On the surface, Hurricane Dorian looks like a real bad hat. It blasted the Abaco Islands in the northwestern Bahamas, and then traversed Grand Bahama, first as a Category 5 monster and then as a Category 4 (monster). It stalled over Grand Bahama for nearly two days, subjecting the island to multiple tidal surges that left Freeport International Airport under six feet of water.
But Dorian will also go down as one of the greatest triumphs ever in hurricane forecasting, and that success bodes well for the future.
As with most storms, Dorian’s early forecasts were widely scattered, ranging from a traversal of the Florida peninsula (including a Category 4 direct hit on Palm Beach), to a relatively harmless turn out to sea. Then the computer models largely fell into agreement and predicted the stall over Grand Bahama, followed by a slow right-angle turn, all the while keeping the center off Florida’s Atlantic Coast, with gradual weakening beginning off South Carolina.
By late morning on Sept. 3, after finally turning northwest, Dorian’s interaction with the land of nearby Florida began to take its toll, as its once-spectacular eye temporarily broke open and it rapidly decelerated into a Category 2 storm — still strong, but no longer “major” in National Hurricane Center parlance.
But prior to stalling, and then turning, Dorian was in fact aimed directly at Palm Beach, moving at a seemingly relentless pace of around ten miles an hour and deviating not a whit in direction. And 20 years ago, that would have prompted a helter-skelter evacuation of at least 5 million people.
Instead, forecasters had remarkably high confidence over Dorian’s stall and its ultimate turn and weakening. Evacuation orders were eventually issued, mainly for flood-prone regions that would affected as Dorian passed closely offshore, from Florida to North Carolina. But nothing was of the concentrated scale that would have ensued with a precautionary evacuation of Palm Beach and the crowded surrounding countryside.
Dorian eventually did cause considerable flooding, especially an overwash of Ocracoke Island, immediately to the south of Cape Hatteras, where it made its final landfall. And obviously, the destruction in the northwest Bahamas was unreal.
But there is a silver lining. Improved geophysical forecasts are an aspect of adaptation to potentially harmful events, including hurricanes and tornadoes. Because of improvements in detection technology and forecasting, tornado deaths dropped precipitously in the 20th Century, as did deaths from hurricanes making landfall. Annoying and costly false alarms have become less commonplace as forecast confidence increases. The calm in Palm Beach, literally staring at the core of a raging hurricane (which was on the horizon for all to see) is a tribute to the National Hurricane Center’s forecasters and the quality of the information that they ingested.
What about the future? The jury is still out on tropical cyclones (the generic term for hurricanes, typhoons, etc…) as temperatures warm. We have been running an experiment for a half-century now, slightly increasing the temperature, with no apparent change in the integrated power of tropical cyclones worldwide. This is a finding from painstaking research by the estimable Dr. Ryan Maue, whose twitter page is a must-visit when hurricanes lurk.
Maue notes an increase in activity from around 1980 to the early part of this century, but also that it wasn’t at all different from another increase in the early 20th Century that occurred before there was much human-induced warming to speak of.
It’s also hard to specifically conflate Dorian’s behavior with warming. The balance of its rapid intensification took place over a pocket of water that was actually slightly below average in temperature. And hurricanes stall all the time, as can be determined with even a cursory perusal of historical tracks available from the National Hurricane Center.
But even if it was bumped by warming, and others storms are similarly promoted a bit, improved forecasting, adaptation, and sophisticated emergency response will save far more lives than a few extra miles per hour could possibly take away. Meanwhile, given current technology, any attempt to seriously reduce carbon dioxide emissions will have little if any immediate effect on the climate, while inducing jarring social change.
There’s precious little evidence for stronger storms. But there is a lot of evidence for adaptation, part of which comes from better forecasts, like the great one made for Hurricane Dorian. Perhaps the strongest evidence for adaptation comes from research by University of Colorado’s Roger Pielke, Jr., who has shown that as a percent of global GDP, weather-related damages are on the decline.
Originally published at The Washington Examiner.