Climate Change Amplifies Flooding Risks from Tropical Cyclones

Tropical cyclones, long known for their devastating flooding, are now expected to bring even greater risks as climate change accelerates. Recent studies examining past hurricanes suggest that under a warmer climate, the extent and intensity of flooding will grow significantly, especially when compound flooding from multiple weather drivers such as storm surge and precipitation interact.

A recent study led by researchers from several institutions, including L.E. Grimley and K.E. Hollinger Beatty, highlights how compound flooding—flooding caused by the combination of storm surge, heavy rainfall, and rising sea levels—will intensify as temperatures rise. The study focuses on hurricanes that struck North and South Carolina, such as Hurricanes Floyd (1999), Matthew (2016), and Florence (2018), comparing flooding in a 4°C warmer future with current conditions.

Using advanced climate models, the research shows that, while precipitation-driven runoff remains the primary cause of flood extent, the role of compound flooding will increase. As sea levels rise and rainfall becomes more intense, areas previously untouched by flooding will be exposed, increasing the total area affected by floods by 65%. Furthermore, flood depths in these regions will rise by 0.8 meters, further exacerbating the damage.

The study’s findings underscore the growing importance of considering the interaction between various flooding factors. For example, storm surge and rainfall typically have been studied in isolation, but their combined effects are much more destructive. In the future, flooding from hurricanes will not be limited to coastal areas but will expand upriver, affecting regions far from the coastline.

Researchers used high-resolution physics-based models, incorporating data from past storms and future climate projections, to simulate how these hurricanes would behave under future warming scenarios. These simulations revealed significant shifts in flood patterns, with new areas being exposed to flooding and the duration of inundation extending longer, which could hinder recovery efforts.