Friday, October 03, 2008

Calculate your own carbon footprint - then send this to a teacher you know

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Are you curious about how much CO2 you’re responsible for? Here’s a simple questionnaire that will help you get a handle on how much carbon you generate with your current lifestyle. All you need is some information about your your cars, an electric bill, and a gas bill.

My husband Ken, a high-school biology teacher, adapted this questionnaire from one on the Population Connection website. Ken uses it in his AP and Honors biology classes. But it could be used for any course -
health, social responsibility, economics, etc. Within a couple of decades, global climate change will affect every aspect of life on planet earth, so it's relevant to everything! As of right now, residents of the United States are the primary drivers of global climate change (per capita). Although China, with 4 times as many people, has recently passed us in terms of their total carbon output.

Here's a short and sweet intro to the questionnaire:


The burning of fossil fuels produces CO2, the greenhouse gas that is the major cause of global climate change. As our atmosphere continues to warm, we'll see oceans rising, coasts flooding, glaciers melting, wildlife extinctions, etc. While climate change is a global issue, many of the causes and solutions lie in individual decisions. The purpose of this activity is for you to calculate the amount of CO2 you produce annually through direct and indirect sources: your “carbon footprint”. Just follow the steps. All you need is some information about the cars in your family, an electric bill, and a natural gas bill.


1. How many cars does hour family have? _____

2. How many miles per gallon does each car average? ________________________

3. How many miles is each car driven per year? _______________________________

4. Divide the number of miles driven for each car by the miles per gallon each car uses to get the total number of gallons of gasoline you use for each car in one year. __________________________

5. Add to get the total number of gallons of gasoline you use in all of your cars. _______________

6. Each gallon of gas releases approximately 20 lbs. of CO2 into the atmosphere. Multiply the number of gallons calculated in step 5 by 20 to get the total lbs. of CO2 released by the cars you drive. ___________________

7. Take a look at a recent electricity bill and use it to estimate the total number of kilowatt-hours (KWH) you use in one year. _________

8. Roughly 75% of the electricity generated in the U.S. comes from burning fossil fuels. Most comes from coal, so we’ll use it as a means for calculating CO2 production. First, multiply the KWH you use by 0.75 to get the total being produced by fossil fuels. ___________

9. One pound of coal is burned to produce one KWH, so if we use “pounds of coal” as a representative fossil fuel unit, all you have to do is take the KWH you calculated in step 8 and use this as the “pounds of coal” required to supply the electricity used in your home. _____________________

10. Two pounds of CO2 are produced for every pound of coal burned to produce electricity, so multiply your answer in step 9 by 2 to give the total pounds of carbon dioxide your family adds to the atmosphere through electricity usage. _____________________

11. If you use natural gas in your home, look at a bill and estimate the total number of “therms” you use in one year. One therm is a measure of the amount of heat, or energy content, in the gas you used. One therm produces 11.7 pounds of CO2. Multiply your number of therms by 11.7 to give the lbs. of CO2 you produced by burning natural gas. ______________

12. Add the total amounts from 6, 10, and 11 to give the total lbs. of CO2 you produced directly through use of gasoline, electricity, and natural gas. _______________

13. Now double that figure to take into account other sources of CO2 you are responsible for, like that produced from the manufacture of the consumer goods you used during the year, like clothes, food, paper, etc., the heating and cooling you took advantage of in public buildings, your use of public transportation, and the industry required to support your lifestyle. The total will give a more accurate estimate of all of the CO2 you’re responsible for.

Now, let’s use this number to estimate the CO2 production for the entire country.

14. Divide the number you got for your family in step 13 by 2000 lbs./ton to convert your answer from lbs. of CO2 to tons of CO2. ___________________

15. Divide that answer by the number of people in your family to get the usage per person. _____________

16. Now multiply that by the number of people in the U.S. (305 million). How many tons of CO2 does this suggest that the country is producing in one year?


According to estimates taken from an on-line carbon footprint calculator (, the per person production of CO2 in the U.S. is about 22.4 tons. How did your estimate compare?

Here some other interesting numbers from that website:

· The average for people in all industrial nations is about 12.1 tons. (We tend to use more).

· The average for people across the world is about 4.4 tons. (Most people live much simpler lives).

We have a big challenge facing us. According to some experts, to combat climate change, the worldwide average needs to be cut by 50-80%, to 2.2-0.9 tons per person.

Through this activity you’ve gotten a handle on how much CO2 is being released into the atmosphere by your personal activities and by the country. It’s a lot! The worldwide release of CO2 from fossil fuel combustion is currently 27 billion tons per year.

Unfortunately, the solving this problem will be even more difficult than these calculations suggest. The world’s population is expected to grow from the current 6.7 billion to 9.2 billion by 2050. With so many more people on the planet, the challenge of lowering our carbon footprint to roughly 2 tons per person will be even greater.

Feel free to use this questionnaire for courses and share it with teachers you know. Please cite Population Connection as well as this blog. Population Connection has a great website, with useful and factual articles about human impact on diminishing natural resources, etc.

Post by Sally Kneidel; questionnaire from Ken Kneidel.


Part of this questionnaire is from "Global warming begins at home" in Population Connection's ( magazine, "The Reporter" (Fall 2007, pg. 22). The questionnaire was modified and expanded by Ken Kneidel, PhD (ecology).

The population statistics in this post were updated by Ken Kneidel using data from the U.S. Census Bureau at (August 1, 2008)

Keywords: Ken Kneidel climate change lesson carbon footprint questionnaire global warming lesson teaching global warming teaching climate change teaching carbon footprint your carbon footprint

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