Ozone Depletion and Ozone Hole

Ozone depletion is the slow but steady decline of ozone volumes from the Earth's stratosphere. Occurring at the rate of 4 percent per decade, the phenomenon has been observed since late 1970s when the ozone layer decreased over the stratosphere and Polar Regions causing the ozone hole.

There are five distinct linkages between ozone depletion and global warming. Stratospheric ozone depletion due to air pollution has long been recognized as a threat to human health as well as to the Earth's ecosystems. It was observed that decline in polar ozone was far larger than anyone had anticipated.

The detailed mechanism by which polar ozone holes form is different from that of mid-latitude thinning. But importantly both are being destroyed by atomic chlorine and bromine. The main sources for them are chlorofluorocarbon compounds commonly called freons and bromofluorocarbon compounds known as halons.

These compounds are transported into the stratosphere after being emitted at the surface. Both ozone depletion mechanisms strengthened as emissions of CFCs and halons increased. CFCs and other contributory substances are commonly referred to as ozone-depleting substances.

A variety of biological consequences such as skin cancer, cataracts, damage to plants and reduction of plankton populations in the ocean's photic zone are said to be resulting from increased UV exposure due to ozone depletion.