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Exercise #4: Carbon Footprint

Learning Objectives


In this exercise, you will learn about how individuals create GHG emissions. You will use a carbon footprint calculator to learn about your own contributions to GHG emissions and you will analyze how your personal GHG emissions compare with those from average US households and average world households. Lastly, you will learn about what actions you can take to reduce your individual GHG emissions. You will choose which actions fit your lifestyle in order to reduce your emissions by 50%.




Background: What is a carbon footprint?

At this point of the class, you have learned that human activities are contributing to a changing climate. You have probably asked yourself “what can I do about that?” The first step toward reducing your personal greenhouse gas emissions is to evaluate how much you are responsible for, and what activities you do that create GHG emissions. You need to know your carbon footprint.

A carbon footprint is the total amount of greenhouse gases produced to directly and indirectly support human activities, usually expressed in equivalent tons of carbon dioxide (CO2). Your carbon footprint is the sum of all emissions of greenhouse gases, which were induced by your activities in a given time frame. Usually a carbon footprint is calculated for the time period of a year.

The pie chart above shows the main elements which make up the total of a typical person’s carbon footprint in the developed world.

A carbon footprint is made up of the sum of two parts, the primary footprint (shown by the green slices of the pie chart) and the secondary footprint (shown as the yellow slices).
1. The primary footprint is a measure of our direct emissions of CO2 from the burning of fossil fuels including domestic energy consumption and transportation (e.g., car and plane). We have direct control of these.
2. The secondary footprint is a measure of the indirect CO2 emissions from the whole lifecycle of products we use — those associated with their manufacture and eventual breakdown. When we buy a new product, that product has substantial embodied energy in it from its manufacture, packaging and delivery. Also, when we visit an air-conditioned store or eat an orange in California that was grown in Florida, we produce indirect carbon dioxide emissions. To put it very simply: the more we buy, the more emissions will be caused on our behalf.

Why carbon? What about the other greenhouse gases?

Many activities cause emissions of greenhouse gases other than carbon dioxide (such as methane and nitrous oxide). In calculating your contribution of greenhouse gases, GHGs other than carbon dioxide are converted into carbon equivalents. A carbon equivalent is the amount of CO2 that would have the same global warming potential (GWP) as the other GHG (like methane and nitrous oxide), when measured over a specified timescale (generally, 100 years). For example the global warming potential for methane over 100 years is 21. This means that the emission of one million metric tons of methane is equivalent to the emission of 21 million metric tons of carbon dioxide. Converting all GHGs into carbon equivalents makes it easier to compare the impacts of activities that produce many kinds of greenhouse gases.

Calculate your carbon footprint

Go to http://www.coolcalifornia.org/calculator to begin calculating your carbon footprint. Fill in the information online. A few tips are given below for some of the entries:

How many people live in your household:  1  (do not include your housemates for this otherwise you will be asked to enter detailed information about them, which you don’t want to have to do).

Electricity ($ or kWh per year):         (You’ll need your gas and electric bill for this part. Use a bill from an average month and just multiply that by 12. If you live in the dorms you can just enter 3500 kWh/year).

Square feet of your living space:         (divide your total living space by the number of housemates you have).

Goods: Click on View individual goods and enter $/month. Also click on View individual other goods and enter $/month.

Services: Click on View individual services and enter $/month.

Answer the following questions:

  • How does your total carbon footprint compare to similar US households?
  • How does your total carbon footprint compare to average US households?
  • Why do you think your total is higher/lower/the same as average US households?
  • How does your total carbon footprint compare to world average households?
  • Why is the world average household number lower than the average US household number?
  • How do your transportation, housing and shopping footprints compare to average US households and world average households?
  • Were you surprised by how many factors went into the calculation?
  • Were there any factors you did not expect to have contributed to your calculation? Which ones?
  • Are there any factors whose contributions to GHG emissions are unclear?
  • Do you think you could reduce your emissions by half?
  • How close would you be to the world average if you did this?
  • What can you do to reduce your carbon footprint?

    After looking at your summary on the website, click the button to “take action.” On this page you can pledge to take actions that will reduce your carbon emissions (and usually save you money). Come up with a plan to reduce your emissions by half using the pledge buttons (as you make pledges your new footprint is reduced). This plan should be realistic, as you will be asked to carry out the plan for one day for your essay assignment.

  • What pledges did you make to reduce your emissions by 50%?
  • Briefly describe how each of your pledges reduces emissions. For example, if you pledged to “Go Organic,” how does what kind of food you buy impact GHG emissions? (Hint: if you click on the pledge you get a summary of how that action impacts GHG emissions).