A decade after the Paris Agreement, the ocean-climate nexus has shifted from the margins to the core of global governance, creating an urgent need for coherent policies that integrate ocean protection, climate action, and biodiversity conservation
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This piece is part of the series 'Governing the Oceans: Rethinking Access and Equity'
Covering over 70 percent of the Earth’s surface, the ocean is not only a vast, multi-dimensional ecosystem, but also the driving force behind the planet’s climate. Acting simultaneously as a carbon sink, a heat reservoir, and an oxygen supplier, it regulates our planet’s balance and shapes cultures and societies. Yet, for decades, its central role remained largely confined to scientific circles with limited translation into global governance frameworks, especially into the United Nations Framework Convention on Climate Change (UNFCC).
A decade after the establishment of the 2030 Agenda for Sustainable Development and the turning point of the Paris Agreement in 2015, the ocean-climate nexus has moved from the margins to the core of international climate negotiations. The challenge now is to turn this effort into coherent governance, effectively implemented policies, and cross-regime integration.
At the heart of the climate machine, the ocean has taken up about a third of anthropogenic CO2 emissions since the Industrial Revolution. It is Earth’s largest climate buffer, capturing 90 percent of the excess heat generated by human activities. Ultimately, it produces around 50 percent of the oxygen produced on Earth. These key findings have been progressively consolidated by the Intergovernmental Panel on Climate Change (IPCC), especially through its Special Report on the Ocean and Cryosphere in a Changing Climate (2019), which proved to be a true “scientific stamp of legitimacy” in establishing the ocean’s capacity as a climate regulator within the international climate agenda.
While the bottom 50 percent of emitters contribute only 13–15 percent of global emissions, up to 3.6 billion people - particularly in coastal and small island regions - live in highly climate-vulnerable contexts and are already disproportionately affected by sea-level rise and extreme events.
However, the ocean - and its vast potential - is under threat.
As suggested by the IPCC in its 2023 Report, “Anthropogenic climate change has exposed ocean and coastal ecosystems to conditions that are unprecedented over millennia”, leading to consequences scientists have defined as “ the deadly trio”, namely warming, acidification, and deoxygenation. In parallel, ocean health has worsened due to anthropogenic drivers of pressures identified by the IPBES Global Assessment Report (2019): overexploitation, pollution, habitat destruction, and invasive alien species.
Significantly, the impacts of these changing conditions are unevenly distributed across regions and populations. While the bottom 50 percent of emitters contribute only 13–15 percent of global emissions, up to 3.6 billion people - particularly in coastal and small island regions - live in highly climate-vulnerable contexts and are already disproportionately affected by sea-level rise and extreme events.
Despite early recognition in the United Nations Framework Convention on Climate Change (UNFCCC, 1992, Articles 1.3 and 3.1), ocean-climate interactions remained largely peripheral in the political agenda for decades.
A major turning point came in 2015 with the adoption of both the Paris Agreement (COP21) and the 2030 Agenda for Sustainable Development, including Sustainable Development Goal 14 - “Life Below Water’. Both frameworks recognised the ocean's crucial role in climate regulation, notably the Preamble and Article 5 of the Paris Agreement.
This political shift was driven by an unprecedented mobilisation of the ocean community, ranging from scientists to civil society, which culminated in the launch of the Ocean & Climate Platform in 2014, ahead of COP21, whose purpose was to serve as a key science–policy interface advocating for the ocean’s inclusion in climate negotiations.
Since then, the ocean has progressively become more embedded in UNFCCC processes. Key milestones include the Ocean Pathway Partnership (COP23, 2017), the Blue COP (COP25, 2019), and the establishment of the Ocean and Climate Change Dialogue and the Glasgow Pact (COP26, 2021), which invited Parties to mainstream the ocean into all UNFCCC processes, and the COP27 decision encouraging States to integrate the ocean into their NDCs. More recently, the Global Stocktake (COP28, 2023) reaffirmed the role of the ocean in mitigation and adaptation, while the ocean was further elevated at the COP30 World Leaders Summit and Global Mutirão (2025).
The Marrakech Partnership for Global Climate Action and its Ocean and Coastal Zones group, organising the Ocean Actions Days at COPs, underscore the mobilisation of non-state actors.
As a consequence, the ocean has progressively entered into Nationally Determined Contributions (NDCs), following early advocacy efforts such as the “Because the Ocean” Declaration (2015) or the “Ocean for Climate” report (2019). Today, more than 60 out of 66 coastal and island countries have included at least one ocean-based climate measure in their 2025 NDCs. Yet, challenges persist: many of them remain insufficiently precise, adaptation dominates over mitigation, and funding is lacking for effective implementation, primarily affecting developing countries.
The ocean provides a critical source of mitigation options. The report “The Ocean as a Solution to Climate Change” shows that ocean-based measures - ranging from ecosystem conservation to marine renewable energy - could deliver up to 35 percent of the emission reductions needed by 2050.
More recently, the Ocean Breakthroughs initiative has translated that potential into five sectoral tipping points: marine conservation, shipping decarbonisation, marine renewable energy, aquatic food, and coastal tourism. These initiatives highlight the need for investors and non-state actors to scale up ocean-based mitigation efforts.
Nonetheless, unlocking and implementing this potential requires overcoming challenges. These solutions remain underfinanced, and their inclusion into climate strategies is often uneven.
Climate change and biodiversity loss are intrinsically linked crises that require a holistic approach to reach the 1.5°C target under the Paris Agreement and the Kunming-Montreal Global Biodiversity Framework. Yet, ocean governance still largely operates in silos. The so-called “sister conventions” of the UNFCCC and the Convention on Biological Diversity share complementary objectives but lack strong coordination mechanisms and a strategic vision. These gaps may lead to the implementation of decarbonisation methods, such as marine carbon dioxide removal (mCDR) technologies, which could harm natural habitats.
The ocean offers a natural “Blue Thread" to bridge climate and biodiversity regimes. While both the UNFCCC and CBD increasingly recognise ocean-related issues, cooperation remains fragmented and insufficiently operationalised.
The ocean offers a natural “Blue Thread" to bridge climate and biodiversity regimes. While both the UNFCCC and CBD increasingly recognise ocean-related issues, cooperation remains fragmented and insufficiently operationalised. Recent progress demonstrates growing attention to synergies: the UNFCCC Global Stocktake stresses the need to address the two crises; the Kunming-Montreal Framework and its targets 8 and 11 aim to minimise the impacts of climate change and ocean acidification; and the COP28 Joint Statement explicitly addresses the ocean.
Aligning national strategies (NDCs and NBSAPs) will be a key opportunity to turn these global commitments into action while integrating solutions such as nature-based approaches and marine protected areas, which deliver climate and biodiversity benefits. These synergies will have to be developed with the recently adopted Biodiversity Beyond National Jurisdiction Treaty (BBNJ Agreement) or under the ongoing negotiations within the World Trade Organisation and the International Seabed Authority.
The challenge ahead for the ocean community is clear. The next phase of ocean-climate governance is no longer about putting the ocean on the table. It will be about implementation: aligning climate and biodiversity governance, strengthening the Ocean and Climate Change dialogue at the UNFCCC, scaling finance towards solutions, improving the quality of NDCs, and tracking implementation.
With a new generation of NDCs submitted, the lead-up to the Global Stocktake in 2028 will be an accountability test for countries to demonstrate that a healthy ocean is integral to achieving climate objectives.
Gauthier Carle is Executive Director at the Ocean & Climate Platform.
Sara Benbalit is Communications Officer at the Ocean & Climate Platform.
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Gauthier Carle is Executive Director of the Ocean & Climate Platform. He works to translate scientific knowledge into concrete policy action, strengthening the integration of ...
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Sara Benbalit is Communications Officer at the Ocean & Climate Platform. She works on strategic and creative communications to integrate the ocean into global climate ...
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