An error in the way carbon is counted in current United States climate legislation and in the Kyoto Protocol could undermine efforts to reduce greenhouse gas emissions through the use of biofuels.

Current carbon accounting measures mistakenly exempt all the carbon dioxide emitted from bio-energy, regardless of the source, according to Phil Robertson, Michigan State University professor of crop and soil sciences.

Professor Robertson and his colleagues issued their findings in the paper Fixing a Critical Climate Accounting Error.

“If we miscalculate the carbon benefits, we may find out later that our policies and practices are counterproductive,” says Mr. Robertson.

Greenhouse gas consequences of bio-energy can vary widely, depending on where the plants used to produce the energy are grown. For example, a fast-growing biofuel crop grown on abandoned farmland can capture more carbon than existing plants and reduce more greenhouse gas emissions.

But if existing forests are cut down for bio-energy crops, the carbon released from the soil and downed trees, plus the loss of future carbon storage, will be greater than the carbon captured by the bio-energy crops.

However, the researchers also point out that while the error is serious, it is also readily fixable. What needs to be done is to count all pollution that comes out of tailpipes and smokestacks, whether from coal, oil or bio-energy, and to credit bio-energy only to the extent it really does reduce greenhouse gas emissions.

The research was supported by the Energy Department and the Michigan Agricultural Experiment Station.

-   Katrice R. Jalbuena