The Impact of Cattle Methane Production on Climate Change

The image shows a cow chewing cud. Cud is the portion of food that cows and other ruminant mammals regurgitate from their specialized section of their stomach called a rumen. Within this section of their stomach, microbes help digest the fibrous food that cows eat. This helps with the cattles’ digestion, but the microbes also produce an unwanted byproduct: methane. Cattle release methane gas from both ends of their digestive tracts, as burps and flatulence. 

Methane is a gas that is very good at trapping heat in the atmosphere, making it a greenhouse gas, and cattle produce a lot of it. Each cow can produce around 100 kg of methane per year. With around 1.5 billion cattle on Earth, these animals contribute around a third of all methane emissions that result from human activity.  This methane that is released into the atmosphere traps heat from the sun and is a major contributor to human-induced climate change and global warming.
 

Driving Question

• In what ways do human activities impact climate and long-term weather patterns on Earth?

Probing Questions

• What might be reasons that cattle in particular are such a substantial contributor to greenhouse gasses?
• How could our scientific knowledge of cattle production of greenhouse gasses help us move towards reducing these emissions?
• How should humans weigh the benefit of producing food to the cost of emitting greenhouse gasses?

Classroom Suggestions

Students could:

• Construct a driving question board at the beginning of a unit or lesson on climate change. They should be familiar with the ideas of climate and weather, but may also have questions about why and how scientists think humans are affecting the Earth’s climate. Students share what they have heard or wondered about in regards to climate. The ideas that students come up with should drive conversations in subsequent classes.
• Greenhouse gasses essentially act as an insulator in Earth’s atmosphere, trapping in solar radiation and heating up the planet. The teacher could relate greenhouse gasses to wearing a thicker coat or blanket to trappin in body heat (i.e. the coat is not generating heat, it is trapping heat in, much like a greenhouse gas). With this metaphor in mind, the teacher could have students draw models of greenhouse gas molecules (e.g. methane) increasing in concentration in an atmosphere, trapping in more heat.  A similar model could be drawn for the blanket/coat.

Relevant Related Resources

• Cow Emissions | PBS.org: Video: PBS video with transcript of a video addressing the problem and potential solution to methane emissions from cattle.
• Greenhouse Effect | PhET Simulation: Simulation: in this simulation, students can model how an increase in the concentration of greenhouse gas molecules in the atmosphere increases the amount of solar radiation that is trapped, thus increasing the temperature of the Earth.