Climate Change Causes Landfalling Hurricanes to Stay Stronger for Longer

is the “fuel” that intensifies and sustains a hurricane’s destructive power, with heat energy from the moisture converted into powerful winds.

“Making landfall is equivalent to stopping the fuel supply to the engine of a car. Without fuel, the car will decelerate, and without its moisture source, the hurricane will decay.”

The researchers found that even though each simulated hurricane made landfall at the same intensity, the ones that developed over warmer waters took more time to weaken.

“These simulations proved what our analysis of past hurricanes had suggested: warmer oceans significantly impact the rate that hurricanes decay, even when their connection with the ocean’s surface is severed. The question is – why?” said Prof. Chakraborty.

Using additional simulations, the scientists found that “stored moisture” was the missing link.

The researchers explained that when hurricanes make landfall, even though they can no longer access the ocean’s supply of moisture, they still carry a stock of moisture that slowly depletes.

When the scientists created virtual hurricanes that lacked this stored moisture after hitting land, they found that the sea surface temperature no longer had any impact on the rate of decay.

“This shows that stored moisture is the key factor that gives each hurricane in the simulation its own unique identity,” said Li. “Hurricanes that develop over warmer oceans can take up and store more moisture, which sustains them for longer and prevents them from weakening as quickly.”

The increased level of stored moisture also makes hurricanes “wetter” – an outcome already being felt as recent hurricanes have unleashed devastatingly high volumes of rainfall on coastal and inland communities.

This research highlights the importance for climate models to carefully account for stored moisture when predicting the impact of warmer oceans on hurricanes.

The study also pinpoints issues with the simple theoretical models widely used to understand how hurricanes decay.

“Current models of hurricane decay don’t consider moisture – they just view hurricanes that have made landfall as a dry vortex that rubs against the land and is slowed down by friction. Our work shows these models are incomplete, which is why this clear signature of climate change wasn’t previously captured,” said Li.

The researchers now plan to study hurricane data from other regions of the world to determine whether the impact of a warming climate on hurricane decay is occurring across the globe.

Prof. Chakraborty concluded: “Overall, the implications of this work are stark. If we don’t curb global warming, landfalling hurricanes will continue to weaken more slowly. Their destruction will no longer be confined to coastal areas, causing higher levels of economic damage and costing more lives.”