Several innovative startup companies (with apparently plenty of funding) are using cutting-edge technology to address climate change by removing carbon dioxide from the oceans. The companies are leveraging the role oceans naturally play in absorbing and storing carbon. They are “geoengineering the sea” as the article states.

Hopefully 2025 is the year we start to see some of their “pilot programs" or their R&D efforts put into actual practice and they can start removing some of the CO₂ we're putting into the atmosphere. 

Captura, a startup that spun out of Caltech, focuses on extracting CO₂ directly from seawater. Using renewable energy, their technology performs an electrochemical process that pulls CO₂ from the water while maintaining the natural balance of the ocean. This approach is promising because the oceans absorb about a third of human-made CO₂ emissions, making it an effective target for removal efforts.

Running Tide combines biology and engineering to remove CO₂ by growing kelp on biodegradable buoys in the open ocean. The idea is to let the kelp absorb CO₂ as it grows, then sink it to the deep ocean, where the carbon remains trapped for centuries. By harnessing nature’s processes, this method could scale up efficiently to remove large amounts of carbon while supporting marine ecosystems.

Although Heirloom is better known for its work on land, the company is exploring ways to integrate its carbon capture technology with ocean systems. Heirloom uses a process that accelerates the natural ability of minerals to absorb CO₂. If adapted for ocean use, it could open new ways for carbon removal that complement other marine-based methods.

Seachange aims to leverage a chemical process that converts CO₂ dissolved in seawater into solid minerals. These minerals can then be safely stored on the seafloor. Their approach provides a long-term solution by locking away carbon in a stable, non-reactive form, helping reduce the CO₂ content in both the atmosphere and the oceans.

Planetary Technologies takes a slightly different route by using alkalinity-enhancing minerals to capture CO₂. When added to the ocean, these minerals chemically react with CO₂, turning it into a harmless compound that helps reduce ocean acidity while storing the carbon permanently. This dual benefit supports marine life and helps fight climate change.

These startups represent the growing field of ocean-based carbon removal, combining science and innovation to tackle one of the world’s biggest challenges. Each approach offers a unique way to use the ocean’s natural capabilities, giving hope for scalable solutions to slow global warming and protect the planet.