Projected increase in the frequency of extremely active Atlantic hurricane seasons

Area of Science:

• Climatology
• Tropical Meteorology
• Climate Change Science

Background:

• Year-to-year variability in North Atlantic tropical cyclone (TC) seasons has significant societal implications for hurricane-prone regions.
• Past and future changes in TC activity and their drivers remain under-researched.

Purpose of the Study:

• To investigate historical and projected changes in North Atlantic TC activity, specifically focusing on interannual variability.
• To evaluate the contribution of anthropogenic forcing to these changes.

Main Methods:

• Analysis of historical TC data to identify trends in interannual variability.
• Utilizing TC-resolving general circulation models to project future changes in TC activity.
• Examining changes in atmospheric variables like vertical wind shear and stability.

Main Results:

• Interannual variability in Atlantic TC activity has already increased, leading to more frequent extreme active and inactive seasons.
• TC-resolving models project a 36% increase in the variance of North Atlantic TC activity (measured by accumulated cyclone energy) by mid-21st century.
• Projected increases in variability are linked to amplified sea surface temperature variations between the Pacific and Atlantic, affecting wind shear and stability.

Conclusions:

• Anthropogenic forcing is robustly intensifying the variability of Atlantic TC activity.
• Future intensification of TC activity variability has critical implications for emergency planning and societal preparedness in hurricane-vulnerable areas.