What Led to Katrina? Jury Still Out on Global Warming
Sept.05 – Is global
warming a culprit in the devastation wrought by Hurricane Katrina? Yes,
no and perhaps are the answers climate scientists give.
Everyone is clear global warming did not cause Katrina and that it is
not causing more hurricanes. The worldwide rate has held pretty steady
at 90 a year for decades, says Kerry Emanuel, professor of atmospheric
science at the Massachusetts Institute of Technology.
But researchers such as Gary Yohe, an economics professor at Wesleyan
University in Middletown, Conn., who studies the economics of climate
change, says rising temperatures – one degree in the past 50 years –
are causing the hurricanes that do form to be stronger and
longer-lasting, and therefore cause more damage.
“The temperature of the tropic oceans is warmer than it’s been in 150
years,” and geological evidence indicates it’s higher than it has been
in thousands, Emanuel says.
But Christopher Landsea, a researcher meteorologist in the hurricane
research division of the National Oceanic and Atmospheric
Administration, says Katrina wasn’t caused by global warming but is
simply a part of the natural cycle of hurricane activity.
Hurricane activity on the Atlantic Coast runs in cycles
William Gray of the Tropical Meteorology Project at Colorado State
University has shown that hurricane activity waxes and wanes over 25 to
30 years. The 1910s and ’20s were bad for hurricanes. Then came a
period of calm, and another bad period in the 1940s and ’50s. From the
1960s to 1995 was a period of calm.
Robert Sheets, director of the National Hurricane Center in Miami from
1987 to 1995, agrees. He doesn’t believe there’s any solid evidence
that Katrina was strengthened by global warming.
“Anything we’ve seen so far is not outside of what has occurred in the past,” he says.
Unfortunately, the latest lull period began just as air conditioning
became widespread, allowing people to move to the sunny and humid
coasts in droves.
“We’ve seen very busy times before, but the big difference is there’s
so many people living in hurricane alley. The coastal population is
doubling roughly every 25 years from Texas to Carolina. That means the
last time we were in a busy period there were many fewer people and
less infrastructure in the way,” Landsea says.