The U.S. should delay implementation of the provisions of the Montreal Protocol, the international agreement banning chlorofuorocarbons (CFCs), manufactured chemicals commonly used in refrigerators and air conditioners that have been blamed for destroying the ozone layer. The U.S. should also withdraw from the treaty. There are two primary reasons for these recommendations: 1) We still do not fully understand the factors controlling stratospheric ozone and 2) there has been a profound misrepresentation of the health and biological effects of ultraviolet light (UV) from the sun.
There is still much we don't know about how ozone is destroyed: We have known since the Climatic Impact Assessment Program of the Super Sonic Transport (1972-75) that chlorine in the stratosphere could destroy ozone, but it wasn't until 1974 that we learned that CFCs could be a significant source of this chlorine. In 1974, F. Sherwood Rowland and Mario Molina discovered that chlorine from CFCs penetrates the stratosphere through photo-decomposition, a process by which chlorine is released by energetic solar UV, thereby freeing it to destroy ozone catalytically (i.e. without being consumed itself). Model calculations through 1990 concluded that continued release of these compounds at then current rates would lead to an ozone decline of five percent by the middle on the 21st Century.
Still, there are many variables affecting ozone that remain uncertain as the Antarctic ozone hole aptly demonstrates. The hole, which appeared in 1985, resulted from very rapid and nearly complete springtime destruction of ozone in the 12 to 22-km layer within the Antarctic winter polar vortex. The hole had not been predicted and could not be explained by the ozone theory without adding such factors as ice particles and/or nitric acid, freezing from their normal vapor states due to extremely cold temperatures, and other variables. Nonetheless, the appearance of the hole was largely viewed as confirmation of the theory and was instrumental in the ratification of the Montreal Protocol in 1987. Our chief negotiator of the treaty, Richard Benedict, later wrote: "Perhaps the most extraordinary aspect of the treaty was its imposition ... against unproved future dangers... At the time of the negotiations and signing, no measurable evidence of [ozone] damage existed."
Unfortunately, the wrong lessons were drawn from the Antarctic experience. Because satellite data indicated more rapid ozone loss than surface observations, an Ozone Trends Panel was formed and after an 18-month review it's leader, NASA's Dr. Robert Watson, issued an executive summary by press release claiming a 1969-86 ozone loss of 1.7 to 3.0 percent from 30 to 64 degrees north. "[Our ozone] models do not predict that ozone decreased the way it did over the Northern Hemisphere during the past 17 years," he said. "Our models are not doing a good job, so we would have to say that they are underestimating decreases in the future."
NASA didn't underestimate again -- to say the least: In a flagrant case of public policy by press release, NASA's Dr. James Anderson announced on February 3, 1992 that the NASA ER-2 plane had detected the highest concentrations of chlorine monoxide it had ever encountered -- even in flights into the Antarctic ozone hole -- over eastern Canada and northern New England, suggesting that an Arctic Ozone Hole could be imminent. Within two days the U. S. Senate voted 96-0 to advance the ban on CFCs from the year 2000 to 1995. Though the hole never materialized -- a consequence, NASA argued, of unusually warm winter air -- that didn't prevent the November 1992 Montreal Protocol meeting in Copenhagen from adopting the five-year acceleration of the CFC phase-out.
There is also a great deal of uncertainty about the health affects of increased surface UV. According to the World Meteorological Organization, a 1% decrease in the depth of the ozone column is equivalent to a 2.3% increase in normal skin cancer incidence. This, in turn, is equivalent to moving just 14 miles closer to the equator.
Meanwhile, there appears to be tangible health benefits from greater UV exposure. An estimated 20-25 million Americans currently suffer from osteomalacia, bone softening that occurs due to inadequate calcium or vitamin D. Among people with this condition, there are over twice as many bone fractures per year as there are new cases of skin cancer per year. Theoretically, additional UV would alleviate this condition in the growing and future generations just as it would lead to additional cases of skin cancer. Considering the number of people affected and the relative severity of the health effects, increased ultraviolet appears to offer a net health benefit, particularly since our bodies are much better able to warn us of too much UV than they are to warn us of too little UV.
The U.S. should withdraw from the Montreal Protocol because it is based on uncertain science and on the presumption of substantial health benefits. Lest there be any doubt, consider this: The "intolerable" five percent decrease in ozone predicted by the mid-21st Century actually occurred in 1993 and is still with us.
Dr. Ellsaesser has served as an atmopheric and climate research scientist at Lawrence Livermore National Laboratory for 23 years. Dr. Ellsaesser also serves on the Science Advisory Council of the National Center for Public Policy Research's Environmental Policy Task Force.