Dry grasslands have been serving as an unexpected carbon sink in recent decades due to fire reductions: study

Dry grasslands may have been providing an unseen helping hand to slow the rate of climate warning, according to a new study which found that these grasslands have been storing more heat-trapping carbon than previously known.

Dry grasslands may have been providing an unseen helping hand to slow the rate of climate warning, according to a new study which found that these grasslands have been storing more heat-trapping carbon than previously known.

It’s an effect that goes hand in hand with the frequency of fires, researchers found – savannas and grasslands where fires had become less frequent had more carbon-storing potential. While it’s far from a climate-crisis-ending impact, researchers say this means we may have another tool in our arsenal to utilize when planning nature-based interventions to slow the warming of the planet.

"In the grand scheme of things, no, this is not really a massive amount of carbon that will put a dent in heat-trapping anthropogenic emissions," study lead author Adam Pellegrini of the University of Michigan said in a press release. "But no one region—neither the Amazon rainforest nor the U.S. Great Plains grasslands nor Canada's boreal forest nor dozens of other biomes around the world—can alone store sufficient carbon to make a large contribution to slowing climate change. However, in aggregate, they can.”

The findings are the result of the reanalysis of 53 long-term fire-manipulation experiments worldwide. Researchers also took soil samples from six of the fields in question for the study, which was published Monday in the journal Nature Climate Change.

Researchers wanted to figure out how fire changed how much carbon was stored in topsoil in more arid regions.

As populations expanded and landscapes became increasingly fragmented into croplands, pastures and smaller regions of grassland separated by roads, the size of wildfires in these regions have become smaller. As fire frequency and size changed, researchers observed that this was reflected in the amount of carbon stored in the topsoil, and that this was most dramatic among dry grasslands or savannas.

"The potential to lose soil carbon with very high fire frequencies was the greatest in dry areas, and the potential to store carbon when fires were less frequent was also the greatest in dry areas,” Pellegrini said.