Why are cows blamed for global warming?

“There were observed buffalo herds that took 2-3 days to pass by the settlement along the Muskingum River.”
~Moravian missionaries, Ohio Valley, 1740s

Historic, pre-European settlement, and present-day contribution of wild ruminants to enteric methane emissions in the United States
by A. N. Hristov

Overall, CH4 emissions from bison, elk, and deer in the presettlement period in the contiguous United States were about 86% (medium bison population size) of the current CH4 emissions from farmed ruminants in the United States (Table 1). If the high bison population estimate is considered for this comparison, wild ruminants in the presettlement period emitted about 23% more CH4 from enteric fermentation than the current domestic ruminants in the United States.

How have enteric methane emissions from beef cattle changed over time?


Exploring the influence of ancient and historic megaherbivore extirpations on the global methane budget
by Felisa A. Smith, John I. Hammond, Meghan A. Balk, Scott M. Elliott, S. Kathleen Lyons, Melissa I. Pardi, Catalina P. Tomé, Peter J. Wagner, and Marie L. Westover


Credit: Frank Mitloehner (see discussion thread on Twitter)