In 1985, scientists discovered a hole in the earth’s ozone layer over Antarctica. By 1987, the hole had increased to the size of the continental United States. Ozone, a modified form of oxygen, is present in only small amounts in the stratosphere, but performs a crucial function to life on earth. It absorbs solar ultraviolet radiation, protecting humans and other forms of life from skin cancer, cataracts, and immune system deficiencies.
In the 1980s, it was confirmed that chemicals like chlorofluorocarbons (CFCs) that we were using in manufacturing and especially in aerosols were acting as catalysts that were breaking down the ozone layer. Over the long term, CFC use threatened to destroy the earth’s ozone shield entirely.
Worldwide concern over this issue led to the signing of an international treaty in 1987 to reduce CFC use by 50%, and in 1990 to eliminate it entirely. This has largely succeeded and there is very limited CFC use around the world today.
A new report issued by NASA confirms what other research has shown: the hole in the ozone layer is shrinking and may disappear entirely but not until the end of this century. NASA calculates that there would have been a 67% depletion of the ozone layer by now if we had not taken action.
The experience with the ozone layer demonstrates that we can rapidly produce major changes in our atmosphere but that it can take a long time for nature to recover. It also shows that it is possible to sustain global cooperative efforts to tackle such problems. It is what is needed now in the face of climate change.
**********
.
Web Links
Good News! The Hole in the Ozone Layer Appears to Be Closing
Photo, posted October 20, 2011, courtesy of the NASA Goddard Space Flight Center via Flickr.
.
Earth Wise is a production of WAMC Northeast Public Radio.