Elevating Ocean-Based Climate Solutions

An Opportunity for U.S. Nonfederal Diplomacy

To advance the climate effort internationally, U.S. states and cities can champion the largely overlooked role of ocean ecosystems.

A supercell storm cloud forms on the east coast of Queensland, Australia. (Getty/petesphotography)
A supercell storm cloud forms on the east coast of Queensland, Australia. (Getty/petesphotography)

When the Trump administration announced its intention to withdraw from the Paris Agreement on climate change, U.S. nonfederal actors—including states, cities, and businesses—launched alliances and initiatives to express their support for the agreement.1 This nonfederal climate movement, once largely a reactive communications exercise, is increasingly engaging in international climate diplomacy.2

One opportunity for the U.S. nonfederal climate movement to lead and advance the global climate effort is to champion ocean-based climate solutions. Ocean and climate issues are inextricably linked—highly protected marine reserves, for example, can sequester carbon and protect coastlines—yet international climate forums have often overlooked the ocean-climate relationship.

Integrating the ocean into mainstream climate diplomacy

Better integration of ocean issues would unlock progress in the international climate effort, given the causal connections between ocean health and climate change. Greenhouse gas emissions are increasing ocean temperatures, with a cascade of physical and socioeconomic effects, including sea level rise, coastal flooding, redistribution of fish stocks, food insecurity, displacement of coastal and island communities, degradation of ocean ecosystems, and loss of human livelihoods.3 Carbon dioxide emissions are also driving ocean acidification, which further threatens marine species and degrades food webs.4

At the same time, ocean ecosystems can affect climate change and the resilience of human communities and economies. Mangrove forests, seagrass meadows, and salt marshes, for example, can capture and store significantly more carbon than terrestrial forests while also defending coastlines from storms and flooding.5 Protecting and restoring these ecosystems is therefore an essential strategy for mitigating and adapting to climate change.6

To date, climate agreements have sparingly recognized the role that the ocean can play in addressing climate change. The U.N. Framework Convention on Climate Change (UNFCCC) mentions the ocean among ecosystems that serve as carbon sinks.7 Similarly, the Paris Agreement notes “the importance of ensuring the integrity of all ecosystems, including oceans” in its preamble.8 Meanwhile, although many countries included references to the ocean in their first set of national climate goals under the Paris Agreement, they were often in the context of climate impacts rather than climate solutions.9

National and subnational governments, however, are increasingly recognizing the promise of ocean-based climate strategies, making it an opportune time to champion international cooperation on these issues. In 2015, Chile and France led more than 20 countries to sign the “Because the Ocean” declaration, which promotes ocean resilience and an ocean action plan under the UNFCCC.10 In 2016, the Pacific Coast Collaborative launched the International Alliance to Combat Ocean Acidification (OA Alliance)—which now includes more than 25 national and subnational governments—in order to mitigate carbon pollution and help ecosystems and communities adapt to changing ocean chemistry.11 In 2017, Fiji, Sweden, and a number of developed and developing countries launched the Ocean Pathway Partnership, which aims to promote ocean-based climate strategies and elevate ocean issues within U.N. climate meetings.12 In 2018, Canada led the G-7 to endorse the Charlevoix Blueprint for Healthy Oceans, Seas, and Resilient Coastal Communities, which commits G-7 countries to advance issues such as coastal resilience and sustainable fisheries. Needless to say, a footnote clarifies that the United States “reserves on the climate related language in the Blueprint.”13

Opportunities for U.S. nonfederal ocean-climate diplomacy

The U.S. nonfederal climate movement is well-positioned to focus on ocean-based solutions in its climate diplomacy. Several U.S. cities and states have already played a leadership role, including Washington state, California, and Oregon, which launched the OA Alliance alongside British Columbia in response to the effects of ocean acidification on oyster hatchery production. Meanwhile, other members of the U.S. Climate Alliance—the coalition of states that are committed to reducing greenhouse gas emissions and supporting the Paris Agreement—are looking for new opportunities to substantively advance the global climate effort.14

There are many countries that have been progressive on climate or ocean issues that could partner with U.S. nonfederal leaders on the interface. Transatlantic cooperation is possible with Germany and France, which have both recently championed causes such as marine protected areas in the Antarctic; transpacific cooperation is possible with small island states, which are on the frontlines of climate and ocean change as existential threats; and cooperation is possible throughout the Americas, where several Latin American countries, such as Chile, are promoting the inclusion of ocean-based solutions in national climate goals under the Paris Agreement.15

As a first step in ocean-climate diplomacy, U.S. state and local governments can join existing coalitions such as the OA Alliance or the Ocean Pathway Partnership. They can also fully integrate ocean issues into their climate summits in order to ensure that they do not reinforce old silos but instead set a global precedent. The Global Climate Action Summit in September 2018, for example, overlooked the ocean-climate relationship in its original program but subsequently created a “land and ocean stewardship” theme among more traditional themes such as clean energy and climate finance.16 The summit also issued an “Ocean-Climate Action Agenda” to guide the integration of ocean issues in future climate diplomacy.17 As U.S. states and cities continue to host these meetings, they can make ocean-based climate solutions a standard focus for programming and commitments.

More broadly, international ocean-climate cooperation and joint commitments can focus on the following areas.18

Reversing the loss of “blue carbon” ecosystems

Blue carbon ecosystems, such as mangrove forests, kelp beds, seagrass meadows, and salt marshes, are efficient carbon sinks. Mangrove forests, for example, can store up to four times more carbon than other tropical forests.19 These ecosystems, however, are under threat. Over the past 50 years, mangrove forests have declined by up to half, and their destruction has caused significant carbon emissions.20 International cooperation and commitments can focus on advancing blue carbon restoration targets; financing the protection of coastal ecosystems domestically and internationally; and incorporating blue carbon strategies into climate goals, including national climate goals under the Paris Agreement.21

Addressing ocean acidification

Carbon dioxide emissions increase not only global temperatures but also ocean acidity. Since the beginning of the industrial revolution, the ocean has absorbed approximately 40 percent of carbon dioxide emissions, with the acidity of surface water increasing 26 percent during that timeframe.22 This threatens marine species, ecosystems, and economies, as illustrated by the 2005 collapse of oyster production in the Pacific Northwest.23 International cooperation and commitments can focus on creating and implementing region-specific ocean acidification action plans. This is the current mission of the OA Alliance, which motivates governments to chart strategies for sustaining coastal communities and livelihoods. As with national climate goals created for the Paris Agreement, acidification action plans can be diverse, reflecting the challenges and opportunities of each region. Elements of these plans can include reducing local drivers or exacerbators of acidification, such as agricultural runoff; restoring blue carbon ecosystems in order to temper local acidification; and devoting resources to scientific research to better understand acidification and its physical and socioeconomic effects.24

Creating and managing marine protected areas

Marine protected areas (MPAs) can play an important role in mitigating and adapting to climate change. Well-managed and well-enforced MPAs can preserve coral reefs, seagrass beds, mangrove forests, and other coastal ecosystems, many of which can help prevent coastal erosion and act as carbon sinks and storm buffers.25 MPAs can also help ensure food security by aiding in the recovery of exploited fish populations.26 International cooperation and commitments can focus on the designation of new highly to fully protected MPAs and the expansion of MPA networks across country lines.27 They can also focus on the research, monitoring, and full range of enforcement activities necessary to maximize the climate, environmental, and socioeconomic benefits of these areas.28

Promoting food security

Increasing ocean temperatures, shifting currents, and ocean acidification are endangering already stressed ocean ecosystems and are causing dramatic changes in fisheries productivity, species abundance, and stock locations.29 With seafood being a major source of protein for more than 3 billion people, global food security hinges on the ability to sustainably manage fisheries and aquaculture operations into the future.30 International cooperation and commitments can focus on ending overfishing; defending against illegal, unreported, and unregulated fishing; and protecting key fishing habitats. They can also focus on financing alternative job training in order to sustain economies that face the depletion of local fisheries. As aquaculture increases as an alternative to wild-capture fisheries, it is important to ensure that operations use sustainable feed and are sited and managed to prevent pollution and avoid fish escapes.

Collaborating on green ports and reducing shipping emissions

Ports are major energy consumers and greenhouse gas emitters. Outdated technology and infrastructure, energy inefficiency, and lack of vessel travel planning all contribute to unnecessary emissions.31 Meanwhile, the shipping industry itself is a growing source of carbon emissions. Without additional efforts, it could account for 17 percent of global carbon emissions by 2050.32 To combat this, the International Maritime Organization aims to reduce international shipping emissions by at least 50 percent from 2008 levels by midcentury.33 International cooperation and commitments can focus on promoting “green port” initiatives, such as implementing sound environmental management for dredging projects and offering a docking discount for vessels that use more environmentally friendly engines; incentivizing emissions reductions through coastal emissions standards; and promoting operational and technological options that can drive decarbonization, such as the “slow steaming” practice of reducing ship speed and thereby reducing fuel consumption.34

Supporting “green infrastructure” for coastal protection

Healthy ocean and coastal ecosystems, including coral reefs, mangroves, and dunes, provide invaluable services to coastal communities, which is why they are referred to as “green infrastructure.” Coral reefs, for example, reduce ocean wave energy, protecting coastlines from flooding.35 Without reefs, global flooding would increase in area by nearly 70 percent, affecting approximately 80 percent more people and more than doubling annual damages.36 Mangroves and seagrasses similarly help protect coastlines from flooding; they also stabilize sediment, reducing coastal erosion.37 With approximately 40 percent of the global population living in coastal areas, protecting and restoring these ecosystems is a key strategy for global climate preparedness.38 International cooperation and commitments can focus on green infrastructure for coastal protection domestically and internationally, with an emphasis on particularly vulnerable regions such as small island states. They can also support multilateral efforts, such as the Adaptation Fund, that implement coastal resilience projects.39

Cooperating on survival plans for climate-threatened marine species

Many marine species are highly migratory, traveling great distances between exclusive economic zones and into the high seas. However, changes in ocean temperatures, currents, and acidity are causing more species to travel farther from their native habitats, with some species extending or altogether moving their habitable ranges poleward.40 Meanwhile, conservation efforts for climate-threatened marine species can be complicated by a lack of regulatory framework for ocean areas beyond national jurisdiction (ABNJs). International cooperation and commitments can focus on the development and implementation of survival plans for transboundary marine species. In order to facilitate the conservation and management of highly migratory marine species in ABNJs, these efforts can also support the development and implementation of a U.N. high seas commission.


Despite the significant role that the ocean plays in mitigating and adapting to climate change, the ocean is still not a mainstream topic for climate diplomacy. By widely pursuing cooperation on ocean-based climate solutions, the U.S. nonfederal climate movement could drive better integration of ocean and climate policy globally, which could be the next major step forward in the international climate effort.

Gwynne Taraska is a senior fellow for International Climate Policy at Climate Advisers. Margaret Cooney is the campaign manager for Ocean Policy at the Center for American Progress.

The authors thank Aimee David, director of ocean conservation policy strategies at the Monterey Bay Aquarium, and Jessie Turner, government affairs and policy specialist at the Cascadia Law Group, for their helpful comments on a draft of this manuscript.  

The Center for American Progress thanks the German Embassy in Washington, D.C., for its support. The Center for American Progress produces independent research and policy ideas driven by solutions that we believe will create a more equitable and just world.


  1. In June 2017, the U.S. administration announced its intention to withdraw from the agreement, although the United States cannot formally withdraw until 2020. Michael D. Shear, “Trump Will Withdraw U.S. From Paris Climate Agreement,” The New York Times, June 1, 2017, available at
  2. Gwynne Taraska, “The Emergence of U.S. Nonfederal Climate Diplomacy” (Washington: Center for American Progress, 2017), available at
  3. Intergovernmental Panel on Climate Change, “Climate Change 2014 Synthesis Report” (2014), available at
  4. Ibid.
  5. These ecosystems can capture up to 10 times more carbon by area. Jennifer Howard and others, “Clarifying the role of coastal and marine systems in climate mitigation,” Frontiers in Ecology and the Environment 15 (1) (2017): 42–50, available at; Ocean Carbon and Biogeochemistry, “Quantifying coastal and marine ecosystem carbon storage potential for climate mitigation policy and management,” available at (last accessed July 2018); Callum M. Roberts and others, “Marine reserves can mitigate and promote adaptation to climate change,” Proceedings of the National Academy of Sciences of the United States of America 114 (24) (2017): 6167–6175, available at
  6. California Ocean Protection Council and others, “Ocean-Climate Action Agenda” (forthcoming September 2018), on file with authors.
  7. U.N. Framework Convention on Climate Change, “United Nations Framework Convention on Climate Change” (1992), available at
  8. U.N. Framework Convention on Climate Change, “Paris Agreement” (2015), available at
  9. See, for example, D. Herr and E. Landis, “Coastal blue carbon ecosystems: Opportunities for Nationally Determined Contributions” (Gland, Switzerland: International Union for Conservation of Nature and Washington: The Nature Conservancy, 2016), available at See also Natalya D. Gallo, David G. Victor, and Lisa A. Levin, “Ocean commitments under the Paris Agreement,” Nature Climate Change 7 (2017): 833–838, including the supplementary material, available at
  10. Tara Expeditions, “Because the Ocean…” (2015), available at In 2016, countries signed a follow-up statement: Tara Expeditions, “Second Because the Ocean Declaration” (2016), available at
  11. International Alliance to Combat Ocean Acidification, “2017 Progress Report” (2017), available at
  12. 2017 U.N. Climate Change Conference, “The Ocean Pathway,” available at (last accessed August 2018).
  13. G7 2018, “Charlevoix Blueprint for Healthy Oceans, Seas and Resilient Coastal Communities” (2018), available at
  14. United States Climate Alliance, “Home,” available at (last accessed August 2018).
  15. German Federal Ministry of Food and Agriculture, “Germany’s Proposal for a Marine Protected Area in Antarctica,” available at (last accessed August 2018); Ministerio de Relaciones Exteriores de Chile, “Submission on the relevance of the ocean in the global response to Climate Change” (2016), available at
  16. Global Climate Action Summit, “Home,” available at (last accessed August 2018).
  17. California Ocean Protection Council and others, “Ocean-Climate Action Agenda.”
  18. For further recommendations, see California Ocean Protection Council and others, “Ocean-Climate Action Agenda”; International Expert Working Group on Oceans and Climate, “Toward a Strategic Action Roadmap on Oceans and Climate: 2016 to 2021” (2016), available at
  19. Daniel C. Donato and others, “Mangroves among the most carbon-rich forests in the tropics,” Nature Geoscience 4 (2011): 293–297, available at
  20. Ibid.; Stuart E. Hamilton and Daniel A. Friess, “Global carbon stocks and potential emissions due to mangrove deforestation from 2000 to 2012,” Nature Climate Change 8 (2018): 240–244, available at
  21. See, for example, the global goal of increasing the area of coastal wetlands 20 percent by 2030. California Ocean Protection Council and others, “Ocean-Climate Action Agenda.”
  22. Tim DeVries, Mark Holzer, and Francois Primeau, “Recent increase in oceanic carbon uptake driven by weaker upper-ocean overturning,” Nature 542 (2017): 215–218, available at; Intergovernmental Panel on Climate Change, “Climate Change 2014 Synthesis Report.”
  23. Washington State Blue Ribbon Panel on Ocean Acidification, “Ocean Acidification: From Knowledge to Action” (2012), available at
  24. International Alliance to Address Ocean Acidification, “The Action Toolkit: Building your Ocean Acidification Action Plan” (2017), available at; Ocean Acidification international Reference User Group, “The Monaco Ocean Acidification Action Plan” (2015), available at; California Ocean Protection Council and California Ocean Science Trust, “Draft California Ocean Acidification Action Plan” (2018), available at
  25. Roberts and others, “Marine reserves can mitigate and promote adaptation to climate change.”
  26. Enric Sala and Sylvaine Giakoumi, “No-take marine reserves are the most effective protected areas in the ocean,” ICES Journal of Marine Science 75 (3) (2017), available at; Diego R. Barneche and others, “Fish reproductive-energy output increases disproportionately with body size,” Science 360 (2018): 642–645, available at
  27. The expansion of fully protected MPA networks across country lines would also help to meet both Aichi Biodiversity Targets 6 and 11. Graham J. Edgar, Trevor J. Ward, and Rick D. Stuart-Smith, “Rapid declines across Australian fishery stocks indicate global sustainability targets will not be achieved without an expanded network of ‘no-fishing’ reserves,” Aquatic Conservation: Marine and Freshwater Ecosystems (2018): 1–14, available at
  28. The 10X20 Initiative, “Scientists’ Consensus Statement on Marine Protected Areas (MPAs): Characteristics, Governance, and Sustainable Financing” (Rome, Italy: 2016), available at
  29. Avery Sicilano and others, “Warming Seas, Falling Fortunes” (Washington: Center for American Progress, forthcoming 2018).
  30. Food and Agriculture Organization of the United States, “The State of World Fisheries and Aquaculture: Contributing to Food Security and Nutrition for All” (2016), available at
  31. Pavlic Bostjan and others, “Sustainable Port Infrastructure, Practical Implementation of the Green Port Concept,” Thermal Science 18 (2014), available at
  32. Directorate-General for Internal Policies, “Emission Reduction Targets for International Aviation and Shipping” (2015), available at
  33. International Maritime Organization, “UN body adopts climate change strategy for shipping,” April 13, 2018, available at
  34. International Transport Forum, “Decarbonising Maritime Transport: Pathways to zero-carbon shipping by 2035” (2018), available at
  35. Edward B. Barbier and others, “The value of estuarine and coastal ecosystem services,” Ecological Monographs 81 (2) (2011): 169–193, available at
  36. Michael W. Beck and others, “The global flood protection savings provided by coral reefs,” Nature Communications 9 (2018), available at
  37. Mark D. Spalding and others, “Coastal Ecosystems: A Critical Element of Risk Reduction,” Conservation Letters 7 (3) (2014): 293–301, available at
  38. Barbara Neumann and others, “Future Coastal Population Growth and Exposure to Sea-Level Rise and Coastal Flooding – A Global Assessment,” PLOS One 10 (3) (2015), available at; Filippo Ferrario and others, “The effectiveness of coral reefs for coastal hazard risk reduction and adaptation,” Nature Communications 5 (2014), available at
  39. Adaptation Fund, “Coastal Zone Management,” available at (last accessed August 2018).
  40. Elvira S. Poloczanska and others, “Responses of Marine Organisms to Climate Change Across Oceans,” Frontiers in Marine Science 3 (62) (2016), available at

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Gwynne Taraska

Director, International Climate Policy

Margaret Cooney

Campaign Manager