We’ve all heard that livestock play a role in climate change. Cattle, especially, are frequently singled out as a prime offender, emitting potent methane that contributes to global warming.
But what if we’ve all been thinking about livestock and climate change the wrong way?
As we’ve discussed in previous posts, livestock play a vital part in the story of our planet, and there’s no denying that animal agriculture has had an impact on the rise in global temperatures that’s been underway since the Industrial Revolution. But livestock are not the villains they’ve been portrayed to be, and they are not the largest source of global greenhouse gas (GHG) emissions contributing to climate change.
In fact, livestock and agriculture, when properly managed, have the potential to reduce the amount of greenhouse gases in the atmosphere. With the right management, methods and technology, they can even help in the fight against global warming. It all starts with knowing the facts — and learning about the possibilities.
How does livestock farming contribute to global warming?
Livestock and agriculture are commonly cited among the most egregious offenders when it comes to greenhouse gases, with claims that emissions from livestock represent anywhere from 14% to 50% of total GHGs emitted into the atmosphere. Some groups even incorrectly claimed that meat production generates more greenhouse gases than the entire transportation sector.
But according to Dr. Frank Mitloehner, director of the CLEAR Center and a professor and air quality specialist at the University of California, Davis, this figure needs clarification, and doesn’t reflect actual livestock emissions in developed countries like the United States, where the number is closer to just 4% of all U.S. emissions.
“Contrast that to the fossil fuel sector contributing to 80% of all greenhouse gases,” said Dr. Mitloehner.
Many of the emissions from livestock come in the form of methane, which comes from both beef cattle and dairy cows. While all greenhouse gases (methane, carbon dioxide, nitrous oxide and fluorinated gases) have the potential to warm our planet, methane is more effective at trapping heat than CO2, making it one of the most potent greenhouse gases. According to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC), methane’s impact over a 100-year timespan is 28 times greater than the impact of carbon dioxide.
However, when analyzing the greenhouse effect and role each greenhouse gas plays in warming the Earth’s average temperature, the impact of cattle-created methane may be lower than we think. Why? Because that methane is actually recycled as part of a natural process known as the biogenic carbon cycle. And because of the role that cattle — and other ruminants — play in that cycle, they have the potential to be a driving force in fighting climate change in the years and decades to come.
Livestock, methane and the biogenic carbon cycle
The biogenic carbon cycle is the process by which plants, animals and the environment recycle carbon. Here’s a look at how it works:
- Plants capture carbon dioxide (CO2) from the air via photosynthesis and convert it into carbohydrates.
- Those carbon-based carbohydrates are sequestered in the soil and stored within the plant, until they are consumed by ruminants like cattle.
- Some of that carbon is released back into the atmosphere in the form of methane via belching and manure.
- Over the next dozen or so years, that methane is broken down and converted back into carbon dioxide in the atmosphere, allowing the cycle to begin again.
The biogenic carbon cycle is a key part of life: feeding plants, which then feed animals, which then feed us.
In the biogenic carbon cycle, carbon is recycled rather than rapidly created and accumulated. And, importantly, the biogenic carbon cycle is relatively quick, taking place over the course of decades rather than the centuries or millennia it takes for greenhouse gases from fossil fuels to be redeposited back into the earth.
Not all greenhouses gases are created equal
That rapidity is what makes methane a different kind of greenhouse gas. Methane behaves differently in the atmosphere from other greenhouse gases, and its long-term effects on global warming are therefore also different. According to the CLEAR Center, the major factor contributing to the warming effect of a greenhouse gas is whether it is a stock or a flow gas.
Stock gases are long-lived, and they remain and accumulate in the Earth’s atmosphere for thousands of years. Carbon dioxide, which stays in the atmosphere for centuries, is a stock gas, and its warming effects on our climate are long-lasting and growing. Flow gases, on the other hand, are short-lived gases that are removed from the atmosphere at a much faster pace. Because flow gases do not build up in the atmosphere, their warming impact has a shorter lifespan than stock gases.
Methane is a flow gas, with an atmospheric lifespan of around 12 years. New sources of methane will add warming to our planet for 12 years, but if the emission rate remains near constant over time, methane is destroyed at roughly the same rate that it is produced. It breaks down into its component molecules, including carbon dioxide, which can then be removed from the atmosphere and recycled through the biogenic carbon cycle.
“What makes methane from animal agriculture a flow gas is that it’s not just produced — it’s destroyed and taken out of the atmosphere,” said Dr. Mitloehner.
The bottom line: methane just doesn’t have the same atmospheric effects as carbon dioxide. That’s why the way we think about it, treat it and strategize around it should be different when it comes to our future plans to mitigate rising greenhouse gas concentrations and the effects of climate change.
How does eating meat affect climate change?
Some sources point to ruminant livestock like cattle and sheep as carbon-heavy food sources due to the methane they emit and the resources needed to raise them. But as we’ve already discussed, the methane emitted by livestock can’t compare to the greenhouse gases emitted through fossil fuel combustion in transportation and other industrial processes.
But if Americans did stop eating meat, what kind of effect would that have on climate change? According to Dr. Mitloehner, the reduction in greenhouse gas emissions in the United States would be less than 3%, as estimated in a 2017 paper by professors Mary Beth White and Robin R. Hall — “a minimal and short-term impact on the climate,” as Dr. Mitloehner describes.
On the other hand, eating meat places us within the biogenic carbon cycle — and allows us to take advantage of land that would otherwise go unused. As part of the biogenic carbon cycle, ruminants like cattle help recycle carbon by eating plants that wouldn’t be edible to humans, like grasses and shrubs. The cellulose formed during the biogenic carbon cycle is found in especially high amounts in plants growing in “marginal lands” where human crops can’t grow, according to the CLEAR Center at the University of California, Davis. Humans can’t digest cellulose — but ruminants like cattle can. The biogenic carbon cycle allows livestock to turn indigestible plants and otherwise unusable land into an important food source for humans.
Smart agricultural practices can help cut down on the impact that raising ruminant livestock can have on greenhouse gas emissions. It’s a trend that’s been happening for decades: As cited by Progressive Cattle, greenhouse gas emissions from cattle per pound of beef have dropped by 6% since 1990. Jerry Bohn, president of the National Cattlemen’s Beef Association, cites a 30% drop in emissions from beef cattle from 1975 to 2017. The pattern is clear — and the opportunities are enormous.
When consumers choose livestock and agriculture farms that employ environmentally friendly farming practices — including methods to help decrease livestock methane emissions, planting cover crops, employing crop rotation and integrating trees into livestock grazing lands through silvopasture practices — they’re investing in the biogenic carbon cycle and supporting farmers who are making a positive impact on climate change.
Decreasing livestock methane emissions
Since methane from agriculture isn’t building up in the atmosphere at the same rate as carbon dioxide, it has staggering implications: If methane from cattle is reduced, it can actually generate a cooling effect in which the biogenic carbon cycle offsets carbon dioxide from fossil fuels. With a deeper understanding of the physical scientific basis of climate change and the role technology can play in helping to mitigate it, farmers can proactively contribute to this effort. There are a variety of ways farmers can decrease the amount of methane produced by their livestock, including:
- Incorporating methane-reducing feed additives like tannins, seaweed, fats and oils, which can help inhibit methanogens in the rumen. Farmers are also turning to solutions like yeast to reduce cattle methane emissions and nitrogen excretion rates — all while increasing milk yield, milk fat and protein content, and nitrogen uptake via improved ruminal bacteria.
- Examining feeding strategies, like increasing the level of dietary fat and adding more grain into cattle feed rations, which have been shown to reduce methane emissions. According to Agriculture and Agri-Food Canada, a diet of crushed oilseeds (like sunflower seed, canola seed or flaxseed) or dried corn distillers grain reduced the energy lost as methane by up to 20% — a major impact from a simple switch.
- Exploring changes in manure management and manure storage, like aerating and composting cattle manure to reduce the amount of methane emitted. Methane produced by manure can even be used as an energy source. Dairy digester technology is turning manure into natural gas, which can be used to run generators or natural gas vehicles, or be resold to local utility companies.
The outlook and the opportunity
Like so many other industries, agriculture and livestock do have an impact on climate change, but the outlook for the industry’s future is bright. By continuing to make smart, efficient, environmentally friendly decisions when it comes to the way livestock is raised, the agricultural industry has the opportunity to do more than decrease emissions — it can help combat climate change on a global scale. And by choosing to support those farmers, everyday consumers can contribute to that effort.
The World Economic Forum has identified the opportunity for the agriculture industry, as well as what’s standing in the way: “While industry innovation has opened the door for farmers to capitalize on incremental advancements in sustainability, we need to help make it easy and profitable for farmers as part of a package that brings positive climate impact.”
Farmers and ranchers need sound information and accessible, science-based solutions that benefit their livestock and the environment. Those solutions need to be readily available to farmers across the globe, with a shared network of information on best practices and ways to adapt them to different countries, cultures and climates. That’s how farmers, ranchers and the livestock industry can help make a positive impact on climate change while Working Together for a Planet of Plenty™.