Un mundo técnico

Interesante reportaje de CNN sobre la polémica sobre las causas de los últimos huracanes que han afectado a EEUU.

Charley, Frances, Ivan and Jeanne tore up parts of Florida last year. After tweaking Florida, Katrina and Rita are wreaking havoc this year along the Gulf Coast from Alabama to Texas.

But don't rush to blame it on global warming, experts warn.

Max Mayfield, director of the National Hurricane Center in Miami, told a Senate subcommittee on Tuesday that we're in a period of heightened hurricane activity that could last another decade or two.( See scientists collect data -- 1:33)

"The increased activity since 1995 is due to natural fluctuations (and) cycles of hurricane activity driven by the Atlantic Ocean itself along with the atmosphere above it and not enhanced substantially by global warming," he testified.

Mayfield's colleague at the National Hurricane Center, meteorologist Chris Landsea, said two recent studies about global warming and hurricanes raise more questions than they answer. He added that the impact of global warming is "minimal for the forseeable future."

Brenda Ekwurzel, climate scientist of the Union of Concerned Scientist National Climate Education Program, told CNN that while global warming might not be causing hurricanes, it already is making them more intense.

"We would never point to a single weather event and blame global warming," she said. "While hurricanes have bedeviled the Gulf Coast region for years, global warming is making matters worse."

Ekwurzel points to recent studies indicating that carbon dioxide is raising ocean temperatures.

"And those warmer oceans are converting low-grade storms into powerful hurricanes," she said. "In short, the warm oceans are like fuel to a hurricane. It's like throwing gasoline on a fire."

The technical name for the engine driving the hurricane cycles is the Atlantic Multidecadal Oscillation, or AMO for short. It can cause droughts in the West and hatch hurricanes in the East.

"This cycle has been repeating back to the Ice Age," Willoughby said. "It's related to changes in the ocean currents that move heat northward. If it's fast, we get a lot of hurricanes."

Studies show the AMO was cool -- and the currents slower -- from 1900 to 1925, warm from 1926 to 1969, cool from 1970 to 1994 and warm since 1995.

And so, to a generation of Americans with little experience with hurricanes, it seems like these monsters are coming out of nowhere.

Gray and Willoughby are among the skeptics who doubt global warming can be blamed for the trend of the past few years. They are joined by the hurricane trackers at the National Hurricane Center.

"We're just entering a busy time here," said Chris Lauer, a meteorologist at the center.

"You see a few decades of slower activity, followed by a few decades of higher oscillation," he said. "Our position is the recent increase in hurricane activity is not caused by global warming."

Gray was more direct. "There are all these medicine men out there who want to capitalize on general ignorance on this subject," he said.

"With all the problems in the world, we shouldn't be dealing with this."

Willoughby believes the debate over hurricanes and global warming is healthy. "It's good for the science," he said.