Cow (Firmafotografen, iStockphoto) Cow (Firmafotografen, iStockphoto) How do beef and dairy cows contribute to climate change? Livestock agriculture is a source of methane, a powerful greenhouse gas. Over the last couple of centuries, Earth has become warmer. That’s because of greenhouse gases released into the
atmosphere. One of the most commonly known greenhouse gases is carbon dioxide (CO2). Carbon dioxide is a colourless, odourless gas. It is released when fossil fuels are burned. Burning fossil fuels releases carbon dioxide into the atmosphere. The carbon in the carbon dioxide was stored for millions of years under the ground in the form of hydrocarbons. After carbon dioxide, the next most abundant greenhouse gas is methane (CH4). Although carbon dioxide is much more abundant in the atmosphere than methane, methane traps roughly 30 times more heat than carbon dioxide. This makes methane an important gas to keep an eye on. CO2 accounts for about 76 percent of total greenhouse gas emissions. Methane, primarily from agriculture, contributes 16 percent of greenhouse gas emissions and nitrous oxide, mostly from industry and agriculture, contributes 6 percent to global emissions. All figures here are expressed in CO2-equivalents. Let’s look more closely at where methane comes from. In particular, let’s look at a source of methane that might surprise you: livestock. What are the sources of methane emissions?Methane comes from both natural sources and anthropogenic (human-related) sources. Natural sources include:
Human-related sources fall into four main categories:
Agriculture-based sources include rice production, livestock, and manure management. Other sources include the burning of biomass, coal mining, and the treatment of waste in landfills and wastewater.  30% of methane comes from natural sources, 40% from agricultural sources and 30% from other human-made sources. How do livestock produce methane?The beef and dairy cattle industry is one of the main contributors to global greenhouse gases. Methane makes up about half of the total greenhouse gases this sector emits. Cows generate methane in two main ways: through their digestion and through their waste. Cows are part of a group of animals called ruminants. Ruminants have stomachs with four distinct chambers. Sheep, goats, and giraffes are also ruminants. In order, from beginning to end, food moves through the A: rumen; B: reticulum; C: omasum and D: abomasum. The first chamber is called the rumen. The rumen is home to a complex ecosystem of microorganisms. These include bacteria, fungi, and protozoa. Some bacteria and protozoa break down the sugar and starch from plants. Others break down the cellulose that makes up plant cell walls. The second chamber is the reticulum. This is where tough-to-digest plants, like grass, are stored. The plants are regurgitated and chewed again and again. This repeated chewing helps physically break the food down. The third chamber is the omasum. It mechanically breaks the food down further. The fourth chamber is the abomasum, or true stomach. Here, nutrients are extracted from the food. The food then proceeds through the digestive process.
An important process called enteric fermentation takes place in the rumen. That’s when bacteria break down complex carbohydrates into simple sugars. The end products of enteric fermentation by bacteria include volatile fatty acids (VFAs) as well as gases, such as carbon dioxide and methane. VFAs are absorbed through the walls of the rumen and transported to the liver where the animals use them for energy.
Can we make cows produce less methane?What cows eat has a big effect on how much methane they produce. Digesting certain types of food produces more methane than digesting other foods. For example, digesting hay and grass produces more methane than corn. Scientists are studying alternatives to cow feed that may produce less methane. For example, scientists are trying adding seaweed to the cows’ food. They hope that seaweed can inhibit a specific enzyme. That enzyme is involved in the production of methane while the cow digests its food. A 2018 experiment showed that adding seaweed to a cow’s diet may reduce their methane production by as much as half! But researchers have found one problem with this solution: cows don’t seem to like the salty taste of seaweed very much! Other scientists are taking a genetic approach. A study published in 2019 found that the type and amount of methane-producing bacteria found in a cow’s stomach is related to its genetic makeup. Knowing this, scientists can breed cows that have less of these bacteria in their stomachs. This will eventually create a type of genetically-modified cow that produces less methane!
What can you do to help fight climate change?Many people like you and me are always looking for ways to keep greenhouse gas emissions down. For example, many of us choose to walk or bike instead of driving. But as you have just learned, methane gas emissions from livestock are a huge problem. So driving less may not be the most important thing we can do to help mitigate climate change. Many experts now believe that eating less meat would actually have a bigger impact.
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Learn moreGlobal Methane Budget (2012) CBC News article by Haydn Watters discussing research that is underway at the University of Guelph that is studying methane released in cow burps and how to breed cows to prevent methane release. The Global Methane Challenge The Global Methane Initiative: take part in a global challenge to reduce your overall methane footprint! ReferencesAgriculture and Agri-Food Canada. (2016, November 8). Greenhouse gases. Government of Canada. United States Environmental Protection Agency. (2019, April 11). Methane emissions. Does livestock contribute to global warming?Livestock is responsible for 14.5% of global greenhouse emissions, researchers estimate. The animals emit gases such as nitrous oxide, carbon dioxide (CO2), and methane in amounts that have significantly changed our atmosphere. And the impact is growing.
How does raising livestock affect the environment?Raising livestock for human consumption generates nearly 15% of total global greenhouse gas emissions, which is greater than all the transportation emissions combined. It also uses nearly 70% of agricultural land which leads to being the major contributor to deforestation, biodiversity loss, and water pollution.
How does increasing livestock farming affect climate change?Raising animals on farms for food production takes a tremendous toll on the health of the environment. Animal agriculture is a contributor to greenhouse gas emissions, including nitrous oxide and methane, water pollution and the destruction of forests and other wild areas that help to regulate the planet's atmosphere.
How does farming cause global warming?Farming in particular releases significant amounts of methane and nitrous oxide, two powerful greenhouse gases. Methane is produced by livestock during digestion due to enteric fermentation and is released via belches. It can also escape from stored manure and organic waste in landfills.
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How does raising livestock contribute to global warming
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