ABOUT GLOBAL WARMING: Global warming refers to an average increase in the earth's temperature, which has risen about 1 degree Fahrenheit over the past 100 years, and to changes in climate. A warmer earth may lead to changes in rainfall patterns, and a rise in sea level, for example, as the polar glaciers melt. Some of this rise is due to the greenhouse effect: certain gases in the atmosphere trap energy from the sun so that heat can't escape back into space. Without the greenhouse effect, the earth would be too cold for humans to survive, but if it becomes too strong, the earth could become much warmer, causing problems for humans, plants and animals.
OTHER GREENHOUSE GASES: Carbon dioxide and water vapor are two significant greenhouse gases, but other gases contribute to the effect as well.
- Methane sources such as cows, oceans, wetlands, and natural gas pipes have considerable impact on the global atmosphere.
- Ozone is also a greenhouse gas, and the main component of smog.
- Nitrous oxide is known as laughing gas but is also used in rocket fuel and automobile racing. For equal weights of nitrous oxide and carbon dioxide, over 100 years nitrous oxide has almost 300 times the greenhouse impact of carbon dioxide.
- There are many others gases that have significant effects, especially because they last a long time in the atmosphere, but most are present in low concentrations.