Are sulfate aerosols responsible for the now‐admitted dearth of warming? In previous testimony I have shown how poorly this argument stands the critical test of the data. Suffice it to say that the record of the three dimensional atmospheric temperature in recent decades does not appear at all consistent with this hypothesis. Instead of repeating that argument, I would simply point out that the southern half of the planet is virtually devoid of sulfates, and should have warmed at a prodigious and consistent rate for the last two decades. Unfortunately, we have very few long‐term weather records from that half of the planet, and almost all come from the relatively uncommon landmasses. However, we do have over two decades of satellite data (Figure 1), adjusted by John Christy for orbital decay and other drifts; it shows no change in temperature whatsoever, although the prominent spike and retreat from the 1998 El Niño is rather striking.
Figure 1. Southern Hemisphere MSU satellite temperatures, drift‐adjusted, from John Christy of University of Alabama, 1/1/79–8/31/99. The sulfate hypothesis implies this zone should be warming rapidly.
The failure of the climate models is much more profound than any error that could simply be corrected by reducing the amount of incoming surface radiation, which is what the sulfate “fix” does. Instead, it is a failure in the vertical dimension that has been occurring for nearly a quarter‐century.
Figure 2 shows the entire concurrency for our three records of “global” temperature, which is limited by the beginning of the satellite MSU data in January 1, 1979. The record is now completing its 21st year.
Our figure shows satellite temperatures, weather balloon temperatures roughly between 5,000 and 30,000 feet, and surface temperatures measured by thermometers. There is an increase in the surface record of 0.15°C/decade. Research by NASA scientists demonstrate that about 0.02°C/decade of this is a result of changes in the sun (Lean and Rind, 1998), leaving a remaining 0.13° C/decade ascribable to human influence or other natural variation. The other two records show no change.
The disparity between the surface, satellite and weather balloon readings is likely to have some basis in reality. The concordance between the satellites and balloons cannot be from chance, so there must be some process occurring in the lowest layers (below 5,000 feet) that is not being picked up in those two records.
Figure 2. Satellite, weather balloon (5,000–30,000 ft.), and surface temperatures since 1/1/79, the beginning of the satellite record.
My research shows that this warming below 5,000 feet is largely confined to the winter half‐year (October‐March in the Northern Hemisphere, April‐September in the Southern); as Figure 3 shows, the ratio of winter‐to‐summer warming is greater than two‐to‐one.
Figure 3. Winter and summer half‐year warming since 1945 shows the dominance of winter temperature change.
Now, when we look at the cold half‐year temperatures in the Northern Hemisphere since World War II, it is apparent that the warming is inordinately confined to Siberia and northwestern North America (Figure 4). These are the two “source regions” for the coldest continental airmasses on earth. Because of their coldness, they are very dry, and because of their dryness they have very little “natural” greenhouse effect and are consequently “warmed” (if changing the temperature from -40° C to -38° C can be called a “warming”!) more rapidly than moist, summer air.
Figure 4. Winter minus Summer warming trends since 1945 show the dominance of warming in Siberia and northwestern North America in winter.
In the winter half‐year, these airmasses occupy around 25% of our hemisphere. Recently published research (Michaels et al., 1999; Michaels et al., accepted) shows that over three quarters of the winter warming is confined to this very cold air. When we compare the average postwar warming in the statistical gridcells that comprise these airmasses to those that don’t, the result is truly stunning. The coldest air is warming up a rate 10 times larger than the remainder of the hemisphere; see Figure 5. That research also proves that the warming is largely confined to the cold air masses, and that the more severely cold they are, the more they warm.
Figure 5. Average warming rate in Northern Hemisphere gridcells that are cold and dry (right) vs. the remainder.
Together, these findings all prove that over the entire concurrency of the surface, satellite and balloon records, there is a warming confined to the bottom 5,000 feet of the atmosphere, but over two‐thirds of it is in the winter, and three‐quarters of that is in the most profoundly cold continental air that we know of. If this is the work of carbon dioxide, carbon dioxide is not a pollutant.
Together, these findings also demonstrate a persistent, damaging, and pervasive error in all climate models, including those that serve as the basis for the Kyoto Protocol.
Figure 6. Warming predicted for today’s change in greenhouse gases and sulfate aerosols by the LLNL model. Note that the entire zone from 5,000 feet to the stratosphere is predicted to have warmed.
Figure 6 shows the projected quarter‐century warming from the Lawrence Livermore National Laboratory (LLNL) climate model incorporating greenhouse warming and sulfate cooling (addition of stratospheric ozone depletion changes the result very little), as originally published by Santer et al. (1996). This finding, more than any other single result, served as the basis for the 1995 IPCC statement that “the balance of evidence suggests a discernible human influence on global climate.” However, there is no reason to single out the LLNL model except for its wide availability; every other one behaves in a quite similar fashion.
The LLNL model and all others are clearly making an egregious error that renders the magnitude of their predictions of global warming virtually useless: They all have dramatically failed to predict what happened between 5,000 feet and the bottom of the stratosphere. This comprises over 80% of the troposphere, or the earth’s active weather zone.
Our chart shows the observed warming in this zone (as published by Santer et al., 1999) for various upper atmospheric records vs. the average warming predicted the current suite of climate models. There is no statistically significant warming in the observed data since the satellite/balloon concurrency in 1979, while the models have an average warming rate of 0.23°C/decade (Figure 7).
Figure 7. Model‐projected average tropospheric warming (left) since 1979 vs. observed values published by Santer et al. (1999).
In other words, the models have been wrong for the last quarter‐century‐the period of greatest greenhouse gas increase‐over 80% of the troposphere.
The atmosphere is a mixed fluid; the behavior in one vertical level depends in part on behavior in others. It is profoundly troubling that, for the last quarter‐century, that projections of surface warming are much closer to observed values, than what has been observed in the remaining 80% of the troposphere. This differential calls into question the validity of any projection, surface or otherwise coming from these models. More important, it indicates that the “sulfate‐greenhouse” paradigm is so inaccurate that it misspecified almost all of the troposphere.
The Ubiquitous Nature of Observed Changes
The National Oceanic and Atmospheric Administration has analyzed postwar temperature trends in the Unites States and found similar results; see Figure 8. The largest warming in the last three decades occurs in winter (January through March) which is the time of year in which severity and presence of the cold high pressure systems that form in northwestern North America largely determine the winter departure from normal. Late summer and early fall temperatures actually show a slight decline.
Figure 8. Seasonal changes since 1966 in the U.S. record, according to the U.S. National Oceanic and Atmospheric Administration.
NOAA has also analyzed U.S. temperatures back to 1895. Even though this record contains some large cities with artificial urban warming there is no statistically significant warming in the overall record (see figure 9).
Figure 9. There is no statistically significant overall warming trend in the record of U.S. temperatures, which is 105 years long.
The record can be broken down decadally, i.e., 1895–1997, 1905–1997, 1915–97, etc…Only one of these combinations shows a significant warming that would exceed the Frye Rule of disqualification for “junk science” (i.e. at the .05 level), and that is the period 1965‐present. The chance that one trend (out of the ten possible ones) would show a warming is statistically common, even at this probability level. It is noteworthy that NOAA, in the report on climate change that served as the basis for figure 8, “chose” the only period (1965–97) in the entire 105‐year record that showed statistically significant warming. Later decadal periods (i.e. 1975–97, or 1985–97) do not; and neither does any earlier period. Perhaps an appropriate question would be to ask why the only such period out of the ten possible ones was selected for analysis and publicity.
An Alternative Interpretation
It is hard for me to believe that the billions of dollars that American taxpayers have invested in climate modeling has produced a completely worthless result with regard to human‐induced climate change. Rather more intriguing is the notion that at least the models have the functional form of the warming right, but instead are indecisive about its magnitude.
Figure 10 shows projected warming from a large family of different climate models. Some increase their atmospheric carbon dioxide at 1% per year, effectively. Others use the U.N. standard of 0.7%, and others have been adjusted for the observed lower rate noted by Hansen (1998). Some have sulfate aerosols in them and others do not.
Figure 10. Output from several representative climate models. Once warming starts, it takes place at a constant rate.
Regardless of all of these varying assumptions about differences in the exponential rate of greenhouse forcing or the presence or absence of sulfates, one clear fact emerges. In general, they are all straight lines. Once greenhouse warming starts, it proceeds as straight line, not as an exponential increase.
What differs between the models is not their functional form‐straight lines‐but the slope (or rate of increase) in those lines. In fact, the mean and standard error of the warming are 0.25°C ± 0.07°C/decade, where the confidence range is at 67%.
Which of these models is likely to be correct? Under the assumption of linearity, nature helps to provide an answer, as global near‐surface temperature has risen as a straight line, too, in the last three decades. The slope since 1968, when warming began, is 0.15°C/decade (Figure 11). This is slightly below the low confidence limit given by the ensemble of models shown here.
Figure 11. The observed linear trend in temperature for the last three decades is lower than the projections of most climate models.
However, Lean and Rind indicate that approximately 0.02°C/decade of recent warming is likely to be caused by solar variation; subtracting away this small amount gives a warming rate of 0.13°C/ten years.
Assuming linearity, this gives a rise of 1.3°C in the next century‐precisely at the midpoint of the range to which I first testified over ten years ago.
Models are also linear with respect to their cold and warm season warmings. Given the differential that we have seen since 1968, the expected winter and summer half‐year warmings work out to 1.45 and 1.15° C, respectively, in the next century.
During this century, we experienced a temperature rise of approximately half of these values. Crop yields quintupled. Life span doubled, in part because of better nutrition. Winters warmed. Growing seasons lengthened. The planet became greener. Increasing carbon dioxide had something to do with each and every one of these. There is simply no logical reason to assume that doing the same, this time in 50, instead of 100 years, will have any different effect in kind. That kind of improvement in the quality of human life could hardly be caused by a “pollutant.”
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