April 2013

Assessing Climate Impacts of Expanding Biofuel Crops

Model indicates increased cultivation could benefit tropical areas.

Click to enlarge photo. Enlarge Photo

Image courtesy of Yadvinder Malhi,
University of Oxford

A recent climate modeling study indicates that global land use strategies that protect tropical forests—such Brazil’s Caxiuanã National Forest, shown here—could dramatically reduce air warming projected in these regions.

The Science

Changes in land use from increased cultivation of biofuel crops can alter climate by increasing greenhouse gas emissions and changing the reflective properties of Earth’s surface. As part of the Massachusetts Institute of Technology’s Joint Program on the Science and Policy of Global Change, a new study by Department of Energy (DOE) researchers investigates how (1) land-use policies and economic factors influence where and how biofuel crops are planted, (2) the potential implications for land-use change and greenhouse gas emissions, and (3) the overall effect on global and regional climates.

The Impact

The results indicate that future activities that promote intensification of land use may result in more tolerable future environmental conditions for local populations in tropical regions.


The study uses the DOE-supported Integrated Global Systems Model (IGSM) to simulate the climate effects of two possible global biofuels futures—one that allows conversion of natural areas to meet the increased demand for land and a second that encourages more intense use of existing managed land and restricts deforestation. The team finds that increased biofuel crop cultivation has a negligible effect on global temperature as warming from increased greenhouse gas emissions from cultivation is balanced by cooling caused by increased surface reflectivity of cropland. Although global temperature will be affected only minimally, more substantial regional warming may occur and not necessarily in the regions where biofuel crops are grown. The model predicts the Amazon Basin and Central Africa will warm by as much as 1.5°C. This effect is stronger in the first scenario that includes the conversion of forests into crop land. The effect is less pronounced when deforestation is limited.


W. Hallgren
Joint Program on the Science and Policy of Global Change
Massachusetts Institute of Technology
Cambridge, MA, 02139


This research is funded by a grant from the U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research


W. Hallgren, et al. “Climate impacts of a large-scale biofuels expansion.” Geophys. Res. Letters 40, 1624–1630 (2013). [DOI: 10.1002/grl.50352].

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Last modified: 1/17/2014 4:07:01 PM