Earth in quiet period for hurricanes, researchers say
November 30, 2000
(CNN) -- The active 2000 hurricane season that ended Thursday
might suggest that the storm onslaught can't get much worse. But
the Earth is actually in a 10-century-long quiet period for
hurricanes, according to researchers.
New research shows that hurricane activity runs in cycles
spanning thousands of years. And while at least 113 major
hurricanes hit the U.S. Gulf and Atlantic Coasts during the last
50 years, the 20th century is at the tail end of a 1,000-year
quiet cycle.
"In the last 1,000 years, the hurricane activities have died down
again," saidProfessor Kam-Biu Liu, of Louisiana State University.
"There were relatively few intense or catastrophic hurricane
strikes along the Gulf Coast."
But this year's hurricane season continued a three-year trend of
above-average storm activity. Fourteen named storms hovered over
the Atlantic Ocean, Gulf of Mexico and Caribbean Sea, eight
becoming hurricanes and three reaching major hurricane strength.
Despite this, no hurricanes directly hit the United States this
year.
"The main reason is that with the bulk of the hurricanes, we had
an upper-level trough in the eastern United States, which helped
steer them up to the north," said Max Mayfield, director of the
NOAA National Hurricane Center. "The trough also provided
unfavorable conditions aloft, which weakens the storms."
While Mayfield says he is familiar with studies in hurricane
activity cycles, he points out that "we've had more tropical
storms and hurricanes in the last six-year period than we've ever
had."
"I try not to get too caught up in forecasting. You can only do
so much with statistics. What really counts is where they hit and
how strong they are at landfall," Mayfield said.
By taking core samples from the sediment at the bottom of coastal
lakes and marshes, researchers can determine storm cycles.
Fine-grained, dark sediment indicates a period when the waters
were calm and there were no hurricanes. But an active storm
season, such as a catastrophic hurricane strike, will wash sand
from the shore into the lake, creating coarser-grained sediment.
After counting sand layers and determining their dates through
carbon dating, researchers can develop a timeline of catastrophic
hurricane strikes and quieter seasons. They can use this science,
called paleotempestology ("paleo" means ancient, while "tempest"
means storm), to predict the future by studying the past.
The Atlantic hurricane season begins June 1 and ends November 30.
The NOAA Hurricane Center will not release predictions for the
next hurricane season until next spring, but Liu had some
long-term predictions.
"What we know is that the climate system is capable of producing
a lot more catastrophic hurricanes that come our way. And so it
is quite possible that this will happen again in the future," Liu
said.
CNN Correspondent David George contributed to this report
SOURCE: CNN
****************************************************************
To post a submission by email at climate-newswire@sidsnet.org
To unsubscribe, email to majordomo@sidsnet.org with the message:
unsubscribe climate-newswire
To receive updates via email, send an email to majordomo@sidsnet.org with the message:
subscribe climate-newswire
No SUBJECTS required either case.
Brought to you on the SMALL Island Developing States Network: http://www.sidsnet.org
This archive was generated by hypermail 2b30 : Fri Dec 01 2000 - 12:23:07 EST