NEWS & EVENTS

This report will discuss the evolution of hazards and climatological features associated with multiple tropical cyclones (TCs) in the context of global warming. Both historical records and future climate projections indicate a significant increase in the probability of sequential landfalling TC events along the U.S. East Coast and the Gulf of Mexico. Under the high-emission scenario (SSP5-8.5), by 2100, the return period for two hazard-producing TCs occurring within 15 days is projected to sharply decrease from the current 10–92 years to just 1–2 years. This shift is driven by sea-level rise, which enhances the destructive potential of weaker TCs, as well as changes in TC climatological characteristics. Notably, by the end of this century, the annual probability of extreme sequential events—such as a Katrina-level storm surge followed by Harvey-level rainfall within two weeks—will exceed 1%, whereas such events did not occur under historical climate conditions.

Basin-wide climate analysis reveals that the primary hotspot for TC clusters is shifting from the western North Pacific to the North Atlantic, a transition modulated by a La Niña-like warming pattern. The increased TC frequency and enhanced synoptic-scale wave activity in the Atlantic Basin are identified as the main drivers of this phenomenon. Together, these two studies underscore that we will face more frequent temporally clustered TC risks in the future. They highlight the urgent need to incorporate compound hazards into coastal resilience planning, emergency management, and climate adaptation strategies.

For additional information, please contact Prof Dazhi XI, dazhixi@hku.hk