Hurricane Dorian largely spared South Carolina, though the storm's rapid intensification and stall over the Bahamas follows a recent trends of more powerful — and slower — hurricanes.
While scientists often shy away from linking any one weather event directly to climate change, Dorian showed many of the changes in storms that have appeared as global average temperatures rise.
James Kossin, a climate scientist with the National Oceanic and Atmospheric Administration, said Dorian is one of "quite an alarming cluster" of powerful, stalling cyclones in the Atlantic basin in recent years, including Hurricanes Harvey in 2017 and Florence in 2018.
"There’s compelling evidence that this is not entirely natural," said Kossin, who in June co-authored a study showing that more and more powerful hurricanes were stalling in place. The trend has not definitively been linked to human-caused climate change, however.
Charleston and the rest of the Palmetto State's coast still sat on a knife's edge of a situation that could have quickly turned dire. If the eye of the cyclone had inched just a few miles closer, forecasters say, the region would have seen stronger winds, higher surge and far more rainfall.
And surge forecasts show that the wall of water thrown off by Dorian reached the Lowcountry roughly as Charleston Harbor was in low tide, negating a surge the National Hurricane Center originally predicted would smother some barrier islands around the region.
The storm's landfall in eastern North Carolina proved more devastating, putting the islands of the Outer Banks largely underwater, the New York Times reported.
But the most notable aspect of the storm was its deadly stall over the Bahamas. As it sat on top of Grand Bahama and Great Abaco islands on Monday, Dorian logged the slowest 24-hour period of any hurricane Category 3 or above, said Jeff Masters, founder of private forecasting company Weather Underground.
The storm was a Category 5, and then 4 during that stall, whipping surge across the islands that mowed down homes and killed a still-undetermined number of people.
A hotter globe and more destructive storms
While there's little evidence to suggest that the total number of annual storms in the Atlantic basin is changing as the Earth warms, scientists have begun to document changing conditions that can boost a cyclone's destructive capacity.
Hurricanes need two things to form and intensify: warm waters (80 degrees Fahrenheit or higher) and cohesive winds blowing in roughly the same way throughout the atmosphere (known as low wind shear).
As with many aspects of climate change, the effects on hurricanes are under continual study. It can be challenging for scientists to figure out the many interlocking global systems that might be altered as planet-insulating gasses are spewed into the atmosphere.
"We’ve always had hurricanes and we’ve always had strong hurricanes and hurricanes have always stalled, but what we're seeing is a slow trend toward more of these types of storms," Kossin said.
Small changes in natural systems like the Gulf Stream, a highway of fast-moving warm water that stretches parallel to the Southeast coast, can make the sea level rise suddenly by inches, and hurricanes can spur that rise. It's still unclear what else causes wobbles in that current.
But one of the simplest connections is the fact that a warmer atmosphere can hold far more water. That's, in part, why more recent storms have had mind-boggling rainfall totals, Kossin said.
For example, a 2017 analysis found that climate change made Hurricane Harvey's soaking rains over the Houston area, which topped out around 60 inches, 20 times more likely.
Steering currents park the cyclone
Though Dorian, like Harvey, stalled, it "broke the mold" in that its major threat was surge, and not rain, Kossin said.
The issue, said Masters, was that the storm was caught between two steering winds moving in opposite directions which essentially muted each other. So, for a day, there was nothing in the atmosphere to influence Dorian's path.
And competing steering winds kept it there, Masters said. He said that Kossin's recent study, showing more hurricanes that stall, tracks with other shifts in the global atmosphere that have been linked to climate change. For example, a Jet Stream that's retreating north means fewer steering currents in the tropics to move storms quickly, Masters said.
Cary Mock, a climatologist at the University of South Carolina, is not entirely convinced by the paper on paused storms. Mock reconstructs the tracks of historical storms, and said that the paper's analysis, which covers storms back to about 1950, is potentially too short to draw firm conclusions.
He said he'd also found a storm eerily similar from the past: an 1838 Category 4 cyclone that formed in the tropics, sat on top of the western Bahamas, buzzed the South Carolina coast and later made landfall in eastern North Carolina.
"I might need to write a paper on that thing, quickly," Mock said.
Ultimately, the storm's slow movement proved a slight challenge to the Hurricane Center forecasters, who originally projected that over the long term, Dorian would cross the Florida peninsula.
The hurricane's crawl through the tropics meant that the winds that would have kept it south eroded, and it never made landfall in that state. But Masters said that an analysis showed that the center's three-day forecasts for Dorian were still more accurate than usual.
The end result of the unusual storm has devastated enough people that the name "Dorian," in use for the first time in 2019, will likely be retired.
"This is obviously a storm that the forecasters will be talking about for a long time," Kossin said.