Seaweed Farming Joins Blue Carbon Frontline in Fight Against Climate Change

In a groundbreaking study published in Nature Climate Change, researchers have demonstrated that seaweed farms—though human-made—are as effective at storing carbon as natural coastal ecosystems. The discovery, backed by the International Atomic Energy Agency (IAEA), significantly boosts the credibility of seaweed farming as a viable, nature-based solution to combat global climate change.

A New Chapter in Blue Carbon Science

The term Blue Carbon refers to the carbon captured and stored by marine ecosystems, such as mangrove forests, seagrass meadows, and salt marshes. These habitats are critical carbon sinks, capable of trapping carbon dioxide from the atmosphere and storing it in their underlying sediments, where it can remain for centuries. Now, with this new research, seaweed farms may join their ranks.

The study analyzed sediment samples from 20 seaweed farms located across five continents. By using nuclear techniques, scientists were able to assess the rate at which organic carbon accumulates in the sediments beneath these farms. Astonishingly, the results showed that the rates of carbon burial in seaweed farms are on par with those of natural Blue Carbon systems.

“This study opens a new chapter in marine carbon removal strategies,” said Dr. Pere Masque, one of the main authors and former IAEA staff member. “We hypothesized that carbon burial in farm sediments would be significant, and global data now confirm it.”

Precision Tools for Deep Insights

To obtain these results, researchers relied on a technique involving the isotope lead-210—a naturally occurring radionuclide with a half-life of 22 years. By collecting undisturbed sediment cores using specialized cylindrical sampling devices, scientists maintained the integrity of sediment layers, which reflect the passage of time. The presence and decay of lead-210 enabled them to date each layer and calculate the rate at which organic carbon was accumulating over the decades.

“This kind of research is exciting because it opens up new areas of scientific exploration,” said Beat Gasser, an IAEA expert involved in the study. “The nuclear tools we use allow us to be highly accurate in measuring carbon burial, a crucial aspect in studying newer, less understood environments like seaweed farms.”

Oceans 2050 and the Push for Scalable Solutions

This pioneering study was conducted with the support of Oceans 2050’s Global Seaweed Project, a global effort aimed at restoring ocean health and harnessing marine ecosystems for climate action. According to Carlos Duarte, Chief Scientist at Oceans 2050 and the paper’s lead author, “Seaweed farming offers a scalable, nature-based solution for carbon removal. It also brings additional benefits such as enhancing marine biodiversity, creating economic opportunities, and contributing to global food security.”

The implications of these findings are enormous. With commercial seaweed farming practiced in over 35 countries across cold, temperate, and tropical waters, the potential for marine carbon sequestration is vast. Seaweed is already in demand globally, not just as food but also as an ingredient in medicines, cosmetics, and fertilizers. Leveraging this industry for carbon capture could revolutionize climate policy and mitigation strategies.

Moving Toward a Global Blue Carbon Inventory

Despite the promise, the study also emphasizes the need for more extensive research. “Additional studies are essential to refine our understanding of carbon burial rates across different oceanic conditions and farming methods,” Duarte noted.

The IAEA is playing a pivotal role by promoting the use of nuclear science to analyze Blue Carbon and by assisting countries in building technical capacity. These efforts are part of a broader strategy to develop a comprehensive global inventory of marine carbon sinks—an essential tool for crafting effective climate policies.

As the world faces the mounting impacts of climate change, seaweed farming emerges not only as a resource for food and industry but also as a potent ally in the fight against global warming.