New Understanding of Microbial Community Processes Improves Carbon Cycle Models

Global soils accumulate C if microbial growth efficiency declines with warming in the microbial model.

The Science

Current Earth system models (ESMs) draw on soil carbon cycle models that use relatively simple representations of the biogeochemical processes performed by microbial communities. Now, investigators at the University of California–Irvine, have developed a new module for the Community Land Model (CLM) that attempts to more accurately represent the distribution of soil microbial communities and their functional processes related to carbon degradation. Projections of climate change impacts on soil carbon stocks using this module showed improved agreement with results observed during experimental studies. Developing improved models of microbial processes will generate more accurate projections of soil carbon feedbacks on climate change and reduce a source of uncertainty in current ESMs.


Compared with traditional models, the microbial model simulates soil C pools that more closely match contemporary observations. It also projects a much wider range of soil C responses to climate change over the twenty-first century. If growth efficiency adapts to warming, the microbial model projects large soil C losses. By comparison, traditional models project modest soil C losses with global warming. Microbes also change the soil response to increased C inputs, as might occur with CO2 or nutrient fertilization. In the microbial model, microbes consume these additional inputs; whereas in traditional models, additional inputs lead to C storage.

BER Program Manager

Dawn Adin

U.S. Department of Energy, Biological and Environmental Research (SC-33)
Biological Systems Science Division
[email protected]


Wieder, R. W., G. B. Bonan, and S. D. Allison. 2013. “Global Soil Carbon Projections Are Improved by Modeling Microbial Processes,” Nature Climate Change. DOI:10.1038/NCLIMATE1951.