"Corn ethanol is not a climate-friendly fuel," said Dr. Tyler Lark, assistant scientist at University of Wisconsin-Madison Center for Sustainability and the Global Environment and lead author of a new study published in the Proceedings of the National Academy of Sciences.
He calculates that ethanol releases at least 24 per cent more carbon into the atmosphere than gasoline. The United States Department of Agriculture has said ethanol releases 39 per cent less carbon than gasoline.
Based on that study, beginning in 2015 the United States government mandated the use of ethanol in gasoline and that immediately propped up corn prices and led to significant increases in acreage planted to corn.
It’s that conversion to corn that Lark has taken into account, plus the release of carbon when soil is tilled and the use of nitrogen fertilizer.
Lark’s research was funded in part by the National Wildlife Federation and U.S. Department of Energy.
Geoff Cooper, president and chief executive officer of the Renewable Fuels Association, called the study "completely fictional and erroneous," arguing the authors used "worst-case assumptions cherry-picked data."
As a result of the mandate, corn cultivation grew 8.7 percent and expanded into 6.9 million additional acres of land between 2008 and 2016, the study found.
Lark said the U.S.D.A. study underestimated the emissions impact of land conversion.