Because sampling of black carbon worldwide is so sparse, it is difficult to know how much of an effect black carbon could have on emissions estimates worldwide. "[One] question is whether Australia is unique in its combination of old soils and importance of fire in the landscape, or whether stores of black carbon are in general greater than they have been thought," said Susan Trumbore of the University of California, Irvine. "As the authors point out, there are not enough data to say at this point." Many parts of the world have landscapes that burn regularly, Lehmann noted. Such areas would be expected to have relatively higher levels of black carbon. But more measurements are necessary, he added. Black carbon has been sampled in only a few locations worldwide, and the amounts can vary widely. Many scientists have expressed concern that as polar regions warm, the thawing soils may release large amounts of CO2 or methane. So, what is the potential for polar estimates to change based on Lehmann's findings? The boreal forest of the far north burns often, according to soil scientist Jennifer Harden of the U.S. Geological Survey in Menlo Park, Calif., but black carbon does not appear to be as prevalent as in Australia. "Our studies have shown only small amounts of truly recalcitrant, stubborn carbon exist. We think it's because most of the protection from decomposition is because it's so cold."
Related Links: U.S. Geological Survey |
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