Methane comprises six percent of the total greenhouse gas (GHG) emissions generated in California. It is a very potent GHG with a global warming potential about 25 times that of carbon dioxide over a 100-year period. Agriculture is responsible for about 60 percent of California’s methane emissions, and the state’s dairies are the primary source of those emissions. Approximately equal levels of emissions come from dairy manure management systems and from the digestive process of enteric fermentation in dairy cattle rumens that generate methane exhaled by the animals.
Source: Adam Kotin, Martha Noble, and Jeanne Merrill; CalCAN, October 2015.