A recent paper by Jinyun Tang and Bill Riley that analyzed how soil organic matter (SOM) decomposition is affected by temperature was highlighted in the October issue of Nature Climate Change. CO2 released from soil is one of the largest actively cycling components of the global carbon cycle and strongly affects predicted 21st century climate change. Scientists study these carbon-climate feedbacks using Earth System Models, such as DOE’s E3SM, which represent a wide variety of terrestrial ecosystem processes, including (SOM) decomposition.
This new research addresses the long-standing problem of how to estimate and interpret the temperature sensitivity of SOM decomposition, an important problem as the climate continues to warm. Applied over the past several decades in hundreds of studies, the traditional approach involves warming soils at different temperatures in the laboratory to increase soil respiration, and applying an assumed model structure to interpret those measurements.
Tang and Riley showed that this approach leads to very large uncertainty (termed equifinality) in inferences of SOM decomposition temperature sensitivity. They also showed that using new model structures that explicitly represent microbial processes can help reduce this uncertainty and improve interpretation of these types of experiments. Their group is working to integrate these new types of model structures into E3SM’s land model.
Riley, a senior scientist in the Climate and Ecosystem Sciences Division at Berkeley Lab, said that the findings discussed in their paper for Biogeochemistry Letters could improve the ability of climate modelers to accurately predict the impacts future climate warming will have on the large amount of carbon stored globally in soil.