait distributions” in situ, in environmental samples. We can thus translate biodiversity into ecosystem functions, and generate mathematical descriptions that interface with ESMs. We have uncovered how intrinsic microbial temperature dependences for processes that form (growth) and destroy (decomposition) organic matter vary across the globe, across seasons, and respond to warming. We have unearthed how temperature trait distributions interact with those for moisture, and determined the ecological and evolutionary mechanisms underpinning change. Our insights can be integrated into existing ESMs, revealing that dynamic microbial feedbacks characterise the earth system.