To paraphrase Peter Drucker, you can’t manage what you don’t measure. Ever since the business guru shared his words of wisdom, the principle has become integral to effectively running an organization. But who knew it also applies to animal agriculture, methane emissions and global warming?
The livestock industry has long been maligned for its carbon footprint, and however unfair some of the accusations are, the fact remains that animal agriculture is a major source of methane, the second-most plentiful and potent of the gases that are heating our planet to dangerous degrees. However, until recently, we weren’t doing an adequate job of measuring its warming. Chalk that up to a fatal flaw in what has been our go-to metric for the past 30 years.
Sometime in the 1990s, well-meaning scientists established GWP – global warming potential – to facilitate comparisons between various greenhouse gases. Using carbon dioxide as the baseline gas, GWP is intended to measure how much energy 1 ton of a specific greenhouse gas will absorb over time, compared to the same amount of carbon dioxide. For the sake of argument, the period is generally 100 years; hence why GWP is sometimes referred to as GWP100.
Methane’s MO
According to the EPA’s explanation of GWP100, of the three most common greenhouse gases, carbon dioxide has a warming potential of 1, regardless of the time period; methane, 27 to 30 over 100 years; and nitrous oxide, 273 during a century’s time.
Because methane packs quite a punch, and animal agriculture accounts for nearly 40% of methane emissions from human activity, GWP100 is an important piece of evidence used to try livestock in the court of public opinion. Many insist that’s where we should focus our climate efforts. To be fair, we absolutely need to focus on reducing methane. But even GWP100 doesn’t really tell us why. And to be clear, GWP100 is a very useful matrix that we will continue to use for years to come.
GWP100 fails to take into account the behavior of methane in the atmosphere. It’s not simply amped-up carbon dioxide. It’s a different animal altogether, what I like to call a “fast and furious” greenhouse gas. Furious because it’s potent and fast because it’s short-lived. It’s produced and destroyed in a way that doesn’t apply to carbon dioxide and nitrous oxide. Those are long-lived gases that stay around for hundreds, if not thousands of years.
With that in mind, scientists at University of Oxford’s Oxford Martin School developed a metric that improves upon GWP100 by addressing methane’s special nature. Known as GWP*, it’s a more accurate system of measuring warming from methane, particularly methane from animal agriculture.
After approximately 12 years, methane is oxidized and broken down into carbon dioxide and water vapor. If the methane came from animal agriculture, it’s part of the biogenic carbon cycle, meaning plants will extract from the atmosphere the carbon dioxide byproduct of methane and use it for photosynthesis, making it food for animals, which becomes food for humans and so on.
Using GWP*, we can see that constant methane emissions will yield no additional warming, and declining methane emissions will produce a cooling effect. Even with rising methane emissions, GWP* shows significant warming. It’s not a get-out-of-jail free card; in fact, it shows with more emphasis the benefits of reducing methane emissions and not increasing them.
The flaw in GWP100 – its inability to deal with methane’s cycling through the atmosphere instead of piling up there – is responsible for overstating the warming potential of methane by three to four times over a 20-year period. Methane not only has a different molecular structure than carbon dioxide, it behaves in a way that’s contrary to carbon dioxide, the most plentiful of the greenhouse gases.
Draining the tub
Think of the analogy of two bathtubs. One is being filled with carbon dioxide, but it has no drain. Thus, the level will continue to rise, and the tub will eventually overflow. That’s basically what’s happening in our atmosphere. On the other hand, the tub that is being filled with methane has a drain. As long as what’s being added doesn’t exceed the drain’s capacity, the methane tub will never overflow. Equalize the tap and the drain, and the tub won’t even fill up. In short, that’s how methane behaves in our atmosphere.
It’s a simplistic illustration that brings to light a crucial point: If the animal agriculture sector strongly reduces methane, it can reduce warming and become climate-neutral. That is, it will reach the point at which it no longer contributes to atmospheric warming. If the industry can cut its methane emissions enough, it can even eat into historical warming, as less methane will be emitted than is being oxidized in the atmosphere. But you wouldn’t know that by looking at GWP100. Under that scenario, the prognosis is bleak.
Using GWP100 and GWP*, researchers at the University of California – Davis CLEAR Center recently laid out three scenarios for the California dairy sector: methane emissions would continue on the same trajectory (business as usual); methane emissions from manure would be reduced by 40% but enteric emissions would continue as usual; and finally, a 40% reduction in methane emissions from manure and reductions in enteric methane emissions due to feeding cows the maximum amount of 3-nitrooxypropanol, a food additive that inhibits methane production in ruminant animals.
In the first and second scenario, GWP* showed slower rates of warming than GWP100 as methane emissions decreased. In the third scenario – the most aggressive plan to reduce methane emissions – warming was negative. The data point to the sector’s ability to become climate neutral in the near future, provided the appropriate changes in production are made.
Precious few – if any – other sectors can do that, but animal agriculture can. And it’s because of the nature of methane and the arrival of a more-accurate system that allows us to better understand its warming impact.
However, getting to climate neutrality is no small thing; reducing methane emissions is a tall order. Yet California is an example of what can be accomplished when policymakers work collaboratively with producers. Bolstered and encouraged by government-funded financial incentives, California dairies have reduced their methane emissions by at least 2.2 million metric tons since 2015, putting them solidly on the path to climate neutrality.
How is it being done? Covered manure lagoons and other new methods of waste management are resulting in lower methane emissions, and food additives are showing great promise in reducing enteric methane emissions. Methane is a problem if we fail to manage it, but if we can manage our emissions, we can find very impactful solutions.
Animal agriculture feeds, and that’s huge. Even so, it might be able to help us mitigate our climate crisis too.
But first, we have to effectively measure to manage our emissions.
