Thursday, July 26, 2007

Smell test

William M. Gray of the University of Colorado writes about "Hurricanes and Hot Air" in today's WSJ. Here are the parts I loved most:
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.

One reason may be that the advocates of warming tend to be
climate modelers with little observational experience. Many of the modelers are
not fully aware of how the real atmosphere and ocean function. They rely more on
theory than on observation.

The warming theorists -- most of whom, no doubt, earnestly
believe that human activity has triggered nature's wrath -- have the ears of the
news media. But there is another plausible explanation, supported by decades of
physical observation. The spate of recent destructive hurricanes may have little
or nothing to do with greenhouse gases and climate change, and everything to do
with the Atlantic Ocean's currents.

People who rely on theory and models and who have little observational experience usually get it wrong. Of course. One has to temper the other.