PARIS—Tropical cyclones may become less frequent this century but
pack a stronger punch as a result of global warming, a paper
published on Sunday said.
The study is an overview of work into one of the scariest yet
also one of the least understood aspects of climate change.
Known in the Atlantic as hurricanes and in eastern Asia as
typhoons, tropical storms are driven by the raw fuel of warm seas,
which raises the question about what may happen when temperatures
rise as a result of greenhouse gases.
Tom Knutson and colleagues from the UN's World Meteorological
Organization (WMO) looked at peer-reviewed investigations that have
appeared over the past four years, when the issue began to hit the
headlines.
Their benchmark for warming is the "A1B" scenario, a
middle-of-the-road computer simulation which predicts a global
average surface temperature rise of 2.8 degrees Celsius (5.4 degrees
Fahrenheit) over the 21st century.
"It is likely that the global frequency of tropical cyclones will
either decrease or remain essentially unchanged," says the
paper.
But storms could have more powerful winds -- an increase of
between two and 11 percent -- and dump more water, it warns.
Rainfall could increase by 20 percent within 100 kilometers (62
miles) of the eye of the storm.
In addition, some storm basins will "more likely than not" see a
big increase in the frequency of high-impact storms.
The overview calls for an effort to fill in some big gaps in
knowledge, including the variability of cyclones in the past and how
global warming will affect storm behavior in specific regions.
It is published online by Nature Geoscience, a journal of
Britain's Nature Publishing Group.
The findings broadly concur with those of the UN's panel of
climate scientists, which in a 2007 report said it was "likely" that
tropical cyclones would become more intense this century, with
heavier rainfall and stronger wind speeds.
However, the panel said it was less confident in concluding
whether the number of cyclones would
decrease.