Carbon dioxide (CO2) levels in earth’s atmosphere have increased steadily from 280 parts per million (ppm) before use of the internal combustion engine to 400 ppm currently. Chemists measure levels in bubbles of glacial ice cores and in the atmosphere. CO2 reflects light in the infra-red range back to earth which causes warming like that created in a greenhouse. Both the amount of infra-red light and corresponding temperature increases have been documented. Additionally, satellites have documented less heat escaping earth as CO2 levels increase. A convincing scientific discovery is that the carbon in CO2 produced by burning fossil fuels is a different isotope than the carbon in naturally occurring CO2. Virtually all of the CO2 causing the increase from 280 ppm to 400 ppm contains the fossil fuel carbon isotope. These are facts, not theory, and represent the simplest way I have found to explain global warming.
Climate change is complicated and affected by many factors such as volcanic eruptions, El Nino/La Nina events, cyclic tilting of the earth, etc. Natural cooling and warming cycles occur which people cite to debate climate change. Information in the above paragraph is fact not theory and should help people understand that man is causing the greenhouse effect.
David Ransom, Ph.D., Boise
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