Some restoration efforts (particularly those most studied such as mangroves and salt marshes) are generally feasible, local, and have high local governability(Gattuso et al., 2018) , however the scale and durability of these efforts will be critical to their success as effective CDR pathways. The restoration of marine habitats and species aligns with several broad-reaching international agreements and domestic laws (NASEM, 2022). Several international agreements and policies that recognize the value and importance of restoring marine life and ecosystems and that may be important when considering scaling up restoration efforts include:

• Parties to the United Nations Convention on the Law of the Sea (UNCLOS)
• The Convention on Biological Diversity (CBD)
• The United Nations Decade of Ecosystem Restoration (2021-2030)
• UNFCCC Paris Agreement
• Coastal ecosystems can be included in Nationally Determined Contributions (NDCs)
• Global Biodiversity Framework
• Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR)
• UN High Seas Treaty (BBNJ Treaty)
• The Habitats Directive (European Commission)

Examples of agreements aimed at protecting marine life

• The Endangered Species Act (United States)
• The Marine Mammal Protection Act (United States)
• The National Marine Sanctuaries Act (United States)
• Marine Protected Areas (Note that MPAs are designed to protect and conserve biodiversity, rather than carbon. For coastal systems, these will be located in national or state waters.)

Examples of US Blue Carbon Policy

• Executive Order 14008: Tackling the Climate Crist at Home and Abroad (2021): Places the climate crisis at the forefront of foreign policy and national security planning.
• America the Beautiful Initiative: Outlines inclusive and collaborative plan for locally led efforts to conserve, steward, and restore land and waters.
• Justice 40 Initiative: A national commitment to environmental justice which includes investments in the reduction of legacy pollution.  
• Ocean Climate Action Plan (OCAP): Includes ongoing and planned federal ocean-based climate mitigation and adaptation activities and recommends new or enhances ocean science and policy actions to tackle climate change. It also includes environmental justice considerations into ocean-based climate solutions.
• CREST Act of 2023: An expansion on the current research and development programs of the Department of Energy for capturing and storing carbon dioxide to include methods like CDR.
• Coastal Habitat Conservation Act of 2023: Authorizes the appropriation of $111.5 million over the 2024-2028 period for the US Fish and Wildlife Service to implement the Coastal Program.

Some restoration efforts (particularly those most studied such as mangroves and salt marshes) are generally feasible, local, and have high local governability, however the scale and durability of these efforts will be critical to their success as effective CDR pathways. The restoration of marine habitats and species aligns with several broad-reaching international agreements and domestic laws. Several international agreements and policies that recognize the value and importance of restoring marine life and ecosystems and that may be important when considering scaling up restoration efforts include:

• Parties to the United Nations Convention on the Law of the Sea (UNCLOS)
• The Convention on Biological Diversity (CBD)
• The United Nations Decade of Ecosystem Restoration (2021-2030)
• UNFCCC Paris Agreement
• Coastal ecosystems can be included in Nationally Determined Contributions (NDCs)
• Global Biodiversity Framework
• Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR)
• UN High Seas Treaty (BBNJ Treaty)
• The Habitats Directive (European Commission)

Examples of agreements aimed at protecting marine life

• The Endangered Species Act (United States)
• The Marine Mammal Protection Act (United States)
• The National Marine Sanctuaries Act (United States)
• Marine Protected Areas (Note that MPAs are designed to protect and conserve biodiversity, rather than carbon. For coastal systems, these will be located in national or state waters.)

Examples of US Blue Carbon Policy

• Executive Order 14008: Tackling the Climate Crist at Home and Abroad (2021): Places the climate crisis at the forefront of foreign policy and national security planning.
• America the Beautiful Initiative: Outlines inclusive and collaborative plan for locally led efforts to conserve, steward, and restore land and waters.
• Justice 40 Initiative: A national commitment to environmental justice which includes investments in the reduction of legacy pollution.  
• Ocean Climate Action Plan (OCAP): Includes ongoing and planned federal ocean-based climate mitigation and adaptation activities and recommends new or enhances ocean science and policy actions to tackle climate change. It also includes environmental justice considerations into ocean-based climate solutions.
• CREST Act of 2023: An expansion on the current research and development programs of the Department of Energy for capturing and storing carbon dioxide to include methods like CDR.
• Coastal Habitat Conservation Act of 2023: Authorizes the appropriation of $111.5 million over the 2024-2028 period for the US Fish and Wildlife Service to implement the Coastal Program.

Some restoration efforts (particularly those most studied such as mangroves and salt marshes) are generally feasible, local, and have high local governability, however the scale and durability of these efforts will be critical to their success as effective CDR pathways. The restoration of marine habitats and species aligns with several broad-reaching international agreements and domestic laws. Several international agreements and policies that recognize the value and importance of restoring marine life and ecosystems and that may be important when considering scaling up restoration efforts include:

• Parties to the United Nations Convention on the Law of the Sea (UNCLOS)
• The Convention on Biological Diversity (CBD)
• The United Nations Decade of Ecosystem Restoration (2021-2030)
• UNFCCC Paris Agreement
• Coastal ecosystems can be included in Nationally Determined Contributions (NDCs)
• Global Biodiversity Framework
• Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR)
• UN High Seas Treaty (BBNJ Treaty)
• The Habitats Directive (European Commission)

Examples of agreements aimed at protecting marine life

• The Endangered Species Act (United States)
• The Marine Mammal Protection Act (United States)
• The National Marine Sanctuaries Act (United States)
• Marine Protected Areas (Note that MPAs are designed to protect and conserve biodiversity, rather than carbon. For coastal systems, these will be located in national or state waters.)

Examples of US Blue Carbon Policy

• Executive Order 14008: Tackling the Climate Crist at Home and Abroad (2021): Places the climate crisis at the forefront of foreign policy and national security planning.
• America the Beautiful Initiative: Outlines inclusive and collaborative plan for locally led efforts to conserve, steward, and restore land and waters.
• Justice 40 Initiative: A national commitment to environmental justice which includes investments in the reduction of legacy pollution.  
• Ocean Climate Action Plan (OCAP): Includes ongoing and planned federal ocean-based climate mitigation and adaptation activities and recommends new or enhances ocean science and policy actions to tackle climate change. It also includes environmental justice considerations into ocean-based climate solutions.
• CREST Act of 2023: An expansion on the current research and development programs of the Department of Energy for capturing and storing carbon dioxide to include methods like CDR.
• Coastal Habitat Conservation Act of 2023: Authorizes the appropriation of $111.5 million over the 2024-2028 period for the US Fish and Wildlife Service to implement the Coastal Program.

Some restoration efforts (particularly those most studied such as mangroves and salt marshes) are generally feasible, local, and have high local governability, however the scale and durability of these efforts will be critical to their success as successful CDR pathways. The restoration of marine habitats and species align with several broad-reaching international agreements and domestic laws. Several international agreements and policies that recognize the value and importance of restoring marine life and ecosystems and that may be important when considering scaling up restoration efforts include:

• Parties to the United Nations Convention on the Law of the Sea (UNCLOS)
• The Convention on Biological Diversity (CBD)
• The United Nations Decade of Ecosystem Restoration (2021-2030)
• UNFCCC Paris Agreement
• Coastal ecosystems can be included in Nationally Determined Contributions (NDCs)
• Global Biodiversity Framework
• Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR)
• UN High Seas Treaty (BBNJ Treaty)
• The Habitats Directive (European Commission)

Examples of agreements aimed at protecting marine life

• The Endangered Species Act (United States)
• The Marine Mammal Protection Act (United States)
• The National Marine Sanctuaries Act (United States)
• Marine Protected Areas (Note that MPAs are designed to protect and conserve biodiversity, rather than carbon. For coastal systems, these will be located in national or state waters.)

Examples of US Blue Carbon Policy

• Executive Order 14008: Tackling the Climate Crist at Home and Abroad (2021): Places the climate crisis at the forefront of foreign policy and national security planning.
• America the Beautiful Initiative: Outlines inclusive and collaborative plan for locally led efforts to conserve, steward, and restore land and waters.
• Justice 40 Initiative: A national commitment to environmental justice which includes investments in the reduction of legacy pollution.  
• Ocean Climate Action Plan (OCAP): Includes ongoing and planned federal ocean-based climate mitigation and adaptation activities and recommends new or enhances ocean science and policy actions to tackle climate change. It also includes environmental justice considerations into ocean-based climate solutions.
• CREST Act of 2023: An expansion on the current research and development programs of the Department of Energy for capturing and storing carbon dioxide to include methods like CDR.
• Coastal Habitat Conservation Act of 2023: Authorizes the appropriation of $111.5 million over the 2024-2028 period for the US Fish and Wildlife Service to implement the Coastal Program.

Some restoration efforts (particularly those most studied such as mangroves and salt marshes) are generally feasible, local, and have high local governability^[1]Gattuso, J.-P., A. K. Magnan, L. Bopp, W. W. L. Cheung, C. M. Duarte, J. Hinkel, E. McLeod, F. Micheli, A. Oschlies, P. Williamson, R. Billé, V. I. Chalastani, R. D. Gates, J. O. Irisson, J. J. Middelburg, H. O. Pörtner, and G. H. Rau. 2018. Ocean solutions to address climate change and its effects on marine ecosystems. Frontiers in Marine Science 5:337. doi:10.3389/fmars.2018.00337. , however the scale and durability of these efforts will be critical to their success as successful CDR pathways. The restoration of marine habitats and species align with several broad-reaching international agreements and domestic laws^[2]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. . Several international agreements and policies that recognize the value and importance of restoring marine life and ecosystems and that may be important when considering scaling up restoration efforts include:

• Parties to the United Nations Convention on the Law of the Sea (UNCLOS)
• The Convention on Biological Diversity (CBD)
• The United Nations Decade of Ecosystem Restoration (2021-2030)
• UNFCCC Paris Agreement
• Coastal ecosystems can be included in Nationally Determined Contributions (NDCs)
• Global Biodiversity Framework
• Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR)
• UN High Seas Treaty (BBNJ Treaty)
• The Habitats Directive^[3]https://environment.ec.europa.eu/topics/nature-and-biodiversity/habitats-directive_en (European Commission)

Examples of agreements aimed at protecting marine life

• The Endangered Species Act (United States)
• The Marine Mammal Protection Act (United States)
• The National Marine Sanctuaries Act (United States)
• Marine Protected Areas (Note that MPAs are designed to protect and conserve biodiversity, rather than carbon. For coastal systems, these will be located in national or state waters.)

Examples of US Blue Carbon Policy

• Executive Order 14008: Tackling the Climate Crist at Home and Abroad (2021): Places the climate crisis at the forefront of foreign policy and national security planning.
• America the Beautiful Initiative: Outlines inclusive and collaborative plan for locally led efforts to conserve, steward, and restore land and waters.
• Justice 40 Initiative: A national commitment to environmental justice which includes investments in the reduction of legacy pollution.  
• Ocean Climate Action Plan (OCAP): Includes ongoing and planned federal ocean-based climate mitigation and adaptation activities and recommends new or enhances ocean science and policy actions to tackle climate change. It also includes environmental justice considerations into ocean-based climate solutions.
• CREST Act of 2023: An expansion on the current research and development programs of the Department of Energy for capturing and storing carbon dioxide to include methods like CDR.
• Coastal Habitat Conservation Act of 2023: Authorizes the appropriation of $111.5 million over the 2024-2028 period for the US Fish and Wildlife Service to implement the Coastal Program.

• Prioritize leadership and partnership with local communities and recognize formal and informal tenure agreements.
• Networks of nations (e.g., International Partnership for Blue Carbon) can aid in building capacity to implement policies that support blue carbon projects.
• New IPCC inventory guidance is needed on emissions inventories for climate mitigation resulting from restoring seagrass, seaweed, and other blue carbon ecosystems (the current lack of guidance here also limits private sector investment)

1. Open systems where the open ocean is directly manipulated to enhance biological production, capture atmospheric CO₂, and export the captured carbon to the deep ocean. In open systems, CO₂ fixation is facilitated by the addition of limiting macronutrients (e.g., phosphorus, nitrogen, silica) and/or micronutrients (e.g., iron) to the ocean’s surface to augment biological production . Open system techniques accelerate natural processes already occurring in the ocean. Most approaches in the open ocean fall into the following two categories (some proposals that do not fit into these categories are also explored).
   1. Surface nutrient addition: the direct addition of nutrients (macro or micro) into ocean waters in situ to increase microalgal growth 
   2. Nutrient upwelling: artificial upwelling of nutrient-rich deep ocean waters to the surface to increase microalgal growth
2. Closed systems where inputs and growth conditions are controlled, and outputs (microalgae) are harvested within the confines of a pond or a photobioreactor. In closed systems, CO₂ fixation is facilitated by the mixing of required inputs (sunlight, nutrients, CO₂, water) and the introduction of microalgae culture with the intention of reproduction and continuous fixation in a contained system . This can be accomplished on shore in cultivation ponds or photobioreactors, or afloat in photobioreactors either stationary or towed at sea .

1. 1. Onshore: encompasses more established methods of microalgae cultivation, including photobioreactors, cultivation ponds, and hybrid onshore configurations. In these systems, all inputs are tightly controlled and regulated, and outputs must be directly managed through either storage or utilization of byproducts. While cultivation techniques are well-established and show high technological readiness, storage and utilization pathways remain underdeveloped and scale is a major consideration. Social and environmental risks for closed onshore systems are easier to monitor and mitigate due to the controlled nature of the system. 
   2. Offshore: includes floating photobioreactors (PBRs) that are incorporated into a floating platform which can be stationary or towed behind a ship. In these systems, cultivation occurs in the photobioreactor, inputs are regulated, and outputs can be actively managed or directed. While at sea, these photobioreactors operate much like their onshore counterparts to cultivate microalgae, however nutrients and energy are provided by the ocean water and wave action, respectively. After microalgae are cultivated, they can be sunk into the deep ocean for sequestration or hauled to shore to be used as biomass. This is an area that has garnered much attention in startup communities (see this Y Combinator request for startups), however, little is available about the technologies in the open-sourced or peer reviewed literature.

• Property rights, coastal and offshore, are often unclear, not well defined, or not enforced, begging the question, who has jurisdiction over what. This is further complicated by the lateral movement of carbon in blue carbon ecosystems.
• Local governance of global commons is further complicated by local contexts, management structures, and benefit-sharing rules (Merk et al., 2022).
• Permitting may also pose an additional obstacle for some restoration projects.
• Regulations for coastal developments could impede coastal vegetated ecosystem restoration and limit the ability to launch larger restoration projects.

• Property rights, coastal and offshore, are often unclear, not well defined, or not enforced, begging the question, who has jurisdiction over what. This is further complicated by the lateral movement of carbon in blue carbon ecosystems.
• Local governance of global commons is further complicated by local contexts, management structures, and benefit-sharing rules^[1]Merk, Christine; Grunau, Jonas; Riekhof, Marie-Catherine; Rickels, Wilfried (2022) : The need for local governance of global commons: The example of blue carbon ecosystems, Kiel Working Paper, No. 2201, Kiel Institute for the World Economy (IfW), Kiel .
• Permitting may also pose an additional obstacle for some restoration projects.
• Regulations for coastal developments could impede coastal vegetated ecosystem restoration and limit the ability to launch larger restoration projects.

• Property rights, coastal and offshore, are often unclear, not well defined, or not enforced, begging the question, who has jurisdiction over what. This is further complicated by the lateral movement of carbon in blue carbon ecosystems.
• Local governance of global commons is further complicated by local contexts, management structures, and benefit-sharing rules^[1]Merk, Christine; Grunau, Jonas; Riekhof, Marie-Catherine; Rickels, Wilfried (2022) : The need for local governance of global commons: The example of blue carbon ecosystems, Kiel Working Paper, No. 2201, Kiel Institute for the World Economy (IfW), Kiel .
• Permitting may also pose an additional obstacle for some restoration projects.
• Regulations for coastal developments could impede coastal vegetated ecosystem restoration and limit the ability to launch larger restoration projects.

1. Open systems where the open ocean is directly manipulated to enhance biological production, capture atmospheric CO₂, and export the captured carbon to the deep ocean. In open systems, CO₂ fixation is facilitated by the addition of limiting macronutrients (e.g., phosphorus, nitrogen, silica) and/or micronutrients (e.g., iron) to the ocean’s surface to augment biological production . Open system techniques accelerate natural processes already occurring in the ocean. Most approaches in the open ocean fall into the following two categories (some proposals that do not fit into these categories are also explored).
   1. Surface nutrient addition: the direct addition of nutrients (macro or micro) into ocean waters in situ to increase microalgal growth 
   2. Nutrient upwelling: artificial upwelling of nutrient-rich deep ocean waters to the surface to increase microalgal growth
2. Closed systems where inputs and growth conditions are controlled, and outputs (microalgae) are harvested within the confines of a pond or a photobioreactor. In closed systems, CO₂ fixation is facilitated by the mixing of required inputs (sunlight, nutrients, CO₂, water) and the introduction of microalgae culture with the intention of reproduction and continuous fixation in a contained system . This can be accomplished on shore in cultivation ponds or photobioreactors, or afloat in photobioreactors either stationary or towed at sea .

1. 1. Onshore: encompasses more established methods of microalgae cultivation, including photobioreactors, cultivation ponds, and hybrid onshore configurations. In these systems, all inputs are tightly controlled and regulated, and outputs must be directly managed through either storage or utilization of byproducts. While cultivation techniques are well-established and show high technological readiness, storage and utilization pathways remain underdeveloped and scale is a major consideration. Social and environmental risks for closed onshore systems are easier to monitor and mitigate due to the controlled nature of the system. 
   2. Offshore: includes floating photobioreactors (PBRs) that are incorporated into a floating platform which can be stationary or towed behind a ship. In these systems, cultivation occurs in the photobioreactor, inputs are regulated, and outputs can be actively managed or directed. While at sea, these photobioreactors operate much like their onshore counterparts to cultivate microalgae, however nutrients and energy are provided by the ocean water and wave action, respectively. After microalgae are cultivated, they can be sunk into the deep ocean for sequestration or hauled to shore to be used as biomass. This is an area that has garnered much attention in startup communities (see this Y Combinator request for startups), however, little is available about the technologies in the open-sourced or peer reviewed literature.

1. Open systems where the open ocean is directly manipulated to enhance biological production, capture atmospheric CO₂, and export the captured carbon to the deep ocean. In open systems, CO₂ fixation is facilitated by the addition of limiting macronutrients (e.g., phosphorus, nitrogen, silica) and/or micronutrients (e.g., iron) to the ocean’s surface to augment biological production . Open system techniques accelerate natural processes already occurring in the ocean. Most approaches in the open ocean fall into the following two categories (some proposals that do not fit into these categories are also explored).
   1. Surface nutrient addition: the direct addition of nutrients (macro or micro) into ocean waters in situ to increase microalgal growth 
   2. Nutrient upwelling: artificial upwelling of nutrient-rich deep ocean waters to the surface to increase microalgal growth
2. Closed systems where inputs and growth conditions are controlled, and outputs (microalgae) are harvested within the confines of a pond or a photobioreactor. In closed systems, CO₂ fixation is facilitated by the mixing of required inputs (sunlight, nutrients, CO₂, water) and the introduction of microalgae culture with the intention of reproduction and continuous fixation in a contained system . This can be accomplished on shore in cultivation ponds or photobioreactors, or afloat in photobioreactors either stationary or towed at sea .

1. 1. Onshore: encompasses more established methods of microalgae cultivation, including photobioreactors, cultivation ponds, and hybrid onshore configurations. In these systems, all inputs are tightly controlled and regulated, and outputs must be directly managed through either storage or utilization of byproducts. While cultivation techniques are well-established and show high technological readiness, storage and utilization pathways remain underdeveloped and scale is a major consideration. Social and environmental risks for closed onshore systems are easier to monitor and mitigate due to the controlled nature of the system. 
   2. Offshore: includes floating photobioreactors (PBRs) that are incorporated into a floating platform which can be stationary or towed behind a ship. In these systems, cultivation occurs in the photobioreactor, inputs are regulated, and outputs can be actively managed or directed. While at sea, these photobioreactors operate much like their onshore counterparts to cultivate microalgae, however nutrients and energy are provided by the ocean water and wave action, respectively. After microalgae are cultivated, they can be sunk into the deep ocean for sequestration or hauled to shore to be used as biomass. This is an area that has garnered much attention in startup communities (see this Y Combinator request for startups), however, little is available about the technologies in the open-sourced or peer reviewed literature.