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One of the most important concepts to understand when learning about global warming is the greenhouse effect, a naturally occurring process. When the sun heats the earth, the earth radiates some of that energy back into space. Atmospheric gases trap some of the outgoing energy, keeping the earth a comfortable, livable temperature. Without the greenhouse effect, the earth would be approximately 30�C lower, and therefore uninhabitable. However, when levels of these greenhouse gases, mainly carbon dioxide, water vapor, methane and nitrous oxide, increase, the greenhouse effect increases. With more outgoing energy being trapped, the average global temperature rises. Human activities are hugely responsible for the increases in these greenhouse gases. �Since the beginning of the industrial revolution, atmospheric concentrations of carbon dioxide have increased nearly 30%, methane concentrations have more than doubled, and nitrous oxide concentrations have risen by about 15%.� (U.S. Environmental Protection Agency.) |
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