One popular solution to global warming is to turn trees and grass into transport fuel, thus reducing our reliance on fossil fuels such as gasoline. But a study published in the October issue of Science finds that these advanced "cellulosic" biofuels could emit more greenhouse gases during the next few decades than burning gasoline will.
Running a computer model that links global economic and biogeochemistry data, Marine Biological Laboratory researcher Jerry Melillo and his colleagues projected that growing energy crops will require cutting down a lot of forest, which releases extra carbon dioxide into the atmosphere. In addition, energy crops will need to be doused with nitrogen fertilizer, which gives off an even more potent greenhouse gas, nitrous oxide.
By the end of the 21st century, the amount of land devoted to biofuels may be greater than the total area currently used to grow food crops. Melillo told Reuters, "In the near term, I think, irrespective of how you go about the cellulosic biofuels program, you're going to have greenhouse gas emissions exacerbating the climate change problem."