A vast blanket of seaweed some 5,000 miles in diameter is threatening beaches along the Gulf of Mexico and the Caribbean.
Visible from space, the so-called Great Atlantic Sargassum Belt is thought to have a few benefits, including serving as a habitat for some fish and shellfish and absorbing carbon dioxide.
But ocean currents are now pushing tons of seaweed onto the beaches, causing big problems.
There it can suffocate corals, devastate coastal ecosystems, and decrease water and air quality as it rots.
Brian LaPointe, a research professor at Florida Atlantic University’s Harbor Branch Oceanographic Institute, told NBC: ‘It’s amazing.
“What we are seeing in the satellite images does not bode well for a year of clean seas.”
Mr. LaPointe, who has studied sargassum for four decades, said huge piles usually wash ashore in south Florida in May, but Key West beaches are already awash with seaweed.
Parts of Mexico’s Yucatan peninsula, including Cancun, Playa del Carmen and Tulum, are preparing to form up to three feet of sargassum over the next few days.
“Even if it’s just out in coastal waters, it can block inlet valves for things like power plants or desalination plants, marinas can get completely flooded, and boats can’t sail,” Brian Barnes, research assistant professor at the ‘University of the South The Florida College of Marine Science said so.
“It can really threaten critical infrastructure.”
Last summer, the US Virgin Islands declared a state of emergency after unusually high amounts of sargassum caused water shortages in St Croix.
Mr. Barnes and his colleagues at the University of South Florida use satellite data from NASA to map the Great Atlantic Sargassum Belt and its movements.
The size of the bloom in recent years would have been inconceivable decades ago, he said.
“Historically, as long as we have records, Sargassum has been part of the ecosystem, but now the scale is much larger.
“What we would have thought was a big bloom five years ago isn’t even a blip anymore.”