Chemicals released years ago are still present in the atmosphere and are contributing to today's peak concentrations. Meanwhile, global climate change is thought to be slowing the ozone layer's healing process. The warming of the atmosphere near the ground causes the stratosphere to become even colder. Cold stratospheric temperatures, particularly during the early Antarctic spring, catalyze the chemical processes that destroy ozone molecules.
Ozone is a relatively simple molecule, consisting of three oxygen atoms bound together.
Yet it has dramatically different effects depending upon its location. Near Earth's surface, where ozone comes into direct contact with life forms, it primarily displays a destructive side. Because it reacts strongly with other molecules, large concentrations of ozone near the ground prove toxic to living things. At higher altitudes, where 90 percent of our planet's ozone resides, it does a remarkable job of absorbing ultraviolet radiation. In the absence of this gaseous shield in the stratosphere, the harmful radiation has a perfect portal through which to strike Earth.