Within the ocean’s vast expanse lie immense reservoirs of carbon – surpassing those found in either the atmosphere or the land.
The ocean actively captures and incorporates carbon through various natural mechanisms, locking in a significant portion that would otherwise circulate within the Earth’s systems, thereby functioning as a continuous carbon sink.
This crucial role mitigates climate change by reducing the amount of carbon which ends up in the atmosphere. If the ocean remains as a net carbon sink, it can aid in offsetting ongoing emissions and slowing global warming.
Unfortunately, a longstanding misconception persists that the ocean has an infinite resilience to human exploitation and negligence – likely stemming from the fact that the consequences of our actions are obscured beneath the surface.
Unsustainable use of the ocean’s resources – such as through overfishing – coupled with warming and acidification progressively erode the ocean’s capacity to regulate carbon and heat and its ability to sustain essential resources and services.
Consequently, rates of carbon sequestration are weakening and the vast carbon reserves held within marine ecosystems are increasingly susceptible to release.
This guest post lays out the climate opportunities presented by “blue carbon” and the challenges these ecosystems face.
Blue carbon is a term that refers to carbon captured by the world’s ocean and coastal ecosystems that has potential to be conserved or enhanced. Blue carbon is stored in vegetated coastal and marine ecosystems such as seagrass, mangroves and salt marshes.
The opportunity of coastal ecosystems
Coastal ecosystems – particularly vegetated ones, such as mangroves, seagrasses and salt marshes – are among the most crucial marine systems for storing carbon. Like plants on land, marine vegetation absorbs CO2 through photosynthesis. Because their waterlogged soils are low in oxygen, the carbon stored there can be locked away for centuries.
Despite only occupying approximately 0.5% of the ocean, these ecosystems boast remarkable carbon sequestration capabilities, contributing more than 50% of total carbon buried in marine sediments.
However, these vital ecosystems also face relentless human-caused pressures, from runoff of nutrients and sediments to urban expansion. They are being destroyed at an alarming pace – an average of 2% loss per year for mangroves – and are among the most threatened ecosystems on the planet.
Nevertheless, amidst this threat lies an opportunity: by reversing the conditions that are causing their decline, we can restore lost ecosystems and harness their potential as carbon sequestration hotspots once more.
The chart below shows the annual carbon storage potential of coastal ecosystems around the world, with yellow and light green indicating low storage potential and darker blues indicating high storage potential. The US, Mexico, Australia, Indonesia and Mexico stand out as countries with particularly high storage potential.
Managing coastal vegetated ecosystems to enhance carbon sequestration, often referred to as “blue carbon”, represents a valuable nature-based strategy for mitigating climate change.
While the amount of carbon that is offset through these methods is estimated to be at least an order of magnitude below other mitigation approaches – such as ocean alkalinisation and direct carbon capture and storage – they have additional benefits.
These ecosystems also enhance adaptation by stabilising coastlines, safeguarding against erosion and storms, enhancing water quality and nurturing marine life – thus promoting biodiversity through the provision of shelter, food and nursery grounds.
Climate and biodiversity
Blue carbon is a prime example of how climate change and the alarming decline in global biodiversity are connected.
Initiatives focused on blue carbon restoration – such as the “Mangroves for Coastal Resilience” project in Indonesia, the largest such initiative in the world – not only enhance carbon sequestration, but also reverse habitat loss and bolster biodiversity. Safeguarding marine biodiversity can also help secure the long-term well-being and prosperity of people whose lives and livelihoods are tightly linked to the oceans.
For example, declines in marine biodiversity undermine ecosystem resilience, heightening vulnerability to environmental disturbances and impacting economies reliant on marine resources. Loss of species degrades the food webs underpinning fisheries, jeopardising food security and livelihoods.
Furthermore, biodiversity loss directly compromises human health by fostering the emergence of zoonotic diseases that pass from animals to humans, diminishing water quality and impeding the exploration of new pharmaceuticals and treatments.
Protecting communities
Coastal restoration projects are already being carried out around the world, from small, local projects to larger initiatives.
They also encompass a range of activities, from planting new mangrove trees to managing tidal flows.
There are several crucial factors that demand careful consideration before implementing such a project.
Among these is the need to prioritise the protection of intact ecosystems. By safeguarding these areas, we can prevent the loss of carbon they have already sequestered and sidestep the time lag associated with re-establishing vital ecosystem services following habitat restoration.
Additionally, it is imperative to address the underlying pressures contributing to ecosystem loss, such as sewage discharge and agricultural runoff.
Restoration efforts must also be designed to withstand potential future challenges, such as changing land-use patterns and the projected impacts of climate change. Proactive measures to safeguard and restore coastal ecosystems should account for these complex and dynamic factors to ensure their long-term success and resilience in the face of ongoing environmental changes.
Local engagement and support for blue carbon initiatives are also needed because coastal communities often directly interact with these ecosystems for livelihoods, fishing, tourism and protection from natural disasters. Engaging these communities ensures that conservation efforts are sustainable. Additionally, tapping into the knowledge and expertise of local communities about coastal ecosystems is essential for informed decision-making.
Integrating carbon sequestration goals with other conservation and management objectives, such as sustainable fisheries and coastal resilience, is possible by empowering local communities to lead blue carbon initiatives. This can help ensure social equity, address economic opportunities and reduce conflicts over resource use.
Ultimately, garnering people’s buy-in for blue carbon solutions is essential for their effectiveness, sustainability and equitable distribution of benefits.
Considering marine sediment
Blue carbon “solutions” can be regarded as any intervention which aims to enhance the ocean’s natural capacity to store and sequester carbon.
As such, one might consider the management of commercial species and natural populations to increase the biomass of, and thereby carbon contained in, marine organisms. Managing interactions with the seabed can also be an important blue carbon solution.
Recent estimates suggest marine sediments are the largest store of organic carbon on the planet. Therefore, activities which disrupt them, such as bottom trawling or deep-sea mining, may be stirring up this sediment and leading to carbon being released back to the atmosphere.
Although the full picture has yet to emerge, examining the impacts of where and how trawling is conducted allows us to make choices informed by all of the potential impacts. And before deep-sea mining activities are further scaled up, a more comprehensive understanding of their impacts is vital.
The post Guest post: The role of ‘blue carbon’ in addressing climate change appeared first on Carbon Brief.
Guest post: The role of ‘blue carbon’ in addressing climate change
June Rubis is a steering group committee member for the Cali Fund, from Sarawak in Malaysian Borneo.
At COP16 in Cali, governments made a significant commitment: at least half of the funding from the new Cali Fund should support the self-identified needs of Indigenous Peoples and local communities, including women and youth. It was a watershed moment for multilateral benefit-sharing.
The challenge now is to translate that commitment into access arrangements that recognise the different institutions, priorities and decision-making processes of Indigenous Peoples and local communities.
For generations, biodiversity and traditional Indigenous knowledge have provided significant value to companies who depend on nature’s genetic diversity to discover new drugs that fight diseases, create products that improve health, and grow crops resilient to extreme heat and flooding events. While some compounds are sampled directly from the source country, increasingly the digital blueprints are held in online public databases which are freely accessible to use for innovation and research.
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The Cali Fund was established at COP16 to encourage commercial users of Digital Sequence Information, or DSI, to share benefits arising from its use. Estimates suggest it could generate over $3.5 billion a year – a stark contrast to the modest $10,656 currently committed to the fund from just five SMEs, underlining how much progress must be made at COP17 over the next two weeks.
The COP16 decision that set up the fund offers two routes for money to reach Indigenous Peoples and local communities: through government authorities, and through direct payments to institutions identified by Indigenous Peoples and local communities themselves.
Varied ways of organising
Indigenous Peoples and local communities organise through a wide range of institutions. Some have national or regional organisations experienced in managing international grants. Others work through territorial organisations, customary institutions, community associations, cooperatives or networks. Some have professional finance teams and audited accounts; others have extensive experience governing territories, collective resources or conservation work without having been organised around international funding requirements.
For direct access, some questions are already apparent. Which institutions should be able to receive funds? How should they be identified? What fiduciary standards should apply? How should safeguards and accountability work where institutional capacities differ? What support may be needed where institutions have strong community mandates but less experience with international finance?
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If access is designed mainly around institutions that already meet the expectations of large international finance mechanisms, early funding will tend to favour those already familiar to funders. They will gain further experience and become better positioned for future funding, while institutions with less administrative capacity may remain outside the system despite strong community mandates and long histories of stewardship.
These first decisions matter most, because they set the terms for everyone who follows.
The role of intermediaries requires care. Some Indigenous organisations may want a fiscal host to hold and manage funds on their behalf. Communities may choose to work through an NGO they trust. Government-facilitated arrangements may work well in particular national contexts.
What matters is the function an intermediary performs and the authority that comes with it. Providing administrative support is different from deciding which Indigenous organisations qualify, which priorities can receive support, or how success will be assessed. Direct access means communities keep that decision-making authority.
Decision-making power
The COP16 decision refers to institutions that Indigenous Peoples and local communities identify. But authority among Indigenous Peoples does not sit in one kind of body. It may sit with territorial organisations, customary institutions, community associations or combinations of these. Legal recognition and customary authority do not always align neatly.
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An important feature of the Cali Fund’s governance is that Indigenous Peoples and local communities participate as full members of the Steering Committee, rather than as observers. Seven Indigenous Peoples and local community representatives, one from each of the seven socio-cultural regions, participate in consensus-based decision-making alongside representatives of governments and UN entities. Six additional representatives from civil society, scientific institutions and the private sector participate as observers.
That representation carries responsibility. Institutional legitimacy, access and representation take different forms across the seven socio-cultural regions. Indigenous Peoples and local communities members therefore have an important role in bringing those differences into the Fund’s governance and in ensuring that arrangements developed for one context do not become the assumed model for everyone else.
Safeguards and clear responsibilities
COP17 can establish the core principles and direction, while allowing operational pathways to develop in ways that respond to different regional contexts. The decisions countries take in Yerevan will shape how that flexibility is realised in practice.
The choices made around access will influence which institutions are able to participate, which routes become established and which forms of authority are recognised within the funding architecture. The aim should be an architecture with enough structure to maintain confidence while allowing for different forms of Indigenous and community governance.
A credible direct-access pathway will need safeguards, financial oversight and clear responsibilities. This would give the 50% commitment a stronger institutional foundation.
The Cali Fund’s importance will ultimately depend not only on how much funding reaches Indigenous Peoples and local communities, but on whether they are able to determine how the money is accessed, governed and used. This requires access pathways that recognise their institutions, priorities and decision-making processes, rather than requiring them to conform to a single predetermined model.
The post COP17 must settle who decides how Cali Fund money is disbursed appeared first on Climate Home News.
COP17 must settle who decides how Cali Fund money is disbursed
The UK government has approved extraction at the Jackdaw gas field in the North Sea, despite acknowledging that this decision could make it harder for Britain to convince other countries to move away from fossil fuel production.
UK energy secretary Miatta Fahnbulleh approved the drilling on Wednesday after months of high-profile debate, fuelled in part by interventions from US President Donald Trump. She argued that the project would boost energy security in the wake of the Middle East fossil fuel crisis, protect hundreds of jobs and add £2.9 billion ($3.88bn) to the UK economy.
She said Jackdaw’s gas would be cleaner than imported gas and would not prevent the UK from meeting its legally-binding carbon targets and its goal of net zero by 2050. As the field is already licensed, she said extraction was consistent with the Labour Party’s 2024 manifesto promise not to issue any new oil and gas licenses.
The same morning, the government announced a new Energy Wealth Fund to reinvest oil and gas revenues in the climate transition. It will start with £2 billion ($2.67bn) from the government and be topped up over time with tax revenues from offshore oil and gas production.
Climate campaigners in the UK and abroad were quick to condemn the decision, while a leading legal expert told Climate Home News it goes against the advice of the International Court of Justice. Meanwhile, the government’s own documents reveal that it recognises the drilling could damage the UK’s reputation and its ability to push forward the global transition away from fossil fuels.
“Climate leadership” blow
The 92-page decision document says Fahnbulleh “acknowledges that international standing on climate is important and accepts that a decision to grant consent may not further the UK’s international climate leadership.”
It adds: “She acknowledges concerns about the potential implications for the UK’s credibility and influence – including the difficulty inherent in encouraging other states to move away from fossil fuel production while the UK continues, in a limited and transitional way, to draw on its own domestic resources.”
While noting that Jackdaw has not been issued with a new license – just permission to extract gas – the document says Fahnbulleh “accepts this does not fully resolve the underlying tension in the UK’s position” but “considers this alongside the substance of the UK’s wider record [on emissions reduction], which remains significant”.
It continues that she accepts these concerns are “legitimate” and weigh against approving gas extraction, but only gives this argument a “moderate negative weight” set against the benefits of gas production.
“Huge” wrong signal
In international climate talks, the UK has long supported the transition away from fossil fuels and is one of very few major oil and gas producers to ban new licenses. Across the North Sea, the Norwegian government continues to make offshore areas available for oil and gas exploration through annual licensing rounds.
Climate experts and campaigners shared the concern, acknowledged in the decision document, that approving Jackdaw could set a precedent for fossil fuel production elsewhere. Sam Fankhauser, professor of climate change economics at Oxford University, said the direct climate impact of Jackdaw is “much smaller than the debate around it would suggest” but the “wrong signal it sends, however, is huge”.
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Bob Ward, policy and communications director at the Grantham Research Institute on Climate Change, said that while Jackdaw’s output will be very small, “it will signal to other fossil fuel producers that they too should carry on with business as usual, less than a month before the COP31”.
Kenyan campaigner Mohamed Adow, director of Power Shift Africa, called the decision “a serious blow to Britain’s international climate credibility” as “the UK cannot expect developing countries to move away from fossil fuels while giving the green light to new drilling in its own backyard”.
International Court of Justice
In July 2025, the International Court of Justice (ICJ) advised that government failure to take appropriate climate action “including through fossil fuel production” may amount to an internationally wrongful act.
The UK voted in favour of a United Nations resolution welcoming the advisory opinion. Yet, in its Jackdaw decision document, it notes that the ICJ opinion is not legally binding and says the UK does not accept the court’s opinion that the customary international law duty to prevent significant harm to the environment applies to climate change.
Fahnbulleh concludes that, although it will have “significant effect on the environment”, gas drilling in Jackdaw “would not lead to significant harm to the environment” – and so does not breach any duty to prevent such harm. Instead, the government document says the duty should be considered “as a matter of policy rather than legal obligation”.
Margaretha Wewerinke-Singh, who led Vanuatu’s legal team pushing for the ICJ’s advisory opinion, told Climate Home News that treating the duty as a matter of policy rather than legal obligation is “not how international law works”. “An advisory opinion is not a judgement,” she said, “but it states the law as it stands, and that law binds the UK whether or not it accepts it.”
“Even as a matter of policy,” she added, “the decision asks the wrong question: whether Jackdaw on its own would cause significant harm. The Court found that accumulated emissions are already causing significant harm. What matters is whether approving new production is consistent with the stringent due diligence the duty requires.”
Public support for decision
While the decision was criticised by climate campaigners and the opposition Green party, polling reported by Politico suggests that 55% of British adults support drilling at Jackdaw, with just 14% opposed. Even supporters of the UK’s net zero target back new drilling by more than two to one, the polling found.
Jackdaw is one of two North Sea oil and gas fields the government has been debating whether to extract more from for months. While Jackdaw is a small gas field, the other, Rosebank, is a much larger field that holds mostly oil.
Rosebank’s emissions are estimated to be around seven times higher than Jackdaw’s. Fahnbulleh told Sky News that Rosebank is “different” to Jackdaw because its oil would be exported, whereas Jackdaw’s gas will be used in the UK, adding that she will consider it “in its own right”.
The Guardian reported on Wednesday that UK officials say Fahnbulleh is minded to refuse approval for Rosebank. She has not yet taken a final decision on Rosebank, the newspaper said, but a ruling is expected later this year.
The post UK approves gas drilling despite admitting blow to “climate leadership” status appeared first on Climate Home News.
UK approves gas drilling despite admitting blow to “climate leadership” status