Analysis highlights shortcomings of ILUC study

By Erin Voegele | August 10, 2009
Report posted Aug. 20, 2009, at 1:20 p.m. CST

Two researchers from Macquarie University in Sydney, Australia, recently published a scholarly analysis of the indirect land use change study co-authored by Tim Searchinger and published in Science in February 2008. The scholarly analysis, which was completed by John Mathews and Hao Tan, found that Searchinger et al. was not based on sound scientific standards and that government agencies relying on the findings of Searchinger et al. would be better served by utilizing other controls.

In the scholarly analysis, Mathews and Tan argue that Searchinger et al. does not report margins of error, discuss the assumptions that are utilized in the study, explore the validity of those assumptions, or take possible trade effects into account. Moreover, the researchers state that Searchinger et al.'s findings are not replicable because the models and parameters used have not been made accessible to other researchers.

Mathews and Tan identified six specific areas in which Searchinger et al. fell short:
1. Direct plantings of biofuels crops around the world are ignored and, instead, a spike in U.S. corn-based ethanol is considered a trigger
2. The U.S. spike is met exclusively by growing corn - but other ways of meeting the U.S. spike, all involving fewer greenhouse gas emissions, are ignored
3. The U.S. spike is met entirely within the U.S. - without regard to trade
4. The Searchinger et al. calculations of carbon release are based on trends recorded in the 1990s but are projected forward up to 2016
5. Improvements in yields around the world are not considered
6. The U.S. spike leads to indirect effects around the world without regard to regulatory limits, even in the U.S.

"You wished to put U.S. ethanol production in the worst possible light, assuming the worst possible set of production conditions guaranteed to give the worst possible set of indirect land use effects, then the assumptions would not be far from those actually presented in the Searchinger et al. paper," Tan said. "Frankly, better science upon which to base rulemaking is available today."

Instead, Tan and Mathews argue that a better approach to factor indirect land use change effects into world trade would be to devise a system where a proof of origin is attached to all biofuels that are produced worldwide. This would allow consumers and importing countries to ensure that they purchase biofuels sourced from preexisting agricultural lands.

"Indirect land use change effects are too diffuse and subject to too many arbitrary assumptions to be useful for rulemaking," Mathews said. "The use of direct and controllable measures such as building statements of origin or biofuels into the contracts that regulate the sale of such commodities would secure better results."