GLOBAL WARMING WARNINGS: A Lot of Hot Air

The rise in temperature resulting from greenhouse gases predicted for the 21st century is not appreciably different from what has occurred over most of our lifetimes, a period in which a majority of people have enjoyed the prospect of later mortality, better nutrition, and increased wealth.

EVER SINCE June 23, 1988, when NASA astrophysicist James Hansen testified before Congress that there was a "strong cause and effect relationship" between "the current climate and human alteration of the atmosphere," global warming has been the world's premier environmental issue. Concern over it created an international treaty, the Framework Convention on Climate Change, and an international protocol, the Kyoto Protocol, designed to implement the original treaty. Leading up to his run for the presidency, Al Gore had written passionately that it is the number-one issue confronting mankind.

Yet, many converging lines of scientific and economic evidence lead to the inescapable conclusion that global warming is now understood to be a much more gradual, more benign process than originally thought. Further, there is no known way of significantly stopping it. Therefore, it is time to move on to more important global environmental concerns, such as poverty.

There is no doubt that Earth's surface temperature is warmer than it was 100 years ago, but warming per se can be irrelevant. What matters more is how the planet warms. For example, if human-induced warming were largely confined to the cold air of winter, few would argue that the issue would be of sufficient magnitude to invoke the enormous costs required for futile attempts at remediation. If the warming were largely confined to the heat of summer, though, the effect would be dramatically different, with withered crops and increasing drought becoming the norm in a world wherein growing population continues to pressure a finite food supply.

The same logic applies to precipitation. Most mathematical models for human-induced global warming project an overall increase in precipitation, and this has undoubtedly been observed in U.S. records. Is this necessarily a bad thing? What if the seasonality results in more water available for agriculture, while at the same time slightly increasing flood frequency? The trade-off is obvious: Many people benefit more by cheaper food than are harmed by floods, and the latter can be contained infrastructurally with modest effort over a long time.

In considering the nature of observed climate change--both before and after human activity induced significant modifications of the natural greenhouse effect--I would like to note that those who argue for large, net negative consequences have an uphill fight. As the greenhouse effect has enhanced, individuals in free societies have seen their life expectancies double, their food production quintuple, and wealth spread and democratize far beyond even the most optimistic projections of 100 years ago.

There are two distinct warmings of similar magnitude. The more recent one has occurred over the last three decades or so, while the first occurred from 1910 to 1940, and is evident in most regional analyses as well. In particular, this early warming is accentuated at high latitudes, where current United Nations Intergovernmental Panel on Climate Change (IPCC) records of temperatures are clearly averaging no warmer than they were 70 years ago (a fact which should have been made clear during recent news reports about the melting of the Arctic ice cap). The ubiquitous nature of the early warming of the 20th century argues against a human cause. That is because human-induced warming, from increases in greenhouse gases, must be accentuated in cold, dry air. Atmospheric temperature responds logarithmically to an increase in a given greenhouse gas--i.e., the amount of heating is greatest for the first increments.

Carbon dioxide and water vapor are two very important greenhouse gases (the latter accounts for nearly 95% of Earth's natural greenhouse effect) that behave quite similarly. Over a portion of their absorption spectra, they are hard to tell apart in their heating ability. Consequently, an atmosphere with very little water vapor in it responds dramatically to an increase in either water vapor or carbon dioxide. Cold air contains much less water vapor than warm air. Over the range of commonly observed surface temperatures, from -40 [degrees] to +40 [degrees] C, the vapor pressure of water varies by a factor of 1,000. Thus, addition of carbon dioxide to cold air warms that air differentially. Further, the first increments of warming then allow more water vapor to exist (as its vapor pressure increases), resulting in an enhanced warming.

If this is tree, the human greenhouse signal should be especially evident in the coldest air of winter that is away from the ocean--i.e., in Siberia and northwestern Canada. The observed temperature trends in the winter half-year in the last half of the 20th century show that the most dramatic warming is indeed taking place in Siberia, where January temperatures have changed from around -40 [degrees] C to -38 [degrees] C.

Over the Northern Hemisphere, the ratio of winter-to-summer warming since World War II is more than 2:1. Within the winter in the Northern Hemisphere, as much as 78% of the warming is confined to the very cold air masses of Siberia and northwestern North America. In fact, the colder it is, the more it Warms.

Cold air masses that originate in Siberia or northwestern North America are responsible for limiting the growing season in more temperate latitudes when they migrate southward under favorable jet-stream conditions. Consequently, warming their inherent coldness results in longer growing seasons. Research by R.B. Myneni found that satellite data showed the high latitudes "greening up" a week earlier in the 1990s than they did in the 1980s. A study by John Magnuson shows the reflection of this phenomenon in the timing of freeze on lakes and streams. Interestingly, his record also indicates that warming has been occurring for a much longer period than what could have been provoked by human activity.

It is worth noting that the greatest summer warming is in or near the Sahara Desert. This is also the driest location, verifying green-house theory. Enhancing the aridity of the Sahara may be about as ecologically consequential as a thunderstorm over the ocean.

Droughts and floods

The most recent (1996) report of the IPCC was ambiguous concerning changes in rainfall extremes, stating that "Warmer temperatures will lead to a more vigorous hydrological cycle, with prospects for more severe droughts and/or floods in some places and less severe droughts and/or floods in others." There is little doubt that, strictly speaking, this covers every eventuality, allowing one even to blame weather that is more normal than average (i.e., "less severe droughts and/or floods") on global warming. This statement has served as well as cover for the argument that virtually any weather anomaly can be related to global warming, using the scientific authority of the UN. However, what is the history of droughts and floods as the greenhouse effect has changed?

For many decades, the standard measure of drought has been the Palmer Drought Severity Index (PDSI). It is a statistical measure based upon the departure from average moisture conditions for a region--taking into account precipitation, evaporation, temperature, runoff, and soil storage. Note that the index is only a relative measure based upon the averages for a given location. As a result, areas that are normally extremely arid, such as Death Valley, Calif. (average annual rain: 1.89 inches), are not considered in a "drought" unless precipitation is below this already minimal figure.

All of the variables that comprise the PDSI are then statistically normalized. As a result, when the PDSI is one standard deviation below the mean, a location is considered in "moderate drought." Mathematically, this works out to either one-sixth of the nation at a given moment, or one-sixth of the time for a given place. This is clearly a very debatable notion on how to assign drought. It is hard to believe that neither human beings nor natural vegetation are adapted to conditions that occur 17% of the time.

When the PDSI is two standard deviations below its mean, a region is officially in "extreme drought." This should occur about 2.5% of the time, or, at any given time, over 2.5% of the U.S. It is worth noting that this is not a small area, and means that, on the average, some significant portion of the country will be in a drought that is sufficient to merit coverage on the network news.

This, along with abuse of the UN's statement of increased drought frequency, leaves a clear public impression that drought is increasing as a result of global warming. This is simply not the case. There is no increasing trend in the PDSI data.

Stories about "intense rainfall" and floods are similarly easy to conflate with the UN's catchall statement. They have also been distorted in political discourse. On Earth Day, 1995, Vice-Pres. Gore, speaking at George Washington University, said, "Torrential rains have increased in the summer in agricultural regions." He was referring to a then-unpublished paper by climatologist Tom Karl, which found that the percentage of total rainfall falling from two-to-three-inch-per-24-hour storms has increased, with 11% of all the national rain now coming from such storms, as opposed to nine percent 100 years earlier. Average annual rainfall in 1900 was around 31 inches and has risen to 34 inches today. The difference due to these "heavy" rains (two inches of rain in the summer is usually welcome) can easily be calculated at 0.95 inches per year. In other words, more than two-thirds of the increase in national rainfall that has occurred in the last 100 years is from gentle rains.

A more appropriate way to integrate the changes in flooding rainfall would be to examine streamflow in undisturbed catchments, as has been done by U.S. Geological Survey scientist Harry Lins. He found no increase in the frequency of observed flooding, but a decrease in the likelihood of lowest (drought) flow categories. In other words, objective streamflow records show decreased drought with no increase in flooding rains.

Finally, it is worth examining the notion that warmer surface temperatures will lead to increased mortality. Even the conservative Wall Street Journal has written that "intense heat waves alone are by 2050 likely to result in increases in death by cardiac and respiratory ills of several thousand per year." The UN's IPCC, based upon data from several North American cities, maintained that "The annual number of heat-related deaths would approximately double by 2020 and would increase severalfold by 2050."

Because there is little hope of any Congressional legislation that would dramatically decrease greenhouse emissions, linking mortality and human-induced warming has long been the holy grail of those seeking massive regulation. That is because demonstration of a health hazard can justify specific executive orders in the absence of legislation.

Research shows that the connection between warming and mortality in the U.S. is simply wrong. Plotting mortality vs. "effective temperature" (an index that combines temperature and humidity) yields a result that is typical for almost all northern locations: There is an overall decline in deaths as effective temperature increases, and there are few very hot days in which mortality is considerably above the observed trend.

These "mortality excursions" are assumed by the IPCC to increase with hotter temperatures. In fact, though, the connection between death and heat has been declining for decades. In many cities, heat-related death excursions have literally been engineered into oblivion thanks to air-conditioning. Further evidence that the decline in deaths is infrastructural is given in newer, southern cities, which have no mortality excursions at high effective temperature.

There are now literally dozens of detailed computer simulations of how the Earth's climate will change as the greenhouse effect enhances. With very few exceptions, they produce a warming with a similar mathematical form--a straight line--despite exponential increases in greenhouse gas concentrations. The main reason for this, as cited earlier, is that the temperature response to greenhouse gas changes begins to damp off at higher concentrations. Therefore, an exponential increase in concentrations is required to simply maintain a constant warming.

In 1996, the UN Climate Panel said, "The balance of evidence suggests a discernible human influence on global climate." This statement is a reasonable summary of the fact that surface warming has largely been confined to the winter half-year and, within that period, to the coldest air masses.

The warming that has evolved in the last third of a century indeed has been a straight line, despite exponential increases in greenhouse gas concentrations. Moreover, the typical climate models also have straight-line warmings.

Accordingly, it becomes eminently clear that, unless almost all of the climate models are wrong, we already know how and how much the atmosphere will warm. We can expect a rise in temperature from greenhouse gases averaging about 1.4 [degrees] C in this century, with around two-thirds (2 [degrees]) of that warming in the winter and about 1 [degrees] in the summer. This is not appreciably different from what has occurred over most of our lifetimes, a period in which a majority of people have enjoyed the prospect of later mortality, better nutrition, and increased wealth. Global warming has been a profound irrelevancy to the quality of our lives.

To reiterate, global warming is impossible to stop. Even if every nation on Earth lived up to its commitments under the Kyoto Protocol, the change in mean surface temperature would be a mere 0.07 [degrees] C by 2050, as calculated by climatologists from the U.S. National Center for Atmospheric Research. The result is enormous expense with no effect on the climate.

There is little doubt that the greatest correlation in global environmental issues is that between poverty and environmental degradation. How ironic that the Kyoto Protocol--an expensive, failed attempt to stop something that isn't even a problem--will result in a worse environment for us all.

Patrick J. Michaels, professor of environmental sciences, University of Virginia, Charlottesville, is a senior fellow in environmental studies, Cato Institute, Washington, D.C.

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