Ruminant livestock emit 80 million tons of methane per year, with US cattle emitting at least 5.5 million tons per year (20% of USA’s total methane emissions)

According to the US Environmental Protection Agency:

“[g]lobally, ruminant livestock produce about 80 million metric tons of methane annually, accounting for about 28% of global methane emissions from human-related activities.

In the U.S., cattle emit about 5.5 million metric tons of methane per year into the atmosphere, accounting for 20% of U.S. methane emissions.”

An adult cow may be a very small source by itself, emitting only 80-110 kgs of methane, but with about 100 million cattle in the U.S. and 1.2 billion large ruminants in the world, ruminants are one of the largest methane sources.

In New Zealand, emissions from agriculture are responsible for half of all greenhouse gases.

Source: Ruminant Livestock – Frequent Questions – How much methane is produced by livestock? – US Environmental Protection Agency

Date: Retrieved 29 March 2010

Source: Potent methane is an overlooked greenhouse gas – Reuters

Date: 30 April 2007