The physiology of microbes living underground could determine the amount of carbon dioxide emitted from soils on a warmer Earth, according to a study published online this week in Nature Geoscience.

Soil carbon emissions have been shown to increase in response to rising temperatures, but the long-term response is uncertain.

Steven Allison and colleagues examined the impact of microbial physiology on soil carbon emissions using a microbial enzyme model. Their simulations suggest that if microbial efficiency declines in a warmer world, carbon dioxide emissions will fall back to pre-warming levels, a pattern seen in some field experiments. But if microbes manage to adapt to the warmth, for instance through increases in enzyme activity, emissions could intensify.