August 25th, 2016 By John Upton climatecentral.org
Years of number crunching that had seemed to corroborate the climate benefits of American biofuels were starkly challenged in a science journal [Climatic Change] on Thursday, with a team of scientists using a new approach to conclude that the climate would be better off without them. Based largely on comparisons of tailpipe pollution and crop growth linked to biofuels, University of Michigan Energy Institute scientists estimated that powering an American vehicle with ethanol made from corn would have caused more carbon pollution than using gasoline during the eight years studied.
Most gasoline sold in the U.S. contains some ethanol, and the findings, published in Climatic Change, were controversial. They rejected years of work by other scientists who have relied on a more traditional approach to judging climate impacts from bioenergy — an approach called life-cycle analysis.
Following the hottest month on record globally, and with temperatures nearly 2°F warmer and tides more half a foot higher than they were in the 1800s, the implications of biofuels causing more harm to the climate than good would be sweeping.
The research was financially supported by the American Petroleum Institute, which represents fossil fuel industry companies and has sued the federal government over its biofuel rules. “I’m bluntly telling the life-cycle analysis community, ‘Your method is inappropriate,'” said professor John DeCicco, who led the work. “I evaluated to what extent have we increased the rate at which the carbon dioxide is being removed from the atmosphere?”
Lifecycle analyses assume that all carbon pollution from biofuels is eventually absorbed by growing crops. DeCicco’s analysis found that energy crops were responsible for additional plant growth that absorbed just 37 percent of biofuel pollution from 2005 to 2013, leaving most of it in the atmosphere, where it traps heat.
…The findings were criticized by scientists whose work is directly challenged by them…..Thursday’s paper provided fresh fuel for a heated debate among opposing groups of scientists over bioenergy’s climate impacts. Some are certain it’s a helper in the fight against climate change. Others are convinced it’s a threat.