Soil erosion due to agriculture is not a net contributor to global climate change, according to researchers at UC Davis, Catholic University of Leuven in Belgium and the University of Exeter, England. Previous estimates of carbon emissions from soil erosion had run as high as 13 percent of global emissions.
Erosion does not release significant amounts or carbon to the atmosphere, the researchers found. On the other hand, neither does it represent a significant ‘sink’ removing carbon from the atmosphere, and erosion is still a Bad Thing because of its other environmental impacts.
Erosion, it seems, brings subsoil to the surface and sends it downhill. On the way it picks up organic material (ie, carbon) but then gets caught up in hollows and reburied. So the process acts as a sort of carbon conveyor belt.
The researchers estimate that erosion captures the equivalent of about 1.5 percent of fossil-fuel carbon emissions.
The team managed to measure how soils move around using cesium-137, an isotope that was scattered around the landscape as a result of nuclear weapons testing decades ago. They could then estimate how much carbon should be in the soil and work out how much had been lost or gained as a result of erosion.
The results are published in the Oct. 26 issue of Science.