Where Corn Pollutes America Most, and Who’s Responsible

by Eric Roston (Bloomberg) Companies want to know the environmental impact of their supply chains. Researchers used a crucial commodity to show them. -- Not every day does an obscure scientific report directly help massive U.S. companies looking to cut costs, use natural resources more efficiently, and make sure their customers know about it. And yet Labor Day saw the quiet unveiling of a project that provides minute detail—down to individual factories—of the movement of corn along America’s sprawling meat and ethanol supply chains.

The ramifications of being able to tie pollution and water use to specific amounts of desirable commodities, and in specific locations, cannot be overstated at a time of accelerating climate change. The opaque title of the Sept. 4 study, however, fails to give away what’s going on. “Subnational mobility and consumption-based environmental accounting...” In English, what the researchers have done is broken out granular geographic information about where corn is produced and transported within two industries that consume it most—meat and ethanol.

The general problem that the researchers took on—prompted by a collaboration with the non-governmental organization the Environmental Defense Fund (EDF)—is that some 75 percent of the carbon dioxide emissions and water use of economic production is bound up in an enormous, poorly documented network of supply chains. Given the importance of corn to both the meat and ethanol industries, and the importance of the meat and ethanol industries to American consumers, they focused on that specific network.

Tyson Foods called the figures cited for their operations incorrect, “since the corn we source is mostly for our poultry business and not the cattle and pigs we buy from independent farmers and ranchers,” said Caroline Ahn, a spokeswoman for Tyson. She said the company’s corn purchases are less than a quarter of the amount stated in the new study. Tyson, which details its environmental program here, is working with the research group World Resources Institute to set science-based greenhouse gas targets and water-use goals, she said. (Other companies either declined to comment or have yet to return a request for comment on the study’s findings.)

Steffen Mueller is principal economist for the Energy Resources Center at the University of Illinois at Chicago. He is an expert in lifecycle modeling of corn and biofuels, and criticized the new study for using 2012 as its base year, a time when devastating drought reduced corn yields to 122 bushels an acre, which is equivalent to 1995 levels, or roughly 28 percent below 2016.

Mueller said that newer data would have been more appropriate, and is concerned with recent examples of outdated data use in research [pdf]. (The researchers wrote they used 2012 data because it’s from the most recent relevant U.S. Department of Agriculture report. Because of the drought circumstances that year, they also ran 2007 numbers and found that the geography of corn was more or less stable between the two years, according to the study.) READ MORE