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A woman cries amid the rubble of her home, destroyed by Hurricane Matthew in Baracoa, Cuba.
Ramon Espinosa/AP

October Hurricanes Aren’t Supposed to Be This Scary

Warmer oceans mean stronger storms.
This story was originally published by Grist.

Hurricane Matthew plowed across Haiti yesterday as one of the strongest storms ever recorded at this time of year — and the most powerful to strike that country in half a century. The United Nations is calling it the worst humanitarian crisis to hit Haiti since the 2010 earthquake. After swiping Cuba this morning, Matthew now threatens the southeastern United States, with potential landfall by this weekend.

Tropical storm season technically runs through November, but August and September — when ocean temperatures peak — are typically the major months of concern. By October, sea surface temps usually decline, reducing storm intensity. (Warm water = jet fuel for hurricanes.)

But CO2-heated oceans, combined with sea-level rise, could increase the danger of strong late-season storms. Recent studies suggest that tropical cyclones might become less frequent in a warmer world — but the ones we do get will be stronger and more damaging.

With surface temps currently at or above average for October, Matthew’s projected track is cause for alarm. The governors of Florida, Georgia, and both Carolinas have declared emergencies, with coastal evacuations — which could include millions of people — beginning today. Matthew might provide a very unwelcome October surprise.

Scott Dodd

Scott Dodd is Grist’s executive editor.

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