Written by Sara Place, Ph.D. Animal Scientist and Sustainability Expert
First, the facts. Cattle do produce green house gas (GHG) emissions, specifically they emit methane, a GHG that is about 28 times more potent at trapping heat than carbon dioxide over a 100-year time period. Nearly all this methane comes from the animals' mouths. Cattle manure can also emit methane and nitrous oxide, another potent GHG (265 times more heat-trapping than carbon dioxide). Methane emitted by cattle and GHG emissions from managed beef cattle manure are 2% of US GHG emissions according to the EPA. The production of feed for cattle and any fossil fuel derived inputs (fertilizer, electricity) from cattle production can also contribute to GHG emissions, but it's the methane that cattle belch out that makes up the bulk of beef's emissions.
However, methane is a short-lived GHG. Once emitted, the methane will be converted to carbon dioxide in the atmosphere in 10-12 years. Cattle are a part of the carbon cycle, temporarily transforming a portion of the carbon in feed they consume to methane, which will be converted to carbon dioxide that can be taken up by plants. The plants can be eaten by cattle and the cycle repeats. This is important when relating how methane emissions affect temperature change.
If methane emissions are steady or slightly declining, methane concentrations in the atmosphere will not increase. Think of it like a bathtub. If the water is entering the tub at the same rate it is draining, the water level will remain constant. The concern with climate change is the water level, or the concentrations of GHG in the atmosphere. In the USA, cattle populations have declined since the mid-1970s. According to the EPA GHG inventory, methane emissions from beef cattle declined linearly by 5.6% from 1990 to 2017. Have US beef cattle been adding to the methane concentration globally (our water level)? Seems unlikely, but this doesn't mean that we shouldn't pay attention to beef's GHG emissions. Further reductions in methane could lead to a cooling effect and maintaining and preserving grasslands can store carbon in the soil. What's clear is that cattle production can be a part of the climate change solution.