Two Northern Arizona University researchers led the study, which challenges previous understanding about how carbon accumulates in soil. Increased levels of CO2 accelerate plant growth, which causes more absorption of CO2 through photosynthesis.

Kees Jan van Groenigen, research fellow at the Center for Ecosystem Science and Society at NAU and lead author of the study, said their findings mean that nature is not as efficient in slowing global warming as we previously thought.

He said that by overlooking this effect of increased CO2 on soil microbes, models used by the Intergovernmental Panel on Climate Change may have overestimated the potential of soil to store carbon and mitigate the greenhouse effect.

In order to better understand how soil microbes respond to the changing atmosphere, the study's authors utilized statistical techniques that compare data to models and test for general patterns across studies. They analyzed published results from 53 different experiments in forests, grasslands and agricultural fields around the world. These experiments all measured how extra CO2 in the atmosphere affects plant growth, microbial production of carbon dioxide, and the total amount of soil carbon at the end of the experiment.

The research has been published in the journal Science.