By Donella Meadows
–June 25, 1992–
Last January scientists warned that the Northern Hemisphere was about to be visited by a massive ozone hole. The hole never appeared.
The community of Times Beach, Missouri, was abandoned because of contamination with dioxin. Two years ago the Environmental Protection Agency launched a reassessment of dioxin’s toxicity.
Until recently everyone “knew” that acid rain was killing forests. Then a ten-year study concluded that the forests might not be dying of acid rain, or of anything.
Scientific revisions like these are confusing enough to citizens trying to understand what is happening to the endangered — or maybe not so endangered — environment. It doesn’t help when they are exaggerated by people with political axes to grind.
Exaggeration can happen in any direction, but at the moment the ozone, dioxin, and acid rain stories, among others, are being misquoted with many chortles by those who do not want to believe that there are any serious environmental problems. Says columnist George Will, for example, “There is a lengthening list of traumas to the planet that were supposed to have happened, but haven’t.”
There is also a lengthening list of traumas that weren’t supposed to happen, but did, from Chernobyl to Bhopal to the Exxon Valdez. Depending on what you want to believe, you can find plenty of evidence that the planet is facing instant disaster, or that environmental worries are always overblown. Science will provide ammunition for both sides, because science progresses by revision and reversal, seesawing back and forth, eventually zeroing in, everyone hopes, on a stable truth.
Last winter’s failed northern ozone hole, for example, is the first good-news revision in a long time in the ozone story. The fact that human-manufactured chemicals could do anything at all to the stratosphere came as a shock in 1974. The opening of a southern ozone hole astounded scientists in the early 1980s. Since then stratospheric ozone everywhere has been declining faster than scientists predicted.
The warning last winter came because chlorine (the contaminant that eats up the ozone) had built up in the northern stratosphere to levels higher than ever before measured. There was every reason to expect that as the sun returned to trigger the destructive chemical reactions, ozone would plummet. It didn’t, scientists now think, because the winter was much warmer than normal. The ice crystals that enhance chlorine’s action did not form. (Because of global warming? No one knows for sure.)
That reversal does not demonstrate that environmental warnings are wolf-crying. It demonstrates that more than one thing at a time is going on in the atmosphere. The chlorine is still up there. Next year a northern hole might open — or might not.
The dioxin story has reversed itself recently in a bad-news direction. The EPA’s new study of this chemical was undertaken at the behest of the Chlorine Institute. Environmentalists were worried that many uses of chlorine, such as bleaching in paper plants, release dioxin as a byproduct. Industry wanted a review to show that small dioxin releases were no problem.
That was a reasonable request. What was unreasonable was to assume the review would acquit dioxin before the results were in. In fact the new study suggests that dioxin is indeed less immediately toxic to humans than had been believed (though it is intensely toxic to some kinds of animals). Dioxin does not make us keel right over and die, but it appears to more destructive than had been expected, even in low doses, to our long-term health. Dioxin switches genes on and off. It messes up signals in the nervous, immune, and hormonal systems. It causes cancer, birth defects, sterility, diabetes, brain damage. It can lodge in fatty tissues and wreak havoc for years. At least that’s the story so far.
Industry, of course, is not the only political force that exaggerates data. In the early 1980s environmentalists heard reports that first 5 percent, then 20 percent, then 50 percent of European trees were dying. The cause was believed to be acid rain. Trees were dying in U.S. forests too, and U.S. rain was undeniably acid because of sulfur and nitrogen oxides released from coal-burning plants and gasoline-burning cars. Many people leapt to the conclusion that American forests were in imminent danger.
Now a government-financed, ten-year study has concluded that the threat to the forests is not that dire, nor that simple, nor totally dismissable. The trees dying before their time in American forests appear to be those most stressed, highest up, or at the edges of their natural range. The cause may not be acid rain, but other forms of air pollution — or both together.
Trees are slow reactors. Whatever is happening to them may not be fully revealed for decades. Periodic washings in rain 10 to 100 times more acid than usual can use up acid storage capacity in soils, release heavy metals, disturb communities of soil organisms. These changes happen very slowly. The acid rain story is not going to be resolved tomorrow. Meanwhile, just to confuse things, in Europe, where forests are both more polluted and more artificial than in the United States, the die-off stopped for several years, and now seems to have started again. No one knows why.
The point is not that environmentalists are always right, or wrong. The point is that in spite of our impressive science we know so little. “What we know is a drop. What we don’t know is an ocean,” said Isaac Newton. If we had appropriate humility, we would not be exaggerating scientific zigzags in any direction. We would be asking, given our great ignorance, whether we should be conducting massive experiments on our own environment, and by whose decision, and for whose benefit.
Copyright Sustainability Institute 1992