Join the Human Impacts Institute’s Community Conversation: How can you adapt your diet to be climate conscious?
Believe it or not, livestock has a tremendous impact on climate change. Livestock refers to cattle (both dairy and nondairy), buffalo, sheep (lamb), poultry, pigs and goats. According to the UN Food and Agriculture Organization, livestock contributes at least 18% of the overall greenhouse gas emissions.According to the U.S. Environmental Protection Agency, cattle alone account for 20% of the methane emissions in the United States per year.
Why does this happen? Emissions from livestock are caused by two main pieces: manure and enteric fermentation. Manure gives off methane and nitrous oxide, two major greenhouse gases. These gases come from the decomposition of manure during storage and application. Specifically, if manure is stored and treated in more wet conditions, the decomposition of the manure produces methane. If the manure is treated as a solid and dried out, it produces little to no methane. Therefore the management of manure is a contributing factor to producing greenhouse gases.
Another factor of the manure and greenhouse gases is the composition of the manure. What livestock eat can actually affect the amount of methane produced, in addition to how manure is treated. Basically, the greater the energy the feed has the increased potential for methane emissions. Feed boils down to either corn or grass. Grass fed livestock actually produces more methane than corn fed, surprisingly. What makes the corn more of a greenhouse gas contributor is the cycle of growing and transporting the corn. Growing the corn takes vast amounts of chemical fertilizers, which requires huge amounts of oil. In addition, transportation of the corn to the livestock feed lots also requires much oil. In fact, a typical corn fed steer effectively consumes about 284 gallons of oil in its lifetime!
Enteric fermentation is basically a very scientific term for belching and flatulence. Essentially, cattle have a rumen, which is a fore stomach, where the feed they eat breaks down into a metabolizing and digestible product. This process enables cattle to digest materials other animals cannot. However, this process causes the belching and flatulence that produces vast amounts of methane. The methane cattle produces is about 35-40% of all global methane emissions.
Regardless of the stinky processes, there is no doubt that livestock is a large contributor to global greenhouse gas emissions. Some estimates say that livestock emissions are as high as 51% of emissions – which is over 32.6 billion tons of greenhouse gas emissions annually–putting livestock emissions on a level playing field as automobile emissions! Not only does livestock production occupy 70% of all land used for agriculture, which accounts for about 30% of the Earth’s land. The impact of livestock production and consumption on our communities is clear. More livestock=less land=more greenhouse gases in our atmosphere=increased climate change. So, when you hear about ‘meat free Mondays’ and other meat-free programs, consider taking the climate challenge! The less greenhouse gas emissions produced, the better for our climate.
By Lauren Lavitt, 2012 Human Impacts Institute’s NYC Climate Coalition Outreach Specialist