The following is an excerpt from a recent radio broadcast: “Heat waves are getting hotter and longer and the forest fires are getting bigger and more severe and there seems to be little doubt that the warming earth, caused by greenhouse gas pollution primarily from fossil fuel burning, is warming the earth and that extra warmth is making the heat waves worse and its making the wild fires worse and its making droughts that we are experiencing worse.” Coast to Coast AM, July 26th, 2012 hour 2: Interview with Jonathan Overpeck, Professor, Department of Geosciences and the Department of Atmospheric Sciences, Co-director of the Institute of the Environment at the University of Arizona, Tucson.
The droughts that are occurring this year on the Great Plains are a true calamity, but to blame them on a “greenhouse gas” mediated “greenhouse effect” is improper from a scientific point of view, since the “greenhouse effect” is hypothetical warming said to be caused primarily by water vapor and droughts are caused by a lack of water vapor. Therefore, droughts and the “greenhouse effect” cannot occupy the same space at the same time—one requires the presence of water vapor and the other requires its absence. I say that the “greenhouse effect” causes “hypothetical” warming because I recently completed a simple scientific study that demonstrates that an increased presence of water vapor is accompanied by a decrease in temperatures, but we will go over those results in a minute.
Let me first say that periodic severe droughts are not unique to the Great Plains as Professor Overpeck himself revealed in a paper that he co-authored in 1998: “Historical documents, tree rings, archaeological remains, lake sediment, and geomorphic data make it clear that the droughts of the twentieth century, including those of the 1930s and 1950s, were eclipsed several times by droughts earlier in the last 2000 years, and as recently as the late sixteenth century. In general, some droughts prior to 1600 appear to be characterized by longer duration (i.e., multidecadal) and greater spatial extent than those of the twentieth century.” Woodhouse, C.A. & Overpeck, J.T., 2000 Years of Drought Variability in the Central United States, 1998 Bulletin of the American Meteorological Society 79: 2693-2714
The subject of this article though is not whether or not the earth is warming or whether or not droughts are getting worse around the world. The subject of this article is whether or not such droughts can be caused by a water vapor mediated “greenhouse effect.” According to the “greenhouse effect” hypothesis itself the “greenhouse effect” requires the presence of water vapor to operate. That is, water vapor not only accounts for the majority of the primary “greenhouse warming” in the atmosphere (60-90% depending upon the author) but it also, via “positive water vapor feedback,” is responsible for the much of the hypothetical warming caused by secondary “greenhouse gases” such as carbon dioxide. So, where there is little or no water vapor there can be little or no greenhouse effect. Take, for example the precipitous nighttime cooling seen in a desert mentioned by John Tyndall.
“Whenever the air is dry we are liable to daily extremes of temperature. By day in such places, the sun’s heat reaches the earth unimpeded and renders the maximum high; by night on the other hand the earth’s heat escapes unhindered into space and renders the minimum low. Hence the difference between the maximum and minimum is greatest where the air is driest.
“In the plains of India, on the heights of the Himalaya, in Central Asia, in Australia—wherever drought reigns, we have the heat of day forcibly contrasted with the chill of night. In the Sahara itself, when the sun’s rays cease to impinge on the burning soil the temperature runs rapidly down to freezing, because there is no vapour overhead to check the calorific drain.” Tyndall, John, On radiation: The "Rede" lecture, delivered in the Senate-house before the University of Cambridge, England, on Tuesday, May 16, 1865
a) Little or no water vapor = little or no greenhouse effect
b) Little or no water vapor = drought
Ergo: droughts cannot possibly be caused by the “greenhouse effect” since the “greenhouse effect” is a hypothetical effect caused primarily by water vapor. Where there is enough water vapor in the air to cause said hypothetical “greenhouse effect” then there will be no drought, because it will be cloudy and rainy instead. Ergo, droughts and the “greenhouse effect” are mutually exclusive. Droughts are, in fact, caused by a “greenhouse gas” deficit, i.e., not enough water vapor in the air!
That having been said, here is the study that I did that demonstrates that the presence of water vapor is associated with cooler temperatures not warmer. I downloaded both the daily mean temperature readings and the daily mean relative humidity readings from the National Weather Service for Prescott, Arizona for the period of June 17th through July 17th of 2012 and separated the days between those that had 30% relative humidity and graphed them against one another along with the concomitant mean temperatures and it produced this graph.
Not being satisfied with just one reading I repeated this study for three other cities in the United States and it produced this graph.
In this graph the red bars were the mean temperatures on the arid days and the blue bars were the mean temperatures on the humid days. As you can see all four cities—Prescott, Salt Lake, Las Vegas and Denver—became cooler as the humidity increased. Ergo a water vapor mediated “greenhouse effect” cannot possibly cause warming because when and where water vapor is higher the temperatures are cooler. So again, droughts and the “greenhouse effect” are mutually exclusive since the “greenhouse effect” requires the presence of water vapor to operate and droughts are caused by an absence of ample water vapor. In those climes where there is ample water vapor present in the air there will be no drought, since water vapor eventually condenses into clouds and makes rain. Clouds and rain, in turn, cool the atmosphere as you can see in the above graphs.