Learning Lesson: Its a Gas, Man
OBJECTIVE | Discover if carbon dioxide has an effect on temperature. |
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OVERVIEW | The demonstration will show that excess carbon dioxide leads to higher temperatures. |
TOTAL TIME | 1 hour |
SUPPLIES | Two (2) clear 2-liter bottles Two thermometers Molding clay Two seltzer tablets Table top lamp used as a source of heat |
PRINTED/AV MATERIAL | None |
TEACHER PREPARATION | None |
SAFETY FOCUS | Summer safety rules |
Carbon dioxide has increased greatly in the atmosphere over the past 100 years. Although it comprises only 0.03% of the atmosphere, it has been linked to global warming.
- Partially fill both bottles with water.
- Add the seltzer tablets to one of the bottles.
- Suspend the thermometers inside the bottles in such a way that you can measure the temperature of the air and seal the tops with molding clay.
- Place the lamp at equal distance between each bottle.
- After an hour, measure the temperature of the water in each bottle.
The seltzer tablets supplied one bottle with a source of carbon dioxide. The "fiz" will have heated faster and to a higher temperature than in the other bottle. The increase in heating ability is due to carbon dioxide's high capacity to hold heat.
It has been thought that an increase in carbon dioxide will lead to global warming. While carbon dioxide in the atmosphere has been increasing over the past 100 years, there is no evidence that it is causing an increase in global temperatures.
In 1997, NASA reported global temperature measurements of the Earth's lower atmosphere obtained from satellites revealed no definitive warming trend over the past two decades. In fact, the trend appeared to be a decrease in actual temperature. In 2007, NASA data showed that one-half of the ten warmest years occurred in the 1930's with 1934 (tied with 2006) as the warmest years on record. (NASA data October 23, 2007 from http://data.giss.nasa.gov/gistemp/graphs/Fig.D.txt)
The 1930s through the 1950s were clearly warmer than the 1960s and 1970s. If carbon dioxide had been the cause then the warmest years would have understandably been in the most recent years. But that is not the case.
The largest differences in the satellite temperature data were not from any man-made activity, but from natural phenomena such as large volcanic eruptions from Mt. Pinatubo, and from El Niño.
The behavior of the atmosphere is extremely complex. Therefore, discovering the validity of global warming is complex as well. How much effect will the increase in carbon dioxide will have is unclear or even if we recognize the effects of any increase.
Fast Facts
To see the full effect of a greenhouse effect, look to the planet Venus. The atmosphere of Venus consists of 96% carbon dioxide, 3.5% nitrogen, with the remaining amount, less than 1%, of other gasses.
The carbon dioxide atmosphere has allowed the temperature of the surface to exceed 900°F (482°C). This is hot enough to melt lead. Space craft that have successfully landed on venus, despite being well protected, have lasted only about an hour in the excessive heat and crushing pressure.
Summer Safety Rules
Help reduce additional heat to the atmosphere by following the following conservation measures:
- Protect windows. Hang shades, draperies, awnings, or louvers on windows that receive morning or afternoon sun. Outdoor awnings or louvers can reduce the heat entering the house by as much as 80%.
- Conserve electricity. During periods of extreme heat, people tend to use a lot more power for air conditioning, which can lead to a power shortage or outage. Vacuum air conditioner filters weekly during periods of high use.
- Keep lights turned down or turned off.
- Avoid using the oven.