By Dr. Roy W. Spencer
Even before Hurricane Florence made landfall somewhere near the border of North and South Carolina, predicted damage from potentially catastrophic flooding from the storm was already being blamed on global warming.
Writing for NBC News, Kristina Dahl contended, “With each new storm, we are forced to question whether this is our new, climate change-fueled reality, and to ask ourselves what we can do to minimize the toll from supercharged storms.”
The theory is that tropical cyclones have slowed down in their speed by about 10 percent over the past 70 years due to a retreat of the jet stream farther north, depriving storms of steering currents and making them stall and keep raining in one location. This is what happened with Hurricane Harvey in Houston last year.
But like most claims regarding global warming, the real effect is small, probably temporary, and most likely due to natural weather patterns. Any changes in hurricanes over 70 years, even if real, can easily be part of natural cycles — or incomplete data. Coastal lake sediments along the Gulf of Mexico shoreline from 1,000 to 2,000 years ago suggest more frequent and intense hurricanes than occur today. Why? No one knows.
Unusual things happen in nature sometimes
The Massachusetts Bay Colony in 1635 experienced a Category 3 or 4 storm, with up to a 20-foot storm surge. While such a storm does not happen in New England anymore, it happened again there in 1675, with elderly eyewitnesses comparing it to the 1635 storm.
Until 2017, the United States went 11 years without a major hurricane strike — something that is statistically very improbable. Nine years into that 11-year hurricane drought, a NASA scientist computed it as a 1-in-177-year event.
My point is that nature varies, and unusual things happen sometimes.
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