THE CENTRAL THESIS UNDERLYING Congressman George E. Brown Jr.'s article in the March issue, entitled "Environmental Science Under Siege in the U.S. Congress," is wrong. Brown creates a straw man "empirical science" that he then proceeds to relegate to the status of pre-science. I will demonstrate here the problems with his position with respect to my areas of expertise, which are global warming and the enhanced greenhouse effect.

Brown's denigration of empirical science implies that dynamic models, such as general culation models (GCMs) of our atmosphere, are the arbiters of scientific truth. In fact, nothing could he farther from the truth. Models are merely formal statements of scientific hypotheses. They are verified, rejected, or modified on the basis of observed data. Somehow, Brown finds fault with this normal process of science.

Brown argues further that "science by consensus" is more reliable than "science by individuals" or by small numbers of people. The demographics of climate science dictate that the empirical scientists be relatively few in number compared to the vast modeling community. That's because it takes an army of Ph.D.s to spin up a GCM but only one fellow with a computer to check the GCM results against the data. These data. not the models, are the adjudicators of scientific truth.

The data put forth by a small group usually referred to as "a vocal band of skeptics" Brown's "empirical scientists" have already changed the consensus of scientists" Washington's name for the reports of the United Nations Intergovernmental Panel on Climate Change (IPCC). In 1990. the consensus, as stated by IPCC. was that "[w]hen the latest atmospheric models are run with the present concentrations of greenhouse gases. . . their simulation of present climate is generally realistic on large scales." (1) The skeptics were appalled by this statement because those models had indicated that the planet should have warmed approximately 1.3 to 2.3 Celsius already.(2) The observed warming was actually O.5 deg Celsius. and much of it occurred before the major changes in the greenhouse effect. Skeptics argued that either something was hiding the warming or the sensitivity of the planet to greenhouse changes had simply been overestimated.

The environmental community ridiculed these scientists, and they were subjected to remarkable abuse at a number of congressional hearings. But their arguments, both in and out of the refereed scientific literature, were cogent and persuasive. So much so that by 1996 IPCC acknowledged them as the new consensus: "When increases in greenhouse gases only are taken into account . . . most GCMS produce a greater mean warming than has been observed to date, unless a lower climate sensitivity is used.... There is growing evidence that increases in sulfate aerosols are partially counteracting the (warming) due to increases in greenhouse gases."(3)

Thus the new paradigm: Either something is hiding the warming, or it's not going to warm up very much. The skeptics "a small, vocal band" of "empirical scientists" presaged this new view, as is often the case in science.

This same group of people is now arguing that the "sulfate-greenhouse paradigm," on which the now-infamous United Nation's statement about a "human influence on the climate" is based, is gravely lacking. How are they attacking this paradigm? Again, on the basis of data.

Sulfates do not reside long in the atmosphere. They are also produced primarily in the Northern Hemisphere. The Southern Hemisphere is relatively pristine and should be warming dramatically compared to the Northern Hemisphere. Indeed, a famous paper published in Nature last summer, which looked at vertical atmospheric data taken from weather balloons from 1963 through 1987, found this to be the case.(4)

Empirical scientists were immediately suspicious because our orbiting satellites provide indisputably accurate data for the layer between 5,000 and 30,000 feet just where the Nature paper found dramatic warming and they show a statistically significant cooling since they began recording in 1979, 18 years ago. These data correlate almost perfectly on a year-by-year basis with the data from the weather balloons so much so that there is only a chance of one in 262,144 that they line up by random chance.

Skeptics wondered if the use of the data from 1963 through 1987 was misleading scientists and the public. They then published (also in Nature) the history of the Southern Hemisphere's "hot spot" using all available data from 1958 to 1995. There was a substantial warming trend in 1963-87, which was cited as evidence for the human influence on climate, but the trend disappears completely if all of the data (1958~95) are used. (5)

Other scientists are now busy trying to find reasons for the lack of predicted warming. Soon we'll hear about tropospheric ozone, stratospheric ozone, and gosh knows what else. And pretty soon, the skeptics will find problems with these explanations. Clearly, we are rapidly approaching the default solution: Climate is not as sensitive as was previously thought. (Just wait until the skeptics argue that climate change is largely for the better!)

Yet all the legislation, scare stories, and proposals for massive regulation and taxation can only be supported if the climate threat is large and real. Thus, by demonstrating that it has been overstated, the skeptics have done the nation (including Congressman Brown), the world, and science, a big, courageous favor.

In closing, I would like to note that Congressman Brown's original essay, which was published last fall, is much more aggressive than his Environment article in its attacks on scientists who disagreed with the disastrous global warming paradigm. While I'm sure that this has something to do with the editorial process, perhaps he is also beginning to reconsider his arguments in the light of empirical science.

Patrick J. Michaels
Research Professor of Environmental Science
University of Virginia
Charlottesville

5. P. J Michaels and P.C. Knappenberger, "Human Effect on Global Climate?" Nature 384 (1996): 522-23.

AS CORRECTLY STATED BY Congressman George E. Brown Jr., the key criticism many level against current federal policies is that "costly environmental laws and regulations are passed despite the lack of sound scientific evidence of a real environmental problem."

Acid rain provides a prime example of a case where the policy response ignored sound scientific evidence. After government agencies spent over half a billion dollars on research, some 3,000 scientists from atmospheric physicists to ecologists concluded that acid rain was only a minor problem that posed not threat to human health and that the damage claims hall been vastly exaggerated.(1) Congress simply didn't like this conclusion, considering it "policy irrelevant," and then went on to pass costly legislation to control a problem that was disappearing on its own. As a result of earlier versions of the Clean Air Act, sulfur emissions were gradually declining as older power plants went out of service. Indeed as soon as the Clear Air Act Amendments were signed in 1990, acid rain miraculously and suddenly vanished from public view as media attention dwindled. Is it credible that a "serious" environmental problem can be solved just by printing a law? Does this example give you reason to suspect that other environmental calamities may just be hype?

Brown's article deals mainly with the issue of ozone depletion, which offers a further example of a case where the policy response ignores sound science. A press release intimating an arctic ozone hole that never actually existed provoked the 1992 decision to ban the production of chlorofluorocarbons (CFCs), having effectively panicked both the Senate and the Bush White House. The fear of a 5 percent loss of ozone in the next century provoked the original 1987 Montreal Protocol.(2) With this figure already exceeded, where are the hyped epidemics of skin cancer, cataracts, and immune diseases not to mention the collapse of the ecosystem? And why, as Brown admits, have we no evidence for an increasing trend of ultraviolet (UV) radiation at the surface the presumed cause of all these calamities? No one disputes, however, the tact that UV increases naturally by 10 percent with a 60-mile move toward the equator--the same UV increase that would be caused by a 5 percent ozone depletion. This sort of information puts the "ozone threat" in perspective.

Even more surprisingly, no one questions the U.S. Environmental Protection Agency's (EPA)incredible claims according to testimony offered by assistant administrator Mary Nichols on 1 August and 20 September 1995 that the CFC control program will yield benefits of $32 trillion. Yes, trillion and a benefit-to-cost ratio of 1.000! The real benefits may not amount to much, but one thing is sure: The control costs will be between $30 billion and $120 billion, depending on whether you accept EPA's low estimate or more realistic values.

When it comes to global warming, the situation is not much better. While theoretical models predict a current warming of 0.5 deg (Fahrenheit) per decade, data gathered from highly accurate weather satellites show a global cooling ever since observations began nearly 20 years ago. (The satellite data are not mentioned in the 1996 United Nations Intergovernmental Panel on Climate Chance s (IPCC) "Policymakers Summary", but are referred to briefly in the IPCC report itself on page 147. The discrepancy between the predictions and observations is as yet unexplained.(3) On the basis of such theories, however, the Clinton White House now proposes a control program on the burning of fossil fuels, the cost of which to consumers will dwarf the costs of all other environmental programs lumped together. The administration's plan combines the worst features of rationing and taxation; Congress can perform a great public service by bringing this fact to the public's attention.

In view of this series of disconnects between theory and reality (i.e., between global warming theory and actual temperature observations), it's strange that Brown would attack "empirical science. "Could it be because the observations do not show the results that politicians want--a confirmation of global warming predictions? In any case, if theory predicts one thing and observations show something else, a careful scientist will first make sure that the measurements are correct and then question the theory to see if it includes all essential factors. My own conclusion is that while theoretical climate models are improving, they are still not adequate for policy purposes. It is still a scientific puzzle why climate models do not accurately simulate what is happening in the real atmosphere. According to the IPCC report itself: possible deficiencies in the models may include inadequate treatment of clouds, inadequate treatment of atmospheric water vapor, uncertainties about the effects of aerosols, or perhaps an inadequate treatment of how solar variations influence climate.

I am also struck by the great emphasis on and selective use of the peer-review process in Brown's article and the original staff report. For example, in a research paper that appeared in November 1993 in Science, two Canadian scientists claimed to have observed increases in ultraviolet radiation of as much as 35 percent per year!(4) This claim generated great publicity in newspapers and enthusiasm among supporters of ozone depletion scenarios. We noticed that the statistical analysis had been mishandled, however; using the same data but a correct analysis, we found the trend to be zero. Our technical comment in Science explains the error.(5)

By Brown's reckoning, the faulty paper is considered peer reviewed but our technical comment is not. While we cannot be sure, Science probably pact reviewed our re-analysis more carefully than the original paper. Regardless, I would argue that any publication in a scientific journal that corrects past work with new data or new analysis should be considered peer reviewed.

The moral of this story is that peer review is never perfect. Nor should it be used as a blunt tool against scientific critics, who fulfill a vital function in advancing the scientific process.

S. Fred Singer
President, The Science & Environmental Policy Project
Fairfax, Va.

5. P. J. Michaels. S. F. Singer, and P. C. Knappenberger, "Analyzing Ultraviolet-B Radiation: Is There a Trend?," Science 264 (1994): 1341 42.