The Great Atlantic Sargassum Belt is carrying a massive bloom of brown seaweed toward Florida and the Caribbean

An unwelcome visitor is headed for Florida and the Caribbean: huge floating mats of sargassum, or free-floating brown seaweed. Nearly every year since 2011, sargassum has inundated Caribbean, Gulf of Mexico and Florida coastlines in warm months, peaking in June and July. This brown tide rots on the beach, driving away tourists, harming local fishing industries and requiring costly cleanups.

According to scientists who monitor the formation of sargassum in the Atlantic Ocean, 2023 could produce the largest bloom ever recorded. That’s bad news for destinations like Miami and Fort…