Global Warming - A Greenhouse Effect Activity

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Mar 1, 2002

Imagine you are returning to car after a long summer day at the beach. The car has been sitting in the sun all day, with the windows rolled. When you open the doors, a gust of hot air hits you in the face, and the inside of the car is much hotter than outside. That is the GREENHOUSE EFFECT, and the same thing is happening to the Earth!

The Earth receives from the sun, and some of the heat is radiated back out into space. However, gases like carbon dioxide, water vapour, methane and nitrous oxide, hold in the heat and keep it around the Earth's surface. They act like a greenhouse and cause the temperature of the Earth to rise, just like the temperature inside the car rose. Another chemical that is responsible for global warming is CFCs or chlorofluorocarbons. CFCs are used in refrigerants, aerosol cans and air conditioners, and in various other industrial processes.

Normally, the Earth keeps the amount of carbon dioxide in the atmosphere with sinks, such as forests, which use carbon dioxide to make food in a process called PHOTOSYNTHESIS. However, we have been cutting down forests at a rapid rate, as well as putting carbon dioxide into the air through the burning of fossil fuels.

If you live a cold part of the country, warmer temperatures may seem pretty good to you. However, there are many harmful effects that global warming can have:
*weather patterns could change, bringing more ferocious hurricanes
*volume of the oceans would increase, polar ice caps would melt, causing flooding of coastal areas
*droughts may affect crop-growing areas
*lower water levels in fresh-water lakes could concentrate pollutants
*people would use air conditioners more, causing more CFCs to be released

Although not all scientists agree on the rate of global warming, there is no question that we should try and reduce the amount of air pollution. Some things that could be done are:
*stop using products with CFCs
*use renewable energy sources instead of fossil fuels
*stop clearing and burning of forests
*plant more trees

A GREENHOUSE EFFECT ACTIVITY

Materials needed: -two clear plastic 2L pop bottles -plastic wrap -2 thermometers, with plastic or cardboard backing (small ones, to fit completely in the bottle) -masking tape -2 large rocks (large enough to fit inside the bottles, about the same size) -sunlight, or if you're doing this inside, a minimum 100W bulb and lamp -utility knife (to cut off tops of bottles - BE CAREFUL!)

Procedure:

1. Cut the tops off the bottles, around 5 inches from the bottom, using the utility knife. Be careful when doing this.

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