Our Precious Envelope
The earth’s atmosphere has been called a precious envelope of protection by many scientists. The atmosphere provides a relatively thin layer of air (about 75 kilometers thick) that provides elements essential for life while blocking dangerous cosmic rays. It many ways, it is like the surface of a bubble. Both are beautiful spheres that are delicate and easily damaged.
Just as the structure of a bubble depends on a precise balance of soap, water, and pressure, the well- being of our atmosphere depends on a delicate balance of gases. This balance provides for a critical stability that is necessary to maintain a relatively constant temperature on the Earth. These gases, which include carbon dioxide, methane, nitrous oxides, and others, help keep the planet warm by trapping some of energy that would otherwise escape into space. Without this natural “greenhouse effect” the Earth would be much colder than it is today. The key to a healthy climate is to maintain a relative balance in the concentration of these gases.
Unfortunately, this balance is being disrupted because human activities are altering the composition of the atmosphere through an increased production of greenhouse gases. According to the Environmental Protection Agency, carbon dioxide concentrations have increased more than 30 percent since the industrial revolution while methane concentrations have more than doubled (EPA, 2002). These increases have enhanced the heat-trapping capabilities of our atmosphere. Of the greenhouse gases, carbon dioxide levels are thought to have the greatest impact on climate change. Though carbon dioxide is consumed through the process of photosynthesis, it is also a product of numerous chemical processes. The increase in carbon dioxide production can be attributed primarily to the burning of fossil fuels such as gasoline, coal, and natural gas. Currently, we are adding carbon dioxide into the atmosphere much faster than it can be recycled.
Table 1: Carbon Dioxide Emissions from 3 Large Countries
Country / Year / CO2 Emissions per Person / Percent Increase Since 1996U.S. / 2006 / 43,000 lbs (19,500 kg) / 7 %
China / 2006 / 10,100 lbs (4535 kg) / 105%
India / 2006 / 2,500 lbs (1133 kg) / 55%
As you can see from the Table 1above, the average American produces about 43,000 pounds of CO2 gas per year compared to the average citizen from India that produces only 2,500 pounds. If we hope to restore proper balance in the atmosphere, wemust learn how to reduce our CO2 production. One of the problems we face is that people are often unaware of their CO2 problem. After all, CO2 is a gas that is odorless and colorless and, as a result, we often don’t realize when it is being produced or consumed. If we can help people to visualize and quantify our production of this gas, maybe we can motivate them to reduce their consumption. You are about to see two interesting demonstrations that use CO2 bubbles to model our overproduction of CO2 as individual citizens. You can judge for yourself whether you think each of them is an effective model.
Adapted from Demonstrations to Save the World, Science Scope, April 2003.