I. BACKGROUND ANALYSIS
As we all know, global warming is caused by the greenhouse effect. That is to say, there is a kind of heat-absorbing gas in the atmosphere which absorbs the infrared in the sunlight of the surface reflection to stop the energy from distributing to the outside atmosphere, so it makes the entire planet and atmosphere like a greenhouse and temperatures continue to rise day by day. Such heat absorbing gases are usually called “greenhouse gases” - including water vapor, carbon dioxide, methane, ozone, nitrous oxide, halide and so on. According to the report of IPCC (intergovernmental panel on climate change), in the greenhouse effect caused by human activities the ratios of the various greenhouse gases are 60% carbon dioxide, 20 % methane, 14% halide, and 6% nitrous oxide. From this we know that the carbon dioxide has played a decisive role to the greenhouse effect.