Greenhouse gases and global warming – In My View

Greenhouse gases and global warming – In My View – Letter to the Editor


In his article “American Primacy: Its Prospects and Pitfalls” (Naval War College Review, Spring 2002), Stephen Walt strongly criticized the Bush administration for its “undiplomatic rejection of the Kyoto Protocol” because it was a unilateral decision to advance U.S. interests. However, nowhere does he address either the urgency (or lack of it) or the effect of ratification on the U.S. economy and national security. The purpose of this note is to examine briefly the science behind the protocol and show that the Bush administration’s decision was the correct one.

The fraction of carbon dioxide ([CO.sub.2]) in the atmosphere has been slowly but steadily increasing since systematic observations began a century ago. Little concern was evident until the mid-1980s, when some researchers suggested that [CO.sub.2] would warm the atmosphere by absorbing infrared radiation emitted by the earth. Environmentalists soon joined on an international scale to clamor for stringent controls on the sources of [CO.sub.2]. The result was the Kyoto Protocol cited above.

The protocol, which is both lengthy and complex, requires large reductions in [CO.sub.2] emissions. (The United States would have to reduce [CO.sub.2] emissions to a level 7 percent below that of 1990 by the years 2008 to 2012–this despite the steady growth of the U.S. population and the phase-out of nuclear power generation.) The “Third World,” including the giants China and India, is exempt. Despite this exemption, Third World countries would, under the terms of the Protocol, accrue “credits” for emissions, which they could sell to the “First World.” In other words, the protocol would become an instrument for transfer of wealth from nations such as the United States to Third World elites, a sort of international welfare scheme under a misleading name.

Carbon dioxide molecules can warm the atmosphere through changes (“excitation”) in their vibrational and rotational properties. (For [CO.sub.2], such excitation occurs in the infrared part of the electromagnetic spectrum, in which the earth is an efficient emitter. Heating of the atmosphere occurs by transfer of energy from [CO.sub.2] to air molecules via molecular collisions.) This compound is not the only atmospheric greenhouse gas, for several others, such as nitrous oxide ([N.sub.2O]) and methane ([CH.sub.4]), are also covered by the Kyoto Protocol. However, water vapor, which cycles through the atmosphere in about a week via evaporation from oceans, lakes, and rivers followed by condensation and precipitation, is far and away the most important greenhouse gas, because it is plentiful in the atmosphere and it strongly absorbs infrared radiation emitted by the earth. Absence from the atmosphere of water vapor would make the entire earth like the Sahara Desert–or, to state it more dramatically, like Mars. In contrast, [CO.sub.2], with a cycle duration of, according to recent analysis, thirty to fifty years, is much less plentiful and absorbs infrared radiation more weakly than does water vapor. The major removal mechanisms for [CO.sub.2] are absorption by vegetation and the oceans.

Other phenomena also strongly influence the heating and cooling processes. For example, clouds formed during the condensation of water vapor reflect sunlight, causing solar radiation reaching the earth to be reduced. Thus, warming of the atmosphere causes increased evaporation of water vapor and more low cloud cover, yielding a “negative feedback” that acts as a thermostat. However, high-altitude (cirrus) clouds tend to trap the earth’s radiation, enhancing the greenhouse effect. To account for all of the phenomena that control atmospheric temperature, one must solve in some manner the various hydrodynamic, thermodynamic, and radiative transfer equations that describe the motion and thermal behavior of the atmosphere. Atmospheric scientists have constructed giant computer programs (“models”) to solve these equations, but they are necessarily limited in their simulation of the real atmosphere. For example, they cannot, perhaps never will, realistically simulate clouds; the oceanic models that must form an esse ntial part of the simulation are quite primitive; and the geometry used in the models is much too coarse grained. (It is interesting to note that the models cannot even predict the present climate.) The early models predicted a temperature rise of 4.5[degrees]C (8[degrees]F) for a doubling of atmospheric [CO.sub.2]. The most recent simulations, made with much-improved models, predict a rise of only about 1.5[degrees]C (3[degrees] F) in the mean atmospheric temperature. In other words, as the models have improved, the predicted temperature rise has steadily decreased.

We know from geologic records, tree rings, and human records that the mean temperature of the atmosphere has varied markedly during the past million years. The most glaring aspect of the record is the series of glacial periods, at least partially associated with the earth’s orbital characteristics, which last on average about ninety thousand years, with “interglacial” periods of about eleven thousand years. A more recent feature of the record is the “little Ice Age,” which lasted from the end of the fourteenth century until about 1850, when began a gradual temperature rise that essentially ended in 1940. This period, which was characterized by low agricultural productivity and frequent famines, may have been due in part to reduced energy output by the sun; sunspot activity was abnormally low during much of the period of low temperature.

The rise in mean atmospheric temperature during this century is often cited as evidence of the warming effect of [CO.sub.2]. Those who cite this “evidence” fail, however, to mention that nearly all of the warming occurred before 1940, as the earth recovered from the “little Ice Age.”

What of the most recent record? Atmospheric temperature measurements are routinely made at airports, in urban areas, at sea, etc. They are also made by balloon-borne radiosondes and (since 1978) by satellites. While the surface measurements do show a small temperature rise (about 0.6[degrees] F since 1980), they are contaminated by the so-called “urban heat island” effect. Urban areas and airports have been emitting greater and greater amounts of heat energy as a result of growing human activity that has nothing to do with the greenhouse effect. Corrections applied to the surface data are unreliable, because a large degree of estimation is involved.

Balloon-borne radiosonde and satellite measurements of the temperature of the “free atmosphere” (i.e., at heights that would capture any heating caused by [CO.sub.2]) are far more reliable. Although the records are characterized by a wild oscillation, one can compute a trend line using standard spreadsheet methods. The observed temperature change decreases slightly with time for the balloon data and is essentially zero for the satellite measurements. The National Academy of Sciences has recognized the conflict between satellite and surface temperature measurements as a major problem with no known explanation.

U.S. energy consumption in 2000 was more than 10 percent larger than in 1990. Thus a 7 percent decrease from 1990 consumption would really mean either a 15 to 20 percent drop below 2000 levels or a very substantial increase in tax rates to purchase “credits” from Third World countries. Despite claims by treaty proponents to the contrary, such a reduction in use would have severe economic consequences, because of the strong dependence of our economy on energy.

William Nordhaus of Yale University has calculated the cost to the world economy of “stabilizing” the climate to be $12.5 trillion (1989 dollars). Since the United States consumes about 25 percent of the world’s fossil fuels, the cost to this nation would be in excess of three trillion dollars, an enormous stress to place on its economy. The national defense would also suffer, because of the enormous fuel requirements for training the armed forces, not to mention those for combat, as in Afghanistan. All this when there is no credible evidence for global warming due to carbon dioxide emissions.


Commander, U.S. Naval Reserve (Retired)

Commander Whitten is a retired NASA research scientist who has performed extensive research in the atmospheres of the earth and other planets. He holds a Ph.D. in physics from Duke University.

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