The dubious science of the climate crusaders.
by William Happer (from First Things)
William Happer is the Cyrus Fogg Brackett Professor of Physics at Princeton University.
The object of the Author in the following pages has been to collect the most remarkable instances of those moral epidemics which have been excited, sometimes by one cause and sometimes by another, and to show how easily the masses have been led astray, and how imitative and gregarious men are, even in their infatuations and crimes,” wrote Charles Mackay in the preface to the first edition of his Extraordinary Popular Delusions and the Madness of Crowds. I want to discuss a contemporary moral epidemic: the notion that increasing atmospheric concentrations of greenhouse gases, notably carbon dioxide, will have disastrous consequences for mankind and for the planet. The “climate crusade” is one characterized by true believers, opportunists, cynics, money-hungry governments, manipulators of various types—even children’s crusades—all based on contested science and dubious claims.
I am a strong supporter of a clean environment. We need to be vigilant to keep our land, air, and waters free of real pollution, particulates, heavy metals, and pathogens, but carbon dioxide (CO2 ) is not one of these pollutants. Carbon is the stuff of life. Our bodies are made of carbon. A normal human exhales around 1 kg of CO2 (the simplest chemically stable molecule of carbon in the earth’s atmosphere) per day. Before the industrial period, the concentration of CO2 in the atmosphere was 270 ppm. At the present time, the concentration is about 390 ppm, 0.039 percent of all atmospheric molecules and less than 1 percent of that in our breath. About fifty million years ago, a brief moment in the long history of life on earth, geological evidence indicates, CO2 levels were several thousand ppm, much higher than now. And life flourished abundantly.
Now the Environmental Protection Agency wants to regulate atmospheric CO2 as a “pollutant.” According to my Webster’s New Collegiate Dictionary, to pollute is “to make or render unclean, to defile, to desecrate, to profane.” By breathing are we rendering the air unclean, defiling or desecrating it? Efforts are underway to remedy the old-fashioned, restrictive definition of pollution. The current Wikipedia entry on air pollution, for example, now asserts that pollution includes: “carbon dioxide (CO2)—a colorless, odorless, non-toxic greenhouse gas associated with ocean acidification, emitted from sources such as combustion, cement production, and respiration.”
As far as green plants are concerned, CO2 is not a pollutant, but part of their daily bread—like water, sunlight, nitrogen, and other essential elements. Most green plants evolved at CO2 levels of several thousand ppm, many times higher than now. Plants grow better and have better flowers and fruit at higher levels. Commercial greenhouse operators recognize this when they artificially increase the concentrations inside their greenhouses to over 1000 ppm.
Wallis Simpson, the woman for whom King Edward VIII renounced the British throne, supposedly said, “A woman can’t be too rich or too thin.” But in reality, you can get too much or too little of a good thing. Whether we should be glad or worried about increasing levels of CO2 depends on quantitative numbers, not just qualitative considerations.
How close is the current atmosphere to the upper or lower limit for CO2? Did we have just the right concentration at the preindustrial level of 270 ppm? Reading breathless media reports about CO2 “pollution” and about minimizing our carbon footprints, one might think that the earth cannot have too little CO2, as Simpson thought one couldn’t be too thin—a view which was also overstated, as we have seen from the sad effects of anorexia in so many young women. Various geo-engineering schemes are being discussed for scrubbing CO2 from the air and cleansing the atmosphere of the “pollutant.” There is no lower limit for human beings, but there is for human life. We would be perfectly healthy in a world with little or no atmospheric CO2—except that we would have nothing to eat and a few other minor inconveniences, because most plants stop growing if the levels drop much below 150 ppm. If we want to continue to be fed and clothed by the products of green plants, we can have too little CO2.
The minimum acceptable value for plants is not that much below the 270 ppm preindustrial value. It is possible that this is not enough, that we are better off with our current level, and would be better off with more still. There is evidence that California orange groves are about 30 percent more productive today than they were 150 years ago because of the increase of atmospheric CO2.
Although human beings and many other animals would do well with no CO2 at all in the air, there is an upper limit that we can tolerate. Inhaling air with a concentration of a few percent, similar to the concentration of the air we exhale, hinders the diffusional exchange of CO2 between the blood and gas in the lung. Both the United States Navy (for submariners) and nasa (for astronauts) have performed extensive studies of human tolerance to CO2. As a result of these studies, the Navy recommends an upper limit of about 8000 ppm for cruises of ninety days, and nasa recommends an upper limit of 5000 ppm for missions of one thousand days, both assuming a total pressure of one atmosphere. Higher levels are acceptable for missions of only a few days.
We conclude that atmospheric CO2 levels should be above 150 ppm to avoid harming green plants and below about 5000 ppm to avoid harming people. That is a very wide range, and our atmosphere is much closer to the lower end than to the upper end. The current rate of burning fossil fuels adds about 2 ppm per year to the atmosphere, so that getting from the current level to 1000 ppm would take about 300 years—and 1000 ppm is still less than what most plants would prefer, and much less than either the nasa or the Navy limit for human beings.
Yet there are strident calls for immediately stopping further increases in CO2 levels and reducing the current level. As we have discussed, animals would not even notice a doubling of CO2 and plants would love it. The supposed reason for limiting it is to stop global warming—or, since the predicted warming has failed to be nearly as large as computer models forecast, to stop climate change. Climate change itself has been embarrassingly uneventful, so another rationale for reducing CO2 is now promoted: to stop the hypothetical increase of extreme climate events like hurricanes or tornados. But this does not necessarily follow. The frequency of extreme events has either not changed or has decreased in the 150 years that CO2 levels have increased from 270 to 390 ppm.
Let me turn to some of the problems the non-pollutant CO2 is supposed to cause. More CO2 is supposed to cause flooded cities, parched agriculture, tropical diseases in Alaska, etc., and even an epidemic of kidney stones. It does indeed cause some warming of our planet, and we should thank Providence for that, because without the greenhouse warming of CO2 and its more potent partners, water vapor and clouds, the earth would be too cold to sustain its current abundance of life.
Other things being equal, more CO2 will cause more warming. The question is how much warming, and whether the increased CO2 and the warming it causes will be good or bad for the planet.
The argument starts something like this. CO2 levels have increased from about 280 ppm to 390 ppm over the past 150 years or so, and the earth has warmed by about 0.8 degree Celsius during that time. Therefore the warming is due to CO2. But correlation is not causation. Roosters crow every morning at sunrise, but that does not mean the rooster caused the sun to rise. The sun will still rise on Monday if you decide to have the rooster for Sunday dinner.
There have been many warmings and coolings in the past when the CO2 levels did not change. A well-known example is the medieval warming, about the year 1000, when the Vikings settled Greenland (when it was green) and wine was exported from England. This warm period was followed by the “little ice age” when the Thames would frequently freeze over during the winter. There is no evidence for significant increase of CO2 in the medieval warm period, nor for a significant decrease at the time of the subsequent little ice age. Documented famines with millions of deaths occurred during the little ice age because the cold weather killed the crops. Since the end of the little ice age, the earth has been warming in fits and starts, and humanity’s quality of life has improved accordingly.
A rare case of good correlation between CO2 levels and temperature is provided by ice-core records of the cycles of glacial and interglacial periods of the last million years of so. But these records show that changes in temperature preceded changes in CO2 levels, so that the levels were an effect of temperature changes. This was probably due to outgassing of CO2 from the warming oceans and the reverse effect when they cooled.
The most recent continental ice sheets began to melt some twenty thousand years ago. During the “Younger Dryas” some 12,000 years ago, the earth very dramatically cooled and warmed by as much as 10 degrees Celsius in fifty years.
The earth’s climate has always been changing. Our present global warming is not at all unusual by the standards of geological history, and it is probably benefiting the biosphere. Indeed, there is very little correlation between the estimates of CO2 and of the earth’s temperature over the past 550 million years (the “Phanerozoic” period). The message is clear that several factors must influence the earth’s temperature, and that while CO2 is one of these factors, it is seldom the dominant one. The other factors are not well understood. Plausible candidates are spontaneous variations of the complicated fluid flow patterns in the oceans and atmosphere of the earth—perhaps influenced by continental drift, volcanoes, variations of the earth’s orbital parameters (ellipticity, spin-axis orientation, etc.), asteroid and comet impacts, variations in the sun’s output (not only the visible radiation but the amount of ultraviolet light, and the solar wind with its magnetic field), variations in cosmic rays leading to variations in cloud cover, and other causes.
The existence of the little ice age and the medieval warm period were an embarrassment to the global-warming establishment, because they showed that the current warming is almost indistinguishable from previous warmings and coolings that had nothing to do with burning fossil fuel. The organization charged with producing scientific support for the climate change crusade, the Intergovernmental Panel on Climate Change (IPCC), finally found a solution. They rewrote the climate history of the past 1000 years with the celebrated “hockey stick” temperature record.
The first IPCC report, issued in 1990, showed both the medieval warm period and the little ice age very clearly. In the IPCC’s 2001 report was a graph that purported to show the earth’s mean temperature since the year 1000. A yet more extreme version of the hockey stick graph made the cover of the Fiftieth Anniversary Report of the United Nation’s World Meteorological Organization. To the surprise of everyone who knew about the strong evidence for the little ice age and the medieval climate optimum, the graph showed a nearly constant temperature from the year 1000 until about 150 years ago, when the temperature began to rise abruptly like the blade of a hockey stick. The inference was that this was due to the anthropogenic “pollutant” CO2.
This damnatia memoriae of inconvenient facts was simply expunged from the 2001 IPCC report, much as Trotsky and Yezhov were removed from Stalin’s photographs by dark-room specialists in the later years of the dictator’s reign. There was no explanation of why both the medieval warm period and the little ice age, very clearly shown in the 1990 report, had simply disappeared eleven years later.
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