The author is a senior associate editor for Hoard’s Dairyman.When it comes to global warming, all greenhouse gases tend to get lumped into the same bucket. In reality, certain gases behave differently, and that affects their impact on climate change. During the June Hoard’s Dairyman webinar, University of California, Davis professor Frank Mitloehner focused on the characteristics of methane.
“It is true that methane is a potent greenhouse gas,” Mitloehner said, calling the gas “fast and furious.” It is furious because of its potency, being 28 times more potent than carbon dioxide. On the flip side, it has a much shorter lifespan. While carbon dioxide will stay in the atmosphere for 1,000 years, methane will remain just one decade.
“After about a decade, the methane is gone,” Mitloehner pointed out. The same is not happening for other greenhouse gases such as carbon dioxide or nitrous oxide. “They don’t have atmospheric removal, and that has a significant impact on how the gas warms the planet,” he explained.
He illustrated this concept using a commute to work. He said if a person lives 20 miles from their job, every time they drive to work, they burn gas and put carbon dioxide into the air. Each day, this adds new carbon to the existing stock of carbon. It collects over time and stays in the air for 1,000 years.
Methane is often treated like a stock gas that accumulates, but Mitloehner said it is a flow gas, which means it is both produced and destroyed. This is the reason methane is often targeted when it comes to reducing emissions from livestock production.
“When you reduce methane, you reduce warming,” Mitloehner said simply. By cutting back methane emissions, we can have an immediate impact on global warming, and reduced methane production can offset the warming effects of other long-lived gases like carbon dioxide, helping bring dairy toward climate neutrality.
Mitloehner said that “business as usual” on farms won’t cut it, though. It will take innovation and adoption of new technologies, from feed additives to covered manure lagoons, to achieve the sustainability goals being set by various organizations, states, and food processors.
Strides in efficiency
The greenhouse gases accumulating in the atmosphere form what Miloehner describes as a blanket that retains solar heat, which serves a good purpose.
“Without this blanket, life on earth would not be possible. It would be too cold,” he said.
“The problem,” he continued, “is that the blanket is becoming too thick, because we are producing too many greenhouse gases.”
In the U.S., Mitloehner said that livestock production contributes just 2% of total emissions, and most of that is methane. This presents agriculture a great opportunity, he said, because when livestock producers reduce methane, we have an instantaneous impact on warming.
Mitloehner noted that farmers have already made great strides in minimizing agriculture’s carbon footprint. In 1950, there were 25 million dairy cows compared to 9 million today, but those 9 million cows make 60% more milk. That means the carbon footprint of a glass of milk is two-thirds of what it was 70 years ago.
In fact, Miloehner said the U.S. is a model for production efficiency. About 80% of global livestock emissions come from developing countries around the world, and that is largely a function of inefficient livestock that don’t have the reproduction and milk production levels we have here.
Meat-free isn’t the answer
Mitloehner also briefly addressed the consumers’ role in reducing food’s carbon footprint. While some people believe eating fewer animal-sourced foods will cut back greenhouse gas emissions, the truth is that these dietary changes would have a very small impact.
He shared that switching from an omnivore diet to a vegan one for a year would reduce carbon dioxide emissions by 0.8 ton. Meanwhile, one trans-Atlantic flight releases 1.6 tons of carbon dioxide per person on board. So, every rider on that airplane would need to consume a vegan diet for two whole years to offset the emissions produced by that one flight.
Another dietary change often promoted is “Meatless Mondays,” which encourages people to not eat meat one day a week. However, Mitloehner shared that if the whole country skipped eating meat once a week, greenhouse gas emissions would be reduced just 0.3%. Taking it a step further, if everybody in the country went vegan for the year, greenhouse gas emissions would only fall by 2.6%.
Furthermore, Mitloehner said most people who take radical action to change their diet (by going vegan, for example), only stick with that plan for a year and then revert back to an omnivore diet. That makes dietary change an unsustainable way to reduce our carbon footprint.
What is the answer, then?
“To me, it is very clear, if we want to reduce the carbon footprint of food, we need to work with farmers,” Mitloehner shared, “and how we do that effectively is to incentivize methane reductions.”