The new version of the high-resolution 20-km-mesh Meteorological Research Institute (MRI) atmospheric general circulation model (MRI-AGCM version 3.2) is able to simulate realistically present-day (1979

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How Will Tropical Cyclones Respond to Global
Warming?
Hiroyuki Murakami and Yuqing Wang
The new version of the high-resolution 20-km-mesh
Meteorological Research Institute (MRI)
atmospheric general circulation model (MRI-AGCM
version 3.2) is able to simulate realistically
present-day (19792003) category 4 and 5 TCs when
driven with observed sea surface temperature
(Fig. 1). This is the first time a global climate
model has been able to simulate the climatology
of such extremely intense TCs over several
decades. To study the future impact of global
warming on tropical cyclone (TC) activity, this
new high-resolution version was driven with
conditions taken from a global coupled GCM run
through the IPCC A1B scenario. As climate warms,
the model shows by 207599 a marked decrease in
the global number of TCs (by 1325), but an
increase in mean TC intensity (by 34).
Moreover, the model projects that the most
intense TCs (category 5) in the western North
Pacific will shift northward (Fig. 2), suggesting
that this region will be at risk for catastrophic
damages due to more frequent very strong tropical
cyclones in the future.
Fig. 1 Global distribution of tropical cyclones
(TCs) in (a) observations, (b) present-day
simulation with MRI-AGCM version 3.2. TC
track-colors reflect intensities.
Fig. 2 Category 5 TC frequency (unit number
per 25 years per 2.5 X 2.5) from 1979 to 2003
in (a) observations and (b) simulation (c)
"projected 20752099, and (d) difference between
present-day and projected simulation.