Marine heatwaves supercharge tropical cyclones, multiply economic losses

Tropical cyclones (TC) moving across exceptionally warm ocean waters associated with marine heatwaves could rapidly intensify and become stronger leading to more severe impacts upon landfall and increasing economic losses, found a new study.

The study, published in Science Advances April 10, 2026, found that TCs experiencing rapid intensification during marine heatwaves resulted in 60 per cent more billion-dollar disasters compared to those without heatwave influence. This difference remains significant even after accounting for coastal exposure, said lead rearcher, Soheil Radfar, University of Alabama, US.

Marine heatwaves are periods during which ocean waters become abnormally warm for several days at a stretch. Such events are occurring with increasing frequency and severity across the globe.

Researchers looked at 1,600 TCs (encompasses hurricanes, cyclones and typhoons) that made landfall since 1981 and found those that went over the extra-hot water were more likely to intensify rapidly, a problem that's becoming more frequent.

The analysis revealed that costlier storms produced consistently higher maximum wind speeds, storm surges and precipitation rates. It showed, "for billion-dollar TCs, even controlling for similar levels of coastal development, MHW TCs cause significantly higher damages than their counterparts, confirming that their enhanced intensity characteristics amplify economic impacts beyond what would be expected from exposure alone".

TCs undergoing rapid intensification exhibit different characteristics when associated with proximate MHWs compared to those without MHW influence. This is primarily because MHWs enhance the maximum sustained wind speeds (up to 20 per cent higher speeds in MHW TCs versus non-MHW TCs) and promote heavy precipitation (up to 12 per cent higher rates in MHW TCs versus non-MHW TCs) before the storms make landfall in rapidly intensifying TCs. 

This behavior highlights the compounding effects of MHWs, which not only make rapid intensification events stronger but also sustain higher wind speeds and precipitation rates both before and after landfall. 

The relationship between maximum storm surge and damage costs showed complex, sometimes counterintuitive patterns across different scenarios. This complexity likely stems from the interaction of multiple factors: Local coastal topography, timing relative to tidal cycles, presence of coastal defenses, and variations in population density and infrastructure placement the study said.

Billion-dollar tropical cyclones occur 1.6 times more frequently when marine heatwaves are present. This amplification effect is particularly concerning amid ongoing warming, as TCs appear to move more slowly over land, stall more frequently, and possibly decay less rapidly after landfall. This increases coastal communities' exposure and vulnerability to storm-related hazards.

Hurricane Milton in October 2024 was one of the most expensive climate disasters of 2024 causing $60 billion in damages and killing 25. Milton came just two weeks after Hurricane Helene struck the US, Cuba and Mexico racking up $55 billion in damages and claiming 232 lives. 

An analysis by World Weather Attribution revealed that Hurricane Helene formed in the Gulf of Mexico above record-hot sea surface temperatures (SST) and climate change was a key driver of Helene's catastrophic impacts that devastated both coastal and inland communities.

MHW influences should receive greater consideration in future strategies for climate adaptation and coastal hazard preparedness. For instance, operational centers could incorporate alert thresholds for local SST anomalies or MHW intensities to enhance the detection and forecasting of rapid intensification events.

A study published in December 24, 2024 in Earth’s Future talks about an ensemble machine learning model that considers storm and marine heatwaves characteristics. This provides a new tool for detecting rapid intensification events that are particularly challenging to forecast in favorable environments created by MHWs and these events tend to produce stronger TCs. The developed model demonstrated higher accuracy in detecting rapid intensification while reducing false alarms.