The following information is courtesy of Dr. Joe C. Paschal, Extension Livestock Specialist, Corpus Christi, TX.
A myth is an unproved or false collective belief that is used to justify a social institution. One popular myth is that cattle production is the major cause of global warming or climate change because of the production and release of greenhouse gases into the atmosphere. These include carbon dioxide (CO2), methane (CH4) and nitrous oxide (NO2) among others. Global warming is caused by the molecules of these gasses trapping the heat of the sun’s radiation as it is reflected from the Earth. A good deal of naturally occurring water vapor is also a major factor causing global warming. Methane and nitrous oxide have a much greater warming potential (25 to 300 times more) than carbon dioxide which is why it is considered more important to reduce them too.
In 2010, carbon dioxide represented 76% of all worldwide greenhouse gas emissions while methane represented 16% and nitrous oxide was 6%. Agriculture and forestry contributed a total of 24% of all greenhouse gas emissions but 20% of that amount was removed from the atmosphere by plants. In 2014, agriculture accounted for only 9% of all greenhouse gases produced in the US, much less than electricity production, transportation and industry. Cows don’t release any carbon dioxide or nitrous oxide but they do produce methane. Methane is created by the digestion of coarse forages and released through eructation or belching, but cows are not the biggest source of methane, agricultural or otherwise. All beef production including dairy, is responsible for only 9.4% all global or 1.9% all US greenhouse gas emissions.
This small level of emissions can be and is being reduced with the use of improved forage varieties, grain finishing, ionophores, and growth implants. Improved forage varieties have lower structural carbohydrates and are more digestible releasing less methane. Grain finishing produces less methane. Grain is more digestible and allows cattle grow faster and more efficiently than on grass. Ionophores reduce methane production in the rumen by shifting the microbial population from methane producers to producers of more easily absorbed volatile fatty acids. Finally, growth implants reduce methane production increasing growth and efficiency, reducing the amount of feed fed overall.
Cattle production does contribute to the greenhouse gas emission as does all of agriculture, but far less than other sources. In addition, cattle producers and the agricultural sciences are continuing to reduce those emissions and improve the efficiency and productivity of beef.