Friday, May 9, 2008

Feedlot cows produce more methane than pasture cows

As more researchers work to understand where ghg emissions occur in ag practices, we can begin to parse growing practices to determine which have a lower carbon footprint.

Environmental Health Perspectives posted recent research, Global Farm Animal Production and Global Warming: Impacting and Mitigating Climate Change, that does some of this parsing by combining the results of various related studies.

Here are some emerging facts from that article:
  1. "Animal agriculture sector accounts for approximately 9% of total CO2 emissions, which are primarily the result of fertilizer production for feed crops, on-farm energy expenditures, feed transport, animal product processing and transport, and land use changes (Steinfeld et al. 2006)."
  2. "Burning fossil fuels to produce fertilizers for feed crops may emit 41 million metric tons of CO2 per year (Steinfeld et al. 2006)."
  3. " Farm animals and animal production facilities cover one-third of the planet's land surface, using more than two-thirds of all available agricultural land including the land used to grow feed crops (Haan et al. 1997). "
  4. "Typically, cattle confined in feedlots or in intensive confinement dairy operations are fed an unnatural diet of concentrated high-protein feed consisting of corn and soybeans. Although cattle may gain weight rapidly when fed this diet (Pollan 2002), it can cause a range of illnesses (Smith 1998). This diet may also lead to increased methane emissions."
  5. And this: "The standard diet fed to beef cattle confined in feedlots contributes to manure with a "high methane producing capacity" (U.S. EPA 1998). In contrast, cattle raised on pasture, eating a more natural, low-energy diet composed of grasses and other forages, produce manure with about half of the potential to generate methane (U.S. EPA 1998)."
So feedlot cattle appear to produce twice the methane as pasture due to the diet. I assume this does not include the any methane from fertilizer or feed growing practices.

The first response seems obvious: eat less meat. The counterpoint is that we need protein. We can of course grow more pasture beef, but at current consumption habits we would have to expand land use for cattle quite significantly if we consume meat at current levels. Also, as health efforts (partially) succeed in getting us to reduce our red meat consumption in this country, as economic progress grows in developing nations, particularly China and India, meat consumption increases potentially negating any ghg reduction we have accomplished.

Ugh. So what can we do?

Since the climate is a global issue the pathway forward needs to incorporate global, national, and local concerns:
  1. Reduce feedlot cattle consumption everywhere.
  2. Increase the production of pasture beef.
    1. Which also decentralizes manure production and reduces the necessity of using fossil fuels to create fertilizers, and then transport them to buyers.
  3. Generate large consumer awareness programs in developing nations that as they turn their diets towards more red meat consumption that they request pasture beef.
    1. Other research shows that pasture beef has more omega 3 fatty acids than feedlot beef (will get source).
  4. Encourage trade policies that incentivize the production of low carbon meat.

Secondary source (primary sources in brackets, available in article): Koneswaran G and Nierenberg D, Global Farm Animal Production and Global Warming: Impacting and Mitigating Climate Change, Environmental Health Perspectives Volume 116, Number 5, May 2008,