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Thursday, September 22, 2005

Jets and hurricanes

Peter N. Spotts in the Christian Science Monitor, "Hurricanes are packing more punch":
Around the world, powerful hurricanes - rated Category 4 or 5 - have become more frequent compared with 30 years ago....

Two studies by researchers in the past two months, using slightly different approaches, have reported a noticeable increase in storm strength and in the share of strong storms a season experiences.

One group finds that over the past 35 years, the number of Category 4 and 5 storms has nearly doubled worldwide. In the 1970s, roughly 10 of these catastrophic-level storms occurred each season. Since 1990, the number is up to 18 a season, according to Peter Webster, a Georgia Institute of Technology atmospheric scientist who led the study team.

...The work follows on the heels of a study published in August noting a significant increase in the power of storms since the mid-1970s. This power index shows a near doubling of storms' destructive potential during the past 30 to 40 years, according to Kerry Emanuel, who specialized in tropical meteorology at the Massachusetts Institute of Technology in Cambridge, Mass. The change reflects a combination of more-powerful storms and storms retaining their peak intensity longer than in the past.
As I noted during last year's hurricane season, scientists increasingly tie higher intensity hurricanes to global warming. The BBC recently had a story on this.

Did you know that air traffic is becoming a serious source of greenhouse gas emissions? NRDC's "onearth" published a provocative piece by Jeff Greenwald in Winter 2005:
Carbon dioxide and water vapor make up the bulk of airplane emissions. According to the Edinburgh Centre for Carbon Management, a consulting company that advises businesses and governments on strategies to mitigate climate change, an average commercial flight in the United States releases nearly 1,800 pounds of greenhouse gas, per passenger, into the atmosphere. This seems like an impossibly large number, since a commercial airplane carries only some 10,000 pounds of fuel. But when those exhaust molecules mix with oxygen, the impact soars. To put it another way, a Boeing 747 traveling from New York to London and back exhales some 440 tons of carbon dioxide -- roughly equal to what 80 SUVs cough up during a year of rush-hour driving.

So consider this:
In the early 1990s, contrails were responsible for less than 1 percent of global warming, and aircraft emissions overall contributed 4 percent. By 2050, the effect of contrails will have increased sixfold, and air travel will be responsible for about 17 percent of global warming.
As Johnny Carson used to say, "I did not know that."

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