Dairy and beef cattle production is continually cited and maligned as a major source of greenhouse gas (GHG), contributing substantially to climate change. These allegations are based on three myths that are now being debunked by scientists in the United States and the United Kingdom.
In fact, animal agriculture could actually become climate neutral, says Frank Mitloehner, an air quality specialist with the University of California-Davis. He recently spoke at Alltech’s ONE Virtual Experience.
Myth 1. Methane, the most common GHG in animal agriculture, acts like other GHGs in the environment.
There are three main greenhouse gases: carbon dioxide (CO₂), nitrous oxide (NO) and methane. CO₂ and NO are stock gases, which are long-lived and build up in the atmosphere. CO₂ has a lifespan of 1,000 years; NO, 110 years. Methane is a flow gas which has a lifespan of just 10 years. “The only time you really add new additional methane to the atmosphere with the livestock herd is throughout the first 10 years of its existence,” says Mitloehner. Methane levels don’t increase if herd size doesn’t change since methane is being broken down at the same rate as it is being produced.
Myth 2. Current methods for assessing global warming potential are accurate
Mitloehner and Myles Allen from Oxford University say current methods over-state methane’s warming potential because current calculations don’t account for the fact methane is a flow gas and is in the atmosphere just 10 years. The calculations understate CO₂ contribution because it remains in the atmosphere for 1,000 years.
Myth 3. To keep up with growing food demand globally, the United States must continue to increase the number of dairy and beef cattle, thus increasing methane emissions.
This ignores the fact that the U.S. dairy and beef industries have improved efficiency and increased productivity while reducing cattle numbers. In 1950, the dairy cow herd peaked at 25 million head. Today, it is at about 9 million cows while producing 60% more milk.
Through continued improvement in efficiency and incentives for anaerobic digesters and other alternative manure management systems and practices, Mitloehner believes methane production from livestock can actually be reduced. “If we indeed achieve such reductions of greenhouse gas, particularly short-lived GHGs such as methane, then that means that our livestock sector will be on a path for climate neutrality,” he says.
For more detail on the Alltech ONE Virtual Experience, click here.