AIR POLLUTION MAY RESULT IN GLOBAL WARMING

A similar effect occurs in Earths atmosphere, which, like glass, is transparent to visible light emitted by the sun. The ground absorbs this energy but radiates infrared waves. 

False-color image of ozone levels over the Northern Hemisphere, recorded by NASA s total-ozone mapping spearometcr fTOMS). Purple and blue areas are areas of ozone depletion green through red areas are areas of higher-than-normal ozone levels. 

Glass aas as a one-way valve, letting vi.sible light in and preventing infrared energy from exiting. 

ITie greenhouse effect in Earth s atmosphere. Visible light from the sun is absorbed by the ground, which then emits infrared radiation. Carbon dioxide, water vapor, and other greenhouse gasses in the atmosphere absorb and reemit heat that would otherwise be radiated from Earth into space. 

Lev els of atmospheric carbon dioxide and global temperattircs appear to be closely related to each other. 

There has been an unprecedented level of international cooperation toward banning ozone-destroying chemicals. The first major step was the signing of the 1987 Montreal Protocol on Substances That Deplete the Ozone Layer, which called for the reduction of CFC production to one-half of 1986 levels by the year 1998. However, only a few years after the protocol was ratified, in 1990, scientists confirmed that the CFC problem was much more serious than they believed in 1987 when the protocol was drafted. The protocol was soon amended to call for cessation of all CFC production by 1996. Even with the protocol in place and the continued cooperation of all signatory nations, however, the ozone-destroying actions of CFCs will be with us for some time. Atmospheric CFC levels are not expected to drop back to the levels found before the ozone hole was formed until sometime in the 22nd century. 

What does it mean to say that the greenhouse effect is like a one-way valve  

---