By William D. Balgord
The severity of this year’s heat wave and drought, compared with that of 1934 and 1936, is in some dispute. Let’s explore whether the 2012 record supports the idea of a dramatically warming planet.
The underlying cause of the 2012 heat wave, like those of the 1930s Dust Bowl, has been a persistent ridge of high-pressure running northward from Mexico to Canada. The blocking pattern forms in response to cooler than normal ocean water off the coast of California. As a result, fewer and weaker storms moved inland from the Pacific across the continental United States throughout the summer.
The droughts of the previous century — 1988, 1956, especially the extended 1930s — dwarf 2012. Based on the Palmer Drought Index, 60 percent of the nation has been abnormally dry or experiencing extreme drought. But at its maximum, the 1930s mega-drought encompassed more than 85 percent of the contiguous United States.
Most state all-time high records had been set by 1939, with the greatest number (statistical mode) in 1936. Fourteen states established their all-time highs during the infamous heat wave of July 1936 that killed more than 5,000 U.S. residents. Keokuk had already recorded 118 degrees Fahrenheit, the state’s all-time high, on July 20, 1934. Peak highs fell short of these marks in 2012.
With July 2012 on the books, a record U.S. monthly average high was announced by the National Climatic Data Center. But the ubiquitous satellite temperature record does not show this July to be warmer than those in earlier years of the past decade. Contradiction begs explanation.
In his August Senate testimony, John Christy, director, Earth System Science Center for the University of Alabama, points out that NCDC calculated the records using a data set known as T-mean. No longer does NCDC base its inter-annual comparisons of heat waves on maximum temperature alone. Instead T-mean is calculated by averaging the high and low temperatures recorded at a particular weather station on a given date. This procedure sounds reasonable until the underlying climatology is examined.
T-max accurately reflects the maximum observed in midafternoon when the lower atmosphere is well mixed and offers a “representative sample” of air around the station. T-Min is observed at or just before dawn. In rural settings, the early observation is a good indication of the true temperature at the site, but only near the ground.
When residential and commercial development encroach on a station, it no longer produces representative data. As a result, disturbed airflow patterns cause warmer air aloft to mix in with that cooled by overnight radiation at ground level. Thus, T-Min and also T-mean are progressively contaminated with a positive bias.
The “record high” temperature of July 2012 reflects in part the overarching influence of urbanization. If, for example, records of July 1936 had been affected to the same degree by urbanization, the new U.S. record of July 2012 would have fallen far short.
Warmists dismissed the recent cold winters of this decade as “just weather.” Should we believe that the comparatively warm 2012 winter and recent U.S. heat wave signal catastrophic climate change? While much of the U.S. sweltered in triple digits, our Olympic athletes opened the 2012 games in abnormally chilly and wet England.
About the only places around the globe where summer temperatures were much above normal were the eastern two-thirds of the U.S. (approximately 1 percent of Earth’s surface) and southeastern Greenland.
The 2012 U.S. heat wave was not global in extent, nor was it real evidence of “global warming.”
William D. Balgord of Waukon has a Ph.D. in geochemistry, has researched climate change for more than a decade and heads Environmental & Resources Technology Inc., a consultant firm. Comments: E&RT email@example.com