An unwanted visitor has arrived on the beaches of Cancún, Mexico—again. Sargassum, the brown seaweed that in recent years has beset the Caribbean’s tourism industry and marine ecosystems, began matting local beaches in March in quantities that could rival last year’s record algal invasion. The earlier-than-expected seasonal sargassum influx, unfortunately, was not limited to Cancún. As of late March, heavy concentrations were also reaching various Caribbean islands, Florida’s east coast and the Florida Keys. Since 2011, unusually large annual blooms of sargassum have occurred in a vast area of the Atlantic that lies between West Africa and the Gulf of Mexico—a recurring phenomenon known as the Great Atlantic Sargassum Belt. Scientists don’t fully understand why so much more sargassum is growing and matting beaches in the Caribbean and beyond. A currently prominent view holds that unusual weakening of North Atlantic air pressure systems—associated with a... [Log in to read more]