Climate change likely intensified Hurricane Helene’s catastrophic flooding, study finds

Hurricane Helene made landfall on Florida on September 26, 2024, causing widespread destruction from the Gulf Coast to the Appalachians. The first attribution research shows climate change likely increased rainfall by 50%.

Hurricane Helene, a Category 4 storm, battered coastal cities like Tampa and Cedar Key, Fla., with fierce winds, heavy rain, and widespread destruction. Flooding overwhelmed drainage systems and knocked out power for millions. As the storm moved north, it brought heavy rainfall to Georgia and the Carolinas.

As Helene reached the Appalachians, torrential rains triggered catastrophic flooding in Tennessee, the Carolinas, and Virginia. Rivers overflowed, and landslides completely isolated communities. The flooding in these areas was unprecedented, with some regions seeing record-breaking rainfall of up to 15 inches in just 48 hours. Emergency services were stretched thin as rescue efforts struggled to reach isolated areas, leaving many residents stranded.

Recently, the first rapid attribution study by was conducted on Helene, and the findings suggest that climate change significantly amplified Helene's impact. Using a Granger causal inference attribution methodology, researchers estimate that climate change caused over 50% more rainfall in some parts of Georgia and the Carolinas, and it made this event 20 times more likely to happen.

For comparison, attribution studies for Hurricane Harvey, which also produced historic rainfall in Texas, found that human-induced climate change likely increased rainfall accumulations in the most affected areas of Houston by at least 18.8%.

Rapid attribution studies are scientific analyses conducted shortly after extreme weather events to assess how much human-caused climate change influenced the event's likelihood or severity. These studies use climate models and observational data to quickly determine whether and by how much global warming contributed to extreme events.

The goal is to provide timely insights into how climate change affects specific events, offering valuable information for policymakers and the public.