All greenhouse gas emissions are of significant concern if we are going to make substantial progress in limiting climate change. The livestock sector is no exception, but their rate of emissions is often exaggerated. In Canada, all of agriculture is responsible for just over 8 percent of greenhouse gas emissions, and that number includes both animal and crop production. The dairy sector emits approximately 2 percent of all Canadian greenhouse gases.
So where does the bulk of Canada’s greenhouse gas emissions come from?
Fossil fuel dependent sectors. Oil and gas production, along with transportation, are responsible for 52 percent of Canadian greenhouse gas emissions. It’s clear that fossil fuel dependent industries contribute significantly more to climate change than agriculture, and even more than livestock specifically.
Furthermore, animal agriculture has the opportunity to be part of the climate solution. Yes, methane is a strong pollutant. Compared to CO2 it is 28 times stronger. But it does not contribute 28 times more warming than CO2. That’s because it only stays in our atmosphere for 10 years, while CO2 stays in our atmosphere for one thousand years.
That’s not all we neglect to factor in. Methane from ruminants is cyclical. Think back to your grade school years when you learned about how plants grow. What do they need?
They need water, sunshine and CO2. That CO2 is converted into carbon in the plant in the form of carbohydrates, which are then consumed by cattle. Some of that carbon from the ingested feed is then digested and forms methane (CH4), which is then belched out into the atmosphere, where in 10 years an atmospheric radical comes along to steal a hydrogen atom away from the methane, turning the carbon from methane into CO2. It is the same carbon that was in the plant, which was captured from the atmosphere. It is recycled carbon. This is called the biogenic carbon cycle.
Let’s say we have a herd of 100 cows, and after 10 years it hasn’t grown, it’s not adding any additional methane to atmosphere, because for every pulse of methane released, one is being destroyed in the atmosphere by that radical I mentioned earlier. And if you are not adding additional methane to the atmosphere, you are not adding any additional warming, which is ultimately what we care about. On the other hand, CO2 from fossil fuels is not cyclical. It’s a one-way street that pulls carbon from the ground and juts it straight into the atmosphere where it stockpiles and builds up, continuously adding warming.
Make no mistake, we need to do all we can to reduce emissions where we can. If animal agriculture can manage to reduce methane, then it can help reduce warming, making it even more important that farmers, regulators and researchers work together to find ways to do so.
– Dr. Frank Mitloehner, University of California, Davis