With few exceptions, reactionary environmentalists have adopted their beliefs and values not because of science but in spite of it. The reactionaries are not averse to using the authority of science when the findings of scientific studies happen to fit. But when their beliefs are at odds with the scientists, they simply ignore science. Progressives know that any intelligent environmental policy must be based on scientific facts. And when progressives take a close look at the facts, they find the reactionaries are often wrong.
Case Study: Acid Rain. One controversial provision of the new Clean Air Act seeks to reduce the amount of acid rain in order to reduce the acidity of our lakes. Its regulations are based on the assumption of a lengthy causal chain: Midwestern utility companies burn coal, which releases sulphur dioxide, which is carried across the continent by wind. The sulphur dioxide accumulates in clouds and is deposited in lakes and streams in places as distant as the Northeast and Canada by "acid rain."
Fortunately, the theory is mostly wrong. Beginning in 1980, the federal government funded a ten-year, $500 million study of acid rain, the National Acid Precipitation Assessment Program (NAPAP).  It was the most comprehensive study ever conducted on a single environmental issue. Its principal finding: acid rain has very little impact on the acidity of lakes.
Although all rainfall is naturally acidic, some man-made emissions, primarily oxides of sulphur, can increase the acidity of rain, fog or snow. 
Yet there is almost no correlation between acid rain and acid lakes.
Instead, almost 80 percent of the acidity in lakes is caused by the acidity of nearby topsoil.
Lakes and streams get more than 90 percent of their water not from rain but from surface runoff, which is filtered through topsoil around the lake. The topsoil can become acidic because of a natural buildup of decayed and decaying vegetation. The myth that acid rain is the chief culprit is disproved by evidence collected in this country and around the world. [See Figure IX.]
Rain in Florida is only one-sixth as acid as rain in the Adirondacks, yet the concentration of acid in Central Florida lakes is six times higher than in Adirondack lakes.
Frazier Island in Australia receives no man-made emissions, yet 78 percent of its lakes and 98 percent of its surface water are highly acidic.
A major conclusion of the NAPAP study is that the approach taken under the new Clean Air Act is an expensive way to accomplish very little:
If the proposals cut sulphur emissions by 50 percent, we would have to wait decades for any observable effect, and the cost would be in excess of $100 billion.
Even then, NAPAP estimates that only about 80 lakes would improve.
By contrast, scientists can reduce the acidity of lakes directly by using crushed limestone. We can neutralize all the acid lakes in the Northeast, whether the acidity is natural or caused by man, by liming at a cost of only $500,000 per year. 
Case Study: Global Warming. For years, the most extreme alarmists have warned that a significant increase in average temperatures would cause ecological disaster. Some have suggested that palm trees would grow in Canada, tropical rain forests would become deserts, the ice caps would melt, coastal regions would be flooded, major crop-growing regions of the world would experience recurrent droughts, and hurricanes would become more frequent and destructive. U.S. Senator and presidential candidate Albert Gore, Jr. even compared global warming to the Holocaust.  Are these predictions justified?
Many of the climate modelers who made dire predictions about global warming a few years ago have substantially changed their tunes:
Whereas in 1988 global warming theorists were predicting a temperature rise (from doubled carbon dioxide in the atmosphere) of between 4.5 and 6.0 degrees Celsius, the most likely projection now is 1.5 degrees; and the respected Max Planck Institute is predicting only 0.7 degrees. 
Whereas the climate modelers in 1980 were forecasting an increase in sea level of 30 feet, that forecast fell to three to five feet by 1988, and the current worst-case forecast is only 12 inches. 
New evidence shows that the polar ice caps are growing, not melting, and almost all of the warming at the poles is occurring during the polar winters, when no melting can occur. 
New research on hurricanes shows that they are not produced by global warming and, if anything, warmer temperatures make hurricanes less severe. 
Most of the warming so far has occurred at night, reducing the number of frosts and increasing the growing season for farmers – 1990, one of the warmest years in recent history, was year for crops. 
Moreover, as scientists look more closely at temperature data, the evidence of warming is becoming more elusive:
In the U.S., which has the best climate records in the world, data adjusted for urbanization show no statistically significant temperature increase in the 48 contiguous states over the last century.  [See Figure X.]
Similarly, new urban-adjusted temperature records in Europe and Canada show no evidence of global warming there. 
A recent MIT study shows no significant warming in ocean temperatures over the past 120 years. 
Satellite measurements of global temperature, which are not distorted by their surroundings, show no warming trend over the past decade.  [See Figure XI.]
In the scientific community, there is a debate over global warming. Media coverage tends to assume the debate is between those who say climate will change and those who say it won't. This is misleading. The actual debate is between those who argue that there will be a large and catastrophic increase in global temperatures and those who believe that any climate change will be quite small, generally beneficial and possibly indistinguishable from normal climate variability. Increasingly, scientists are moving toward the latter position, yet most media reports remain wedded to the idea of an apocalypse.