http://www.gfdl.noaa.gov/reference/bibliography/2004/tk0401.pdf
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Previous studies have found that idealized hurricanes, simulated under warmer, high-CO2 conditions, are more
intense and have higher precipitation rates than under present-day conditions. The present study explores the
sensitivity of this result to the choice of climate model used to define the CO2 -warmed environment and to the
choice of convective parameterization used in the nested regional model that simulates the hurricanes. Approx-imately
1300 five-day idealized simulations are performed using a higher-resolution version of the GFDL hur-ricane
prediction system (grid spacing as fine as 9 km, with 42 levels). All storms were embedded in a uniform
5 m s 21 easterly background flow. The large-scale thermodynamic boundary conditions for the experiments—
atmospheric temperature and moisture profiles and SSTs—are derived from nine different Coupled Model In-tercomparison
Project (CMIP21) climate models. The CO2 -induced SST changes from the global climate models,
based on 80-yr linear trends from 11% yr 21 CO2 increase experiments, range from about 10.88 to 12.48C in
the three tropical storm basins studied. Four different moist convection parameterizations are tested in the
hurricane model, including the use of no convective parameterization in the highest resolution inner grid. Nearly
all combinations of climate model boundary conditions and hurricane model convection schemes show a CO2 -induced
increase in both storm intensity and near-storm precipitation rates. The aggregate results, averaged
across all experiments, indicate a 14% increase in central pressure fall, a 6% increase in maximum surface wind
speed, and an 18% increase in average precipitation rate within 100 km of the storm center. The fractional
change in precipitation is more sensitive to the choice of convective parameterization than is the fractional
change of intensity. Current hurricane potential intensity theories, applied to the climate model environments,
yield an average increase of intensity (pressure fall) of 8% (Emanuel) to 16% (Holland) for the high-CO2
environments. Convective available potential energy (CAPE) is 21% higher on average in the high-CO2 envi-ronments.
One implication of the results is that if the frequency of tropical cyclones remains the same over the
coming century, a greenhouse gas–induced warming may lead to a gradually increasing risk in the occurrence
of highly destructive category-5 storms.
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