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Testimony to the Foreign Affairs Committee, U.S. House of Representatives

March 9, 1993

Patrick J. Michaels

Associate Professor of Environmental Sciences

University of Virginia

Virginia State Climatologist'

This testimony does not represent any official view of the University of Virginia or the Commonwealth of Virginia, but rather is the personal testimony of Patrick J. Michaels, tendered under the traditional protection of academic freedom.

Thank you for inviting my testimony on the problem of global warming and the enhanced greenhouse effect.

While this hearing is primarily concerned with policy, one must ask an important question before proceeding with that policy: do the facts warrant any considerable expenditure to remediate global warming? I believe that they do not; rather, the facts indicate that projections of the amount and effects of global warming that have been presented to the Congress of the United States have been based upon a forecast that is already failing.

Consequently, my testimony centers around disparities that have arisen between forecasts of global warming and actual observations. The implication is that the political process has intervened in a scientific issue before that science had matured.

Four years ago I testified to the Subcommitee on Energy and Power that the politically popular vision of global warming caused by an enhanced greenhouse effect--ecological and agricultural chaos caused by dramatic daytime heating, and meters of sea level rise--was flawed. I emphasized that the observed data on climatic change had, even then, indicated that projected warming had not occurred in the regions in which it was forecast to be most pronounced. Further, I pointed out that one very reliable set of data (though limited to the coterminous United States) indicated that almost all warming had taken place at night. which is a benign climatic change.

Since my original testimony, I have on several occasions been asked to speak before House and Senate Committees on this subject. In each succeeding testimonial, additional evidence has been presented that bolsters my original view. I believe it is reasonable to state that my original view, once thought of as heretical by some in the Congress, is now becoming a mainstream scientific synthesis of the global warming problem.

Science proceeds by entertaining hypotheses that can be supported by observed data. In the case of global warming, the most refined hypotheses we have are known collectively as General Circulation Climate Models (GCMs). A typical example of this type of calculation, taken from Schlesinger and Mitchell (1986) is shown in Figure 1. The salient features are the projection of overall average warming and the concentration of that warming in the highest latitudes (the polar regions) of the Northern Hemisphere.

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30W 0 30E 60E 90E 120E 150E 180 150W 120W 90W 60W 30W 0 30E

Figure 1. Change in mean temperature calculated for doubling atmospheric carbon dioxide, December-February (Northern Hemisphere Winter). These projections are typical of those of the mid-1980s GCMs.

Together, the mean equilibrium warming predicted by the mid-1980's generation of these models for an effective doubling of atmospheric carbon dioxide (CO2) was 4.2°C. According to data presented on page 246 of the 1990 report of the United Nations Intergovernmental Panel on Climate Change, the earth's mean temperature has never been on target for that projection in the last half-century.

The observed data on global warming therefore have consistently argued that the mean projections of warming were overestimated, both in magnitude, and in societal and ecological effect.

Following are some examples of the differences between forecasts and reality that have arisen:

GCM hypotheses indicate that the Northern Hemisphere should warm more rapidly than the Southern Hemisphere, because land (which predominates in our hemisphere) heats faster than water. Has this been the case?

The top portion of Figure 2 (Idso and Balling, 1991) is a plot of net carbon emissions. This actually underestimates the greenhouse effect enhancement because postwar increases in

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GCMs predict that Northern Hemisphere should warm first and fastest. In fact, the Northern Hemisphere stopped warming at the rate it was warming as the greenhouse enhancement became important.

Temperature Departure (°C)

other greenhouse gases are not included. Nonetheless, the dramatic change after World War II is evident.

The middle graph is the ENSO-corrected Northern Hemisphere ground-based temperature history of Jones et. al., published by the U. S. Department of Energy. A search of the scientific reference, The Citation Index, indicates that scientists refer to their ground-based temperature histories more than to any others. An objective trend line has been placed through the data from when the record begins in 1880 to when the greenhouse enhancement becomes pronounced, and that trend is continued to 1990. Every temperature reading after the greenhouse effect begins its dramatic rise is below the warming trend established before it was enhanced. The net warming in our hemisphere since 1935 is statistically indistinguishable from zero. The Southern Hemisphere continues to warm, although at a somewhat slower pace than it did prior to the greenhouse enhancement.

It is doubtless that some of the warming at the end of these ground-based histories results from increasing urbanization around weather stations rather than true global warming. In fact, if one compares NASA satellite-sensed temperatures since the platforms became operational in 1979 to the ground based records, it is apparent that the satellite sees none of the southern hemisphere warming trend that is in the ground-based record.

Figure 3 details the satellite records, which are now in their 15th year. They have been monitoring global temperature during the period of the most rapid enhancement of the greenhouse effect.

It is apparent that they find no warming. Further, the brief, but sharp cooling from the 1991 volcano Mt. Pinatubo is very evident in the Northern Hemisphere record. While some have stated that a correct prediction of cooling from Mt. Pinatubo would indicate an analogous understanding of global warming, in fact that is not the case. A volcano scatters sunlight and increases atmospheric turbidity, and the concept of what happens to the daytime temperature when the sun goes behind a cloud is not hard to appreciate or forecast. The results of a greenhouse enhancement are much more difficult to comprehend, and in fact the data forces one to conclude that they have been misapprehended.

Rather, the obvious signature of Mt. Pinatubo in the satellite data indicates that the satellite data (rather than the computer forecasts) on global temperatures are correct. There is simply no net warming observed in this record.

In addition, the satellite finds no warming whatsoever in the high latitudes of the Northern Hemisphere, which is the region projected to warm the most. This finding is corroborated by a recent analysis of military records over the same region (Kahl, 1993). Statements that this is consistent with forecasts (See Science News, 1/28/93) are simply in error, as shown by Figure 4.

Temperature Departure (°C)

Northern Hemisphere

1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 YEAR

Figure 4a. Mean Northern Hemisphere temperature as measured by satellite (Christy, 1993). The accuracy of this record is thought to be ±0.01°C. The cooling signature of Mt. Pinatubo is evident, attesting to the reliability of this record.

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Southern Hemisphere

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1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993

YEAR

Figure 4b. Mean Southern Hemisphere temperature measured from satellite.

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