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The Carbon Dioxide Game

by Sashi Kaufman

Climate is one of the most influential abiotic factors on our planet. But studying climate and climate change presents unique challenges to educators: How to bring the concept of climate change, which is a vast and multifaceted topic, down to a level where students can explore it in a hands-on interactive way? How to address in a positive way the role that humans play in climate change? By the time they reach middle school, most students have heard of global warming and the greenhouse effect. They have some idea that rising global temperatures are attributed to human activities that have dramatically increased the levels of heat-trapping gases in the atmosphere. However, it is important that students also understand that the greenhouse effect is a positive process by which the atmosphere keeps the planet at a relatively uniform temperature.

The Carbon Dioxide Game is a fun, active way to explain the greenhouse effect and human contribution to global climate change. The game can be played with groups of up to 30 students age 10 and older.


• To demonstrate the greenhouse effect by showing how CO2 in the atmosphere traps heat and insulates the
• To show that human activities affect the concentration of greenhouse gases in the atmosphere.

Time: 20 minutes, including time for debriefing
Materials: An open area, chalk, a small bag with the words “What did humans do?” written on it, and action cards representing human actions that affect CO2 levels in the atmosphere. (Download sample cards, and free to add your own).



Draw two concentric circles on the ground, one about 2 feet in diameter, and a larger one about 15 feet in diameter. The smaller circle represents the Earth and the larger one represents Earth’s atmosphere.

The game is played in several rounds. For round one, choose two students to be CO2 molecules, and place them anywhere in the Earth’s “atmosphere.” Once they are in the atmosphere they cannot move their feet. The rest of the students are sunbeams representing energy from the sun.

The object of the game is for the sunbeams to enter the atmosphere, tag the Earth (by touching the inner circle with a foot or hand) and then escape the atmosphere without getting tagged by a CO2 molecule. Sunbeams who are tagged must stay standing still in the atmosphere. Those who avoid being tagged bounce back out of the atmosphere into space. Each round lasts approximately 30 seconds and during that time the sunbeams try to tag the Earth only once. This simulation recreates the greenhouse effect: energy from the sun is trapped as heat by CO2 and other gases and particles in the atmosphere.

After the first round, have the escaped sunbeams form a circle around the atmosphere to check how much energy has been trapped. Discuss how this may affect the temperature of the planet. Remind students that a certain amount of CO2 is necessary to keep the planet consistently warm enough to support life. During the first round, most of the energy will have escaped the atmosphere because CO2 levels are low. Before continuing the game, clear all the trapped sunbeams out of the atmosphere.

For the second round, increase the number of CO2 molecules in the atmosphere. Do this by reaching into the “What did humans do?” bag and pulling out an action card (for this round, include only cards that add CO2 to the atmosphere). After a student reads the card, increase the number of CO2 molecules in the game (dictated by card) and play again.

For the third and subsequent rounds, put all of the action cards in the bag so that CO2 levels will go up or down depending on which card is drawn. Discuss what happens each time. The game should demonstrate that when you increase the amount of CO2, more heat gets trapped (illustrated by the student sunbeams standing in the atmosphere) and the Earth warms up. The action cards demonstrate how even small-scale actions can decrease the amount of greenhouse gas that we emit to the atmosphere.

Wrap-up: Review how energy from the sun gets trapped in the Earth’s atmosphere. Discuss how human actions, particularly burning fossil fuels, can enhance the greenhouse effect by putting more CO2 into the atmosphere. The game can be a springboard into a variety of other explorations such as researching alternative energy sources, discussing sustainable lifestyles, and examining the different choices humans can make in relation to the environment.

From Green Teacher 70, Spring 2003, available for purchase

Sashi Kaufman lives in Maine where she is currently pursuing a Master’s Degree in middle school science education. She taught hundreds of students to play the Carbon Dioxide Game while working at the Ferry Beach Ecology School in Saco, Maine.