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DERRICK Z. JACKSON

Global warming? You better believe it

AS THE MEDIA screams about the one-two punch of Hurricanes Katrina and Rita, the question becomes how many more times does America need to be knocked to the canvas before we answer the bell on global warming.

The only talk from our leaders is about rebuilding. In his address to the nation from a ghostly New Orleans, President Bush said, ''When one resident of this city who lost his home was asked by a reporter if he would relocate, he said, 'Naw, I will rebuild but I'll build higher.' That is our vision of the future, in this city and beyond. We will not just rebuild, we will build higher and better."

It figures that Bush would talk about building higher in the lowest city in the United States, in a presidency where he has ignored the rising waters of the planet. He said, ''Americans have never left our destiny to the whims of nature and we will not start now."

Actually, there is no better time to start understanding that nature is at the mercy of our whimsy. Our destiny depends on it.

In this tragic season of hurricanes, research continues to increasingly tie global warming to an increase in the intensity of tropical storms.

One was published last month in the journal Nature by Kerry Emanuel, a professor of atmospheric science at the Massachusetts Institute of Technology. Another was published last week in the journal Science by atmospheric researchers at Georgia Tech and the National Center for Atmospheric Research.

While there has been no increase in the actual number of storms worldwide, the Georgia Tech/NCAR study found the number of hurricanes that reached categories 4 and 5, with winds of at least 131 miles per hour, have gone from comprising 20 percent of hurricanes in the 1970s to 35 percent today. This is with only a half-degree centigrade rise in tropical surface water temperatures.

The percentage of big storms in the North Atlantic has increased from 20 percent to 25 percent. The rise is much worse in the rest of the world, where millions of less fortunate people cannot flee the coast in SUVs on interstate roads.

In the 1970s, no ocean basin saw more than 25 percent of hurricanes become a 4 or 5. Today, that percentage is 34, 35, and 41 percent, respectively, in the South Indian, East Pacific, and West Pacific oceans. The biggest jump was in the Southwestern Pacific, from 8 percent to 25 percent.

Emanuel, who formerly doubted that hurricane intensity was tied to global warming, said that he was stunned when his research showed that just that half-degree rise in tropical ocean temperatures has also seen a 50 percent rise in average storm peak winds in the North Atlantic and East and West Pacific in the last half century.

The accumulated annual duration of storms in the North Atlantic and the western North Pacific has shot up by 60 percent.

''I wasn't looking for global warming," Emanuel said by cell phone in Spain where he is conducting research on Mediterranean storms. ''But it stuck out like a sore thumb."

Emanuel originally thought that a half-degree rise in ocean temperatures should have resulted in wind speeds much lower than that. Emanuel said he hoped the more recent findings would be taken as a signal for action. The average hurricane, he said, releases the equivalent of worldwide electrical capacity. Hurricanes Katrina and Rita are 10 times stronger.

Not surprisingly, these new findings have drawn skepticism from scientists who cling to past climate models and flat denials from a Bush administration that has all but censored serious talk about global warming.

The National Oceanic and Atmospheric Administration's website says, ''The strongest hurricanes in the present climate may be upstaged by even more intense hurricanes over the next century as the earth's climate is warmed by increasing levels of greenhouse gases,"

But Max Mayfield, director of NOAA's National Hurricane Center, testified this week before a Senate committee that increased hurricane activity ''is due to natural fluctuations" and is ''not enhanced substantially by global warming."

The one-two punch of Katrina and Rita does not yet have us reaching for the smelling salts. We are still waiting for global warming to hit us below the belt.

Derrick Z. Jackson's e-mail address is jackson@globe.com.

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