The science in the controversial report on indirect land use by Tim Searchinger et al "fell far short of acceptable scientific standards" according to the findings of an analysis of the material by Professor John Mathews and Dr. Hao Tan, researchers from Macquarie University in Sydney, Australia. The new study, published today (19th August), claims that the framework used by Searchinger et al was inappropriate in that it started with assumptions as to diversion of grain to ethanol production in the US, but then extrapolated these to parts of the world, such as sugarcane growing in Brazil, which are actually (much) more bio-efficient.

"Indirect land use change (ILUC) effects are too diffuse and subject to too many arbitrary assumptions to be useful for rule-making," stated Professor Mathews. "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."

The issue is where to draw the boundary for life cycle analysis and how to address ILUC effects within the boundary. Non-industry experts are concerned that this is taking regulatory action too far, and the science underpinning such actions, including the ILUC calculations of authors such as Searchinger et al., cannot stand the scientific weight being placed upon them.

The Mathews and Tan analysis states that the real target of the Searchinger et al paper would appear to be the model of US ethanol production developed by the Argonne National Laboratory in the US Researchers at Argonne have developed a model for biofuels production and consumption in the US that takes full life cycle analysis issues into consideration as well as some attention to land use changes. But the Argonne work does not extend to indirect land use changes, which are considered too uncertain to be modeled - and so it has come in for much criticism from Searchinger et al. as well as others.

"If you wished to put US 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," commented Dr. Hao Tan. "Frankly, better science upon which to base rule-making is available today."

The Mathews and Tan analysis identified six areas in which Searchinger et al. fell short:

    * Direct plantings of biofuels crops around the world are ignored, and instead a spike in US corn-based ethanol is considered a trigger;

    * The US spike is met exclusively by growing corn - but other ways of meeting the US spike, all involving fewer GHG emissions, are ignored;

    * The US spike met entirely within the US - without regard to trade (such as half of the spike being met by Brazilian sugarcane and imported into the US);

    * The Searchinger et al. calculations of carbon release are based on trends recorded in the 1990s but are projected forward up to 2016;

    * Improvements in biomass yields around the world are not considered;

    * The US spike leads to indirect effects around the world without regard to regulatory limits (even in the US).

"These six shortcomings, together with the fact that the paper is not replicable, since the models and parameters used are not accessible, places a question mark over the refereeing procedures used for this paper by the journal Science," added John Mathews. "A paper that seeks to place a procedure in the worst possible light, and refrains from allowing others to check its results, is perhaps better described as ideology than as science."