NCPA - National Center for Policy Analysis


February 20, 2008

Converting corn to ethanol in Iowa not only leads to clearing more of the Amazonian rainforest, but also would do little to slow global warming -- and often make it worse, according to a study published in Science magazine.

According to University of Minnesota ecologist, and co-author, David Tilman:

  • Converting the grasslands of the United States to grow corn results in excess greenhouse gas emissions of 134 metric tons of CO2 per hectare -- a debt that would take 93 years to repay by replacing gasoline with corn-based ethanol.
  • And converting jungles to palm plantations or tropical rainforest to soy fields would take centuries to pay back their carbon debts.

Diverting food crops into fuel production leads to ever more land clearing as well, according to Joseph Fargione of The Nature Conservancy, and study co-author:

  • Ethanol demand in the United States, for example, has caused some farmers to plant more corn and less soy.
  • This has driven up soy prices causing farmers in Brazil to clear more Amazon rainforest land to plant valuable soy.
  • Because a soy field contains far less carbon than a rainforest, the greenhouse gas benefit of the original ethanol is wiped out.

The environmental price tag of biofuels now joins the ranks of other, cheaper domestic fuel sources --such as coal-to-liquid fuel -- as major sources of globe-warming pollution as well as unintended social consequences.  As a result, 10 prominent scientists have written a letter to President Bush and other government leaders urging them to "shape policies to assure that government incentives for biofuels do not increase global warming."

By David Biello, "Biofuels Are Bad for Feeding People and Combating Climate Change," Scientific American, February 7, 2008.

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