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A major scientific study undertaken by US researchers indicates that biofuels – even those from cellulosic crops such as grasses or fast-growing wood – will indirectly lead to large increases in greenhouse gas emissions through displacement of food crops.

Most countries currently count carbon emissions from land committed solely to biofuel production, but additional emissions occur when cropland or pasture is turned over to biofuel production, displacing agricultural activity to another site.

These additional emissions arising from ‘land-use changes’ are harder to measure and, therefore, more controversial to include in emissions monitoring or reporting.

But this could be a major oversight, according to the figures calculated by the researchers , which indicate that carbon emissions from land clearing can be twice as high as those arising from the production of the biofuel crops themselves.

“Our analysis, which we think is the most comprehensive to date, shows that direct and indirect land-use changes associated with an aggressive global biofuels program have the potential to release large quantities of greenhouse gases to the atmosphere,” says scientist Jerry Melillo from the Marine Biological Laboratory.

These unintended consequences of global biofuels programmes are adding to climate change, says Melillo, particularly in areas where forest clearing is happening as a result.

Meanwhile, a report from the United Nations Environment Programme (UNEP) says that a more sophisticated approach to biofuels is needed if there are to provide an environmentally-friendly energy source.

While some first generation biofuels, such as the ethanol from sugar cane being produced in Brazil, can reduce emissions by 70-100% when replacing petrol, other biofuel production can lead to the massive emission increases predicted by the research report.

The UNEP report cites as an example the production of biodiesel from palm oil on deforested peatlands in the tropics, which can lead to increases of greenhouse gas emissions of up to 2000% compared with fossil fuels.

“'Biofuels are neither a panacea nor a pariah but like all technologies they represent both opportunities and challenges,” says UN Under-Secretary General and UNEP executive director Achim Steiner.

For further information:
J. M. Melillo, J. M. Reilly, D. W. Kicklighter, A. C. Gurgel, T. W. Cronin, S. Paltsev, B. S. Felzer, X. Wang, A. P. Sokolov, C. A. Schlosser. Indirect Emissions from Biofuels: How Important? Science (October 22, 2009) DOI: 10.1126/science.1180251
www.mbl.edu/
www.unep.org/
www.unep.fr/scp/rpanel/pdf/Assessing_Biofuels_Full_Report.pdf

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Carbon emissions from land-use change caused by the displacement of food crops and pastures by a global biofuels program may be twice as much as emissions from lands directly devoted to biofuels production. (Credit: Chris Neill, MBL)