Was Global Warming Behind Hurricane Season 2004?
- Was Global Warming Behind Hurricane Season 2004?
June 22, 2005
Reporting by Shauna Dineen
Rising ocean surface temperatures in the tropical north Atlantic are
resulting in increased amounts of moisture in the atmosphere, reports
climate expert Kevin Trenberth of the National Center for Atmospheric
Research in Colorado. It is this excess moisture, according to
Trenberth, which is responsible for brewing up this past hurricane
Trenberth's study, "Uncertainty in Hurricanes and Global Warming,"
published in the June 17 issue of Science, explains that atmospheric
water vapor levels have increased by five percent over the last
century. Given present models, Trenberth's study predicts that there
will be a seven percent increase in moisture in the atmosphere for
every degree Celsius that the air temperature rises. "Trends in human-
influenced environmental changes are now evident in hurricane
regions," Trenberth says.
The climate shift and resulting rising atmospheric moisture levels is
truly bad news for the southeastern U.S., as according to Trenberth,
it most likely means a longer hurricane season. It most definitely
promises more rain, which equals more flooding, damage, and rising
storm damage costs.
Article published Jun 17, 2005
Climate expert predicts stronger, wetter storms
The scientist says warmer ocean waters are the cause.
By CATHY ZOLLO
A pair of scientists say that warmer oceans -- the result of global
warming -- will likely lead to more damaging hurricanes in the future.
Climatologists can't yet tell if there will be more storms, but
rising ocean temperatures will likely affect hurricanes in two ways,
Kevin Trenberth, a climate expert with the National Center for
Atmospheric Research reported Thursday in the journal Science.
Warmer ocean waters will likely allow for more thunderstorms that
could lead to hurricanes in areas that typically produce them. And
warmer waters also mean that once a hurricane takes shape, it will
have more fuel to grow and will take in more moisture.
The climate shift also likely means a slightly longer hurricane
season and stronger storms early in the season.
But that doesn't mean every storm will be a monster, Trenberth said.
While sea surface temperature is probably the most important
ingredient in determining a storm's strength, other factors come into
One is wind shear high in the atmosphere that might slice off the top
of a growing storm.
"It's sort of like if you are in the bathtub watching the water going
down the drain, and you move your leg," he said. "You'll knock it
out, and it'll take a few minutes to form again."
Trenberth said Tropical Storm Arlene, the first of the 2005 Atlantic
season, and Hurricane Catarina, which formed in March 2004 off
Brazil, a place where hurricanes aren't supposed to form, are other
indications of the change that could be under way.
Hurricanes have a natural intensity limit. But researchers at the
NOAA's Geophysical Fluid Dynamics Laboratory in Princeton, N.J., say
global warming will likely intensify storms by about half a category
over the next 80 years.
"You move to a warmer climate where there are warmer sea surface
temperatures, and that upper limit will increase," said Tom Knutson,
a research meteorologist with the lab.
And while more powerful winds are part of the picture, Trenberth said
the bigger problem will be flooding because future storms will dump
"It's not just about the hurricane itself or even the strength of the
winds," Trenberth said. "It's every bit as much about the rainfall
and the flooding."
Globally, the amount of water vapor in the atmosphere has risen 5
percent over the last century and 10 percent in the area where
hurricanes form, Trenberth said.
More moisture in the storm means more rain when a hurricane or
tropical storm makes landfall.
Trenberth says it's bad news for coastal communities and inland ones
The tiny town of Cruso, N.C., is a case in point.
When most people think of Hurricane Ivan's devastation, they don't
think of the town that sits near the Tennessee state line, hundreds
of miles from the Gulf of Mexico coast where Ivan struck land.
After blowing across Florida and Alabama and heading north, Ivan
dumped 17 inches of rain on the North Carolina town, causing
flooding, closing roads and washing out bridges. Of the 92 deaths
directly attributed to Ivan, eight were in North Carolina and 14 were
Climatologists say with global warming, coastal cities and places as
far inland as Cruso ought to prepare for stronger, wetter storms like
Ivan in years to come.
According to the Federal Emergency Management Agency, the five
hurricanes that hit the United States in 2004, four in Florida and
one in Gaston, S.C., caused more than $850 million in flood damage.
Ivan accounted for $650 million of that.