SOURCE: Phys.org

DATE: March 9, 2017

SNIP: Soils could release much more CO2 than expected into the atmosphere as the climate warms, according to new research by scientists from the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab).

Their findings are based on a field experiment that, for the first time, explored what happens to organic carbon trapped in soil when all soil layers are warmed, which in this case extend to a depth of 100 centimeters. The scientists discovered that warming both the surface and deeper soil layers at three experimental plots increased the plots’ annual release of CO2 by 34 to 37 percent over non-warmed soil. Much of the CO2 originated from deeper layers, indicating that deeper stores of carbon are more sensitive to warming than previously thought.

Experts estimate soils below 20 centimeters in depth contain more than 50 percent of the planet’s stock of soil organic carbon. The big questions have been: to what extent do the deeper soil layers respond to warming? And what does this mean for the release of CO2 into the atmosphere?

“We found the response is quite significant,” says Caitlin Hicks Pries, a postdoctoral researcher in Berkeley Lab’s Climate and Ecosystem Sciences Division. She conducted the research with co-corresponding author Margaret Torn, and Christina Castahna and Rachel Porras, who are also Berkeley Lab scientists.

“If our findings are applied to soils around the globe that are similar to what we studied, meaning soils that are not frozen or saturated, our calculations suggest that by 2100 the warming of deeper soil layers could cause a release of carbon to the atmosphere at a rate that is significantly higher than today, perhaps even as high as 30 percent of today’s human-caused annual carbon emissions depending on the assumptions on which the estimate is based,” adds Hicks Pries.