Hurricanes to less intense, but more frequent in the future
By Justin Caudell
Hurricanes are expected to increase in intensity and have more intense
rainfall on average in the future.
But a new model simulation of Atlantic hurricane activity for the last two
decades of this century projects fewer hurricanes overall according to findings
reported in a study by scientists at the National Oceanic and Atmospheric
Association’s Geophysical Fluid Dynamics Laboratory in Princeton, N.J.
“This study adds more support to the consensus finding of the
Intergovernmental Panel on Climate Change and other reports that it is likely
that hurricanes will gradually become more intense as the climate continues to
warm,” said Tom Knutson, research meteorologist and lead author of the report.
“It's a bit of a mixed picture in the Atlantic though because we're projecting fewer
hurricanes overall.”
The scientists involved in the study performed hurricane simulations using
a new regional model that offers both higher resolution and an improved ability
to simulate past observed changes in Atlantic hurricane activity. In a preliminary
study published last October in the Bulletin of the American Meteorological
Society, the new model was shown to successfully reproduce Atlantic hurricane
counts year-by-year from 1980 to 2006, including the observed increasing
trend.
In the new study, the model was used to test the influence of greenhouse
gas warming on Atlantic hurricane activity through the end of the 21st century.
Tropical Atlantic sea surface temperatures have increased over the past
century and several studies have reported strong correlations between
increasing tropical Atlantic sea surface temperatures and measures of hurricane
activity since at least 1950. It is widely accepted in the climate change research
community that increases in greenhouse gases have caused most of the global
warming of the last half century and that increasing greenhouse gases and
hurricane activity is correlated.
Simulations from the model, however, revealed higher levels of wind shear
and other changes which are forecasted to reduce the overall number of
hurricanes. Suggesting that in the Atlantic basin, global warming from increasing
greenhouse gases will have little impact, or perhaps cause some decrease, in
tropical storm and hurricane numbers.
“But we'll need to keep an eye on upcoming model studies to see how
robust the projected increase in wind shear over the Atlantic turns out to be,”
said Knutson.
It is unsure how factors such as wind shear will impact Atlantic hurricane
activity in the near future, but the 2008 Atlantic Hurricane Season begins
Sunday, June 1.