Study casts doubt on indirect land-use change estimates

Source: Amanda Peterka, E&E reporter • Posted: Tuesday, November 18, 2014

Economic models tend to overestimate the greenhouse gas effects of indirect land-use change, according to a new study by Iowa State University researchers that boosts the ethanol industry’s arguments against ILUC estimates.

The study looked at actual land-use change since the mid-2000s, when prices for agricultural commodities rose, compared to predictions of models used by California, U.S. EPA and the European Commission. It found that farmers around the world tend to more intensively use existing agricultural land in response to high global crop prices, rather than convert new lands to agriculture — contrary to what the models predicted.

“The contribution of this study is to confirm that the primary land use change response of the world’s farmers from 2004 to 2012 has been to use available land resources more efficiently rather than to expand the amount of land brought into production,” the Iowa State University study says. “This finding is not necessarily new … however, this finding has not been recognized by regulators who calculate indirect land use.”

Indirect land-use change has been a subject of debate since the release of a controversial 2008 paper that tied biofuels production in the United States to ILUC elsewhere in the world. Opponents of ethanol, including environmentalists, argue that the increased diversion of corn to ethanol production and resulting higher corn prices have caused farmers elsewhere to convert land to agriculture and that ILUC emissions should be counted in ethanol’s greenhouse gas footprint.

The ethanol industry, on the other hand, has long criticized models that attribute ILUC emissions to domestic production.

The new study was published by the university’s Center for Agricultural and Rural Development and received a grant from the Renewable Fuels Foundation, the research arm of the ethanol trade group Renewable Fuels Association.

Study authors Bruce Babcock and Zabid Iqbal of CARD compared average land uses across the 2004-06 time frame to average land uses measured across 2010-12.

They examined “extensive” land-use change, or instances in which new land was brought into agriculture, as well as “intensive” changes, or the increased use of existing agricultural land. Intensive changes included the increased use of practices such as double cropping and reductions in unharvested, fallow and mowed pasture land.

The study found that conversions of new land into agricultural uses occurred in African countries, but those changes likely were not tied directly to higher world commodity prices because global prices typically aren’t transmitted to most rural African markets.

A few other countries experienced high rates of conversion — Argentina, Indonesia, Brazil and Southeast Asian countries — but outside of Africa, almost 15 times as much land-use change in the last decade was of the “intensive” type, rather than the conversion of new acres to agricultural uses.

“That countries primarily responded to higher world prices by intensifying land use rather than by converting land from forests and pastures should not be surprising,” Babcock and Iqbal wrote. “Many countries, such as China and India, simply do not have available land to bring into agriculture.”

Economic models typically overestimate land-use change and related greenhouse gas emissions, the study found, because they tend to group all changes into the extensive category.

“The pattern of recent land use changes suggests that existing estimates of greenhouse gas emissions caused by land conversions due to biofuel production are too high,” the study says. “Intensification of land use does not involve clearing forests or plowing up native grasslands that lead to large losses of carbon stocks.”

The Iowa State authors said they plan further research involving the creation of a statistical model to explain why some countries did convert more land to agriculture instead of increasing the intensity on existing lands.