Dozens of people were killed across multiple states this week as Hurricane Helene swept across parts of the Southeastern United States, bringing heavy rains and a 15-foot storm surge.
Coastal towns and cities in Florida were devastated when the Category 4 hurricane made landfall, but communities inland bore a similar brunt as the storm carved a path through North Carolina, South Carolina, Georgia, and Tennessee.
“Turn around, don’t drown,” North Carolina Governor Roy Cooper urged drivers in a press conference.
At least 42 people have died from the storm. As of Friday, Florida reported seven deaths. Georgia, meanwhile, reported 15, and South Carolina, 17. In both of the latter states, most of the known fatalities were from falling trees and debris. North Carolina reported two deaths, including a car crash that killed a 4-year-old girl after a road flooded.
Atlanta received 11.12 inches of rain in 48 hours, breaking its previous record of 9.59 inches in the same time period from 1886, according to Bill Murphey, Georgia’s state climatologist. More than 1 million Georgia residents also lost power in the storm, particularly in southern and eastern parts of the state.
In western North Carolina, officials sounded alarms and went door-to-door evacuating residents south of the Lake Lure Dam in Rutherford County after the National Weather Service warned that a dam failure was “imminent.” Emergency crews also conducted more than 50 swift water rescues across the region, with one sheriff’s department warning it could not respond to all of the 911 calls due to flooded roads. The North Carolina Department of Transportation warned on social media that “all roads in Western NC should be considered closed” due to flooding from Helene.
In Tennessee, more than 50 people were stranded on the roof of a hospital due to heavy flooding and had to be rescued by helicopter. Residents of Cocke County in Tennessee were also asked to evacuate after reports that a separate dam could fail, although officials later said the dam failure had been a false alarm. In South Carolina, the National Weather Service said the storm was “one of the most significant weather events… in the modern era.”
The hurricane’s widespread flooding was worsened by climate change, scientists told Grist. Hurricane Helene was an unusually large storm with an expansive reach. After forming in the Caribbean, it traveled over extremely warm ocean waters in the Gulf of Mexico that enabled the storm to intensify more quickly than it may have otherwise. In fact, Helene went from a relatively weak tropical storm to a Category 4 in just two days. Warmer air also holds more moisture, supercharging the storm’s water content and leading to more rapid rainfall and intense flooding.
“When that enhanced moisture comes up and hits terrain like the Appalachian Mountains,” said University of Hawaiʻi meteorology professor Steve Businger, “it results in very, very high rainfall rates, exceptionally high rainfall rates and that unfortunately results in a lot of flash flooding.”
Shel Winkley, a meteorologist at the scientific group Climate Central, said research has shown that the Gulf’s current extra-warm ocean temperatures were made up to 500 times more likely with climate change. “One of the things that we’re seeing with these big storms, especially as they seem to become more frequent, is that they’re no longer natural disasters, but that they’re unnatural disasters,” Winkley said. “It’s not just a normal weather system anymore.”
Hurricanes are naturally occuring, of course, but the conditions that led to Helene’s severity — its rapid intensification and heavy rainfall — were partially driven by warmer ocean and atmospheric temperatures from the burning of fossil fuels. “There is a fingerprint of climate change in that process,” Winkley said.
“This summer was record warm globally and there was a record amount of water vapor in the global atmosphere,” said Daniel Swain, a climate scientist at the University of California, Los Angeles, or UCLA. Both factors contributed to what the Southeastern U.S. experienced this week. “This is one of the more significant flood events in the U.S. in recent memory.”
Initial estimates for the storm’s damage to homes, businesses, and infrastructure range between $15 billion and $26 billion, the New York Times reported. Businger said he expects the enormous loss to fuel more conversations about the precarity of the existing property insurance system. “The cost to society is becoming extravagant,” he said.
Scientists noted that the fact that the storm’s winds increased by 55 miles per hour in the 24 hours before it made landfall also made it deadlier.
“It was so strong and moving so fast it just didn’t have time to weaken very much before it made it far inland,” Swain said. Rapid intensification is particularly dangerous, he said, because people often make decisions on how to prepare for storms and whether or not to evacuate based on how bad they appear to be initially.
“It was one of the faster intensifying storms on record,” Swain said. “This is not a fluke. We should expect to see more rapidly intensifying hurricanes in a warming climate.”
