November 26 (UPI) – At least a quarter of all the carbon stored on Earth's soil is encased in minerals approximately six feet below the surface. But new research suggests that this unique carbon deposit will be less efficient at storing carbon as the planet warms.
To better understand how increasing levels of carbon dioxide in the atmosphere will affect the planet's climate, scientists need to more accurately model the many carbon cycles on Earth. The soil hosts one of those carbon cycles.
As part of a new survey, the first of its kind, researchers detailed how carbon binds physically and chemically to minerals in soils around the world. The results of the survey were published Monday in the journal Nature Climate Change.
"We know less about soils on Earth than about the surface of Mars," said Marc Kramer, an associate professor of environmental chemistry at Washington State University in Vancouver, in a press release. "Before we can start thinking about storing carbon in the soil, we really need to understand how it gets there and how likely it is to stay in. This finding highlights an important advance in our understanding."
After analyzing climatic data and soil samples collected from 65 different excavation sites in the Americas, New Caledonia, Indonesia and Europe, the researchers created a global map of carbon sequestration in soil.
The new data shows that minimal amounts of carbon are stored in the sediments of deserts and dry forests, but approximately six feet below the surfaces of the humid forests, the scientists found a large amount of carbon bound to reactive minerals.
The persistence of decaying water and organic matter in the forest floor helps to leach the carbon from above and transport it to the minerals below.
"This is one of the most persistent mechanisms we know about how carbon builds up," Kramer said.
According to the new research, global warming will not affect the carbon that is already stored below the surface of the wet forest floors, but will alter the way in which the new carbon is stored. Increases in temperature are likely to minimize the amount of water that runs through the forest floor, even if the precipitation levels remain stable.