The BBNJ high seas treaty is now in force. What its four pillars actually do, and where high-seas governance touches — and misses — blue carbon.
Nearly two-thirds of the ocean lies beyond any country's jurisdiction, and for most of history almost nothing governed what happened there collectively. That changed on 17 January 2026, when the BBNJ Agreement — the United Nations agreement on biodiversity beyond national jurisdiction, adopted in June 2023 after nearly two decades of negotiation — crossed its sixty-ratification threshold and entered into force. Coverage of the "High Seas Treaty" has been animated by whales, squid and deep-sea wilderness. Less discussed is what it does for the ocean's carbon system: deep sediments that hold centuries of organic carbon, the biological pump that ferries CO₂ to the deep, and the new generation of carbon-removal proposals that want to operate far offshore. The honest answer is two-part: BBNJ matters for ocean carbon governance in the long run — and it creates no carbon market, and no blue-carbon credit, of any kind. Here is what the treaty actually does.
Genetic material from high-seas organisms — microbes, deep-water fauna, floating seaweed communities — feeds bio-prospecting worth real money. BBNJ establishes rules for access and for sharing the benefits: notification of collection cruises, standardised identifiers for samples and sequence data, and both monetary and non-monetary benefit-sharing back toward all states, especially developing ones. It applies the same logic to digital sequence information, the genetic data that now matters more than the physical samples.
The agreement creates a legal mechanism to designate marine protected areas beyond national jurisdiction — something that was previously possible only in fragments (the Southern Ocean via CCAMLR, the North-East Atlantic via OSPAR). Proposals will be science-based, consultative and adopted through the treaty's Conference of the Parties. This is the pillar that connects BBNJ to the global "30×30" commitment to protect 30% of the ocean by 2030, made under the separate Kunming–Montreal biodiversity framework.
States must now ensure that EIAs are conducted for planned activities in areas beyond national jurisdiction that may cause substantial pollution or significant harmful change — with screening, public notification, and consideration of cumulative effects. This pillar gives the world, for the first time, a baseline duty to look before leaping in the high seas.
The fourth pillar funds and organises the transfer of science, monitoring capability and technical know-how to states that lack them, backed by a dedicated funding mechanism. In a treaty that governs two-thirds of the ocean, this is not decoration: rules only work where the capacity to use them exists.
Here is the essential geography. Almost everything the carbon markets call "blue carbon" — mangrove, seagrass and saltmarsh restoration and protection; kelp forest and seaweed pathways still seeking methodologies — happens inside national jurisdiction, in territorial seas and exclusive economic zones. It is counted, or aspires to be counted, through the Paris Agreement machinery we map in blue carbon policy and Article 6 and the ocean. National carbon accounting rewards coastal habitats precisely because nations can claim them.
Beyond the last maritime border, none of that applies. The deep ocean holds enormous carbon stocks in sediment, and the biological carbon pump transfers gigatonnes downward each year — but no country can put high-seas carbon in its nationally determined contribution, and no registry can issue a credit for it. The high seas are, in carbon terms, a commons with no ledger.
Deep-sea sediments accumulate organic carbon on very long timescales, and research attention has turned to how bottom-contact fishing and other disturbances re-suspend and remineralise it. Estimates are debated and the science is young; what is not debated is that intact benthic systems store large, slow-accumulating carbon pools. BBNJ's area-based tools now give the international community, for the first time, a legal instrument that could protect some of those areas. Whether early high-seas MPA proposals will cite carbon alongside biodiversity is one of the quiet negotiations to watch in the first COPs. But frame expectations correctly: protection of a carbon-rich high-seas canyon would never generate a "credit" — there is no buyer-side mechanism, and that may be healthy. The value is planetary, not tradeable.
Whatever one thinks of ocean CDR — the emerging landscape spans alkalinity enhancement, biomass sinking and more — several of its proposed deployment zones are in or near the high seas. BBNJ's EIA pillar now sets a treaty-level expectation that such activities be screened, assessed publicly, and evaluated for cumulative effects. In parallel, the London Convention and London Protocol regulate the deliberate placement of matter at sea and have adopted resolutions addressing marine geoengineering; exactly which ocean-CDR activities fall within each regime's remit remains a live legal question, worked through in who governs ocean carbon removal. BBNJ raises the procedural floor everywhere — publication, consultation, scientific review — and that floor will shape how ocean-CDR research earns its licence.
Perhaps the deepest long-run touchpoint is cultural. BBNJ encodes the principle that what is learned from the high-seas commons — samples, sequences, monitoring data — should return benefit to the commons. That expectation will travel. MRV systems for ocean carbon, high-seas ecological baselines, even the payment-for-services models behind open coastal data will increasingly be judged against it. (Tidewright's own open-data policy — a fictional company's stance in this demonstration — is built on the same conviction that monitoring commons produce more value shared than held.)
Three signals will say whether BBNJ changes ocean carbon governance in practice. First, the COP's rules of procedure and finance decisions — a weak institutional start starves every pillar. Second, the first high-seas MPA proposals — the regions tabled, and whether carbon-rich sediments feature in their scientific rationales. Third, whether ocean-CDR trials begin citing BBNJ EIA standards unilaterally as a credibility signal, which would mark the treaty's norms travelling faster than its institutions.
For coastal blue carbon, BBNJ's most immediate gift may be comparative: every ocean constituency now has fresh momentum, and the measurability gap between well-governed coastal habitats and the open ocean sharpens the case for the kind of science that makes restoration investable. Marine protected areas are older tools that show both the promise and the practice of ocean protection — see the science of MPAs for that groundwork.
No. The BBNJ Agreement contains no crediting, trading or offsetting mechanism of any kind. Carbon accounting for the ocean runs through national systems under the Paris Agreement, and no country can count high-seas carbon in its NDC. Any product marketed as a "high-seas carbon credit under the treaty" misrepresents the treaty.
No one, in market terms — which is rather the point. High-seas sediment carbon and the biological pump are part of the global commons. There is no registry, no tenure and no financial instrument for them. Protection of those stocks, if it comes, will come through area-based conservation and activity regulation, not through tradeable tonnes.
No — it was explicitly negotiated "not to undermine" existing legal instruments and bodies. Regional fisheries management organisations, the International Maritime Organization and the International Seabed Authority keep their mandates. BBNJ adds a biodiversity framework around them and requires cooperation, which makes its eventual MPAs slower to build but harder to ignore.
Mostly encouragement rather than obligation. Kelp restoration happens within national waters, so BBNJ does not govern it directly. Indirectly, the treaty's arrival raises expectations for impact assessment, data sharing and benefit-sharing across all ocean work — standards that strong coastal projects should already meet, and that signal where scrutiny is heading. Tidewright's (fictional) reading is that this is healthy: rigour travels downhill from law to norm faster than most industries expect.
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