Climate Change Made Helene Worse, Scientists Say

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The science of how climate change affects specific storms is complex and often precarious. Climate change is measured on a long timescale, while hurricanes and other severe weather events are the products of short-term weather patterns. We know climate change is increasing the likelihood of formerly unlikely events, but when an historic, devastating storm becomes fact, who is to say how unlikely it was?

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An emerging field known as attribution science is attempting to answer this question. By running thousands of simulations in different climate models, some with the effects of human-caused climate change and some without, scientists are able to better understand what role climate change played in a given event.

On Wednesday, the attribution science organization World Weather Attribution released their analysis of the role climate change played in Hurricane Helene. According to WWA, global warming made a storm with a severity like Helene – a storm whose death toll is at least 232 as of Monday – about 2.5 times as likely to occur. While in a pre-warmed world a storm like Helene may occur once every 130 years in the Gulf Coast, now the likelihood is one in every 53 years. In a similar comparison, maximum wind speeds of today’s storms are estimated to be 11% more intense than in the pre-industrial period.

One factor that contributes to a hurricane’s intensity is sea temperature. In a positive feedback loop, warmer waters lead to higher rates of evaporation and greater temperature differentials between the resulting warm, moist air and the cooler, surrounding air, which pressurizes the system and strengthens the storm. According to WWA, the high sea surface temperatures that enabled Hurricane Helene were made 200 to 500 times more likely due to climate change.

WWA’s analysis of Helene is in line with the group’s broader research theme: human-caused climate change is making hurricanes undergo more rapid intensification, leading to increased rainfall and more stronger impact. And as Hurricane Milton wreaks a path of destruction through central Florida, the role of climate change in increasing extreme weather events becomes harder to ignore.