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Lesson Plans for Teachers
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How Cheeseburgers Impact the Oceans

Duration: 1 class
Students will:
  • Examine the carbon emissions associated with cheeseburgers
  • Calculate the carbon footprint associated with cheeseburgers
  • Extrapolate how much carbon from cheeseburger production enters the ocean each year
  • Vocabulary:

    Carbon footprint - The carbon released into the atmosphere during the production of a product or during an activity, usually in the form of CO2 and methane

    British Columbia PLO's:

    • Science 6, 7, 8
    • Math 6, 7, 8

    Background:

    In this activity, students will examine the energy required to make a cheeseburger and calculate its associated carbon footprint (the numbers used are borrowed from a study that was done in Sweden in 2000, but apply to most industrialized countries). This is a good activity to use mid-way through a climate change unit when the students have a basic understanding of the impacts and causes of climate change.

    Reducing the amount of carbon that we put into the atmosphere is increasingly more important. The activities of humans since the industrial age have greatly increased the carbon dioxide (CO2 ) levels in the atmosphere, and the planet is heating up as a result.

    Everything we do – from turning on a computer to eating food – has an associated carbon footprint. A carbon footprint represents all the carbon, mostly in the form of CO2, but also in methane (CH4), that is being released as a result of our activities, and is usually represented in grams or kilograms of carbon.

    The average American consumes about 100 burgers a year. The Canadian average is likely similar to this value. In July 2007, Canada 's population was approximately 33 million people; using this and the carbon footprint of a burger, we can estimate how eating hamburgers in Canada is affecting climate change.

    Materials:

    Procedure:

    1. Read with the class the Ocean News article What the deep sea and cows have in common.
    2. Place a graph of methane emissions sources (see resource section).
    3. Have the students brainstorm how eating a cheeseburger can impact the environment and contribute to climate change. Some ideas they might come up with include: clearing land for farms; feeding cows (that expel methane); transportation of goods across the country; storage of goods (energy demands); package waste ending up in the landfill, etc.
    4. Introduce the activity of calculating the carbon footprint of a cheeseburger with the components that we will include in the estimates: bread, hamburger, lettuce, freeze dried onions, pickles, and cheese.
    5. Put the values for energy required for burger processing up on the overhead or print out the values on a handout.
    6. Using the high and low estimate values for processing, get half the class to calculate the high estimation of total energy use for each part of the cheeseburger, and the whole cheeseburger. Ask the other half of the class to calculate the low estimates. Everyone should end up with values in megajoules per burger.
    7. Once the students have their estimates for the total amount of energy in megajoules, get them to convert their value to grams of carbon. To do this they will need to determine what processes require gas/diesel (milling, crops etc.) and what processes require electricity (storing, cooking, etc.)
    8. Once the processes that require gas or diesel are determined, get the students to sum them and convert the values to grams of CO2 using similar conversions given in the example sheet. Depending on the comfort level of the students, you can lead them through the calculations or give them the numbers and have them problem solve.
    9. The electrical component can then be split into whatever your local electricity is powered by. You can usually find this out from your local power company (coal, natural gas, hydro-electric dams etc.). Once you know how your area is powered you can convert from megajoules to grams of CO2.
    10. Now have the students calculate the methane output of a cow per year and convert it to a per burger amount. Give them the values of cow mass, methane output, lifespan, and methane-CO2 equivalent and have them problem solve the answer.
    11. For both the high and the low estimates, have the class add the methane output for a burger to their values.
    12. On a piece of graph paper, ask the students to graph the high and low estimates side by side for comparison. The different components of the hamburger can be shaded in a bar graph to show the energy requirements for the different parts of the burger (ask them to use different colours for each component). Discuss why there is a high and a low number and what the difference tells us about how to reduce carbon emissions.
    13. Ask the students to numerically and pictorially represent on their graphs the amount of carbon that enters the oceans due to the production of one cheeseburger. (Since the oceans are absorbing roughly a third of the CO2 currently released into the atmosphere, it will be a third of their values).
    14. By a show of hands, estimate how many burgers the students in the class eat, and what the carbon footprint entering the oceans is. How are Canadian burgers impacting the oceans? (Remember there are 33 million people in Canada ).
    15. Discuss what the affects increased levels of CO2 are having on the oceans. Brainstorm what organisms the elevated levels of CO2 will affect.
    16. Remember to discuss with students that this activity is not meant to make them stop eating hamburgers. Instead, it's meant to draw attention to how choices we make everyday impact the environment around us.
    17. If time permits watch the 7 minute video from the Science and Technology for Canadians archive with the students that discusses methane as a greenhouse gas and the contribution from livestock.

    Discussion:

    • What inputs need to be considered when calculating the carbon footprint of food items?
    • How could you reduce the carbon footprint of a cheeseburger?
    • How does eating locally grown food reduce the carbon footprint of the food item?
    • How does eating fresh food rather than frozen items reduce the carbon footprint of a food item?
    • What does the low estimate represent when compared with the high estimate?
    • What are the sources of error in our calculations?
    • How does examining the carbon footprint of a cheeseburger draw attention to our everyday choices?
    • What other sources of greenhouse gases involved in fast food have we missed in our calculations? (Garbage removal?)

    Extension and Resources:

    • The article that inspired this activity is The Cheeseburger Footprint. Students can read this article to see how their values compare.
    • Values are taken from the Swedish report Energy Use in the Food Sector.
    • One methane emission graph showing specific anthropogenic sources is from the Environmental Protection Agency.
    • The Science and Technology website has a report from the archive that can be shown students to illustrate the science around livestock diet. You can also find an associated teacher's guide with the video. This episode was aired in November 1998 so the information is slightly out of date but the methane studies are still relevant. It talks about how the US signed Kyoto, which they did but as of december 2007 they have not ratified into law.
    • Sample calculations and conversions can be found along with this lesson plan and used in the classroom with students as overheads or handouts.
    • Conversions can be made several different ways, this website shows many different units that can be added to this exercise to gain a better understanding of the processes involved
    • The Environmental Protection Agency in the US also has a good website that can be used for converting units.
    • This document reviews usage of electricity and carbon output (although it is American data, comparisons can be made to Canadian provinces of similar size).
    • A good site for looking at other forms of energy and how to convert the units
    • A great visual aid that illustrates ecological footprints for different countries.
    • Have the students keep a food journal for a week. At the end of the week, get them to do a qualitative analysis on what their carbon footprint is. Where does the largest part of their carbon footprint come from?
    • Conduct a school-wide survey on burger consumption and have the class do a carbon footprint for the school. Get the class to do a report on the schools carbon emissions due to burger consumption and ask the students to display their results where school community members can see them.

    Risk management:

    Thankfully, calculating the carbon footprint of a cheeseburger does not have high levels of fat, cholesterol, or carbon output associated with it, so calculate away!

    Downloadable PDF of this lesson plan.

    For more information please contact the Public Education Department at the Bamfield Marine Sciences Centre or OceanLink

    Author: Jennifer Provencher, 2007. All content has been created by the Bamfield Marine Sciences Centre, or used with permission of the owner where indicated. Material may be used for education and teaching purposes, but not for resale or paper distribution without permission from BMSC or the owner of the image.