As of 2021, atmospheric carbon dioxide levels have reached historically unprecedented levels, higher than at any time in the past 800,000 years. Worldwide efforts to reduce emissions by creating a more efficient, carbon-free energy system may not be enough to stabilize the climate and avoid the worst impacts of climate change. Carbon dioxide removal (CDR) strategies, which remove and sequester carbon from the atmosphere, likely will be needed to meet global climate goals. The ocean, covering 70% of the Earth's surface, includes much of the global capacity for natural carbon sequestration; the ocean also holds great potential for uptake and longerterm sequestration of human-produced CO2. This report builds on previous work from the National Academies to assess what is currently known about the benefits, risks, and potential for responsible scale-up of six specific ocean-based CDR strategies as identified by the sponsor, ClimateWorks Foundation. It describes the research needed to advance understanding of those approaches and address knowledge gaps. The resulting research agenda is meant to provide an improved and unbiased knowledge base for the public, stakeholders, and policymakers to make informed decisions on the next steps for ocean CDR, as part of a larger climate mitigation strategy; it is not meant to lock in or advocate for any particular approach.

Contents

• The National Academies of SCIENCES • ENGINEERING • MEDICINE
• COMMITTEE ON A RESEARCH STRATEGY FOR OCEAN-BASED CARBON DIOXIDE REMOVAL AND SEQUESTRATION
• OCEAN STUDIES BOARD
• Preface
• Acknowledgments
• Summary
  • THE OCEAN AS A STRATEGY
  • TECHNOLOGIES CONSIDERED
  • CDR POTENTIAL
  • RESEARCH RECOMMENDATIONS
  • CONCLUDING REMARKS
• 1. Introduction
  • 1.1. HUMAN PERTURBATIONS TO THE GLOBAL CARBON CYCLE
  • 1.2. CLIMATE MITIGATION, DECARBONIZATION, AND CARBON DIOXIDE REMOVAL
  • 1.3. SEAWATER CO₂ AND CARBONATE SYSTEM CHEMISTRY
  • 1.4. OCEAN CARBON CYCLE AND OCEAN ANTHROPOGENIC CO₂ UPTAKE
  • 1.5. OCEAN-BASED CARBON DIOXIDE REMOVAL
  • 1.6. ORIGIN AND PURPOSE OF THE STUDY
  • 1.7. STUDY APPROACH AND FRAMEWORK FOR ASSESSMENT
• 2. Crosscutting Considerations on Ocean-based CDR R&D
  • 2.1. LEGAL AND REGULATORY LANDSCAPE
  • 2.2. SOCIAL DIMENSIONS AND JUSTICE CONSIDERATIONS
  • 2.3. OTHER CROSSCUTTING CONSIDERATIONS
  • 2.4. ADDRESSING RESEARCH GAPS
• 3. Nutrient Fertilization
  • 3.1. OVERVIEW
  • 3.2. KNOWLEDGE BASE
  • 3.3. EFFICACY
  • 3.4. SCALABILITY
  • 3.5. VIABILITY AND BARRIERS
  • 3.6. SUMMARY OF CARBON DIOXIDE REMOVAL POTENTIAL
  • 3.7. RESEARCH AGENDA
  • 3.8. SUMMARY
• 4. Artificial Upwelling and Downwelling
  • 4.1. OVERVIEW
  • 4.2. KNOWLEDGE BASE
  • 4.3. EFFICACY
  • 4.4. SCALABILITY
  • 4.5. VIABILITY AND BARRIERS
  • 4.6. SUMMARY OF CARBON DIOXIDE REMOVAL POTENTIAL
  • 4.7. RESEARCH AGENDA
  • 4.8. SUMMARY
• 5. Seaweed Cultivation
  • 5.1. OVERVIEW
  • 5.2. KNOWLEDGE BASE
  • 5.3. EFFICACY AND SCALABILITY
  • 5.4. VIABILITY AND BARRIERS
  • 5.5. SUMMARY OF CDR POTENTIAL
  • 5.6. RESEARCH AGENDA
  • 5.6. SUMMARY
• 6. Recovery of Marine Ecosystems
  • 6.1. OVERVIEW
  • 6.2. KNOWLEDGE BASE
  • 6.3. EFFICACY
  • 6.4. SCALABILITY
  • 6.5. VIABILITY AND BARRIERS
  • 6.6. SUMMARY OF CARBON DIOXIDE REMOVAL POTENTIAL
  • 6.7. RESEARCH AGENDA
  • 6.8. SUMMARY
• 7. Ocean Alkalinity Enhancement
  • 7.1. OVERVIEW
  • 7.2. KNOWLEDGE BASE
  • 7.3. EFFICACY
  • 7.4. SCALABILITY
  • 7.5. ENVIRONMENTAL AND SOCIAL IMPACTS
  • 7.6. MONITORING AND VERIFICATION
  • 7.7. VIABILITY AND BARRIERS
  • 7.8. SUMMARY OF CARBON DIOXIDE REMOVAL POTENTIAL
  • 7.9. RESEARCH AGENDA
  • 7.10. SUMMARY
• 8. Electrochemical Engineering Approaches
  • 8.1. OVERVIEW
  • 8.2. KNOWLEDGE BASE
  • 8.3. EFFICACY
  • 8.4. SCALABILITY
  • 8.5. VIABILITY AND BARRIERS
  • 8.6. SUMMARY OF CARBON DIOXIDE REMOVAL POTENTIAL
  • 8.6. RESEARCH AGENDA
  • 8.7. SUMMARY
• 9. Synthesis and Research Strategy
  • 9.1. A GENERAL FRAMEWORK FOR OCEAN-BASED CARBON DIOXIDE REMOVAL STRATEGIES
  • 9.2. COMMON COMPONENTS OF ANY RESEARCH IMPLEMENTATION
  • 9.3. SUMMARY OF ASSESSED OCEAN-BASED CARBON DIOXIDE REMOVAL STRATEGIES
  • 9.4. PROPOSED RESEARCH AGENDA
• REFERENCES
• Acronyms and Abbreviations
• Appendix A. Committee Biographies
• Appendix B. Workshop and Meeting Public Presentations to the Committee

Suggested citation:

National Academies of Sciences, Engineering, and Medicine. 2022. A Research Strategy for Ocean-based Carbon Dioxide Removal and Sequestration. Washington, DC: The National Academies Press. https://doi.org/10.17226/26278.

Digital Object Identifier: https://doi.org/10.17226/26278 Library of Congress Control Number: 2022933129

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