Holy cow!, came the exclamation, when a colleague recently read about emissions from cow burps and farts potentially rivaling the global warming pollution of the world’s cars and trucks. So, I pulled the short straw and here I am ruminating on cow farts and climate change for our April Fool’s Day post.
My mom grew up on a dairy farm and talked about her favorite Guernsey cow Daisy, chewing her “cud.” Come to think of it, until now, I never really knew what cud was.
For those of us who weren’t members of the Future Farmers of America in high school, here’s a little Animal Husbandry 101: It turns out that cows, sheep, beef cattle and goats are “ruminants,” or animals with a specialized digestive system that allows them to process otherwise unusable plant material. Cows and other ruminants regurgitate their food (creating the cud) and digest it in multiple stomachs.
Through this prolonged digestive process, known as “enteric fermentation,” dairy cows and beef cattle release methane, mostly from burping, but also from farting.
Though recently maligned by budget-conscious politicians, and a tongue-in-cheek favorite focus of the media, cow flatulence and indigestion is really no joke: measuring and reducing methane emissions from all of the world’s livestock is a serious area of study. And like everything to do with climate change – a topic not without controversy.
The 2006 study by the United Nations’ Food and Agriculture Organization, Livestock’s Long Shadow –Environmental Issues and Options brought attention to agricultural emissions by observing that “the livestock sector generates more greenhouse gas emissions as measured in CO2 equivalent – 18 percent – than transport.”
Comparisons between emissions of cows and cars are not clear-cut, however, because vehicles that burn fossil fuels emit carbon dioxide, while cows primarily emit a less prevalent, but more potent, greenhouse gas – methane. Farm operations also produce some nitrous oxide, another global warming gas.
One critic of the UN study, a UC Davis researcher who works with the agricultural industry, argues that the study counted “farm to table” emissions for every step of livestock emissions, but the transportation statistic did not include emissions from “well to wheel.”
Nonetheless, there is general agreement that livestock farming worldwide is a significant source of greenhouse gas emissions, producing 80 million metric tons of methane a year, or about 28% of global methane emissions from human-related activities.
Meanwhile, researchers at the University of New Hampshire had to defend their $700,000 Department of Agriculture grant to study reducing emissions from cow burps at organic dairy farms, when it wound up on Oklahoma Sen. Tom Coburn’s list of the most wasteful government programs.
Researchers in Argentina don’t think cow farts are a laughing matter either. They have strapped plastic tanks to cows’ backs in order to trap and measure the amount of methane each animal produces (a 1200-pound cow produced 800 to 1000 liters of emissions each day). With about 55 million head of cattle grazing on grasslands in its beef industry, Argentina has a significant stake in understanding this source of its greenhouse gases (which could be as high as 30 percent of its total emissions).
California cows may be happy, in the words of the clever ad campaign, but according to “the Fart Chart,” the roughly 2.2 million cows in confined animal feeding operations in California emit the most greenhouse gas emissions in a state-by-state comparison of U.S. dairy cows, followed by the 1.9 million cows in Wisconsin and the 947,000 cows in New York at #3.
While we may not have a Beano formula for cattle, there are still solutions to be found. One is to simply increase the efficiency of farm operations, according to the Environmental Protection Agency. Through genetic and dietary improvements, the U.S. dairy industry has been successful in increasing milk production while reducing methane emissions.
Like Jon and Tami Tollenaar’s family farm in Elk Grove, CA, more farmers are also experimenting with biogas digesters. This basic technology captures the methane from manure and converts it into electricity, either to power farm operations or to sell back to the power grid.
Check out the 160 commercial livestock farms around the country that are voluntarily using anaerobic digesters, many partly funded by US Department of Agriculture Rural Development grants from the 2002 and 2008 Farm Bills.
These methane-munching digesters are preventing the direct emission of about 50,000 metric tons of the gas a year, while producing 396,000 megawatt-hours (MWh) of electricity (enough to power the average electricity use of nearly 36,000 residential customers for a year). Just think, cow power might light up your new high def TV!
So, in case you’re wondering, what about people’s personal methane emissions (farts, to be blunt)? Oddly enough, only one or two out of every five people release methane in their flatulence (seriously), and, so far, at least, the impact on global warming is considered negligible. So, relax and enjoy April Fool’s Day!
Lisa Hayden is climate change writer for The Nature Conservancy
Photo by: Flickr® user lucia_clay (Cows in Illinois, 2007). Used under a Creative Commons license.
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