Climate Denial Crock of the Week

NBC News:

“It’s incredible,” said Brian LaPointe, a research professor at Florida Atlantic University’s Harbor Branch Oceanographic Institute. “What we’re seeing in the satellite imagery does not bode well for a clean beach year.”

Sargassum’s growth varies from season to season. LaPointe, who has studied it for four decades, said huge piles typically come ashore in South Florida in May, but beaches in Key West are already being inundated with algae. Parts of Mexico’s Yucatán Peninsula, including Cancun, Playa del Carmen and Tulum, are preparing for up to 3 feet of sargassum buildup in the coming days.

Giant mounds of sargassum are more than a nuisance and an eyesore, said Brian Barnes, an assistant research professor at the University of South Florida’s College of Marine Science.

“Even if it’s just out in coastal waters, it can block intake valves for things like power plants or desalination plants, marinas can get completely inundated and boats can’t navigate through,” he said. “It can really threaten critical infrastructure.”

Last summer, the U.S. Virgin Islands declared a state of emergencyafter unusually high quantities of sargassum caused water shortages on St. Croix.

Other impacts to human health are coming into focus. As the seaweed rots, it releases hydrogen sulfide, which can cause respiratory problems for tourists and residents in the vicinity, LaPointe said.

“Following the big 2018 blooms, doctors in Martinique and Guadeloupe reported thousands of people going to clinics with breathing complications from the air that was coming off these rotting piles of sargassum,” he said.

Then there are the economic concerns. Sargassum invasions can stifle tourism, and removing hundreds of tons of algae from beaches is costly.

“Before 2011, it was there but we couldn’t observe it with satellites because it wasn’t dense enough,” Barnes said. “Since then, it has just exploded and we now see these huge aggregations.”

A 2019 study in the journal Science estimated that more than 20 million metric tons of sargassum blanketed the Atlantic in what has been nicknamed the “Great Atlantic Sargassum Belt.” 

Barnes said the mass of seaweed appears to be increasing each year, but 2018 and 2022 had the largest accumulations. This year is approaching those records, he added.

In investigating the factors driving this dramatic growth in sargassum, scientists, including LaPointe, have found that human activities and climate change are seeding rivers that flow into the Atlantic with nitrogen and other nutrients. That then feeds the algae blooms.

“You have the Congo, the Amazon, the Orinoco, the Mississippi — the largest rivers on the planet, which have been affected by things like deforestation, increasing fertilizer use and burning biomass,” LaPointe said. “All of that is increasing the nitrogen concentrations in these rivers and so we’re now seeing these blooms as kind of a manifestation of the changing nutrient cycles on our planet.”

Many of these effects are exacerbated by climate change, he said, which can increase flooding and runoff into major waterways.