In April 1991 the National Academy of Sciences released Policy Implications of Global Warming, a report that many say represents a major shift in “official” thinking about the enhanced greenhouse effect. In fact, a close read reveals much greater complexity.
As most academy documents, this is a committee product, and it therefore attempts to accommodate the range of opinion of the participants. Consequently, depending upon which aspects of the report one chooses to emphasize, it can be interpreted either as a very conservative document-emphasizing great scientific uncertainty and recommending modestly expensive policies-or, because it recommends action, as a repudiation of the perceived U.S. policy of caution and forbearance on global warming.
In fact, it is two reports. One is a very cautious summary of the science (or nonscience) surrounding global warming, and the other a series of policy recommendations that are made despite the first section. This dichotomy is hardly surprising, given the makeup of the various subsidiary panels that generated the final document. The chair of the “synthesis panel” was former Senator and Governor Daniel Evans of Washington, and by my best guess only one of the fourteen panel members is a bona fide climatologist by training. Seven may best be characterized as environmental administrators, with a strong bent towards the United Nations.
Committee science is a risky undertaking. Thomas Kuhn’s wonderful Structure of Scientific Revolutions (required reading at my alma mater, the University of Chicago-let it never be deconstructed) demonstrates that science tends to advance when a few individuals exploit inconsistencies in a prevailing paradigm. Doing science by committee is therefore guaranteed to be behind the times, as dissenters are not likely to be represented.
At any rate, on the science side, “[t]he panel concludes there is a reasonable chance of the following:”
Scientific Conclusion #1: In the absence of greater human effort to the contrary, a greenhouse gas concentration equivalent to a doubling of the preindustrial level of CO2 will occur by the middle of the next century.
Where should these “greater human efforts” concentrate? It is the developing nations-not economic powers such as the United States-that are dramatically increasing their contributions of CO2. In fact, the academy report demonstrates that after allowing for our large area and bicoastal population, the United States is the most efficient producer of carbon dioxide per unit of economic output (meaning that we emit the least) in the world. A look at the report’s accompanying table, reproduced here as Table 1, is instructive. The centrally “planned” economies produce the most greenhouse gases per unit of economic output. The United States-with the largest transportation needs of any nation-produces approximately one-third, or 1.0 metric ton/$1,000 GNP, of the centrally planned output of CO2. All of the nations that produce less than the United States are smaller geographically. Japan, often cited for its efficiency, is second from the bottom of the table, but almost all its citizens live near each other, and the country is highly nuclear. France, the cleanest of all, is also the most nuclear and emits .34 metric ton of CO2/$1,000 GNP.
Table 1: Carbon Dioxide Emissions per Units of Economic Output
|Country Emissions (metric tons CO2/year||GNP (billions of $/year)||Emissions/GNP Ratio (metric tons CO2/year)|
a Estimates of GNP for centrally planned economies are subject to large margins of error. These estimates are as much 100 times larger than those from other sources that correct for availability of goods or use free-market exchange rates.
b The emissions/GNP is also likely to be underestimated for centrally planned economies.
Source: National Academy of Sciences, Policy Implications of Global Warming (Washington, D.C.: 1991).
Because of our transportation needs, without nuclear energy it is unlikely that the United States will get much below .75 ton. And even with nuclear energy Americans will still use a lot of cars, trains, and planes to travel long distances, so we probably shall not get much below .5 ton. “Reforestation” is a temporary fix, as mature (nongrowing) trees do not accumulate carbon.
Now how much does this mean in terms of global warming? If we accept the climate models (obsolete ones from the mid-1980s) that fuel the popular vision of catastrophe with their mean global warming of 4.2°C for a doubling of CO2, our reduction would cut global emissions by 10 percent, good for, say a .2°C reduction in warming. (It has to be one-half of the 10 percent figure because the other (non-CO2) greenhouse gas increases account for about 50 percent of prospective warming.) We shall also limit chlorofluorocarbons, as noted below, and that will buy an additional .4°C or so. Under the apocalyptic climate scenario, one would never notice this small a reduction in temperature unless he had been told that it had happened. In fact, some policymakers are finally asking what must be the most politically incorrect question about mitigation of global warming: Is it really worth the effort?
Perhaps the most interesting aspect of all this is that the industrialized democracies should not be the target. They are the most efficient producers of goods and services with respect to carbon dioxide emissions. Rather, the communist nations are the ones that produce the most CO2 per unit of economic output. That will not change until their economies are much more efficient, that is, no longer centrally planned. Thus, action on global warming would be more effective if it involved destabilizing communism abroad rather than imposing collectivist ideals at home.
There is, of course, another means of reducing carbon dioxide emissions in the West: economic stagnation. In a country with the transportation needs of the United States, this could easily be accomplished with a large carbon-based energy tax. Although this seems absurd, the desirability of stagnation was the point of the keynote speech at the Interparliamentary Conference on the Environment chaired by Sen. Albert Gore last year, when the audience was informed that “sustainable economic growth” was impossible to achieve without destruction of the global environment.
Scientific Conclusion #2: The sensitivity of the climatic system to greenhouse gases is such that the equivalent of a doubling of CO2 could ultimately increase the average global temperature by somewhere between 1°C and 5°C.
The operative points here are ultimately and the specified range of temperature. In fact, this NAS report has reduced the lower limit of expected change from previous reports and has broadened the expected range. Translation: The uncertainty about global warming has increased, as has the length of time that warming may take.
Why? If the warming of the past 100 years (.5°C) is taken to be a response to human greenhouse alterations-an argument that is made more often than not in environmentalist literature-the expected warming for a doubling will be only slightly more than a degree-something again that no one would notice unless he was told that it had happened. On the other hand, if very little of the observed slight warming is thought to be from the greenhouse effect (a view that is more prominent in the scientific literature, because much of the warming of the past 100 years was before most of the greenhouse gases were emitted), then the time frame over which warming will take place will be very long-probably long enough to spread it out beyond the political statute of limitations-somewhere around 200 years.
Scientific Conclusion #3: The transfer of heat to the deep oceans occurs more slowly than within the atmosphere or the upper layers of the ocean. The resulting transient period, or “lag,” means that the global average surface temperature at any time is lower than the temperature that would prevail after all the redistribution has been completed. At the time of equivalent CO2 doubling (2050) the global average surface temperature (increase) may be as little as one-half the ultimate equilibrium temperature (increase) associated with those concentrations.
This is an admission that the time to the expected warming of 1°C to 5°C may be very long indeed, for the atmosphere responds in such a way that the second half of the warming will take approximately twice as long as the first half. Translation: if the doubling time for the effective increase in CO2 is 2050, the associated warming would not be fully realized until 2150. Does anyone seriously believe that we are prescient enough now to understand the society and technology that will exist then? Should we alter our way of life dramatically now, when we do not even know that such a world may in fact find adaptation to warming quite easy?
Suppose that this was 1890 and that a paper just published said that a doubling of carbon dioxide would raise the temperature five degrees (such a paper was published by Svante Arrhenius in 1896). If someone said that in the next 100 years, as a result of the intellectual capital generated along with that increase, human life expectancy would increase by 42 percent, corn would routinely yield 150 bushels per acre, and people would fly around in aluminum tubes at 600 miles an hour while listening to a Beethoven symphony played from a box in their shirt pocket, he would have been dismissed as a lunatic. But that is what happened. To say that over the next 150 years similar developments will not take place-including the continued technological control of ecosystems-flies in the face of history. Might it not be a bit cynical of us to compromise future development by purposefully limiting economic growth now?
Scientific Conclusion #4: A rise of sea level may accompany global warming, possibly in the range of 0 to 60 cm. (0 to 24 inches) for the temperature range listed above.
This projection represents a dramatic reduction in estimates of sea level rise from the highly publicized (and scientifically irresponsible) projections of up to 25 feet that were fashionable a decade ago. The reason for this change is that the National Academy of Sciences has finally recognized something long known to mere climatologists: if the polar regions warm slightly, snowfall (and ice depth) increases dramatically. Right now, the winters there average around -40°C, and it is literally too cold to snow. Warm that up a few degrees and the air will hold more moisture, which must fall as snow at those temperatures. Evidence? The Greenland ice cap is growing, and the only air mass that shows significant warming is the Siberian Express-which has warmed up from -40°C to -38°C. This will represent no great loss to Florida citrus.
Scientific Conclusion #5: Several troublesome, possibly dramatic, repercussions of continued increases in global temperature have been suggested. No credible claim can be made that any of these events is imminent, but none of them is precluded.
This is the new argument being generated as climate models cut back their expected warming and the planet itself warms so little: “Yes, but we cannot discount the possibility of surprises in the future.” Try this: imagine a future without surprises.
The chapter “Recommendations” begins, “Despite great uncertainties, greenhouse warming is a potential threat sufficient to justify action now.” The following are recommended:
1. Continue the aggressive phaseout of CFC (chlorofluorocarbons) and other halocarbon emissions and the development of substitutes that minimize or eliminate greenhouse gas emissions.
This is the course that the United States recently proposed to the draft climate treaty meeting in Chantilly, Virginia, last February, because it is the most efficient way to reduce warming emissions in the near term. An additional advantage is that the putative cause of global stratospheric ozone reduction is also eliminated. While this latter issue is somewhat complicated by the fact that the cancer-causing type of radiation that stratospheric ozone blocks is decreasing (it should be increasing) at the surface, chlorofluorocarbons remain a very exotic, long-lived chemical that people will gladly replace if the substitution process is not prohibitively expensive.
2. Study in detail the “full cost social pricing” of energy, with a goal of gradually introducing such a system.
This recommendation has generated the most controversy and with good reason. Among other things, it implies a degree of central command and control of the energy economy that most will find onerous, as well as inefficient. Nonetheless, the operative words here are study and with a goal, which are far short of direct implementation.
3. Reduce the emission of greenhouse gases during energy use and consumption by enhancing conservation and efficiency.
The NAS report calls for such measures as more energy-efficient building codes, improved efficiency of the U.S. automotive fleet (via CAFE and taxation), improving appliance efficiency standards, and “encouraging public education and information programs for conservation and recycling.”
The question remains as to how these programs are to be implemented. It seems that energy efficiency is economically desirable, so is it necessary that the federal government mandate it so? Apparently. The next recommendation says, “The United States should adopt a systems approach that considers the interactions among supply conversion, end use, and external effects in improving the economics and performance of the overall energy system.” Maybe global warming really is the last redoubt of the central planners.
You get the idea. Finally the report suggests that global deforestation should be reduced (which does not mean limiting timber harvests; rather, it means managing forest resources in a way that increasing amounts of carbon dioxide are captured by trees), that we should research how to adapt crops to different climates, and that we should build dams and levees with the consideration that climate does vary, which incidentally it will do with or without the greenhouse effect.
But perhaps the most interesting of the recommendations calls for serious investigation of so-called “geoengineering” to combat climate change, including fertilization of the southern ocean (which is currently limited by iron availability) to stimulate the capture of carbon dioxide, and the possibility that maybe we could enhance cloudiness (and thereby reverse warming) with purposeful emissions.
Why is this so interesting? Because it is an admission that we cannot stop a major warming without draconian economic interference. In fact, if warming is going to be bad-and both the observed data and the climate model suggest more and more that things are looking otherwise-we shall have to actively fight our way out of it with high technology rather than with a foolish and ineffective romance with self-induced poverty.