Jersey cow

Organic milkMuch has been written about cows’ role in producing greenhouse gas emissions. (Think burps and farts.) 

A 2006 United Nations report stated that livestock were responsible for 18% of these emissions. To be fair, this statistic also included land use and degradation, deforestation, pesticide use and water pollution. Cow flatulence, however, continues to incur blame (not to mention really dorky jokes). 

Fear not, bovine lovers: Researchers at the University of Arkansas and Michigan Technological University have found that the dairy industry is responsible for only about 2% of all U.S. greenhouse gas emissions. 

Using 2007 and 2008 data from more than 500 dairy farms and 50 dairy processors, as well as data from more than 210,000 round trips transporting milk from farm to processing plant, Arkansas researchers examined the trail of carbon emissions—from dairy farms to the milk in your coffee. They concluded that total greenhouse gas emissions associated with the fluid milk Americans consume were lower than previously reported. 

Meanwhile, Michigan Tech researchers focused on the carbon footprint of feed crops, which are definitely “a major contributor to carbon emissions,” says David Shonnard, PhD, a professor of chemical engineering and director of the university’s Sustainable Futures Institute. His team analyzed the impact of numerous variables on animal feed: fertilizer, herbicides, harvesting methods and transportation. 

“We also looked at a Michigan feed mill, where grain gets combined with any of over a hundred different additives,” he says. (FYI: Changing to natural feed rich in omega-3 fatty acids has been associated with fewer greenhouse gas emissions, as has increasing cows’ longevity.) 

But there’s still room for improvement: 

  1. “Growing crops is becoming more productive all the time, and we may be able to use less land to satisfy demand,” Dr. Shonnard says.
  2. Manure management, feed production, energy management, processing, transportation and enteric methane (cow gas) are areas that can be improved.
  3. Eutrophication of water—what happens when manure and fertilizer reach surface water—causes an overbloom of algae that sucks oxygen from the water and kills fish. More research is needed to prevent this process. 

Top photo by Stephen Kennedy, courtesy of the Innovation Center for U.S. Dairy