Natural and Forced North Atlantic Hurricane Potential Intensity Change in CMIP5 Models

Abstract:

Possible future changes of North Atlantic hurricane intensity and the attribution of past hurricane intensity changes in the historical period were investigated in this study using the Climate Model Intercomparison Project phase 5 multi-model, multi-ensemble simulations. To this end, we used the potential intensity (PI), the theoretical upper limit of the tropical cyclone intensity given the large-scale environmental conditions.

The multi-model mean PI averaged over the tropical North Atlantic showed a significant increase toward the end of the 21^st Century under both the rcp4.5 and rcp8.5 emission scenarios. The anthropogenically induced warming would put the North Atlantic PI largely above the historical mean by the mid-21^st Century even considering the multidecadal natural variability. We further show that the sea surface temperature anomalies associated with the Atlantic Multidecadal Variablity (AMV) are more effective than that associated with climate change in causing Atlantic PI changes, due to the localized nature of the AMV SST anomalies, confirming the role of remote SST impact on hurricane PI in the climate change scenarios.

During the historical period, both aerosols and greenhouse gases contribute to the forced changes in PI. The decrease in PI caused by aerosol forcing and the increase due to greenhouse gas forcing largely canceled each other, and the sharp increase in PI in the recent 30 years was dominated by the multi-decadal natural variability associated with the positive phase of the AMV.