As the planet warms, the soil underfoot could release more carbon than previously thought, a new study has found.
“Previously, I think people thought that the surface is what matters,” said Caitlin Hicks Pries, an ecosystem ecologist Lawrence Berkeley National Laboratory in California. “They didn’t realize that there were these large carbon stores at depth as well.”
For a long time, we humans have been caught up with what’s going on in the top soil – down to about 20 centimeters (7.9 inches) or so – largely because that’s how deep the roots of our food crops usually extend. But that focus hasn’t given us an accurate picture of what happens to the carbon held below that depth when the temperature rises, it seems.
Hicks Pries led a team of researchers who dug deeper – to 100 centimeters (39.4 inches) to be exact – to figure out what we might be missing. Their research, published March 9 in the journal Science, showed that a 4-degree Celsius rise in temperatures would notch up the soil’s release of carbon dioxide by 34-37 percent – almost double what previous surface-level investigations had figured. If other types of soil behave similarly in response to a hotter planet, that could mean a big influx of climate-warming carbon into the atmosphere that “should not be ignored,” the authors write.
A spike of 4 degrees is about what many scientists expect for California by the year 2100, where the study took place, based on a model by the Intergovernmental Panel on Climate Change, Hicks Pries told Mongabay.