Merchants of doom

Jeremy Rifkin (author of "The Hydrogen Economy"), writing in today's Guardian, blames his fellow Americans for the devastation caused by hurricanes:

Katrina and Rita are the entropy bill for increasing CO2 emissions and global warming. The scientists have been warning us about this for years. They said to keep our eyes on the Caribbean, where the dramatic effects of climate change are first likely to show up in the form of more severe and even catastrophic hurricanes.

[...]

Katrina and Rita, then, are not just bad luck, nature's occasional surprises thrust on unsuspecting humanity. Make no mistake about it. We Americans created these monster storms. We've known about the potentially devastating impact of global warming for nearly a generation. Yet we turned up the throttle, as if to say: "We just don't give a damn."

The problem for doom merchants like Rifkin is that there's little evidence that hurricanes are becoming either more frequent or more severe. Take a look at this table of hurricane strikes to hit the US mainland over the last 150 years, showing the number of hurricanes by decade and the number of major events (Category 3 or greater).

1851-1860.....19.... 6
1861-1870.....15.....1
1871-1880.....20.....7
1881-1890.....22.....5
1891-1900.....21.....8
1901-1910.....18.....4
1911-1920.....21.....7
1921-1930.....13.....5
1931-1940.....19.....8
1941-1950.....24....10
1951-1960.....17.....8
1961-1970.....14.....6
1971-1980.....12.....4
1981-1990.....15.....5
1991-2000.....14.....5
2001-2004.......9.....3


[Source: National Hurricane Center]

If anything, the data indicates a reduction in the number and severity of hurricane strikes since the 1940s. Here's what the AOML's Hurricane Research Division has to say on the issue:

[It] is highly unlikely that global warming has (or will) contribute to a drastic change in the number or intensity of hurricanes. We have not observed a long-term increase in the intensity or frequency of Atlantic hurricanes. Actually, 1991-1994 marked the four quietest years on record (back to the mid-1940s) with just less than 4 hurricanes per year. Instead of seeing a long-term trend up or down, we do see a quasi-cyclic multi-decade regime that alternates between active and quiet phases for major Atlantic hurricanes on the scale of 25-40 years each.

Regardless of the data and contrary to the opinions of experts in the field, a lot of people are blaming Katrina on global warming. We'd do well to remember that many of the people peddling this line, like Jeremy Rifkin, are not members of the evidence-based community but shrill polemicists pursuing their own agenda.

UPDATE
And, talking of shrill polemicists...