Farmer's Take

Greenhouse gas emissions and agriculture

Posted 12/14/21

With agriculture and greenhouse gas, just like with so many other topics of conversation that are happening right now, it’s become too easy for us to take a meme or quick word as cold, hard …

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Farmer's Take

Greenhouse gas emissions and agriculture


With agriculture and greenhouse gas, just like with so many other topics of conversation that are happening right now, it’s become too easy for us to take a meme or quick word as cold, hard fact. It’s something that makes my blood boil a bit, because most of the information being given to the public is either partial information or nonfactual and doesn’t give the entire story.

I’m not saying we in the ag industry don’t contribute to the problem, but the way we do and by how much is vastly different than most understand it to be.

For example, according to the EPA’s latest study from 2019, the agriculture sector is responsible for emitting 10 percent of our country’s greenhouse gases, with livestock only contributing four percent of that 10 percent. Of that four percent, roughly two-thirds is due to enteric fermentation, which, in a very simplified manner, is when the animal burps methane gas (not when they fart, as is commonly misunderstood). The last third is from manure management, which is mainly the methane released from the manure of livestock as it breaks down.

The main greenhouse gas (GHG) that livestock are responsible for adding to the environment is methane. This is important to note because methane reacts very differently in the environment than does carbon dioxide, which is the most abundant GHG. Methane is referred to as a flow gas, meaning that once it’s released into the environment it doesn’t stay in the environment forever; in fact, it breaks down back into carbon dioxide in approximately 10 years as part of a biogenic carbon cycle.

Why is this important? Carbon dioxide that is released into the environment from fossil fuels takes approximately 1,000 years to degrade and will continue to build up in the meantime. Methane, as part of this biogenic carbon cycle, doesn’t continue to build in the environment but will stay at a constant level when inputs (number of cattle and production of methane) stay the same.

Let’s review this cycle for further understanding. Plants such as the grass and forage that livestock consume convert carbon dioxide to carbohydrates and release oxygen through photosynthesis. The livestock then consume the forage and through enteric fermentation, carbs are broken down and converted into methane gas which is released from the animal by burping. The methane is released into the environment and will then degrade (in about a decade) back into carbon dioxide and starts the cycle all over again.

Now because the ag industry, especially in the United States, has focused on reducing its environmental impact and focused on good husbandry practices for healthier, more efficient livestock, our total number of animals over the past 50 years has decreased each decade. That means that each time methane is broken down, it’s at a lower level than the previous decade.

Also important to note on the manure-breakdown side of things: the industry has focused on harvesting the methane produced in waste breakdown to convert into a useable fuel source and reduce methane in the environment. By reducing the overall methane production in this cycle, farmers can actually create a negative warming or cooling effect in regard to GHGs, because the biological carbon cycle will still require carbon dioxide to complete the cycle.

In effect, if we in the ag Industry continue to work on reducing our methane emissions, we can assist in fixing the high levels of GHGs rather than adding to them. I think that makes our industry quite impressive, but that’s just this Farmer’s Take.

For a more in-depth and visual explanation, I recommend you watch the video “Rethinking Methane,” created by Dr. Frank Mitloehner from the University of Davis/Clear Center. Find it here:

¹Reports do vary. Project Drawdown argues the ag sector contributes 24 percent of total greenhouse gases; that includes deforestation and biomass burning. The EPA separates out “agriculture-related land-use and land-use conversion activities, such as cultivation of cropland, grassland fires, aquaculture, and conversion of forest land to cropland.”   

methane, ag industry, greenhouse gas, global warming


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