Measure, reduce, and remove your organization's carbon footprint all in one place.

Climate Solutions Platform

With businesses looking for a way to take meaningful action against climate change, carbon dioxide removal (CDR) solutions hold the key to meaningful, long-lasting impact.  Most recently, marine CDR (mCDR) projects in particular have been receiving a lot of attention for their potential to be a significant player in the fight against climate change. Earlier in February 2024, the National Science Foundation (NSF) issued a request for information (RFI) to gather feedback on what it calls the “Marine CDR Plan” to advance critical mCDR research. You can learn more about Climate Vault’s recommendations here. In our comments, we highlighted four marine CDR projects that could save the planet, and hold the key to scalable climate impact. In this blog, we will share the four we will be keeping an eye on and why. 

Marine CDR and Climate Change 

“Marine CDR” refers to various methods and approaches that leverage the ocean’s natural capacity to absorb and sequester CO2 from the atmosphere. MCDR projects are critical in combating global warming for several reasons:

  1. Massive Storage Potential: The ocean covers over 70% of the Earth’s surface and has significant capacity to store CO2, particularly when compared to the sequestration capacity of terrestrial solutions. Enhancing this natural process could play a critical role in reducing atmospheric CO2 levels.
  2. Mitigating Climate Impacts: Reducing CO2 concentrations in the ocean has the dual impact of countering ocean acidification, which occurs when too much CO2 is in the water, as well as enabling the ocean to absorb additional CO2 from the atmosphere. Both elements help to decrease the total amount of CO2 in the atmosphere. 
  3. Complementing Other CDR Strategies: MCDR solutions do not compete with arable land or require fresh water, and some of the infrastructure and operations that are needed for certain projects are already in place from existing industries. As a result, mCDR can work alongside terrestrial and technological carbon removal methods and emission reductions to provide a comprehensive approach to addressing climate change.

4 Marine CDR Project Types to Watch

At Climate Vault, we know it will require a mosaic of solutions to combat the worst effects of climate change. Researching and developing a variety of mCDR solutions simultaneously is critical to identifying which solution(s) are most effective and scalable. In particular, we believe these 4 mCDR projects could save the planet and would benefit from dedicated research efforts under the Marine CDR Plan: 

1 – Blue Carbon

Blue carbon projects include the restoration and sustainable management of coastal and marine ecosystems—such as mangroves, seagrasses, and salt marshes—that naturally sequester and store significant amounts of CO2. These ecosystems are known as blue carbon ecosystems because they capture and store “blue carbon,” the carbon found in coastal and marine environments.

Blue carbon ecosystems are highly efficient at capturing and storing CO2. Mangroves, for example, can sequester up to five times more carbon per area than tropical forests. These projects are also essential to coastal resilience, supporting wildlife habitats and biodiversity, and bolstering local economies, such as fisheries. Blue carbon projects represent a vital intersection of climate mitigation, environmental conservation, and socioeconomic benefits. Despite these many positives, blue carbon projects face significant challenges, and their success will depend on answering critical questions on scalability and permanence.

2 – Macroalgae

Macroalgae projects focus on the cultivation, harvesting, and sinking of large seaweeds (macroalgae) to the deep ocean. Macroalgae grow quite rapidly and absorb notable amounts of CO2 via photosynthesis; therefore, growing and sinking these seaweeds offers a promising path to permanently sequestering CO2. However, much remains unknown about the effectiveness and impacts of sinking significant quantities of macroalgae to the deep ocean, and this is why further scientific exploration is needed on this topic. 

3 – Ocean Alkalinity Enhancement

Ocean Alkalinity Enhancement (OAE) involves adding alkaline substances, such as crushed olivine or lime, to ocean water. When alkaline substances are added to water, they react with CO2 in the water to form a solid mineral. This locks away the CO2 so that it cannot return to the atmosphere. Alkalinity also helps to counteract ocean acidification, a harmful consequence of rising CO2 levels that affects marine life.

While the chemistry behind OAE is well-understood, most OAE research to date has been confined to modeling and lab studies. Field trials are needed in order to better observe and quantify the effects of OAE on ocean chemistry, local ecosystems and coastal communities,  and to develop more precise accounting for carbon sequestration capacity. 

4 – Direct Ocean Capture

Direct Ocean Capture (DOC) projects involve technologies that directly remove CO2 from seawater. Once the CO2 is removed, the ocean absorbs more CO2 from the atmosphere in order to maintain a natural equilibrium. The CO2 that is removed from the seawater can then be permanently stored underground or used in long-lived products, such as cement used in construction materials, to prevent the CO2 from re-entering the atmosphere. DOC has significant potential as a mCDR approach; however, these projects currently remain in earlier stages of development and implementation.  

The Path Forward

Marine CDR projects offer a promising path forward to saving the planet by reducing the amount of CO2 in the ocean and enabling the ocean to naturally draw down more CO2 from the atmosphere. However, these projects are in earlier stages of development and implementation compared to other terrestrial or technological CDR solutions. Additionally, the vastness and complexity of the ocean makes modeling and executing mCDR projects uniquely challenging.   Continued research, pilot projects, and collaboration are essential to advance mCDR technologies and realize their full potential as a critical component of global climate change mitigation strategies. In the United States, the Marine CDR Plan could mark an important step in supporting and scaling these promising mCDR technologies, and we look forward to seeing how this important research initiative unfolds.

Dive deeper into mCDR solutions and Climate Vault’s oceanic pathway for innovative CDR projects. Watch our webinar on demand and hear from two mCDR project developers about the state of the oceanic pathway and the promise of these solutions for removing historic carbon.