Curbing global warming: is the cost too high?

USA Today (Society for the Advancement of Education), July, 1998 by Murray L. Weidenbaum

"... A carbon tax sufficient to stabilize emissions at 1990 levels by 2010 would slow down real wage growth, worsen the distribution of income, and make Americans feel as if they were living through the oil price shocks of the 1970s and early 1980s all over again."

The most controversial environmental issue facing the U.S. today is hot to respond to the pressure to fight global warming by substantially reducing emissions of carbon dioxide ([CO.sub.2]), the leading greenhouse gas. This was demonstrated anew at the meeting in Kyoto, Japan, in December, 1997, to sign a successor treaty to the United Nation's voluntary 1992 Framework Convention on Climate Change, with much of the responsibility being placed on the developed nations to to cut their use of fossil fuels.

It is with some reluctance that I suggest that, before acting, we should examine both the seriousness of the problem and the feasibility of the suggested solution. On the surface, my proposal would not seem to be exactly outrageous.

However, it is used to have to acknowledge that we in the U.S. have reached the point where it is personally--and professionally--dangerous, if not foolhardy, to criticize in any way any proposal to "do more for the environment." Just raising a question is guaranteed to result in the intrepid individual being castigated as caring more about dollars than ecology and having his or her viewpoint dismissed as defending "the polluters." I will save for another day the task of explaining why each of us is a "polluter," either as a producer, a consumer, or both.

Nevertheless, let us begin by examining the question of global warming or, to use the more neutral (also more ambiguous) term, climate change. Proponents of quick action rely for support on a widely quoted passage from a 1995 report of the UN's Intergovernmental Panel on Climate Change (IPCC), an impressive group of scientists and government officials: "The balance of evidence suggests that there is a discernible human influence on global climate." That is such a modest and vague statement that one has to wonder why people rely so heavily on it to support specific proposals for action.

In fact, that modest statement on "discernible human influence" is preceded by a caveat which is quoted far less widely: "Our ability to quantify the human influence on global climate is currently limited because the expected signal is still emerging from the noise of natural variability and because there are uncertainties in key factors." The report then goes on to tell about those technical uncertainties.

Yet another shortcoming of the IPCC summary has been identified. Normally, a summary conforms to the body of the report. Apparently, that was not the procedure followed by those who edited the document. It seems that the editor, after writing the summary, went back and deleted sections of the report that did not conform to it. Here are two of the deletions: "None of the studies cited above has shown clear evidence that we can attribute the observed [climate] changes to ... increases in greenhouse gases." Also, "No study to date has positively attributed all or part [of the climate change observed to date] to anthropogenic causes."

My understanding of all this is that knowledgeable scientists, including those who advocate tough action, admit that great uncertainty exists in the chain of causation from emissions of [CO.sub.2] by human (anthropogenic) activities to increases in global temperature. This relationship is far from simple.

It is not a question of totally eliminating humanly generated greenhouse gases. It clearly is a matter of degree; a slight warming may result in agriculture becoming more productive, for example, but very substantial emissions may lead to genuine harm. Moreover, climate changes due to natural causes may swamp the anthropogenic influences. Historically, of course, the Earth's climate has changed dramatically with no help or interference from mankind.

We also need to raise a troublesome side issue: Why focus so heavily on [CO.sub.2]? After all, it is not the only greenhouse gas. There are others that humans put into the atmosphere, notably methane, the second largest source of such emissions. Yet, scientists tell us that [CO.sub.2] persists much longer than methane and therefore, it is the most worrisome source of greenhouse gases. So far, less attention has been given to nitrous oxide, another long-lasting greenhouse gas. If all this gets across the notion that global climate analysis is not a neat, pat, fully accepted matter, that is surely correct.

In this century, the bulk of the modest warming that has occurred preceded the bulk of the buildup of the greenhouse gases. (Logic would lead us to expect that, if the gases caused the warming, the sequence would be the other way around.) Moreover, weather satellites seem to show a mild cooling trend since 1979, which could be a normal recovery from a previous natural warming. However, we're told that this is too short a period to worry about. In any event, the Earth's temperature appears to have risen by about one degree over the past century.