Last millennium hurricane activity linked to endogenous climate variability.

Area of Science:

• Paleoclimatology
• Climate Science
• Atmospheric Science

Background:

• Understanding long-term hurricane activity is crucial for assessing future risks in a warming climate.
• Current instrumental records are too short to capture natural variability in hurricane frequency.
• Projected trends in hurricane frequency under climate change remain highly uncertain.

Purpose of the Study:

• To reconstruct Atlantic hurricane activity over the last millennium.
• To compare paleohurricane reconstructions with statistical models and instrumental data.
• To investigate the drivers of past hurricane activity and its relationship with climate variability.

Main Methods:

• Developed two independent estimates of past hurricane activity: sedimentary paleohurricane records and a statistical model using sea surface temperatures (SSTs).
• Validated reconstructions by comparing them with the instrumental record and each other.
• Utilized a hurricane-permitting climate model to simulate hurricane activity drivers.

Main Results:

• Found statistically significant agreement between the sedimentary reconstruction and the SST-based statistical model.
• Determined that late 20th-century hurricane frequency falls within the range observed over the past millennium.
• Simulations indicate that endogenous climate variability, linked to anomalous SSTs (warm Atlantic, cold Pacific), likely drove hurricane activity.

Conclusions:

• The study provides a millennium-long perspective on Atlantic hurricane activity, suggesting recent frequencies are not unprecedented.
• Internal climate variability appears to be a significant driver of hurricane activity, alongside SST anomalies.
• Volcanic eruptions may influence hurricane activity but are likely masked by natural variability in the proxy record.