Science for the Planet: Sinking Seaweed for Sequestration

This second video for Science for the Planet series explores the idea of sinking sargassum seaweed deep in the ocean, taking carbon with it.

Francesco Fiondella
January 17, 2024


Biological oceanographer Ajit Subramaniam, from the Climate School’s Lamont-Doherty Earth Observatory, explains how sargassum seaweed might help reduce carbon dioxide levels in our atmosphere to counteract climate change. He’s studying the practicality and impacts of sinking massive amounts of the surface-growing plant down to the seafloor, which would trap it—and the carbon it absorbs via photosynthesis—for at least a century.

“The idea is that if you collect the sargassum offshore where ocean depths are about 2,000 meters and you sink it to the seafloor quickly, then you would be taking out the carbon dioxide that was fixed—and that’s making up this biomass—and basically put it out of contact with the atmosphere for at least 100 years,” says Subramaniam.

Researchers think climate change has helped fuel massive sargassum blooms, which have been piling up and rotting on the shores of popular tourist beaches in the Caribbean—an all-too-visible example of how communities who’ve contributed the least to the climate crisis are the most impacted by it.

“When the sargassum washes up on the beaches, it emits hydrogen sulfide, which is potentially injurious to human health, but more importantly, it completely drives away the tourism that many of these communities depend on,” says Subramaniam.

This is the second video of Science for the Planet, a short explainer series about how Columbia Climate School scientists and scholars are trying to understand the effects of climate change and help solve the crisis.