What is global warming?

(Lansing State Journal, Sept. 18 1996)

'Global warming' is the term used to describe a steady increase in the Earth's average temperature. In order to understand global warming, first one must understand a natural process called "The Greenhouse Effect."

Every day, the sun's rays are absorbed by the Earth and converted to heat. As the Earth cools down at night, it loses a lot of the heat that it has absorbed into outer space, but thanks to the Earth's atmosphere, not all. The Earth's atmosphere is a mixture of gases. It is mainly nitrogen and oxygen, but it also contains methane (CH₄), carbon dioxide (CO₂), and nitrous oxide (N₂O). These latter three gases are able to absorb heat lost by the Earth and radiate it back to the Earth. This radiation is crucial for the survival of life on Earth.

All three of these gases exist naturally. The problem is that the amount of CO₂ in the atmosphere has been steadily increasing. More heat is being radiated back at the Earth; hence the temperature of the Earth is slowly rising. Scientists estimate that a change of just a few degrees will drastically alter the planet. Since CO₂ is a product of the combustion of fossil fuels (such as gasoline and coal), many people believe that the increase in CO₂ is due to pollution. But this is difficult to prove, which is why global warming is a controversial issue.

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