|
|
| 1. Atmospheric ozone encircles the globe, providing a protective barrier against harmful solar UV-B radiation for all living things on the earth's surface. Life appeared on the earth’s surface only after this protective layer of ozone developed.
|  |
|
| 2. Without this protective layer of ozone in the stratosphere, UV-B radiation causes a variety of health problems for most living things: skin cancers, cataracts, and immune suppression in humans; changes in plant growth, form, and development; orientation and motility in phytoplankton- the base of the food chain for ocean creatures; and damage to early developmental stage of fish, shrimp, crabs, amphibians.
|  |
|
| 3. Beginning in the 1930's, industry began using new chemical agents called CFCs (chloro-fluoro-carbons) for such innovations as aerosol sprays, refrigeration and air conditioning. |  |
|
| 4. A theory of ozone depletion by CFCs was published in Nature Magazine in June, 1974. Despite these warnings,by 2000 these chemicals had reduced the ozone layer by as much as 66% over Antarctica. This created an ozone hole equivalent in area to that of the continental United States. |  |
|
| 5. Ozone depletion is greatest at the poles, but occurs hardly at all near the equator. At temperate latitudes, where most people live, ozone depletion is sufficient to produce a variety of documented human health problems. |  |
|
| 6. Unchecked, the depletion of atmospheric ozone will eventually affect all life on the surface of the earth. Protection from more intense UV-B radiation might require humanity to either live underground,under several meters of water,or wear protective clothing over every inch of our body. |
|
| 7. Industry pressure and scientific skepticism, prevented action by governments until the 1985 Vienna Convention. The efforts of scientists and public opinion led governments to negotiate a number of international treaties to regulate and eventually eliminate the various chemical agents that destroy atmospheric ozone. |
|
| 8.Today, the global production of CFCs has been banned in developed countries and is scheduled to be phased out in developing countries by 2010. To date, production of banned ozone depleting chemicals has been reduced by 90%. Other ozone depleting chemicals are scheduled to be phased out by 2030. |  |
|
| 9. Even if this reduction in ozone depleting chemicals occurs on schedule, it will take at least 50 to 100 years for the atmospheric ozone layer to return to its state before 1980. This is because once released, these ozone depleting chemicals continue to destroy atmospheric ozone for many years. The most common agents (CFCs) remain active for approximately 50-150 years. |
|
| 10. Some ozone depleting chemicals are also greenhouse gasses, such as HFCs. The greenhouse effect also impacts ozone depletion since heating of the atmosphere affects dynamics of the stratospheric ozone layer. |
|
| 11. The story of the depletion of atmospheric ozone is a simple example of how a seemingly useful and benign kind of material throughput very quickly led to the serious degradation of a global ecosystem that supports all terrestrial life, including humans. The scale of certain types of economic activity (the production and sale of ozone depleting chemicals), threatens the health and survival of plant and animal life on the earth’s surface. This destruction will continue until at least 2050 because of the long life of these chemical compounds.
|
|
|
;)
;)
;)
;)
;)
;)