Biofuel demand 'will increase GHGs'
Growing demand for biofuels could actually increase greenhouse gas emissions as farmers clear forests and grassland to create more cropland, according to a new US study.
Presenting the results of the study at Imperial College, London, Professor Tim Searchinger, one of the authors of the study, said increasing demand for food will put even greater pressures on farmers to convert land for agriculture.
He said: "There's already a carbon benefit being provided by land and previous analyses of the benefits of biofuels haven't taken that into account.
"Using cropland to produce biofuels will cause large increases in greenhouse gases from land use change."
According the team's calculations, biofuels produced from soybeans reduce emissions by 70% compared to regular fuel, but when land use change is factored in, this changes to a 50% increase in emissions.
The study - first published in Science magazine - calculated that it could take decades for biofuels to pay back their carbon debt if forests and grassland were converted to grow them or to grow the food crops displaced by biofuel crops.
Professor Searchinger recommended that national governments should stop setting mandatory levels of biofuel use, and should provide producers with incentives to get their biofuels from existing agricultural land.
It was vital to find new ways to increase crop yields to meet demand for both food and biofuels, he added.
He said: "We are going to need more agricultural expansion to feed everybody and we are going to need big yield increases to keep the impact down.
"We need a massive worldwide strategy to boost yields using existing agricultural land."