July 20, 2010
In a recent Mother Jones article, writer Kiera Butler asks the experts if eating responsibly raised meat can actually be good for the planet. One of the responses comes from Joel Salatin, star of Food, Inc., Fresh and a personal hero of mine. Joel makes some strong points that uphold the merits of an ethically- and environmentally-sound diet that includes animal products. However, one of his arguments struck me as unsound:
“…far more herbivores (bison) existed in the Americas 600 years ago than exist today: The notion that methane from burping herbivores causes climate change is both unscientific and ridiculous.”
With all due respect to Joel, here’s why I think he’s missing the mark.
“…far more herbivores (bison) existed in the Americas 600 years ago than exist today.”
True, there are fewer bison alive today, and I don’t have numbers on the total numbers of herbivores then and now. But if we’re talking about climate change, large ruminants – animals with multiple stomachs and a penchant for belching large amounts of methane, a potent greenhouse gas – are the animals we’re concerned about.
The best historical estimates put the number of bison roaming the Great Plains at 30 million (1,2,3). In 2008, the USDA reported the U.S. cattle inventory at 96 million head (4). That’s three times as many large ruminants alive in the U.S. today (not accounting for moose and their ilk).
“The notion that methane from burping herbivores causes climate change is both unscientific and ridiculous.”
Not so. Burping ruminants have contributed to climate change throughout history, and the dominant large ruminants in the U.S. currently contribute roughly three times as much as they used to. The 30 million bison roaming the Great Plains are estimated to have released 46 Tg CO2e enteric methane emissions annually (3), compared to the 140 Tg CO2e methane released in 2008 by U.S. beef and dairy cattle (about 85% of which are grazing at any particular point in time, the rest are in feedlots) (5).
These are rough comparisons. They don’t account for other ruminants like deer, sheep and goats, though these smaller animals contribute far fewer methane emissions than cows and bison (6). Moose may be another story, though I suspect the number of cattle (wild and domestic) in the U.S. has far outweighed moose populations. The data are limited to enteric methane emissions (belching only) and exclude greenhouse gas emissions from manure and other sources. Further, no one knows exactly how many bison roamed the U.S. Still, the available data strongly suggest that our current livestock production model produces far more annual greenhouse gases than Great Plains bison ever did.
These finer points don’t detract from Joel’s other arguments, and I still hold that raising livestock under certain conditions can have numerous ecological benefits. Still, it’s important to set the record straight about red meat, dairy and climate change. To satiate the U.S. demand (and to a lesser degree, the international demand) for meat and dairy, we raise far more large ruminant animals than would otherwise naturally occur, and the effects on climate change are heavy.
– Brent Kim
1. D. Flores (1991) Bison Ecology and Bison Diplomacy: The Southern Plains from 1800 to 1850. The Journal of American History 78 (2).
2. H. Epp and I. Dyck (2002) Healthy Human-Bison Population Interdependence in the Plains Ecosystem. Great Plains Research 12 (2002).
3. F. M. Kelliher and H. Clark (2009) Methane emissions from bison-An historic herd estimate for the North American Great Plains. Agricultural and Forest Meteorology 150 (3), pp. 473-577.
5. US EPA (2010) 2010 U.S. Greenhouse Gas Inventory Report.
6. N.M. Swainson et al. (2008) Comparative methane emissions from cattle, red deer and sheep. Proceedings from the New Zealand Society of Animal Production 68.