While the projection of a poleward shift of the Southern Hemisphere (SH) storm track and cyclone activity is widely accepted, together with a small decrease in the total number of extratropical cyclones, as discussed in the 5th Assessment Report of the Intergovernmental Panel on Climate Change (IPCC AR5), projected change in cyclone intensity is still rather uncertain. Several studies have suggested that cyclone intensity, in terms of absolute value of sea level pressure (SLP) minima or SLP perturbations, is projected to increase under global warming. However, other studies found no increase in wind speed around extratropical cyclones.
In this study, CMIP5 multi-model projection of how the frequency of extreme cyclones in terms of wind intensity may change under global warming has been examined. Results suggest significant increase in the occurrences of extreme cyclones in the Southern Hemisphere. In the Northern Hemisphere, CMIP5 models project a northeastward shift in extreme cyclone activity over the Pacific, and significant decrease over the Atlantic.
To understand the dynamics behind these projected changes, model-to-model variations in the projected changes in extreme cyclones are related to model-to-model differences in the projected changes in large scale environmental parameters. Results from these analyses will be presented at the meeting.