Are marine heatwaves making natural disasters in Europe more severe?

Hurricanes, floods, droughts: all these extreme weather events have been intensifying over the past few years and have also been happening more often, according to experts.

And although these events happen on land, one common driver for them lies in the ocean.

Scientists have found that long stretches of high sea surface temperatures, called marine heatwaves, can amplify phenomena such as storms and heavy rainfall. 

That was notably the case for hurricanes Helene and Milton, which hit the US state of Florida in just two weeks in autumn 2024. 

Marine heatwaves intensify tropical cyclones, called hurricanes when they happen over the Atlantic, by over 35% compared to cyclones without marine heatwaves, according to one study published in the science journal Nature.

They are also associated with precipitation-heavy storms.

But this interplay between the ocean and the weather does not only affect the US coast. Europe has lived through extreme weather events over the past year, too: after a summer of record heatwaves across the continent and multiple wildfires in the Mediterranean region, Spain, France and Portugal got battered by Storm Kirk, which was the tail-end of a hurricane at the beginning of October.

Marine heatwaves can also worsen an unusual weather event that only happens in the Mediterranean Sea: so-called ‘medicanes’, which designate a hurricane forming in the Mediterranean.

One such storm devastated the Libyan coast in autumn 2023, causing at least 4,300 deaths and several dams collapsing.

At the same time, there is some evidence that marine heatwaves can be linked to droughts, and they often occur at the same time as heatwaves on land.

To find out how exactly marine heatwaves could be making natural disasters like these worse, watch our explainer above.