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December 24, 2005

More on Hurricanes

Inevitable cries of global warming

When the inevitable cries went up claiming that the series of abnormally fierce hurricanes leading up to Katrina was linked to Global Warming, I posted findings from Benny Peiser at Liverpool John Moore's University in the UK showing that hurricane intensities were actually greater in the late nineteenth century.

Since then, Dave Schilling has supplied a further take by computing a range of moving averages over the dataset, starting with a 20 year moving average and going up by 5 year increments to 50 years. His results boiled down to showing a period of maximum intensities around 1876, followed by another at 1940--64 years apart. And sure enough, 64 years after that brings us to 2004.

I spent some time in northwest Florida for a while as a boy, in 1953, and one of the things I remember was that people didn't build much by the water because of the hurricane risk. For the most part, the beaches were empty of constructions from one horizon to the other. Things calmed down through the 50s, and it was only then that the southward migrations of retirees began, with the appearances of miles of beach homes, hotels, apartments, condos, and the like. Memories are short, I suppose.

This fits in well with studies by climatologists (as opposed to Global Warming scaremongers) that find the engine driving these cycles to be a mechanism called the Atlantic Multidecadal Oscillation, or AMO, that triggers drought in the western United States while spawning hurricanes in the Atlantic, and can be traced back for something like 500 years, with some researchers putting it as far as two millennia. The findings indicate that the period of intense hurricanes that we've seen beginning can be expected to last for 10 to 20 years, once again occurring as part of a cyclical process that they put at 65-70 years. Full report: Storm frenzy is not an anomaly, but a phase by Bill Coats, St. Petersburg Times, September 13, 2005

Note added December 29, 2005
Henry Palka drew my attention to a piece by Dr. Robert E. Davis at Tech Central Station entitled Climate Cycle or Climate Psychic? describing another recent discovery called the Pacific Decadal Oscillation, which affects conditions in the Pacific Northwest, Rockies, and Desert Southwest, again with a period varies in the range 50 to 70 years. It went through its last swing sometime around 1977-78, and of course the results were blamed on manmade greenhouse gases. But geographers at UCLA, using tree-ring data from a hydrologically sensitive species of pine found in California and Alberta, were able to reconstruct the record all the way back to 993 A.D.

 
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