Other Chemicals for Concern

We also have other chemicals in the earth's atmosphere that are increasing. Chlorinated fluorocarbons (CFCs) were invented in the late 1930's, so they did not exist in the earth's atmosphere before that time. They are very stable compounds and are removed from the atmosphere very slowly. This allows time for these compounds to diffuse into the stratosphere where they can be broken down by ultraviolet light creating free chlorine atoms that can combine with ozone to create diatomic oxygen and therefore serve as a means of depleting stratospheric ozone.

Nitrous oxide is another gas in the earth's atmosphere whose concentration is increasing. Natural sources of nitrous oxide in the soil are augmented by the use of nitrogen fertilizers leading to increased atmospheric concentrations. Nitrous oxide, like the CFCs, has a very long lifetime in the atmosphere and also can lead to destruction of stratospheric ozone. A loss of stratospheric ozone allows increased amounts of ultraviolet light to reach the surface of the earth and damage living tissue. Cases of skin cancer in New Zealand and Australia are experiencing a dramatic rise, in part due to this increase in ultraviolet light. Tiny ocean organisms, called phytoplankton, in regions where stratospheric ozone has been depleted are vulnerable to damaging levels of ultraviolet radiation.

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