Thursday, September 01, 2005

Has Global Warming Increased the Number and Power of Hurricanes?

Has global warming increased the number and power of hurricanes? No, according to an article from National Review Online:

Has global warming increased the frequency of hurricanes? One of the nation's foremost hurricane experts, William Gray, points out that if global warming is at work, cyclones should be increasing not just in the Atlantic but elsewhere, in the West Pacific, East Pacific, and the Indian Ocean. They aren't. The number of cyclones per year worldwide fluctuates pretty steadily between 80 and 100. There's actually been a small overall decline in tropical cyclones since 1995, and Atlantic hurricanes declined from 1970 to 1994, even as the globe was heating up.

It seems that Atlantic hurricanes come in spurts, or as the National Oceanic and Atmospheric Administration puts it in more technical language, "a quasi-cyclic multi-decade regime that alternates between active and quiet phases." The late 1920s through the 1960s were active; the 1970s to early 1990s quiet; and since 1995 — as anyone living in Florida or Gulfport, Miss., can tell you — seems to be another active phase.

But if hurricanes aren't more frequent, are they more powerful? Warm water fuels hurricanes, so the theory is that as the ocean's surface heats up, hurricanes will pack more punch. An article in Nature — after questionable jiggering with the historical wind data — argues that hurricanes have doubled in strength because of global warming. Climatologist Patrick Michaels counters that if hurricanes had doubled in their power it would be obvious to everyone and there would be no need to write controversial papers about it.

Indeed, if you adjust for population growth and skyrocketing property values, hurricanes don't appear to be any more destructive today. According to the work of Roger Pielke of the University of Colorado, of the top five most destructive storms this century, only one occurred after 1950 — Hurricane Andrew in 1992. An NOAA analysis says there have been fewer Category 4 storms throughout the past 35 years than would have been expected given 20th-century averages.

(Hat tip to Ace of Trump)

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