Extreme sea levels during heatwaves are becoming more frequent.

New research shows a significant rise in the frequency of concurrent heatwaves and extreme sea level events along the world's coastlines.

Experts say global strategies are needed to mitigate the risks posed by these simultaneous natural hazards.

A new study reveals that between 1998 and 2017, there was an increase in the incidence of concurrent heatwaves and short-term extreme sea level rises at the same coastal locations, compared to the previous two decades. 

This phenomenon, dubbed a ‘concurrent heatwave and extreme sea level’ (CHWESL) event, poses significant threats to coastal communities, especially during extended summer seasons which differ in timing between the Northern and Southern Hemispheres.

Researchers Shuo Wang and Mo Zhou analysed data from 1979 to 2017, observing that around 88 per cent of global coastlines experienced at least one CHWESL event. 

The study also projects a dramatic rise in these occurrences. 

Under a high emissions scenario, coastal areas might face an average of 38 days per year with simultaneous heatwaves and extreme sea levels between 2025 and 2049—an increase from just seven days per year between 1989 and 2013.

The combination of heatwaves and elevated sea levels can have severe implications for human health, primarily due to excessive heat, and can exacerbate issues in low and middle-income countries which often lack adequate resources to combat such challenges. 

The authors say effective risk mitigation strategies are needed to enhance preparedness and resilience against these increasing threats.