内容摘要：Louai El Amrousy, from left, Tahar Rahim, Melissa Boros, director Julia Ducournau, Emma Mackey and Tahar Rahim pose for photographers at the photo call for the film ‘Alpha’ at the 78th international film festival, Cannes, southern France, Tuesday, May 20, 2025. (Photo by Scott A Garfitt/Invision/AP)

Louai El Amrousy, from left, Tahar Rahim, Melissa Boros, director Julia Ducournau, Emma Mackey and Tahar Rahim pose for photographers at the photo call for the film ‘Alpha’ at the 78th international film festival, Cannes, southern France, Tuesday, May 20, 2025. (Photo by Scott A Garfitt/Invision/AP)

Questions also linger about how long the carbon capture will last.It’s a point especially important to companies working with algae, wood chips, or other organic materials, because depending on where they decompose, they could release carbon dioxide back into the atmosphere.

The deeper the plants and algae sink, the longer the carbon stays locked away. But that’s no easy feat to ensure. Running Tide, a now-shuttered company that sank nearly 20,000 metric tons of wood chips in Icelandic waters, said carbon could be sequestered for as long as three millennia or as little as 50 years.Sugarcane residue bundled into burlap sacks sits inside equipment on the deck of a research vessel, Monday, May 6, 2024, as part of an experiment by Carboniferous to sink the crops to the ocean floor. (Carboniferous via AP)Sugarcane residue bundled into burlap sacks sits inside equipment on the deck of a research vessel, Monday, May 6, 2024, as part of an experiment by Carboniferous to sink the crops to the ocean floor. (Carboniferous via AP)

Even if these solutions do work long term, most companies are operating on too small of a scale to influence the climate. Expanding to meet current climate goals will take massive amounts of resources, energy and money.“The question is, what happens when you scale it up to billions of tons every year?” said David Ho, an oceanography professor at the University of Hawaii at Manoa and co-founder and chief science officer of the nonprofit [C]Worthy, which works on verifying the impact of ocean-based carbon removal. “And that’s still to be determined.”

Planetary’s Burt imagines a future in which minerals are pumped out through power plants and water treatment facilities on every major coastline in the world. But that would require a large, steady volume of magnesium oxide or similar minerals, along with the energy to mine and transport them.

Seaweed and algae growth would need to expand exponentially. The National Academies of Sciences, Engineering, and Medicine has estimated that nearly two-thirds of the world’s coastline would need to be encircled by kelp to even begin to make a dent in global warming. The company Seafields, which is running tests in the Caribbean, says it envisions building a Sargassum farm between Brazil and West Africa more than 200 miles wide.Marielle Louw, raised hands, and Andries Louw, missionaries from South Africa, pray during a worship service at Surf Church in Matosinhos beach in the suburbs of Porto, Portugal on Sunday, Aug. 18, 2024. (AP Photo/Luis Andres Henao)

Seminarians leave after morning Mass at Ritapiret Major Seminary in Maumere, East NusaTenggara province, Indonesia, Friday, Aug. 23, 2024. (AP Photo/Tatan Syuflana)Seminarians leave after morning Mass at Ritapiret Major Seminary in Maumere, East NusaTenggara province, Indonesia, Friday, Aug. 23, 2024. (AP Photo/Tatan Syuflana)

A woman who escaped the Good News International Church in Shakahola after she said she was sexually assaulted, enters a house in the coastal city of Malindi, in southern Kenya, on Friday, Sept. 6, 2024. (AP Photo/Brian Inganga)A woman who escaped the Good News International Church in Shakahola after she said she was sexually assaulted, enters a house in the coastal city of Malindi, in southern Kenya, on Friday, Sept. 6, 2024. (AP Photo/Brian Inganga)