1. Do CFC's Contribute to Stratospheric Chlorine?

Scientific data published in 1991 indicated that stratosphere chlorine shows an upward trend with time, about half that of stratospheric fluorine. The accepted interpretation is that manmade sources of chlorine, principally CFCs, contribute to stratospheric chlorine--along with natural sources, such as volcanoes and the oceans.

It is important to point out that this changed view is based on an actual change in the underlying data. Peer-reviewed papers, published as late as 1987, showed no upward trend in stratospheric chlorine, consistent with the idea that manmade sources were of little importance.

The issue to be investigated is why the Montreal Protocol to control CFCs was entered into in 1987, at a time when the most reliable scientific information suggested that CFCs were of no consequence.

2. Is Stratospheric Ozone Decreasing on a Global Scale?

Beginning with a press conference by an ad-hoc "Ozone Trends Panel" in March 1988, the public has been subjected to a barrage of reports and press releases claiming that the ozone layer is being depleted at a rate that is "worse than expected."

[Since "expectations" must be based on theory, this begs the question as to whether the theory is wrong, or the observations are wrong, or if they are bow wrong.]

There is doubt as to whether the data can be trusted, whether the calibration of the instruments has been maintained, and whether other gases, such as sulfur dioxide, have been interfering with the ozone measurements.

Even if the data turned out to be sound, there is the question whether a long-term trend can be established with such a short record, in view of the large natural variations of ozone levels in the stratosphere. [One notes for example, that a March 1995 EPA pamphlet on "Stratospheric Ozone Depletion" presents no evidence for such a downward trend but merely states (on page 5) that "stratospheric ozone levels fluctuate periodically."]

Even if the data record becomes long enough to show a downward trend, one cannot automatically assume that it is due to manmade causes. Since ozone levels vary with sunspot activity, one would expect to find naturally occurring long-term ozone variations, extending over decades.

3. Does CFC Theory Support Ozone Destruction?

According to published calculations, chlorine from CFCs should be effective in diminishing ozone in the upper layers of the stratosphere, around 40 km. But the bulk of the ozone exists between 20 and 25 km, in the lower stratosphere. Both theory and measurements suggests that hydrogen-containing molecules, not chlorine, are the main destruction agent for ozone in the lower stratosphere.

If this argument is correct, then we should consider the possibility that human activities other than CFC production could be affecting the ozone layer. A theory published in 1971 suggested that manmade methane could affect stratospheric ozone by increasing the concentration of water vapor in the stratosphere. Such a long-term increase in stratospheric water vapor has just been detected and reported in the journal Nature. Increased air traffic is yet another mechanism for injecting water vapor into the lower stratosphere.

4. Is There an Increasing Trend in Ultraviolet Radiation at the Earth’s Surface?

In spite of the fact that a downward ozone trend should result in an upward trend of UV, no such trend has ever been reported. In November 1993 two Canadian researchers, J.B> Kerr and C.T. McElroy, published a paper in Science claiming to have measured large upward trends of UV, as much as 35 percent per year for certain wavelengths. Their results were deemed suspicious since they showed no error bars or other measures of uncertainty. Indeed, a re-analysis of their data, also published in Science, showed that the "trend" was consistent with zero percent.

The Kerr/McElroy paper created great excitement. Even though they no longer claim the existence of a trend, researchers in other fields continue to blame a UV trend for such things as the disappearance of frogs and the rise in melanoma skin cancers. Ignored is the undisputed fact that UV increases strongly as one approaches the equator; the feared 10% increase due to ozone thinning—if it were to exist—would correspond to a 60 mile move towards the equator.

5. Does Ultraviolet Radiation Cause Malignant Melanoma Skin Cancers?

In 1987, the EPA published the results of a cost-benefit analysis, claiming three million skin cancer deaths in the United States in the next century, unless CFC production were curtailed. Their analysis seems to have been based on the assumption that malignant melanoma, the deadly form of skin cancer, is caused by exposure to UV-B radiation [wave length interval 280 to 320 nanometers]. Actual measurements in the laboratory, published in July 1993, have now demonstrated that melanoma is induced primarily by UV-A [320—400 nm].

Ozone absorbs in the UV-B but not in the UV-A. Put another way, the induction of melanoma does not depend on the level of ozone. If this conclusion is borne out, then EPA’s cost-benefit analysis will require some major corrections. It could call into question our present policy to ban the production of halocarbons on an accelerated time scale. (The EPA still claims benefits of up to $32 trillion and a benefit-to-cost ratio of 1000!)