Every summer, a band of floating brown seaweed stretches thousands of miles across the tropical Atlantic, from West Africa to the Gulf of Mexico. The Great Atlantic Sargassum Belt is the largest macroalgal bloom on Earth, and it has grown roughly sevenfold since a regime shift around 2014. It now buries Caribbean and West African shorelines, costs coastal economies hundreds of millions of dollars, and releases hydrogen sulfide as it rots.
This is a fully interactive, visual piece: animated satellite bloom maps from 2002 to 2026, the statistically detected change point, the driver analysis, and an honest look at whether the biomass could be turned into a resource rather than a hazard. It is the accessible companion to our formal Perspective manuscript, with the same facts and the same caveats.