According the United States Environmental Protection Agency the 100 million cattle in the US emit 5.5 million metric tons of methane. Globally, cattle flatulence and belches account for 66 million metric tons and methane is 25 times more potent as a greenhouse gas than CO2 - carbon dioxide.
What if we ended dairy and beef operations today? What might be the possible long term consequence? Felisa Smith of the University of New Mexico, Albuquerque, may have the answer.
She suggests that 13,400 years ago the Americas were extensively populated by large herbivores particularly 12,000 - 20,000 pound woolly mammoths. This was the end of the Wisconsin glacial period and a time of rising temperatures. By 11,500 years ago and roughly 1000 years following the development of Clovis technology, 80% of these animals were extinct. Dr. Smith postulates in Nature Geoscience that human predation (and a warming environment) led to their extinction which led to a corresponding plunge in methane levels. She calculates that 13,400 years ago, these mega-herbivores produced 9.6 million metric tons of methane per year. She suggests that the resulting drop in methane levels shown in ice cores from 700 parts per billion to 500 was a direct result of extinction leading to a rapid global cooling and a "mini ice age," 12,800 to 11,500 years ago, at the very end of the Wisconsin glacial period.
If Smith is right, humans have been changing global climate for millennia. Significantly, today, if humans change their lifestyle and diet, eliminating herbivores from our diet, we may have a realistic approach to reversing the warming we have created.
