Biofuels -- why we should proceed with care

	Growing crops that could be converted into biofuels will indirectly cause substantial greenhouse gas emissions, if farmers clear forests and use more fertilizer in order to cultivate the land, according... Click here for more information.

While biofuels are an attractive alternative to fossil fuels for meeting global energy demands, the picture isn't all rosy, scientists say in the October 23 issue of Science. Growing crops that could be converted into biofuels will indirectly cause substantial greenhouse gas emissions, if farmers clear forests and use more fertilizer in order to cultivate the land, according to a new study. Likewise, current rules for applying the Kyoto Protocol and national cap-and-trade laws also do not accurately account for the carbon released to the atmosphere as the result of biofuel production, according to a Policy Forum in the same issue.

In the first study, Jerry Melillo and colleagues used a model that simulated economic and environmental changes to predict the indirect effects, in terms of land use, of growing cellulosic biofuel crops. These are grassy or woody plants that have lately been considered a better alternative than corn or soy, in part because they don't need fertilizer and shouldn't be affected by global food prices. The problem is, we have a finite amount of land where new crops could be grown. Melillo and colleagues now report that if biofuel crops replace food crops on current farmlands, then the clearing of forested land for additional food crops will release more carbon from the soil there than in the areas where the biofuel crops themselves are being grown. And, using fertilizer to sustain the growth of these new crops would release important amounts of nitrous oxide - a far more effective heat-trapping molecule than carbon dioxide. "A global greenhouse gas emissions policy that protects forests and encourages best practices for nitrogen fertilizer use can dramatically reduce emissions associated with biofuels production," the authors write.

In the Policy Forum, Timothy Searchinger and colleagues warn that rules for applying the Kyoto Protocol and national cap-and-trade laws contain a major but fixable "accounting" flaw in assessing bioenergy. If not corrected, this flaw will severely undermine greenhouse-gas reduction goals. These rules exempt carbon dioxide emissions from bioenergy use, regardless of the source of the biomass. But, they also do not count emissions from land-use activities involved in generating the biomass. That essentially treats all bioenergy as carbon neutral. In reality, while some sources of biomass absorb or withhold additional carbon from the atmosphere, other biomass derives from clearing forests to provide fuel wood or to grow energy crops, both of which may cause large net releases of carbon. If applied globally, this discrepancy could lead companies or countries to clear much of the world's forests as carbon caps tighten according to several studies.

Article #18: "Indirect Emissions from Biofuels: How Important"," by J.M. Melillo; D.W. Kicklighter; T.W. Cronin; B.S. Felzer at Marine Biological Laboratory in Woods Hole, MA; J.M. Reilly; A.C. Gurgel; T.W. Cronin; S. Paltsev; A.P. Sokolov; C.A. Schlosser at Massachusetts Institute of Technology in Cambridge, MA; A.C. Gurgel at University of Sao Paulo in Ribeiro Preto, Brazil; B.S. Felzer at Lehigh University in Bethlehem, PA.

Contact: Jerry M. Melillo at +1-508-289-7494 (phone), or jmelillo@mbl.edu (email)

News: A related news article by Bob Service will be available on Wednesday, 21 October 2009.

Note: This paper will be published online by the journal Science, at the Science Express website, on Thursday, 22 October. See http://www.sciencexpress.org.

Article #1: "Fixing a Critical Climate Accounting Error," by T. Searchinger; M. Oppenheimer at Princeton University in Princeton, NJ; S.P. Hamburg at Environmental Defense Fund in Boston, MA; R.N. Lubowski at Environmental Defense Fund in Washington, DC; J. Melillo at Marine Biological Laboratory in Woods Hole, MA; W. Chameides at Duke University in Durham, NC; P. Havlik; M. Obersteiner at International Institute for Applied Systems Analysis in Laxenburg, Austria; D.M. Kammen at University of California at Berkeley in Berkeley, CA; G.E. Likens; W.H. Schlesinger at Cary Institute of Ecosystem Studies in Millbrook, NY; P. Robertson at Michigan State University in East Lansing, MI; G.D. Tilman at University of Minnesota in St. Paul, MN.

Contact: Timothy Searchinger at +1-202-465-2074 (phone), or tsearchi@princeton.edu (email). Steven P. Hamburg at +1-401-225-2216 (phone), or shamburg@edf.org (email).