Black is black

Anssi Vähätalo of the University of Jyväskylä in Finland and colleagues have demonstrated that a smaller proportion of black carbon created during combustion will remain in the soil than was previously estimated. The finding could have implications for modeling the potential for climate change mitigation of burying the waste product of slash-and-burn and controlled burning of fields. The burning of organic matter creates 40–250 million tons of black carbon every year through incomplete combustion of organic matter. Advocates of burying such waste, an approach to carbon sequestration, had assumed that black carbon would remain locked away in the soil for millennia. This, the work by Vähätalo and colleagues suggests, is not the case, and that sampling of world rivers suggests that 27 million tons of black carbon per year will reach the oceans. The results prove that the proportion of water soluble black carbon may be as much as 40 per cent of black carbon created annually, the team says.