GLOBAL warming crusaders like to say science is “settled” and only members of the Flat Earth Society doubt their theories. But to accept that claim, citizens must ignore centuries of weather data, as was made clear at a recent U.S. House subcommittee hearing.
In recent years, global warming believers have typically described every major weather event — whether drought, ice storm, tornado, or hurricane — as both “unprecedented” and an outcome of man-made climate change. Yet John R. Christy, distinguished professor of Atmospheric Science at the University of Alabama in Huntsville, warned lawmakers such conclusions are largely unsupported, with many claims based on as little as 50 years of data instead of centuries.
Where long-term data is available, it often undermines portrayals of recent weather events as unnaturally extreme. Christy noted “our nation experienced droughts in the 12th century, the so-called megadroughts, which were much worse than any we've seen in the past century.”
A 500-year history of moisture in the upper Colorado River basin actually “indicates the past century was quite moist” compared to other centuries. From 3,000 to 1,500 years ago, Christy noted, the Great Plains were so dry “a significant parabolic sand dune ecosystem developed,” particularly in western Nebraska and northeastern Colorado.
“In other words, parts of the Great Plains resembled a desert,” Christy said. Similar drought reoccurred during Medieval times (900-1300 AD) before the “climate moistened and cooled beginning around 1300 AD to support the shortgrass prairie seen today ...”
In the Antarctic, a reconstruction of 308 years of temperature variations (from 1702-2009) using stable isotopes found a recent warming trend, but also showed “this warming trend is not unique.” More dramatic warming and cooling trends occurred in the mid-19th and 18th centuries.
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