The "ozone crisis'' has lurched sideways another few paces with the publication by J. B. Kerr and C. T. McElroy,
In order to converge on the truth, we must come to terms with each research paper that we read regardless of whether or not its authors have made errors. Even if we ultimately decide to ignore even the raw data itself as falsified or unreliable (not justified in the papers below), this decision must be carefully rational and not visceral.
J. W. Waters,
Engineering and Science (Caltech), pp 3-13 (summer 1993) entitled "The Chlorine Threat to Stratospheric Ozone'' gives a beautiful four-color history of the saga of "ozone vs. man.'' Initiated by M. J. Molina & F. S. Rowland, Nature Vol. 249, pp 810-812 (1974), this hypothesis has grown to the following state: 1. Carbon compounds of chlorine and fluorine, CFCs, are released by industrial activity and ascend into the stratosphere where they mingle with the ozone layer about 10 miles above the earth's surface. This ozone (O3) layer is produced by the absorption by oxygen (O2) of UV light in the wavelengths between 1600 Å and 2400 Å. This produced ozone then absorbs longer wavelength UV and thereby reduces UV radiation in wavelengths up to about 3200 Å. Ozone thus broadens the energy range of absorbed UV radiation. Radiation in these wavelengths is not eliminated by ozone and oxygen - it is reduced. Plants and animals are designed to live under this oxygen and ozone shield and would be adversely affected if it were to disappear.2. CFCs also absorb UV light to make chlorine atoms which react with ozone to produce chlorine monoxide and oxygen. Chlorine monoxide reacts with atomic oxygen to release reactive chlorine atoms which then destroy more ozone in a cycle that repeats until the chlorine is eliminated by other atmospheric reactions. This happens to a small extent throughout the ozone layer, but it is markedly accelerated on the surfaces of ice clouds which form during part of the year over the antarctic and occasionally over the arctic regions. Predicted CFC caused thinning of the world averaged ozone layer is about 5% , while thinning in ice cloud regions is about 50%.
3. Any thinning of ozone permits additional UV light to reach the earth where it may be harmful to plants and animals. It is estimated that a 5% decrease in ozone would lead to 100,000 additional skin cancer cases per year in the United States. Therefore, industrial use of CFCs should be prohibited regardless of the fact that this prohibition will probably cost several hundred billion dollars.
Scientific support for this hypothesis is as follows:
1. There is a strong correlation between regions of high chlorine monoxide concentration and low ozone concentration in the stratosphere. (See the J.W. Waters article for several pages of remarkable satellite measurements of this in living color.) 2. CFCs are found in the stratosphere along with chlorine compounds from natural sources. Although only a very small part of atmospheric chlorine is from CFCs, measurements indicate that disproportionately large amounts of CFCs reach the stratosphere.
3. The chemical reactions upon which these hypotheses depend are well known and do occur under the conditions of interest.
4. Measurements in Antarctica have recorded a progressive depletion of ozone in ice cloud regions during the past decade. This depletion, allowing for fluctuations, is approximately 50%. All such large depletions have been observed only over unpopulated regions, but these depletions are potential evidence for the overall hypothesis.
5. Skin cancer, especially non-fatal types, is caused by UV light. (In nutrition and cancer experiments for example, my coworkers and I induced this cancer in thousands of hairless mice by means of quantitative radiation with UV light.) UV light is a primary factor in the induction of this cancer in humans. Deaths from UV-induced skin cancer are very rare. (False claims from the EPA of 100,000 cancer deaths are not, however, the fault of scientists on either side of this issue. They are from unethical attempts to gain political power.)
Evidence and arguments contrary to this hypothesis are:
1. Correlation does not prove causality. It has not been shown that the additional chlorine from man-made sources is causing additional destruction of ozone. Ozone is highly reactive. It is both being produced and destroyed at high rates naturally. It is unproved that CFCs have shifted the steady state concentration of ozone, although it is reasonable to postulate that this might happen. There is unfortunately no historical record with which to compare recent ozone fluctuations.
2. The 50% reduction of ozone during some months over Antarc-tica may not be caused by CFCs. G. Dobson (for whom the standard unit of ozone concentration is named) wrote (Applied Optics, March 1968), "....the values for September and October 1956 were about 150 units lower than we expected. We naturally thought that Evans had made some large mistake or that, in spite of checking just before leaving England, the instrument had developed some fault. In No-vember, the ozone values suddenly jumped up to those expected from the Spitzbergen results. It was not until a year later, when the same type of annual variations was repeated, that we realized that the early results were indeed correct and that Halley Bay showed most interesting difference from other parts of the world. It was clear that the winter vortex over the South Pole was maintained late into the spring and that this kept the ozone values low.'' This reduction of ozone by 150 Dobson units is about 50% - observed by Dobson in the 1950s and before any significant industrial release of CFCs into the atmosphere.
3. It is not established that reductions in ozone must be correlated with increases in UV light at the earth's surface. For example, ozone concentration fluctuates with solar intensity (see, for example, No-vember
Access to Energy), because ozone is produced by solar UV radiation. J. Scotto, G. Cotton, F. Urbach, D. Berger, and T. Fears, Science, Vol. 239, p. 762 (1988) found that UV radiation at test stations in the United States decreased as ozone decreased. As solar radiation decreased toward the solar minimum in 1986, stratospheric ozone decreased about 0.5% per year, while UV light decreased about 1.5% per year. Apparently the trend in ozone in the early 1980s was caused by fluctuations in solar activity or other factors that work in a direction opposite to the postulated CFC effect.4. The estimates of increased cancer risk (see, for example, S. Ma-dronich and F. R. de Gruijl,
Nature, Vol. 366, p. 23 (1993)) assume that human behavior is constant regardless of sun intensity and that humans are now receiving more UV radiation than is compatible with optimum health. There is, however, a literature on the possible biological benefits of UV radiation. Although it is likely that over-exposure to the sun resulting in deep tans and burns is not healthful due to skin cancer and other potential harmful effects, it is quite possible that under-exposure to UV light as a result of modern customs of indoor work and recreation is also harmful and that people are currently under-exposed. Our home at 42°N, for example, has UV transmitting plastic skylights and UV electric lights to make up for indoor losses.The optimum healthful human exposure to UV light is unknown. Therefore, it is erroneous to assume that even people in colder climates are already receiving UV light greater than optimum and will be harmed by any additional amount. UV-induced skin cancer, for example, is seldom fatal, whereas other diseases which might increase as UV light decreases could be fatal. Moreover, humans can adapt. Wearing a hat, spending a little more time indoors, or living a little closer to the equator cancels the hypothetical effect.
Politicians like Al Gore, enviroagitators, industrialists who control expensive substitutes for CFCs, and other opportunists lost no time in turning the CFC vs. ozone hypothesis into warnings of global catastrophe and 100,000 cancer deaths per year. They say we can only escape these horrors by giving them some of our remaining freedom and money. International bureaucrats have even seized upon the "ozone crisis'' as a new reason for world government.
Scientists, especially those hopeful for new or continued government funds, are scrambling to adjust their research programs and research papers to this "crisis.'' Advertising departments are churning out ads stating that their
products, unlike those of their competitors, are "ozone friendly.'' Suddenly a whole new anti-CFC industry has been born and nourished by EPA regulations. Government regulations will soon force Americans to buy hundreds of billions of dollars of products from that industry - products that are valueless if CFCs are, in fact, safe.Dr. William Happer, Jr., top scientist at the Department of Energy, was fired ('Gored' might be a better term) in part, because he supported additional UV radiation measurements to test the hypothesis.
It is no longer politically correct to test the hypothesis. Too much has been invested on the assumption that it is right. So.....
Cargo Cult Science has started to replace the real thing:
This brings us back to the Kerr and McElroy paper with its "upward trend of UV-B radiation linked to ozone depletion'' at Toronto which the authors clearly imply is further linked to CFCs.
The most remarkable thing about this paper is that, although the entire point is supposedly the discovery of a correlation between decreased ozone and increased UV light at 3000 Å, nowhere in the paper is there a graph of ozone vs. UV light. There are also no numbers enabling the reader to construct such a graph. All that is given are the plots shown here of measured values of UV light and ozone for 1989 to 1993 and slopes of the calculated "trend'' lines for summer and winter (heavy and light lines respectively).
Inspection of these plots (easier in the colored original in
Science) shows why the trend graph was omitted. There is no trend. By enlarging the plots I have estimated the approximate summer median values for these five years. These values are 336, 331, 333, 327, and 312 for ozone and 0.056, 0.051, 0.063, 0.052, and 0.071 for 3000 Å UV light for the years 1989, 1990, 1991, 1992, and 1993 respectively.During the first four years, ozone and UV light rise and fall together in confirmation of the earlier American studies and opposite to the "trend'' claimed by the authors. They could not show an appropriate graph, because this would negate their conclusion.
In the fifth year of measurement, however, they finally hit pay dirt. Ozone levels fell worldwide during 1993 as shown on the third figure adapted from the J. W. Waters illustration of work by J. Gleason and co-workers from the Total Ozone Mapping Spectrometer.
Waters also gives extraordinary satellite spectrometer maps show-
ing the enormous plumes of sulfur dioxide emitted by the eruption of Mount Pinatubo in June 1991. Notice that ozone begins its decrease below the usual range in late 1991 and reaches extraordinarily low levels in 1993. Waters attributes this decrease in ozone to aerosols formed from sulfur dioxide which provided a world-wide stratospheric enhancement of decomposition of ozone by a mechanism usually restricted to the polar ice clouds. He believes, but has not proven, that this was exacerbated by chlorine from CFCs.
Since this ozone decrease was, unlike those in previous years, not caused by solar fluctuations, UV light intensity increased with decrease in ozone as would be expected, and the spectrometers in Toronto registered not a "trend'' but an unusual change caused by a volcanic eruption. By averaging this data with that of previous years and reporting only slopes of lines, the authors manufactured a trend.
And what about those slopes? Kerr and McElroy report - 4.1% and -1.8% per year for ozone and 35% and 6.7% per year for UV light for winter and summer respectively. These are inverse changes of 8.5 to 1 and 3.7 to 1! Yet the expected inverse ratio for simple absorption of UV light by ozone at 44°N latitude (Toronto) is approximately 1 to 1. (See S. Madronich and F. R. de Gruijl,
Nature, Vol. 366, p. 23 (1993).Kerr and McElroy give these slopes to two significant figures with no error analysis and with no reference to expected ratios. The reasons are obvious. Their data scatter barely justifies one significant figure,
and their calculated ratios differ from expectation by 4 to 8 fold. They obtained their entire "trend'' from one event, ignored the correlations in previous years, and wrote their paper in such a way as to obscure the politically incorrect items they wished to ignore. Select the data you want to see and create a correlation that satisfies your need. Look at their line and their data in the second, 300 nm (3000 Å) plot. There is no upward trend at all in the data for the first four years.
Yet they are certainly not alone. The Madronich and de Gruijl paper from which I obtained the expected ozone to UV light ratio goes on to calculate expected increases in skin cancer to in, some cases, three significant figures! This is done theoretically and assumes incorrectly that the Mount Pinatubo reductions in ozone are permanent.
Does any of this prove that CFCs are harmless or helpful? No. Will we be better off with a little less UV light or a little more? Do CFCs actually have much effect on ozone levels or on UV light levels? The answers to these questions are, as yet, unknown.
We do know that observed fluctuations of ozone and UV light are relatively minor and well within the envelope of natural variations in which we live (as are the changes predicted by the CFC hypothesis).
In the course of time, research will resolve these interesting atmospheric questions which, in any case, clearly do not portend a "crisis.'' Meanwhile, Americans are going to spend several hundred billion dollars eliminating CFCs. That money would buy a lot of airplanes and wonderful cargoes for our imaginary runways.
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Vol. 21, No. 5
Newsletter: Access to Energy Newsletter Archive Volume: Issues Issue/No.: Vol. 21, No. 5 Date: January 01, 1994 02:47 PM (For actual publication date see newsletter.) Title: Cargo Cult Science
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