A carbon footprint reflects the impact of a person’s activities on the environment.

Our planet owes its comfortably warm temperatures to greenhouse gases. Solar radiation travels through the atmosphere, strikes Earth’s surface, and is changed to heat (see Figure 1). Some of the heat is released into space, but much is trapped near the Earth by the dome of greenhouse gases. Without these gases, Earth’s surface would be very cold.

Figure 1

surface temperature to rise. Global warming is an overall increase in the Earth’s temperature due to a thickening of the greenhouse gases in the atmosphere. The two primary greenhouse gases are carbon dioxide and methane.

Carbon dioxide is released into the atmosphere by combustion of fossil fuels. The principal sources of carbon dioxide emissions are power plants and transportation. As a result, many of our daily activities create carbon dioxide emissions. Every time you plug in an appliance or flip on a light, you are increasing levels of greenhouse gases. The same thing happens when you ride in a car, bus, or plane. In this activity, you will learn more about your carbon footprint, which shows how much you contribute to greenhouse gases.

Time Required

55 minutes

Materials

• access to the Internet

• science notebook

Please review and follow the safety guidelines at the beginning of this volume.

Procedure

• To learn more about a carbon footprint, go to the Web site http://www.thenatureconservancy.com/initiatives/climatechange/ calculator/?src=f1. This site is provided by The Nature Conservancy, a nonprofit environmental organization, that can help you determine how much carbon dioxide your activities contribute to the atmosphere.
• Read the information under “Get Started” and select the number that tells how many individuals live in your home. Then select “Calculated for My Household.”
• Under “Home Energy,” indicate the type and number of bedrooms in your home. Select the state in which you live. Answer the questions under “What Have You Done to Change Your Impact?” Then click “Continue.”
• Under “Driving and Flying,” answer the questions related to your family’s travel habits. Click “Continue.”
• Under “Food and Diet,” answer the questions related to your family’s eating habits. Click “Continue.”
• Under “Recycling and Waste,” answer the questions related to your family’s habits. Click “Continue.”
• Record you carbon footprint in your science notebook.
• Read the tab titled “Climate Saving Tips” on the left side of the page.
• Repeat the calculation procedure again. This time, indicate that your family:

a. does not fly

b. drives only 5,000 miles (mi) (8,047 kilometers [km]) each year

c. uses Energy Star appliances

d. has done everything possible to conserve energy

e. eats organic food

• Answer Analysis questions 1 through 8.
• 10. To learn about compact fluorescent light (CFL) bulbs, go to the HowStuffWorks Web page: http://home.howstuffworks.com/ question236.htm. Read the information on this site.
• Answer Analysis questions 9 and 10 in your science notebook.
• To learn more about energy efficient light bulbs, go to http://www. energystar.gov/index.cfm?c=cfls.pr_cfls. This Web site is provided by the Environmental Protection Agency (EPA). Read the paragraph on CFL bulbs.
• Answer Analysis questions 11 and 12 in your science notebook.

Analysis

1. What is your family’s carbon footprint?
2. How did the carbon footprint change after step 8?
3. Some companies offer the opportunity to offset one’s carbon footprints. If individuals make a donation, the companies will use the money to help offset your use of electricity. What are some of the ways the Nature Conservancy helps offset carbon footprints?
4. Describe some of the ways Patrick Gonzalez, who was discussed under “Climate-Saving Tips,” reduced his contributions to the greenhouse effect.
5. List five things you and your household could do to reduce global warming.
6. How can planting more trees reduce your carbon footprint?
7. Explain in your own words what the phrase, “think globally, act locally,” means.
8. What is The Nature Conservancy? What has it accomplished since its inception?
9. What is a CFL bulb?
10. Why does an incandescent bulb get hot while a CFL bulb remains relatively cool?
11. How much electricity could we save if everyone replaced one incandescent bulb with a CFL bulb?
12. How much energy does a CFL bulb save compared to an incandescent bulb?

Although levels of greenhouse gases were relatively stable for thousands of years, they have been increasing since 1750. During the era of the Industrial Revolution, which occurred in the mid–1800s, the atmosphere experienced a sharp increase in carbon dioxide levels (see Figure 2). Studies have shown that as levels of carbon dioxide have increased, so has Earth’s surface temperature.

The problems caused by increasing carbon dioxide and rising temperatures are global. However, the actions of each individual can make a difference. Everyday choices can help in two ways: they can reduce greenhouse gases and increase the uptake of carbon dioxide. Each person can adjust his or her lifestyle to cut back on activities that produce greenhouse gases. Selecting locally grown food, resetting the thermostat to use less electricity, and using public transportation are good options that help the environment.

Figure 2

Connections

Scientists know that the Earth’s surface is getting warmer because of studies they have done on ancient ice. At the poles, new snow and ice are laid down annually on top of earlier years’, creating layers. By taking ice cores (see Figure 3), scientists can analyze ice that is thousands of years old. Bubbles of gas trapped in each layer tell us what, and how much, gases were present.

figure 3

Analysis of ice cores confirms that Earth’s surface temperature is gradually getting warmer and levels of carbon dioxide and methane are rising. Since the Industrial Revolution, carbon dioxide levels have increased by 3.3 percent. Methane levels show a similar increase.

The Intergovernmental Panel on Climate Change (IPCC) predicts that at the current rate of warming, the Earth’s surface temperature will increase enough by 2100 to cause sea levels to rise as much as 3 feet (ft) (0.9 meters [m]). The IPCC provides information on each country’s  contributions to global warming. Industrialized countries like the United States and European nations are the biggest offenders. Citizens of these well-developed societies are responsible for working together and taking the lead toward a global solution.