National Agricultural Literacy Curriculum Matrix
Carbon Hoofprints: Cows and Climate Change
9 - 12
Students will explore the carbon cycle and evaluate the carbon footprint of beef cattle. Using critical thinking skills, students will use the Claim, Evidence, and Reasoning model to determine the effect of cows’ methane production on the environment and investigate the extent cattle contribute to climate change.
- Carbon Hoofprint Matching Cards
- Carbon Cycle Photos and Captions, 1 copy per class
- Carbon Cycle 3D Video
- A Cow’s Digestive System video
- Ruminant Digestive Model, 1 copy per student
- Interactive science notebooks or 1 sheet of blank paper per student
- Markers, pens, or colored pencils for labeling
- Carbon Hoofprints: Claim, Evidence, and Reasoning handout, 1 per student
- The Conversation article, digital access or a hard copy for each student
Essential Files (maps, charts, pictures, or documents)
- Carbon Hoofprints: Claim, Evidence, and Reasoning
- Carbon Cycle Photos and Captions
- Carbon Cycle Photo Example
- Carbon Hoofprint Matching Cards
- Ruminant Digestive Model
carbon: the chemical element of atomic number 6, a nonmetal which has two main forms—diamond and graphite
carbon compound: a substance formed from two or more elements chemically united in fixed proportions
carbon cycle: the series of processes by which carbon compounds are interconverted in the environment, involving the incorporation of carbon dioxide into the living tissue by photosynthesis and its return to the atmosphere through respiration, decay of dead organisms, and the burning of fossil fuels
carbon dioxide: a colorless, odorless gas produced by respiration and burning carbon and organic compounds
carbon footprint: the amount of carbon dioxide and other carbon compounds emitted due to the consumption of fossil fuels by a particular person or group
chemical element: a substance that cannot be broken down into any simpler chemical substances and is made of atoms all of the same type
climate: the weather of a particular region over a series of years
climate change: a change in global or regional climate patterns attributed largely to the increased levels of atmospheric carbon dioxide produced by the use of fossil fuels
enteric fermentation: a digestive process by which carbohydrates are broken down by microorganisms into simple molecules for absorption into the bloodstream of an animal
global warming: a gradual increase in the overall temperature of the Earth's atmosphere generally attributed to the greenhouse effect caused by increased levels of carbon dioxide and other pollutants
greenhouse effect: the trapping of the sun’s warmth in a planet’s lower atmosphere
greenhouse gas: a gas that contributes to the greenhouse effect by absorbing infrared radiation
methane: a colorless, odorless flammable gas which is the main constituent of natural gas
ruminant: an even-toed ungulate mammal that chews the cud regurgitated from its rumen; ruminants include cattle, sheep, goats, deer, and bison
upcycle: reuse discarded material in such a way as to create a product of higher quality or value than the original
weather: the state of the atmosphere in regard to heat or cold, wetness or dryness, calm or storm, clearness or cloudiness
Did you know? (Ag Facts)
- Beef production is responsible for about 2% of U.S. greenhouse gas emissions.1
- Almost 90% of what grain-finished beef cattle eat is not in competition with the human food supply. 82% consists of human inedible forages growing on rangeland and grassland, and 7% is human inedible byproducts.2
- If Americans eliminated all animal protein from their diets, they would reduce U.S. greenhouse gas emissions by 2.6%.3
- Grain-finished beef has a lower carbon footprint than grass-finished beef. Cattle that are fed grain produce less methane and reach market weight more quickly, thus using fewer natural resources.4
Background Agricultural Connections
Interest Approach – Engagement
- Pass out each of the six Carbon Hoofprint Matching Cards to students in the class, or hang the photos on the board in no particular order.
- Ask students to study the pictures. Explain that each picture has a match. Using the photos as clues, have students use their background knowledge to pair each of the cards and explain their reasoning for why the images match.
- Allow students time to brainstorm thoughts and ideas as they match each of the cards.
- Once students have correctly matched each of the photos, discuss key concepts of each photo and its corresponding card. Use the following questions to guide your discussion:
- "Why does the diamond belong with the Periodic Table of Elements?" (Diamonds are the solid form of the element carbon. Carbon is a chemical element that naturally cycles through the earth and atmosphere.)
- "What kind of digestive system do cows, sheep, and goats have?" (Ruminant digestive systems. The stomach of a ruminant has four compartments. Animals with ruminant digestive systems produce methane as they eat and digest forages.)
- "What is the common name for CH4?" (Methane) "What is depicted in the photo with the earth and sun?" (The carbon cycle. Methane, a chemical compound of carbon, is a greenhouse gas that traps heat in the Earth's atmosphere.)
- Explain to students that they will be exploring the relationship between carbon, methane, and ruminants.
Activity 1: What is the Carbon Cycle?
- Divide students into pairs.
- Prior to class, print one copy of the Carbon Cycle Photos and Captions and cut the images and word strips into separate pieces. Pass out one hexagonal photo or caption to each pair of students. There are 14 photos and eight captions (22 total), so some pairs might get more than one photo or caption depending on the class size.
- Instruct students to create a carbon cycle diagram as a class by placing the photos and captions on the board and drawing arrows between photos and captions. The class may work together to assemble the cycle. Students may also use markers to draw more illustrations or add more captions.
- Engage all students by asking questions about the carbon cycle.
- Why did your group place this photo here?
- How does this photo relate to carbon?
- Show the video clip Carbon Cycle 3D Video to students. If necessary, occasionally pause the video clip and allow students to make changes to their original cycle on the board. They may need to rearrange photos or add more captions.
- Explain to students that the amount of carbon on Earth is constant and is like any other chemical element—it is neither created nor destroyed. Carbon is continuously cycled throughout carbon reservoirs such as the earth, atmosphere, ocean, and living organisms. Carbon atoms then combine with other atoms to create greenhouse gases like carbon dioxide and methane. Greenhouse gases trap the sun’s heat in the Earth’s atmosphere which contributes to climate change.
- Bring students’ attention to the cows on the carbon cycle.
- Ask students how cows contribute to the carbon cycle.
- Allow students to brainstorm thoughts and ideas.
Activity 2: The Carbon Hoofprint
- Remind students that cows are ruminant animals, and ruminant animals—including bison, elk, sheep, and goats—all produce methane. Ruminants are able to eat forages that humans and monogastric (single stomach) animals can’t digest.
- Pass out a Ruminant Digestive Model to each student and ask students to insert the models in their interactive science notebooks so the Ruminant Digestive Model can flip up.
- Tip: If you don't use interactive notebooks, give each student a blank sheet of paper to complete the same activity as an interactive activity sheet rather than in a notebook.
- Show the video clip A Cow’s Digestive System, and have students follow along on their ruminant digestive models.
- Ask students to color each of the labeled compartments, fill in information on feed digestion, and draw arrows depicting how feed travels through a ruminant system. Supplement information from the video clip with the information below and from the Background Agricultural Connection paragraph.
- Rumen: The “fermentation chamber." Food can’t be digested when it first gets to the rumen, so cows regurgitate boluses of food and chew cud. Once the cud has been swallowed, the microbes can now penetrate the cell wall and begin microbial fermentation.
- Reticulum: The “honeycomb stomach.” Catches dense feed or heavy objects (nails, wire, rocks) that the cow may accidentally swallow.
- Omasum: This compartment contains many folds like pages in a book which increases surface area and helps absorb all of the water.
- Abomasum: The “true stomach.” This compartment digests the feed like a monogastric system. Hydrochloric acid and digestive enzymes are released.
- Ask students to brainstorm how this ruminant system produces methane. What compartment produces the methane?
- Using the Background Agricultural Connection paragraph, explain to students how the microbes in a ruminant digestive system produce CH4 (methane) as a byproduct when forages and feeds are digested. Explain to students that it is a common misconception to believe that cow flatulence causes the release of methane into the atmosphere; however, the majority of methane is actually found in a cow’s mouth. Ask students to brainstorm cow burps and the environment. Ask, "How could cow burps be the "culprits" of climate change? If we eliminated all beef cattle, would that slow climate change?"
- Ask students to add the following key terms to the rumen section on their digestive models: microbial fermentation, enteric fermentation, CH4, and methane production.
Activity 3: Claim, Evidence, and Reasoning
- Ask students what other questions come to mind after discussing the carbon cycle, methane, and cows. Allow students to brainstorm thoughts and ideas with each other. Examples include:
- If humans stop eating beef, will this slow climate change?
- Are cows the biggest contributors to climate change?
- What other factors contribute to climate change?
- How can humans help lower carbon emissions?
- Give each student one copy of the Carbon Hoofprints: Claim, Evidence, and Reasoning handout.
- Introduce the Claim, Evidence, and Reasoning Model. Explain that after a question is asked, this model can be used to find a credible answer to a question by using the following steps:
- Claim: State a direct response to the question.
- Evidence: Find reliable information that supports the claim.
- Reasoning: Link the claim to evidence by explaining how the evidence supports the claim.
- Instruct students to complete two of the four steps. They should choose one question they would like to answer about the carbon cycle, cows, or methane production. Next, they will formulate a claim by answering their question. Let students know we will come back to the evidence and reasoning portions momentarily.
- Have students turn to the backside of their handout. Let students know that they will be gathering evidence by reading a study published by Professor Frank M. Mitloehner at the University of California, Davis.
- Instruct students to individually read the article from The Conversation and fill out the graphic organizer as they read. Students should answer each of the questions on the back page of their handout. These questions each address common misconceptions about cows and climate change.
- Ask students to write down or highlight words they might not understand. Take time to explain unfamiliar words in the article such as "panacea".
- Discuss science-based responses to each of the statements found on the graphic organizer.
- "Cattle produce more greenhouse gases than the transportation sector."
- False. In 2016, transportation accounted for 28 percent of greenhouse gas emissions. All of animal agriculture contributes about 3.9 percent of GHG emissions in the United States. Some misconceptions stemmed from a 2009 analysis that measured food and animal emissions differently than the transportation sector creating a skewed result.
- "Cattle have negative impacts on the environment."
- Cattle do contribute to greenhouse gas emissions, creating a negative impact on the environment. However, in context, their impact is less than many other contributing factors such as transportation, industry, etc.
- "Participating in 'Meatless Mondays' will make a big impact to help save our planet."
- If all Americans adopted the practice of 'Meatless Monday', we'd see a reduction of 0.5 percent in greenhouse gas emissions, a small amount when considering the full picture.
- "Feeding cattle to produce meat is a waste of resources. We should be growing food for humans instead."
- As ruminants, cattle can receive nutrition from plants that humans and other monogastric animals cannot. Cattle convert plants with no nutritional value (to humans) to food of high nutritional value (meat and milk).
- "It's easy to eliminate meat from our diet and still receive adequate nutrition from other foods."
- Meat provides many essential micro- and macronutrients for good health. While it could be possible to receive these from other foods in developed nations, it is much more difficult in developing nations.
- "Cattle produce more greenhouse gases than the transportation sector."
- Once students have completed the graphic organizer on page 2 of the handout, instruct them to return to the first page of the handout and fill out the "Evidence" and "Reasoning" sections to complete the handout.
- After completing the activity, students should recognize that beef production and eating meat both affect the environment; however, these sectors are not the leading contributors to climate change as some might believe.
Concept Elaboration and Evaluation
After conducting these activities, review and summarize the following key concepts:
- Carbon is a chemical element found in the atmosphere that is neither created nor destroyed.
- Changes in global or regional climate patterns is known as climate change. It is attributed largely to the increased levels of atmospheric carbon dioxide produced by the use of fossil fuels.
- Some perceive cattle to be a major contributor to climate change due to the methane produced in ruminant digestion. However, beef production is estimated to contribute to about 2% of total greenhouse gas emissions in the United States.
We welcome your feedback! Please take a minute to tell us how to make this lesson better or to give us a few gold stars!
Discuss the dietary trend to choose beef labeled as "grass-fed" in context of the environment. Introduce the concept to students that different agricultural practices (i.e. how cattle are fed) have varying impacts on the environment. To learn more about "grass-fed" vs. "grain-finished" beef, see Activity 2 of the lesson Beef: Making the Grade.
- Note: Listen to the podcast (#099: Frank Mitloehner: Cattle, Climate Change and the Methane Myth) for an explanation of why grass-finished beef has a larger carbon footprint than grain-finished beef. The concept is addressed at 6:07.
To dig deeper into the science and chemistry concepts of climate change and cattle production, listen to the AgFuture podcast, #099: Frank Mitloehner: Cattle, Climate Change and the Methane Myth. In this podcast Dr. Mitloehner explains in greater depth the difference between carbon and methane output in cattle and how the overall efficiency of agricultural systems can reduce greenhouse gas emissions.
Suggested Companion Resources
- How Reducing Food Waste Could Ease Climate Change (Multimedia)
- How to Feed the World in 2050: Actions in a Changing Climate video (Multimedia)
- Some Like it Hot: Climate Change and Agricultural Pests (Multimedia)
- TedTalk- How to Fight Desertification and Reverse Climate Change (Multimedia)
- The Price of Climate Audio Series (Multimedia)
Agricultural Literacy Outcomes
Agriculture and the Environment
- Evaluate the potential impacts of climate change on agriculture (T1.9-12.e)
- Evaluate the various definitions of “sustainable agriculture,” considering population growth, carbon footprint, environmental systems, land and water resources, and economics (T1.9-12.f)
- Understand the natural cycles that govern the flow of nutrients as well as the way various nutrients (organic and inorganic) move through and affect farming and natural systems (T1.9-12.h)
Plants and Animals for Food, Fiber & Energy
- Evaluate evidence for differing points of view on topics related to agricultural production, processing, and marketing (e.g., over-grazing and loss of plant species diversity; monocultures contributing to genetic vulnerability; use of fertilizers and pesticides increase crop production but may contaminate water sources; creating open space; farmland preservation; animal welfare practices; immigration issues; world hunger) (T2.9-12.d)
Education Content Standards
HS-LS2 Ecosystems: Interactions, Energy, and Dynamics
HS-LS2-5Develop a model to illustrate the role of photosynthesis and cellular respiration in the cycling of carbon among the biosphere, atmosphere, hydrosphere, and geosphere.
HS-LS2-7Design, evaluate, and refine a solution for reducing the impacts of human activities on the environment and biodiversity.
Common Core Connections
Reading: Anchor Standards
CCSS.ELA-LITERACY.CCRA.R.1Read closely to determine what the text says explicitly and to make logical inferences from it; cite specific textual evidence when writing or speaking to support conclusions drawn from the text.
Speaking and Listening: Anchor Standards
CCSS.ELA-LITERACY.CCRA.SL.2Integrate and evaluate information presented in diverse media and formats, including visually, quantitatively, and orally.
Writing: Anchor Standards
CCSS.ELA-LITERACY.CCRA.W.1Write arguments to support claims in an analysis of substantive topics or texts using valid reasoning and relevant and sufficient evidence.
CCSS.ELA-LITERACY.CCRA.W.2Write informative/explanatory texts to examine and convey complex ideas and information clearly and accurately through the effective selection, organization, and analysis of content.