Response to CO₂ doubling of the Atlantic hurricane main development region in a high-resolution climate model

Response of climate conditions in the Atlantic hurricane main development region (MDR) to doubling of atmospheric CO₂ has been explored using the new high-resolution coupled climatemodel, version 2.5 (CM2.5), developed at the Geophysical Fluid Dynamics Laboratory (GFDL). In the annual mean, the SST in theMDR warms by about 2°C in the CO₂ doubling run relative to the control run; the trade winds become weaker in the northern tropical Atlantic and the rainfall increases over the ITCZ and its northern region. The amplitude of the annual cycle of the SST over the MDR is not significantly changed by CO₂ doubling. However, the authors find that the interannual variations show significant responses to CO₂ doubling; the seasonal maximum peak of the interannual variations of the SST over the MDR is about 25% stronger than in the control run. The enhancement of the interannual variations of the SST in theMDRis caused by changes in effectiveness of the wind-evaporation-SST (WES) positive feedback; WES remains a positive feedback until boreal early summer in the CO₂ doubling run. The enhancement of the interannual variability of the SST over the MDR in boreal early summer due to CO₂ doubling could lead to serious damages associated with the Atlantic hurricane count and drought (or flood) in the Sahel and South America in a future climate.