Most crops grown in the United States and Europe to make "green" transport fuels actually speed up global warming because of the industrial farming methods, says a report by Nobel prize - winning chemist Paul J. Crutzen.
The findings could spell particular concern for alternative fuels derived from rapeseed, used in Europe, which the study concluded could produce up to 70 percent more greenhouse gases than conventional diesel.
The study suggested scientists and farmers focused on crops, which required less intensive farming methods, to produce better benefits for the environment.
Biofuels are derived from plants that absorb the planet-warming greenhouse gas carbon dioxide as they grow, and are meant as a climate-friendly alternative to fossil fuels.
But the new study shows that some biofuels actually release more greenhouse gases than they save, because of the fertilizer used in modern farming practices.
The problem greenhouse gas, nitrous oxide, is more famous as the dentists' anesthetic "laughing gas", and is about 300 times more insulating than the commonest man-made greenhouse gas carbon dioxide.
"The nitrous oxide emission on its own can cancel out the overall benefit," co-author Professor Keith Smith said.
The results, published in "Atmospheric Chemistry and Physics Discussions", were based on the finding that fertilizer use on farms was responsible for three to five times more greenhouse gas emissions than previously thought.
They cast further doubts on the credibility of biofuels as a climate cure, following the revelation of other unintended side effects such as rainforest clearance and raised food prices, from competition with forests and food for land.
(China Daily 09/29/2007 page 11)
（英語點津 Linda 編輯）
About the broadcaster:
Marc Checkley is a freelance journalist and media producer from Auckland, New Zealand. Marc has had an eclectic career in the media/arts, most recently working as a radio journalist for NewstalkZB, New Zealand’s leading news radio network, as a feature writer for Travel Inc, New Nutrition Business (UK) and contributor for Mana Magazine and the Sunday Star Times. Marc is also a passionate arts educator and is involved in various media/theatre projects in his native New Zealand and Singapore where he is currently based. Marc joins the China Daily with support from the Asia New Zealand Foundation.
