Managing terrestrial ecosystems to increase the carbon contained in soils can remove carbon dioxide from the atmosphere. As such, it is recognised as one of a few realistic strategies to curb climate change. Soil carbon is also key to supporting ecosystem functioning and is therefore critical for sustainable land use. Investigating the role of the tremendous diversity of microscopic soil organisms in regulating soil carbon, this project will bridge fundamental knowledge gaps in climate science and ecology, and will inform farmers and policy makers of the potential benefits of promoting soil life for climate change mitigation and sustainable production.