Climate Change May Speed Up Due to Carbon Loss from Soil

Higher levels of carbon dioxide in the atmosphere trigger soil microbes to emit more carbon dioxide further accelerating climate change, a new study claims.

Researchers at the Northern Arizona University found that excess levels of carbon provide fuel to the microorganisms present in the soil whose by-product is carbon dioxide. This by-product when released in the atmosphere contributes significantly to climate change. This finding challenges previous claims that elevated carbon dioxide levels accelerate plant growth, which leads to more absorption of carbon dioxide through photosynthesis.

Till date it was assumed that carbon is packed in the wood and soil for years, gradually curbing climate change.  But the two researchers in the current study found that the excess of carbon causes the soil to release more carbon dioxide that further contributes to climate change.

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

To further understand how soil microbes respond to the drastically changing atmosphere, researchers opted for a statistical technique that compared data, models and test to see the patterns across all studies.

They evaluated the published results of 53 experiments that were conducted in forests, grasslands and agricultural fields around the globe. All these experiments looked at how excess levels of carbon dioxide in the atmosphere affected the plant growth, microbial production of carbon dioxide and the total amount of soil carbon at the end of the experiment.

Bruce Hungate, director of the Center for Ecosystem Science and Society at NAU and study author said that it was long assumed that soil was a stable and safe place to store carbon. But this new study knocks all such previous claims. 

The finding was published in Science.