Ozone is found in two places in Earth’s atmosphere. At ground-level, ozone is a dangerous air pollutant with a wide variety of human-health effects. About 25 miles above us, the ozone layer shields us from the Sun’s harmful ultraviolet radiation. Without ozone in the stratosphere, the Earth would be uninhabitable by higher forms of life….like us.
About 30 years ago, during the Antarctic spring, scientists began to notice higher levels of ultraviolet light were reaching the ground: the ozone layer was thinning.
The cause of the ozone hole was found in some complex chemistry. The culprit: chloroflurocarbons, such as Freon, that were widely used in air conditioners and other facets of modern life. With the ban on chlorofluorocarbons in 1990, the problem should have been solved.
Why isn’t its repair more rapid? One problem stems from the persistence of chloroflurocarbons in the atmosphere.
It will take a long time for all the chloroflurocarbons ever produced to mix into the stratosphere, where they will be destroyed, taking some ozone with them. Last spring, the ominous signs of ozone destruction were seen at northern latitudes, where the greater ultraviolet light could reach large cities and areas of agriculture.
Another problem stems from continued releases of other compounds with the same effect, such as methyl bromide—a fumigant used in agriculture. Farmers claim there is no adequate substitute, and the U.S. routinely asks for an exemption from the ban on methyl bromide. Yet various seed companies have developed crop strains that don’t need methyl bromide.
Technology can beat this environmental problem if we have the will to apply it.
Photo courtesy of NASA Goddard Space Flight Center via Flickr.