Conservation more effective than biofuels for fighting global warming
August 15, 2007
Comparing emissions from various fuel crops versus carbon storage in natural ecosystems, Renton Righelato and Dominick Spracklen write that "forestation of an equivalent area of land would sequester two to nine times more carbon over a 30-year period than the emissions avoided by the use of the biofuel."
"Taking this opportunity cost into account, the emissions cost of liquid biofuels exceeds that of fossil fuels," they conclude.
In developing their argument, Righelato and Spracklen note that vast areas of land would need be cleared to meet the modest goal of substituting 10 percent of oil and diesel using with biofuels: 43 percent of current cropland area in the United States and 38 percent in Europe. The authors say that the conversion of additional forest land would result in "a large up-front emissions cost that would... outweigh the avoided emissions."
Forest clearance for oil palm in Ecuador. © World Land Trust
Righelato and Spracklen say that this will continue to be the case until carbon-free biofuel technologies are developed and introduced -- probably some 30 years out into the future. By then, they suggest, the technology will exist to convert standing forest directly into biofuels.
In the meantime, the authors believe policymakers should focus on increasing the efficiency of fossil-fuel use, conserving existing forests and savannahs, and restoring natural habitats on cropland that is not being used for food production.
"In addition to reducing net carbon dioxide flux to the atmosphere, conversion of large areas of land back to secondary forest provides other environmental services (such as prevention of desertification, provision of forest products, maintenance of biological diversity, and regional climate regulation), whereas conversion of large areas of land to biofuel crops may place additional strains on the environment," they write. "For the longer term, carbon-free transport fuel technologies are needed to replace fossil hydrocarbons."
Renton Righelato and Dominick V. Spracklen (2007). Carbon Mitigation by Biofuels or by Saving and Restoring Forests? SCIENCE VOL 317 17 AUGUST 2007 10.1126/science.1141361
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