MARINE CARBON REMOVAL
Advancing responsible and inclusive marine carbon sequestration
To avoid the worst impacts of climate change, the world will need to remove vast amounts of carbon dioxide from the atmosphere. Marine carbon dioxide removal could play a decisive role, if we invest now in the science, tools and governance to unlock its potential responsibly.
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The oceans are the largest pool of carbon on earth, holding about 50 times more carbon than the atmosphere. New innovations that harness the ocean’s interactions with the atmosphere could deliver 8 gigatonnes of carbon removals annually by 2050, if proven safe and effective.
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Philanthropy is uniquely positioned to shape governance, fund early science, and ensure equity and ethics guide development.
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Compared to land-based removals, ocean pathways remain underexplored and underfunded.
Not so at sea.
The ocean already holds more carbon than anywhere else on Earth, and has the potential to contribute much more. New innovations that harness the ocean’s natural biological, chemical and physical processes could remove up to 8 billion tonnes of CO₂ per year by mid-century.
But these approaches are at an early stage. Funding is scarce, evidence is limited, and public debate is becoming polarized. Some environmental groups are rightly raising concerns about unintended impacts, weak governance and moral hazard: the risk that removals are used to excuse delayed emissions cuts.
As a result, the field risks stalling or advancing in fragmented ways, without the scientific, social and ethical foundations needed to succeed.
PROBLEM
The scientific consensus is clear: to give ourselves the best chance of limiting warming to 1.5°C – the goal set out in the Paris Agreement – we must slash emissions and remove billions of tonnes of CO2 from the atmosphere. Right now, we’re falling short on both. Emissions are not declining fast enough, and every year of delay increases the scale of removals required to avoid dangerous warming.
Most carbon removal so far has come from nature-based solutions on land, such as protecting forests and restoring ecosystems. These approaches are vital but constrained by how much land is suitable and available and how permanently they lock up carbon. Engineered technologies like direct air capture are still in their infancy, removing the tiniest of fractions of today’s emissions. On land, there is a scale problem.
GRANTEES
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GRANTHAM ENVIRONMENTAL TRUST
The Grantham Environmental Trust is focused on reducing and reversing global environmental degradation. It works to redesign our energy systems, improve soil health, spare the ocean from acidification and recapture carbon from the atmosphere.
OPPORTUNITY
The Advancing Marine Carbon Sequestration initiative is designed to build the scientific scaffolding, governance frameworks and social license needed for responsible marine carbon dioxide removal (mCDR).
Led by the Grantham Environmental Trust, the initiative is building a clearer picture of which mCDR approaches can safely and sustainably contribute to carbon removal at scale, under what conditions and at what risk. It is strengthening governance by engaging policymakers, climate justice organisations, conservation leaders and coastal communities early and meaningfully, ensuring concerns are addressed before deployment accelerates.
At the same time, it is developing robust new standards for monitoring and verification, so claims are credible, comparable and trusted. And it is accelerating the most promising pathways, without undermining the imperative to cut emissions first and fast.
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US$1bn
in public funding supporting a mature mCDR innovation ecosystem by 2040
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>100m tons
At least one approach on a pathway to scale: <US$100 per tonne and >100 million tonnes of CO₂ per year by 2040.
IMPACT GOAL
By 2028, mCDR will have moved from a promising idea to a credible, well-governed and investable field. The initiative will have helped establish a shared foundation for mCDR, with clear guardrails, trusted monitoring and verification tools, and the social license needed to develop and deploy responsibly.
The goal is twofold: a mature mCDR innovation ecosystem supported by more than US$1 billion in public funding, and at least one approach on a pathway to safe, cost-effective removals at scale – below US$100 per tonne and above 100 million tonnes of CO₂ per year by 2040.
Ultimately, this effort lays the groundwork for marine carbon removal to play a safe, ethical and transformative role alongside rapid emissions cuts, helping close the widening gap between where global emissions are headed and where they must go.
WHAT WE FUND
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![Northern lights over snow-capped mountains and ocean, night sky with stars.]()
ARCTIC CONSERVATION
Safeguarding ecosystems and Indigenous livelihoods
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![A man in a brown jacket and wide-brimmed hat is standing in a body of water, holding a large fish. Two boats are nearby in the water, with a backdrop of trees and a cloudy sunset sky.]()
BLUE CARBON+
Protecting and restoring mangroves, seagrass, saltmarsh and kelp
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![Two elderly people, a man and a woman, are repairing fishing nets. The woman is wearing a purple hijab, while the man is wearing a white shirt.]()
COASTAL FRONTLINE INITIATIVE
Strengthening community resilience and securing tenure rights
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![Aerial shot of a sandy coastline with clear green water and artisanal fishing vessels pulled up on the foreshore]()
MARINE CARBON REMOVAL
Responsible and inclusive ocean-based carbon removal
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![A white wind turbine against a clear blue sky.]()
OFFSHORE WIND
Enabling fast, fair & responsible development in emerging markets
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![A large cargo ship with colorful containers sailing in calm waters under a partly cloudy sky.]()
DECARBONIZING SHIPPING
Accelerating zero-emission fuels, ports and policy frameworks
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![Two fishermen sitting on traditional round basket boats on a beach at sunset, with fishing boats anchored in the background under a cloudy sky.]()
OCEAN-CLIMATE DIPLOMACY
Embedding ocean priorities in global climate policy
