The United States has spent about $100 billion eliminating ozone-destroying chemicals from air conditioners and refrigerators, by some estimates.
Now, NASA is spending $12 billion to measure how quickly replacement refrigerants could get elevated into the stratosphere and whether they could have an impact on the ozone layer.
Chlorofluorocarbons “are relatively heavy molecules, but the Earth?s atmosphere is stirred relatively thoroughly by various mechanisms,” said David Starr, mission scientist at Goddard Space Flight Center in Greenbelt, Md. “The effect of gravity is relatively weak, compared to the mixing of the atmosphere.”
The TC4 mission ? which relies on seven satellites, three aircraft and various ground observations to measure this “mixing” in real time ? hopes to show whether the refrigerants sold in appliances today could survive this mixing and possibly still destroy ozone.
NASA reported in the early 1990s that the ozone layer, which filters out much of the sun?s harmful ultraviolet light, was diminishing, resulting in a large hole over Antarctica.
By 1995, CFCs were banned because the chlorine breaks free and destroys ozone molecules in the stratosphere, according to information on the National Academy of Sciences Web site.
Fred Singer, atmospheric physicist at George Mason University, disputes the effects of CFCs on the ozone. He said the “worst-case scenario” predicts a 10 percent increase in ultraviolet radiation hitting the Earth. However, someone who moves from Washington, D.C., to Richmond, Va., would experience the same increase just because of their change in latitude.
“The unfortunate outcome [if the CFC-ozone link proves false] may be an unconscionable waste of resources, a loss of public trust and a real setback for the environmental effort,” Singer said in an article in Aerospace America.
NASA scientists remain convinced that 75 to 85 percent of the ozone-depleting chlorine in the stratosphere comes from human sources such as leftover CFCs in discarded pre-ban refrigerators.
“We want to make sure some of these new compounds actually degrade before they are boosted up into the stratosphere,” Starr said.
