Tuesday, July 31, 2007

Hurricane (Non)Activity and GW

William Gray's article on Hurricane Activity and Global Warming at Wall Street Journal Online here:
Some scientists, journalists and activists see a direct link between the post-1995 upswing in Atlantic hurricanes and global warming brought on by human-induced greenhouse gas increases. This belief, however, is unsupported by long-term Atlantic and global observations.

Consider, for example, the intensity of U.S. land-falling hurricanes over time -- keeping in mind that the periods must be long enough to reveal long-term trends. During the most recent 50-year period, 1957 to 2006, 83 hurricanes hit the United States, 34 of them major. In contrast, during the 50-year period from 1900 to 1949, 101 hurricanes (22% more) made U.S. landfall, including 39 (or 15% more) major hurricanes.

The hypothesis that increasing carbon dioxide in the atmosphere increases the number of hurricanes fails by an even wider margin when we compare two other multi-decade periods: 1925-1965 and 1966-2006. In the 41 years from 1925-1965, there were 39 U.S. land-falling major hurricanes. In the 1966-2006 period there were 22 such storms -- only 56% as many. Even though global mean temperatures have risen by an estimated 0.4 Celsius and CO2 by 20%, the number of major hurricanes hitting the U.S. declined.

Mr Gray attributes the 1995 in Hurricane increase in the Atlantic due to the currents strength increasing. The climate modelers don't account for ocean current activity along with the atmospheric activity.

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