Carbon Dioxide Removal

Mitigating Ocean Acidification

View NOAA’s Carbon Dioxide Removal Research Strategy >

What is Carbon Dioxide Removal?

Carbon dioxide removal aims to remove carbon dioxide (CO2) from the atmosphere and store it on land, underground, or in the ocean.

Carbon dioxide removal (CDR) aims to remove carbon dioxide (CO2) from the atmosphere and store it long-term underground or in the ocean. There are many techniques and strategies to remove CO2 from the atmosphere, some of which operate on land whereas others are in the ocean. Ocean-based methods are often referred to as marine CDR (mCDR). These techniques differ in their readiness for deployment and there are many unknowns about scalability, effectiveness, cost, and social and ecological impacts.

View ocean-based CDR techniques
View land-based and other CDR techniques

NOAA’s CDR Research Strategy presents the benefits and risks of different land-based and ocean-based techniques and NOAA assets available to assess them.

Marine CDR & Ocean Acidification

Some of the proposed mCDR approaches may have potential to mitigate ocean acidification. Learn more about how mCDR and ocean acidification are related and these approaches.

How is marine CDR related to Ocean Acidification?

While emissions reductions are the most direct, reliable, lasting, and effective way to mitigate ocean acidification, CDR methods that lower the concentration of CO₂ in the atmosphere also have the potential to slow it. Some marine CDR methods may also improve local ocean conditions that support ecosystems and economies.

Leveraging existing processes

Several existing processes in wastewater treatment facilities, golf courses and coastal management could be augmented to also draw down carbon dioxide. Leveraging these resources and processes can buffer local effects of ocean acidification. NOAA’s ecological monitoring and research programs can help answer questions of effectiveness and scale for these approaches.

Alkalinity Enhancement

Alkalinity enhancement aims to increase the ocean’s CO₂ storage capacity by changing the chemistry of the sea water to encourage greater absorption of CO₂ from the atmosphere. This method converts CO₂ to stable carbonate forms, which reduces ocean acidification. It could be a valuable, albeit slow, acidification mitigation mechanism, but many unknowns around these techniques remain. NOAA has a well demonstrated ability to detect changes in ocean alkalinity and ocean carbon content on broad scales that can help evaluate concerns around these approaches.

Image Credit: Sarah Battle, NOAA

Kelp Farming & Afforestation

Kelp farming or ocean afforestation uses the fast growth of kelp or other algae to capture CO₂ from surface waters, potentially mitigating ocean acidification. Carbon in kelp tissue would then be stored in ocean sediments when kelp sinks to the bottom. While this may be a natural process to efficiently capture CO₂, it may only have local or seasonal mitigating effects or benefits over short timescales. This approach may risk displacing existing phytoplankton productivity or produce other negative biogeochemical impacts. NOAA can provide modeling and observing capacity to assist siting and help answer questions about sequestration, storage, and impacts.

Valuable on Multiple Timescales

Even short-term or local-scale carbon removal could provide valuable benefits during times of heightened sensitivity by marine life or during episodic events. The scale, timing, and approach to carbon removal determines how effective it is at mitigating ocean acidification. NOAA has demonstrated expertise and assets to address many unknowns around the potential of ocean acidification mitigation by CDR.

NOAA's Investment in CDR Research

Why is NOAA investing in CDR research?

NOAA’s existing observational network and research programs position it to lead in the analysis of impact, effectiveness, feasibility, and risk of many CDR techniques. NOAA was created more than 50 years ago to study linkages between the ocean and atmosphere. Assessing the effectiveness of CDR approaches is directly related to its mission.

Read the Key Messages (PDF)

Voluntary carbon markets are increasing in value and there is potential for CDR to become over a trillion dollar industry by 2050.
Private industry is moving forward with carbon dioxide removal pilots. NOAA serves as a trusted agency to research and monitor efforts that can de-risk and provide integrity to this emerging market.
NOAA’s emphasis on big-picture, long-term monitoring and its existing research capabilities are ideally suited to understand, evaluate, and verify public and private entities’ exploration of CDR efforts and their potential for success.
NOAA's existing mandates, programs, and activities already intersect with CDR research.

Strategy for NOAA Carbon Dioxide Removal Research
NOAA’s CDR research strategy outlines what we know about existing technologies and what we need to learn to make the best decisions moving forward to meet climate goals.

NOAA can contribute to advancing our understanding through:

Coastal observing networks and data assimilation
Modeling, scaling & projecting CDR pathways
Ecosystem research & assessing impacts
Decision support

Carbon Dioxide Removal Projects

Click here to Read about recent mCDR projects.

Carbon capture and ocean acidification mitigation potential by seaweed farms in tropical and subtropical coastal environments

PI(s): Andreas Andersson
Fiscal Year Funded: 2023, 2024, 2025
Grant Award # NA23OAR0170512

Partners: Marine Biological Laboratory (MBL), Okinawa Institute of Science and Technology, Pacific Marine Environmental Laboratory (PMEL), Scripps Institution of Oceanography, Sunburst Sensors

This project will explore the carbon capture capacity and ocean acidification mitigation in three operational seaweed farms in Florida and Okinawa, Japan...

Multiscale observing system simulation experiments for iron fertilization in the Southern Ocean, Equatorial Pacific, and Northeast Pacific

PI(s): Dennis McGillicuddy
Fiscal Year Funded: 2023, 2024, 2025
Grant Award # NA23OAR0170514

Partners: National Center For Atmospheric Research (NCAR), NOAA Geophysical Fluid Dynamics Laboratory (GFDL), Woods Hole Oceanographic Institute

This project will address the effectiveness of ocean iron fertilization as a carbon dioxide removal technique, identify potential unintended ecological consequences, and determine the necessary systems for monitoring carbon and..

Electrolysis-driven weathering of basic minerals for long-term ocean buffering and CO2 reduction

PI(s): Burke Hales
Fiscal Year Funded: 2023, 2024, 2025, 2026
Grant Award # NA23OAR0170506

Partners: Oregon State University, Pacific Marine Environmental Laboratory (PMEL)

This project aims to demonstrate proof-of-concept that alkalinity addition and wave power systems could be used in tandem. The work will also informs a regulatory roadmap to highlight existing research..

Carbon Dioxide Removal Resources

Fact Sheets

Carbon Dioxide Removal Fact Sheet

This State of the Science fact sheet explains the current status of carbon dioxide removal and various approaches to accomplish it.

Reports

Workshop on Marine Carbon Dioxide Removal (Outputs from 2024 Meeting)

Strategy for NOAA Carbon Dioxide Removal Research

CDR Graphics Gallery

This gallery is a collection of graphics from the NOAA Carbon Dioxide Removal Research Strategy that demonstrate various approaches of carbon dioxide removal.

Other Resources

2024 NOPP mCDR Meeting: Measurement, Monitoring, Reporting, and Verification (MMRV) Panel

2024 NOPP mCDR Meeting: Permitting Panel

2024 NOPP mCDR Meeting: Data Management Panel

2024 NOPP mCDR Meeting: Social and Ethical Considerations

Get involved with ocean acidification

The NOAA Ocean Acidification Program exists to meet the ocean acidification research and monitoring needs of the U.S. See how you can get involved to serve your community and participate in cutting-edge research and education and outreach.