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More Models to Measure Land Use Change

September 17, 2008
As the U.S. EPA and California’s Air Resource Board seek to implement their respective Renewable and Low-Carbon Fuel Standards, economists continue to refine models to measure and predict indirect land use change emissions associated with biofuels.

Many of the original critiques of the Searchinger paper in Science that initiated this debate commented on the uncertainty in attributing indirect land use change to biofuels. Prof. Roger Sylvester-Bradley of ADAS UK Ltd., for instance, summarizes many of the issues that must be worked out in the analysis of indirect land use change. According to Sylvester-Bradley, “Deforestation may also be driven by meat production, timber extraction, accessibility, migration, and other changes. To what extent should ILUC be attributed to the biofuel?”

A few groups have advocated dividing biofuels into groups that are more or less likely to produce land use change. E2 is a national community of business leaders who advocate for good environmental policy while building economic prosperity. They are allied with the NRDC. In a position paper they state, “Current food crops have a large indirect land-use penalty and that will continue unless productivity improvements can outpace demand for food and fuel resulting in no increase in total land use.”

Still other researchers are attempting to model and measure the exact effects of biofuels on land use change.

According to University of California Berkeley researchers active in helping to define California’s LCFS, “The market-mediated climatic land use effect of crop-based biofuels appears to be very large.” These researchers sought to quantify and validate the model originally proposed by Searchinger. They found that any ecosystem converted to crop production releases a significant amount of carbon, not just rainforests. What matters is how much the world market for crops must expand in order to meet the biofuel mandates set by the United States and other countries. According to these Berkeley researchers, many factors create uncertainty in measuring indirect land use change, including whether other crops can be substituted in meeting the demand for corn, how much yields might increase through technological innovation, how baseline demand is measured, whether additional cropland is available, as well as trade policies, regulations, and investment dynamics.

Recently, the American Chemical Society held a briefing on Capitol Hill to explore the question, “How Do Biofuels Impact Greenhouse Gas Emissions?”
Wallace Tyner, a professor of Agricultural Economics at Purdue University, gave one of the presentations at the briefing. He asked, “What do we need to consider to be able to isolate the effects of biofuels?” and presented the following short list:

  • Energy prices – major biofuels driver

  • Demand – population, incomes, etc.

  • Supply – yield increases, policy on idled land, water supply issues, environmental issues

  • Exchange rates

  • Policies in the rest of the world

Tyner recently contributed to an analysis of the combined effects of the U.S. and EU biofuel goals on land use throughout the rest of the world. The paper uses models data from 2001 to 2006 and uses it to predict rises in crop land and declines in forest and pastureland through 2015 as a direct result of U.S. and EU biofuel policies. The paper also factors in the effects that oil prices have had.