Marine Carbon Dioxide Removal: What It Is and How It Works

Key Takeaways

• Near-term role for carbon removals: The revised Science-Based Targets Initiative (SBTi) Corporate Net Zero Standard (CNZS) v2.0 proposes requiring or recognizing interim carbon dioxide removal (CDR) targets before companies reach net zero. This shift aims to scale up the CDR industry in line with climate science and ensure companies address residual emissions earlier rather than deferring action until their net-zero target year.‍
• Revised target frameworks and increased accountability: The draft standard introduces key changes, including separate targets for scope 1 and 2 emissions, enhanced scope 3 target-setting guidelines, and the recognition of market-based mechanisms for indirect mitigation of scope 3 emissions. It also requires companies to publicly disclose transition plans and assess implementation progress against targets.‍
• Potential for stronger action on removals: While the proposed updates are a step forward, the final standard should make near-term CDR targets mandatory rather than optional and should expand to include those for projected scope 3 residual emissions, not just scope 1. Without these stronger mandates, demand for early-stage CDR investments may remain limited, potentially slowing progress toward net-zero goals.‍
• Companies should prepare now: Businesses should start integrating CDR into their climate strategies now so they are equipped to navigate procurement of high-quality removal credits in the voluntary carbon market. Preparing ahead of the final CNZS v2.0 release will help companies align with science-based decarbonization pathways and demonstrate climate leadership.

What the Latest SBTi Update Means for Corporate Climate Action

On 18 March, 2025, the Science Based Targets Initiative (SBTi) released its draft Corporate Net Zero Standard (CNZS) v2.0, significantly updating its framework for corporate net-zero target setting for the first time since 2021. The draft proposes new approaches for companies to support carbon dioxide removal (CDR) in the transition to net-zero emissions, a move that could help scale the nascent CDR industry.

This release is part of a broader revision, with key proposed updates including:

• Requiring public disclosure of transition plans after companies set targets.
• Separating targets for scope 1 and 2 emissions.
• Enhancing the scope 3 target-setting framework using an impact-based prioritization process.
• Recognizing indirect mitigation (e.g., book-and-claim commodity certificates) for hard-to-trace scope 3 emissions.
• Defining a role for emissions removals in the transition to net zero.
• Providing options to recognize company leadership in beyond value chain mitigation (BVCM).
• Assessing corporate progress against targets to bolster accountability.

While formal recognition of removals in the transition to net zero is a positive step, stronger incentives will be needed in the final CNZS to ensure companies take meaningful early action on CDR. The draft standard is open for the first of two public consultations until 1 June, 2025, with a finalized version expected to launch in 2026.

What Remains the Same From the Current Standard?

SBTi’s framework remains focused on three core requirements for companies:

• Reducing emissions year-on-year to reach an approved science-based target (SBT) by 2050 or earlier.
• Investing in beyond value chain mitigation (BVCM) in the transition to net zero to support near-term global decarbonization efforts.
• Neutralizing remaining emissions from the net-zero year (achieved after at least 90% emissions reductions) and onwards with high-quality, permanent carbon removal.

Carbon credits representing emissions reductions and removals remain ineligible for meeting reduction targets within a company’s value chain (SBTs).

What’s New in CNZS v2.0 for Carbon Removals?

Until now, the SBTi encouraged companies to invest in CDR through mechanisms such as BVCM, but has not proposed requiring removal before their target net-zero year. As a result, organizations had little clarity or incentive to invest in CDR ahead of their net-zero target date, dampening near-term demand for carbon removal and delaying the industry's growth.

The new draft changes this by proposing three options for the V2.0 Standard that address the impact of residual emissions during the transition to net zero:

• Option 1 (requirement): Companies are required to set near- and long-term removal targets, including interim CDR milestones,¹ to address projected residual emissions.
• Option 2 (optional with recognition): Companies can set and receive recognition for removal targets to address projected residual emissions.
• Option 3 (flexibility of mechanism): Companies have the flexibility to address expected residual emissions either entirely through additional emissions reductions within their value chain, entirely through removals, or via a combination of both.

Notably, all three approaches apply only to residual scope 1 emissions.

On top of these approaches, SBTi has suggested two options for the minimum durability threshold of CDR purchases in their draft standard. Removals will either need to follow a ‘like for like’ approach,² where CDR storage must match the atmospheric lifetime of residual emissions, or a gradual transition approach, where carbon storage durability increases over time.

Why Mandating CDR Matters

Mandating near-term CDR reinforces the need for immediate climate action, ensuring that carbon removals complement emissions reductions rather than being deferred until the net-zero target year. The urgency of early CDR investment is clear:

• Limiting global warming to well below 2°C above pre-industrial levels requires removing billions of tonnes (gigatonnes) of carbon dioxide annually by mid-century.
• The CDR industry is in its early stages and requires sustained investment today to scale in time.
• If companies wait until their net-zero year to purchase CDR, the supply of high-quality removal credits is unlikely to be sufficient.

As part of the proposed removal targets in Option 1 (above), the CNZS v2.0 would require companies to gradually increase CDR purchases over time, ramping up to 100% of a company’s projected residual scope 1 emissions in the net-zero target year (<10% of baseline year emissions).³

What More Can Be Done?

The potential introduction of required removal targets would be a significant and welcomed step, reinforcing the importance of near-term CDR investment to support industry maturation and climate goals. However, mandatory near-term CDR targets represent only one of three potential pathways for the V2.0 standard. Moreover, neutralization of residual emissions on the path to net zero is only proposed for scope 1 emissions. While the SBTi provides clear rationale for this,⁴ SBTi should not let the complexity of projecting scope 3 emissions be a barrier to climate change mitigation. Scope 3 emissions represent the majority of emissions from SBTi-aligned companies. Furthermore, companies with high scope 3 emissions typically have a higher ability to pay compared to their industrial counterparts with high scope 1 emissions.

If interim removal targets are made optional, and scope 3 emissions remain excluded, the demand signal for near-term CDR will be limited. The public consultation (and advice of Expert Working Groups that SBTi is convening) will be essential in determining which proposed guidance matures into the final standard; consultation feedback can be provided here prior to June 1, 2025.

How Businesses Can Prepare for CNZS v2.0

Companies aligning with SBTi’s evolving guidance should begin to integrate CDR into their climate strategy now. This means:

• Understanding their residual emissions forecast and planning early investments.
• Developing a company-specific climate strategy to incorporate CDR into their sustainability roadmaps in tandem with plans to reduce value-chain emissions.
• Engaging early in the voluntary carbon market to implement these strategies and develop procurement processes to support high-quality removal projects.
• Ensuring credibility by selecting removal projects aligned with scientific best practices.

Conclusion: A Step in the Right Direction, But More Certainty Is Needed

The CNZS v2.0 draft represents a critical turning point for corporate climate action with options to formalize the role of early CDR investment through interim removal targets for signatories. However, SBTi must take a stronger stance in the final version of the revised standard by choosing to adopt requirements for near-term neutralization (rather than leaving this optional), including projected residual scope 3 emissions in near-term CDR targets, aligning durability requirements with climate science, and defining removal quality standards to ensure these efforts drive meaningful climate impact. Organizations seeking to align with this guidance should prepare by developing a comprehensive climate strategy that accounts for science-based decarbonization pathways and recognizes the role of early-stage investment in CDR solutions.

Key Takeaways

• Improved forest management (IFM) increases measurable long-term carbon storage in living trees and durable wood products.
• At the same time, it can provide strong social and ecological co-benefits.
• IFM projects like the ones developed by Weyerhaeuser and the Indigenous community of Petcacab in collaboration with Relae (formerly Carbon Direct) show how IFM practices can align climate goals with social and environmental benefits.

Forests Are Climate Solutions If We Manage Them Wisely

Forests remove carbon dioxide from the atmosphere, but they need to be thoughtfully managed to keep doing so. As buyers look to scale carbon removal, improved forest management (IFM) is gaining traction in the voluntary carbon market (VCM).

IFM focuses on enhancing how existing forests are managed to increase carbon storage over time. It’s a nature-based solution that supports climate outcomes, community livelihoods, and environmental benefits when done well.

This piece explains how IFM works, what makes a project high-quality, and how real-world IFM projects like those developed by Weyerhaeuser and Petcacab in collaboration with Relae (formerly Carbon Direct) are delivering credible results for buyers and local communities alike.

What Is Improved Forest Management?

Improved forest management is a catch-all phrase that describes management techniques that decrease emissions from forests or increase carbon removal and storage. Some management techniques, like transitioning a working forest to a conserved status, decrease emissions from forest harvest and primarily create credits for avoided emissions. Other management techniques, like harvesting forests less frequently, can lead to greater carbon removal and storage over time and create credits for additional carbon removal. 

Examples of IFM Practices Include:

• Extending harvest rotations to allow more carbon accumulation
• Reducing the impact of logging on soil and surrounding trees
• Managing fire and pest risks to enhance forest health
• Transitioning some of a forest to conservation status

These strategies help forest carbon stocks grow beyond business-as-usual baselines. In carbon markets, IFM can generate carbon removal or avoided emissions credits, depending on the project's design and carbon accounting methodology.

What Makes a High-Quality IFM Carbon Removal Credit?

Buyers today face increased scrutiny around carbon credit quality. In this context, IFM projects must go beyond basic registry standards to demonstrate climate integrity and social and environmental benefits. 

Relae developed the Criteria for High-Quality Carbon Dioxide Removal, an annual report published in collaboration with Microsoft to establish science-backed quality standards. This includes six core principles that define high-quality carbon removal, all of which apply to IFM projects: 

• Social harms, benefits, and environmental justice - The extent to which the project prevents new social harms to people and communities, reduces existing harms, and provides meaningful benefits distribution. Since IFM projects take place in communities around the world, benefits will naturally vary from project to project.  
• Environmental harms and benefits - The extent to which the project minimizes and mitigates environmental harms, as well as provides environmental benefits. Because IFM projects enhance management practices, environmental co-benefits of high-quality IFM projects are usually substantial.
• Additionality and baselines – Evidence that the project’s carbon removal would not have occurred without carbon finance. Many IFM projects fail to present compelling additionality data and narratives. High-quality projects will be able to identify the actions the project took to increase carbon storage that would not have happened without carbon finance. 
• Measurement, monitoring, reporting, and verification (MMRV) – The ability to accurately quantify carbon removal in a repeatable and verifiable way, and to develop a plan for long-term monitoring of the project. IFM projects must have robust forest inventory, growth modeling, and occasional remeasurement to verify the additional carbon storage. 
• Durability – The likelihood that removed carbon remains stored over time, with mechanisms in place to mitigate reversal risk. Enhanced management of fire, pests, and disease in IFM projects can enhance forest carbon durability. 
• Leakage – Evaluation of whether project activities cause increased emissions elsewhere. If an IFM project substantially reduces timber supply, market demand can drive increased harvesting in other forests, undermining some of the project’s climate benefits. High-quality IFM projects minimize this risk by limiting harvest reductions, and account for any remaining leakage by issuing fewer credits.

Relae uses these criteria as part of our diligence framework when advising buyers evaluating projects and co-developing our own projects.

IFM Projects Delivering Real Impact

Weyerhaeuser: Applying Science at Scale

Weyerhaeuser, one of the largest forest owners in North America, is applying improved forest management practices across over 200,000 acres of working forests.

The IFM projects led by Weyerhaeuser are located in rural areas in the US, with low wildfire risk. These IFM projects sequester carbon by extending harvest rotations and forgoing harvest in established streamside management zones. 

Relae supported Weyerhaeuser with hands-on scientific collaboration to confirm that every IFM project met the Criteria for High-Quality Carbon Dioxide Removal. 

Why it matters to buyers:

• High-quality climate impact at large scale
• Transition of working forests from traditional management techniques to maximize climate impact
• Responsible forestry practices aligned with SFI® standards
• Rigorous carbon accounting and high-quality project baseline established using historical harvest records

The IFM projects led by Weyerhaeuser are some of the largest in the US today and a model for scaling science-backed forest carbon solutions.

Petcacab: Indigenous-Led Conservation in the Yucatán Peninsula

Located in the communal lands of Petcacab, Mexico, this IFM project is led by Indigenous Mayan ejidatarios—community members who have legal rights to manage the land.

Historically, forests in the ejido have been degraded through unsustainable harvesting and extensive damage from hurricanes. Through carbon finance, they are developing new forest management plans and sustainable forestry models, with revenue reinvested in health, education, and job creation.

“The rainforest for me represents my home, my work, my present, my future. We have a very daring challenge: to transform how we manage our forest, shifting from harvesting and selling timber to conserving it through the sale of carbon credits that support the development of our community.”
— Celso Chan Rivas, Carbon Project General Manager

What makes Petcacab stand out:

• Equitable benefit-sharing and strong Indigenous governance
• Critical habitat protection for endangered species
• Increased additional carbon storage through forest management and reduced land use conversion 
• Transparent reporting and verified outcomes

Petcacab is recognized by Relae as a high-quality community IFM project in Mexico, with clear social, environmental, and climate outcomes.

Investing in Forests That Deliver More Than Carbon

Improved forest management is more than a carbon strategy, it’s an investment in ecosystems, communities, and long-term impact. For buyers seeking high-integrity carbon removal with social and environmental co-benefits, IFM projects offer a compelling opportunity.

IFM projects like the ones developed by Weyerhaeuser and Petcacab in collaboration with Relae show what’s possible when forests are managed with science and care. They also reflect what the voluntary carbon market needs more of: quality, transparency, and impact beyond the metric ton.

Key Takeaways

• Marine carbon dioxide removal (mCDR) uses ocean-based processes—primarily ocean alkalinity enhancement (OAE) and direct ocean removal (DOR)—to capture and durably store atmospheric carbon dioxide (CO₂), without the land and freshwater constraints of terrestrial methods. 
• The ocean already absorbs roughly 29% of human-caused CO₂ emissions each year, according to the 2025 Global Carbon Budget, and mCDR technologies aim to safely enhance that natural uptake without worsening ocean acidification.
• For corporate carbon buyers and project developers evaluating mCDR, the Criteria for High-Quality Marine Carbon Dioxide Removal, developed by Microsoft and Relae, outlines standards to guide responsible mCDR deployment at scale.

Reducing carbon dioxide (CO₂) emissions alone is no longer sufficient to limit global warming to 1.5°C. To effectively address climate change, scientific consensus highlights the need to remove carbon dioxide already present in the atmosphere. Marine carbon dioxide removal (mCDR), a form of ocean-based carbon removal, offers a scalable solution by leveraging the ocean’s natural ability to absorb and store carbon, without the land and resource limitations associated with terrestrial carbon removal methods.

This guide explores the fundamentals of marine carbon dioxide removal, including how it works, the technologies involved, and its role in global decarbonization.

What Is Marine Carbon Dioxide Removal?

Marine carbon dioxide removal uses ocean-based processes to capture and store carbon dioxide from the atmosphere. mCDR techniques fall into two primary categories: 

• Biotic CDR, which includes using photosynthetic fixation, microalgae cultivation, and terrestrial biomass sinking, to capture and store carbon. 
• Abiotic CDR, which influences CO₂ concentrations and carbonate chemistry in the seawater to absorb atmospheric CO₂ without increasing acidity. There are two main abiotic mCDR pathways: ocean alkalinity enhancement (OAE) and direct ocean removal (DOR). 

How Does Marine Carbon Dioxide Removal Work?

Marine carbon dioxide removal functions via the air-sea gas exchange—a process by which the atmosphere and surface seawater maintain equal CO₂ concentrations—meaning a shift in one leads to a corresponding change in the other. This exchange allows the ocean to absorb or release CO₂ back into the atmosphere depending on concentration levels and factors like pH. 

Once absorbed by the ocean, CO₂ exists in several forms, including dissolved CO₂, carbonates, and bicarbonates, influencing the ocean's pH levels. As atmospheric CO₂ levels rise, the oceans absorb roughly 12 GtCO₂ annually, approximately 29% of anthropogenic CO₂ emissions. This increase is disrupting the natural CO₂ balance and contributing to ocean acidification. 

mCDR methods like ocean alkalinity enhancement and direct ocean removal use safe and controlled processes to increase the amount of CO₂ absorbed from the atmosphere while mitigating acidification.

Understanding Ocean Alkalinity Enhancement (OAE)

Ocean alkalinity enhancement (OAE) captures and stores atmospheric CO₂ as dissolved carbonates in the ocean by increasing the alkalinity of seawater using one of two primary methods:

• Adding alkaline minerals such as olivine or basalt to seawater.
• Using electrochemical methods to add alkaline compounds to seawater.

Both of these methods increase the alkalinity of seawater and, thereby, its capacity to absorb atmospheric CO₂ without acidification. 

OAE methods can also differ by location and the manner in which seawater interacts with alkaline substances and atmospheric CO₂. This interaction may occur in the open ocean or within a controlled mCDR project facility. Each approach involves trade-offs: open ocean methods tend to be less energy-intensive but present greater uncertainties and challenges in measurement, reporting, and verification (MRV).

Understanding Direct Ocean Removal (DOR)

Direct ocean removal (DOR), also called direct ocean capture (DOC), removes CO₂ dissolved in seawater using the controlled acidification of seawater in a closed system using one of two primary methods: 

• Electrochemical methods such as electrolysis of seawater or electrodialysis
• The addition of minerals like olivine and basalt. 

The acidified and CO₂ depleted seawater is neutralized to native pH and allowed to equalize with and remove atmospheric CO₂. Once removed, CO₂ can be safely stored using geologic storage with a durability of >1,000 years.

Key Benefits of Marine Carbon Dioxide Removal

Understanding how mCDR works highlights its potential to address climate challenges. Here are the key benefits that make it a critical tool in global decarbonization strategies.

• Scalable carbon removal without land constraints: Marine carbon dioxide removal does not require large land areas or significant freshwater resources, making it highly scalable.
• Harnessing the ocean’s natural carbon sink: The ocean absorbs about 25% of human-generated CO₂ annually. mCDR enhances this natural process, increasing carbon storage without accelerating ocean acidification.
• Diverse technological pathways for flexibility: Technologies like ocean alkalinity enhancement and direct ocean removal offer flexible solutions tailored to different environments and project needs.
• Global reach with a large surface area: Covering over two-thirds of the Earth’s surface, the ocean provides an expansive platform for mCDR technologies globally. 
• Potential to mitigate ocean acidification: Some mCDR methods, such as ocean alkalinity enhancement, not only remove CO₂ but also help restore ocean pH levels, supporting marine ecosystem health.

Challenges of Marine Carbon Dioxide Removal

While mCDR holds significant promise, it also presents challenges that must be addressed for responsible deployment.

• Technical scalability and efficiency: Scaling mCDR technologies to achieve meaningful carbon removal while maintaining energy efficiency remains a significant hurdle.
• Potential environmental impacts: Altering ocean chemistry may pose risks to marine ecosystems, with long-term effects still not fully understood.
• Measurement, reporting, and verification (MRV) complexity: Accurately measuring CO₂ removal and ensuring its durability requires advanced monitoring systems, which are still evolving.
• Regulatory and governance gaps: Clear global policies are needed to oversee mCDR deployment, manage environmental risks, and ensure accountability.
• Public perception and ethical considerations: Concerns around geoengineering and potential unintended consequences may impact public acceptance and policy support.

Deploying Marine Carbon Dioxide Removal 

As mCDR technologies evolve, effective deployment will rely on adaptive management practices to address technical, environmental, and regulatory challenges. This includes robust MRV systems for accurate CO₂ removal tracking and continuous ecosystem monitoring to mitigate potential risks to marine life. 

Collaborative efforts between scientists, policymakers, and project developers are key to establishing clear regulatory frameworks, optimizing technologies for efficiency and scalability, and building public trust. These practices ensure mCDR can be scaled responsibly while safeguarding ocean health. 

The Future of Marine Carbon Dioxide Removal 

As technologies like ocean alkalinity enhancement and direct ocean removal advance, their potential to deliver large-scale, durable carbon removal is becoming increasingly evident. Realizing this potential requires more than technological innovation—it depends on rigorous environmental monitoring, transparent reporting, and strong collaboration among project developers, carbon buyers, and policymakers.

Establishing clear, consistent standards for high-quality mCDR is essential to ensure both climate effectiveness and environmental safety. To support this, Microsoft and Relae have partnered to develop the Criteria for High-Quality Carbon Dioxide Removal. 

Frequently Asked Questions

What is marine carbon dioxide removal (mCDR)?

mCDR uses ocean-based processes, primarily ocean alkalinity enhancement and direct ocean removal, to capture and durably store atmospheric CO₂. It works by increasing the ocean's natural capacity to absorb CO₂ without increasing acidification.

How does marine carbon dioxide removal compare to land-based methods like direct air capture or reforestation?

Unlike land-based approaches, mCDR doesn't require large land areas or freshwater, and the ocean's size gives it significant scaling potential. It's earlier-stage than more established pathways, though, with measurement and environmental monitoring standards still maturing.

Is marine carbon dioxide removal proven and scalable today, or still emerging?

mCDR technologies have shown promising results in lab testing and early deployments, but confirming safety and effectiveness at a large real-world scale requires more monitoring data. It's best described as an emerging pathway with strong near-term momentum, not yet a mature, at-scale solution.

What should a company look for when evaluating a marine carbon dioxide removal project or credits?

Buyers should look for rigorous carbon MRV paired with equally rigorous monitoring of ocean ecosystem health (eMRV), transparent reporting, and adherence to established frameworks like the Criteria for High-Quality Carbon Dioxide Removal.

Key Takeaways

• Emissions cuts alone are not happening fast enough to meet global climate goals. Direct air capture (DAC) removes carbon dioxide (CO₂) that is already in the atmosphere. It has become one of the fastest-growing carbon removal approaches even as it stays capital-intensive.
• DAC's core advantage is flexibility. Because the atmosphere fully mixes within about two weeks, a DAC facility can be sited almost anywhere with clean power and CO₂ storage and still deliver the same climate benefit.
• DAC investment has grown to roughly US$2.2 billion across 37 specialized companies since 2021. Per-tonne costs (currently US$500–1,000 or more) remain the technology's central barrier to scale.
• US federal support for DAC is still unsettled. The US Department of Energy cut its regional DAC hub program from a planned US$3.5 billion to roughly US$1.2 billion between October 2025 and April 2026. This is a signal that deployment funding, not the underlying science, is DAC's biggest near-term risk.

What Is Direct Air Capture?

Direct air capture (DAC) works by sucking in air, filtering it to remove CO₂ that has built up over time and still sits in the atmosphere. To be effective, DAC must draw a lot of air into separating equipment like filter banks or cooling towers. This is similar to the small-scale systems that have scrubbed CO₂ from air in spacecraft and submarines for decades. From there, CO₂ filtering typically involves a chemical process that binds the CO₂ for release later. While the most commonly used chemical compounds in this process are liquid solvents or solid sorbents, other chemical, electrical, and physical processes could also work.

After the filtering process, the captured CO₂ is usually stored in one of two ways. The most important is geological storage, which keeps CO₂ out of the air and oceans indefinitely in deep geological formations (typically a mile down or more) and offers the clearest climate benefits. The second is storing the CO₂ in products like concrete, which offers clearer commercial benefits. A new generation of mineralization projects is expanding this second pathway, turning captured CO₂ into building materials rather than only storing it underground. In addition, CO₂ can be recycled into fuels and chemicals, which prevents net-new CO₂ from being released but does not count as a carbon removal solution since these materials are eventually used, releasing the captured CO₂ back to the atmosphere.

The Advantages of Direct Air Capture

DAC has many advantages as a CO₂ removal approach. First and foremost, it's scalable. In effect, there are no practical limits to our ability to scrub CO₂ from the sky or store it in deep geological formations around the world. This means scaling can be fast and removals profound.

It's straightforward. The devices remove CO₂ from the air, a meter measures it, and operators store and monitor that CO₂. It's clearly additional (meaning it only happens with financial and human intervention), easily verified, and durable (stored for many hundreds of years or more), meeting the bar set by our own Criteria for High-Quality Carbon Dioxide Removal.

It has a small physical footprint. Typical DACe systems do the carbon removal work of trees with 1,000–2,000 times less space. This leaves more room for conservation, agriculture, rewilding, and other important work.

It can be done anywhere with low-carbon energy and CO₂ storage options. Globally, our atmosphere mixes fully every two weeks, meaning that CO₂ released in China or Australia arrives over the US (and vice versa) in this amount of time. Because of this, DAC facilities can be sited anywhere and still have a climate benefit—as long as there is sufficient clean energy available and options for CO₂ storage or use are nearby. This reduces competition for land and provides opportunities for economic development in regions with the right resources.

Finally, and most critically, DAC is a backstop technology. While reducing emissions remains the top priority, there are certain types of emissions that are either very hard or very expensive to abate. The last fraction of hard-to-abate emissions can be managed through DAC, effectively capping global costs to reach net-zero emissions. In fact, the more rapidly DAC scales and deploys, the less total energy and cost are needed to achieve key climate goals.

Challenges and Concerns of Direct Air Capture

Like all climate mitigation approaches, DAC has challenges. The primary challenge today is cost. Today's large-scale systems cost roughly US$500–1,000 or more per tonne of CO₂ removed, depending on the technology and site, though several developers are targeting US$100–150 per tonne over the next 10 years. Although the costs will come down over time through deployment and wider adoption, today's high costs are a barrier to investment and deployment.

Another challenge is around the energy requirements associated with DAC. Pulling one million tonnes per year of CO₂ out of the air requires roughly 200–300 megawatts of zero-carbon energy (a combination of heat and electricity). Given the limited supply of zero-carbon energy available today, there is a valid question about whether this is the best use of that resource today.

Finally, there is the question of environmental risks and community burdens of DAC. Experience to date suggests that the total environmental burdens and consequences of this pathway are among the lowest of any clean energy and climate technology. But since DAC systems involve heavy equipment and chemicals, questions about the full environmental risks and burdens to communities remain, especially given its limited commercial deployment. Although most DAC systems will be sited in remote locations, not near communities, and pose no serious environmental risks, reasonable concerns must be addressed before permitting and building future DAC projects.

Why the Excitement Now?

Although current climate science and added urgency from organizations like the Intergovernmental Panel on Climate Change (IPCC) have driven interest in DAC, other important advances have fed broad interest and excitement about its potential. Since 2017, DAC technology has matured greatly, including the deployment and operation of many projects around the world. Costs have dropped, new pathways have opened, and private investment in DAC-specific companies has reached roughly US$2.2 billion across 37 companies since 2021. 

Two large facilities illustrate where deployment stands today. Climeworks' Mammoth plant in Iceland has been operating since May 2024, although not at full capacity. Occidental's Stratos plant in Texas remains delayed past its most recent 2026 second quarter target due to a component issue, with no confirmed new startup date as of this writing. Both facilities carry substantial commercial offtake agreements from aviation, energy, insurance, and tech companies, agreements that continue to hold even as construction timelines have slipped.

In part, interest results from new policy advancements. In the US, the Inflation Reduction Act's 45Q tax credit, maintained under the 2025 One Big Beautiful Bill Act, currently provides US$180 per tonne for DAC paired with dedicated geologic storage, with added parity for utilized CO₂. The Department of Energy's Regional Direct Air Capture Hubs program, originally planned at US$3.5 billion, was cut back sharply in an October 2025 review. It was then partially restored in April 2026 when the Department of Energy confirmed its two flagship projects, Project Cypress in Louisiana and the South Texas DAC Hub, would proceed. The program's total is now expected to be near US$1.2 billion. In addition, California has amended its Low-Carbon Fuel Standard to allow DAC as a compliance mechanism, and the US Department of Energy has explored a pilot program to purchase valid, durable carbon dioxide removal, including DAC. Recently, the Carbon Dioxide Removal Leadership Act was introduced to Congress, which would require the Secretary of Energy to remove CO₂ directly from ambient air or seawater.

Other programs around the world reflect this growing interest. In the UK and EU, governments have promised CO₂ removal purchases this decade, which will likely include DAC. Research programs have begun in Canada, the UK, Germany, Japan, and China. Developing nations increasingly see DAC as a potential new industry and hope to take advantage of their natural resources to expand energy access while being paid to remove CO₂ from the air and oceans.

The Future of Direct Air Capture

I'm pleased to have played a small role in DAC's new prominence. I've had the good fortune of being at DAC project groundbreakings and ribbon cuttings, led the first-ever government grants program for DAC, worked with scientists to develop new DAC technologies, published analysis over a decade ago on the need for DAC, and testified before the US Congress on the benefits and needs of DAC on three separate occasions. Based on my experience in DAC over the last 16 years, I believe that smart investment, policy, deployment, and community engagement will convert the promise of DAC into thousands of projects. These projects will help avoid the worst outcomes of climate change and restore some natural balance to the world. With federal support now concentrated on fewer, better-resourced flagship projects, rather than spread across two dozen early-stage hubs, the DAC field is being pushed toward fewer high-profile delays and more repeatable, bankable deployments.

Frequently Asked Questions

How does direct air capture differ from capturing carbon at an industrial site? 

Industrial, or point-source, capture removes CO₂ at a smokestack, where concentrations are high. Direct air capture removes CO₂ that is already spread throughout the open atmosphere. DAC facilities can operate almost anywhere with available clean power and storage, not only next to a specific emitter.

Is direct air capture actually operating today, or is it still experimental? 

Direct air capture is operating today; it is not just experimental. Climeworks' Mammoth plant in Iceland has been running since May 2024, and dozens of smaller facilities are active worldwide. However, the largest US projects, including Occidental's Stratos plant in Texas, are still working through startup delays. Once it begins operating, DAC will be fully commercial, although limited in deployment.

How much does it cost to remove one tonne of CO₂ with direct air capture? 

Current large-scale direct air capture systems cost roughly US$500–1,000 or more per tonne of CO₂ removed, depending on the technology and facility site. Several developers are targeting costs of US$100–150 per tonne later this decade, though that has not yet been demonstrated at commercial scale and is likely to take 10 years or more to achieve

Does using direct air capture reduce the need to cut emissions? 

No. Direct air capture is a backstop for emissions that are difficult or costly to eliminate outright, not a substitute for cutting emissions in the first place. Reducing emissions remains a priority; DAC addresses both what is left over (residual emissions) and what’s already in the air and oceans.

Key Takeaways

• High-quality carbon dioxide removal (CDR) projects require robust project management and oversight to deliver credits on time and at the promised volume; delivery risk is a distinct concern that quality standards alone don't catch.
• The sixth edition of the Criteria for High-Quality Carbon Dioxide Removal is the first to provide an approach to evaluating both credit quality and delivery risk, adding a new delivery risk appendix built around the TECOP framework: technical, economic, commercial, organizational, and political risk.
• The 2026 Criteria provides a framework for developers, investors, and buyers to evaluate both project quality and delivery risk.
• This year's update draws on 170 new diligence reports from 2025 and the input of more than 60 subject matter experts, building on a foundation of six years of lessons from professional diligence across hundreds of real-world CDR projects.

The Criteria Create a Shared Standard for Credit Quality

Relae (formerly Carbon Direct) first launched the Criteria for High-Quality Carbon Dioxide Removal (the Criteria) in collaboration with Microsoft in 2021 to help rapidly and justly scale the development of high-quality carbon dioxide removal (CDR) credits. The market didn't yet have a shared definition of what "high-quality" meant, so we laid out transparent, science-based benchmarks that gave developers, investors, and buyers a common foundation to work from. Every year since, we have gone back and sharpened those benchmarks so that they keep pace with the quickly evolving industry.

But a shared definition of quality doesn't guarantee the delivery of credits as planned. The 2026 edition is the first to tackle that gap directly, pairing the Criteria's quality benchmarks with a new framework for evaluating delivery risk.

The Six Principles of High-Quality Carbon Removal

The Criteria defines six science-based principles that apply across engineered, hybrid, and nature-based CDR approaches:

• Social harms, benefits, and environmental justice: The extent to which the project prevents new social harms to people and communities, reduces existing harms, and provides meaningful benefits distribution.
• Environmental harms and benefits: The extent to which the project minimizes and mitigates environmental harms, as well as provides environmental benefits.
• Additionality and baselines: The evidence that the project’s carbon removal would not have occurred without carbon finance.
• Measurement, monitoring, reporting, and verification (MMRV): The ability to accurately quantify carbon removal in a repeatable and verifiable way, and to develop a plan for long-term monitoring of the project.
• Durability: The likelihood that removed carbon remains stored over time, with mechanisms in place to mitigate reversal risk.
• Leakage: The extent to which project activities cause increased emissions elsewhere.

These principles provide a consistent foundation for carbon removal procurement, evaluation, and project benchmarking.

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Supporting the Delivery of High-Quality CDR Credits

"Projects must work better operationally and be more commercial. Quality and delivery risk shape a project's risk profile at every point in its life, and this edition of the Criteria is the first to give buyers a way to judge both at once." Dr. Julio Friedmann, Chief Scientist, Relae

Designing projects to meet high-quality CDR criteria is only part of the challenge. Effective project planning, management, and execution are also essential to ensure that high-quality CDR tonnes successfully reach the market as planned. As discussed in CDR 2.0: Five Pillars of Successful Project Deployment and Delivery, managing delivery risk requires developers, investors, and buyers to understand the risks that can affect project success and align on how these risks are assessed and mitigated.

To support this alignment, the 2026 Criteria introduced a new Delivery Risk Appendix, which establishes a common framework and language for identifying and evaluating key delivery risks for the first time. Drawing on our broader observations of the carbon removal market and established approaches to project risk management, the appendix highlights common delivery risks across two broad CDR project types: open systems and closed systems. It organizes these risks into five categories: technical, economic, commercial, organizational, and political factors, also known as the TECOP framework. 

The TECOP Framework for CDR Delivery Risk

• Technical delivery risks are associated with the technical feasibility of the project design, implementation, and long-term operation of the project
• Economic delivery risks are associated with the project’s financing structure, financial modeling assumptions, and expenditure profile
• Commercial delivery risk reflects the extent to which a project's purchase agreements, supply arrangements, and key contractual relationships are secured or well-advanced. 
• Organizational delivery risks center on the project developer's capacity and capability to successfully plan, execute, and manage a project of the appropriate size and complexity.  
• Political delivery risks are associated with governance, policies, and potential changes in regulatory environments, as well as the local communities’ perception of and willingness to participate in projects.

New Additions to the 2026 Criteria

Since publishing the 2025 Criteria, Relae has conducted an additional 170 diligence reports across established and emerging CDR pathways, ranging from reforestation and enhanced rock weathering (ERW) to direct air capture (DAC). To date, less than 10% of all 900+ projects the team has reviewed have met the bar for high-quality. These diligence efforts, together with insights from market analysis and ongoing synthesis of the latest scientific and technical literature, have deepened our understanding of how CDR project quality has evolved over the past year. 

The 2026 Criteria leverage these insights and the expertise of more than 60 subject matter experts to reflect advances across the CDR industry and address key weaknesses that remain in the market across all pathways. 

A few of the most significant updates to the Criteria include:

Addition of Direct Counterparty Considerations: Direct counterparties are the organizations that developers partner with, and are structurally dependent on, to generate credits. This can include: 

• Primary feedstock providers (e.g., mines, biomass providers, tree nurseries)
• Major implementing partners (e.g., local implementation partners, base facilities, transportation and storage providers, major product offtakers)
• Land owners that make up a significant proportion of project land 

To reflect the key role that direct counterparties play in high-quality credit generation, developers must conduct diligence and disclose on their direct counterparties to demonstrate that they are not causing social or environmental harm.

Increased Rigor for Enhanced Rock Weathering Projects: Over the past year, ERW’s presence in the CDR market has grown substantially, and so too has the market’s understanding of the corresponding scientific and technical rigor required to deliver high-quality tonnes. The 2026 Criteria raised the bar for how ERW projects:

• Measure and prove their carbon removal claims
• Mitigate risks related to potentially toxic elements (PTEs)
• Incorporate more sophisticated farmer protections and benefits 

Projects now have to back up their numbers with multiple physical field measurements, not just computer models; and they must now track and account for every significant loss pathway, from plants taking up minerals to carbon escaping from rivers and oceans.

Use of Dynamic Baselines for ARR Projects: ARR projects are increasingly using dynamic baselines to provide a more accurate reflection of the counterfactual scenario (e.g., what would have happened in the absence of the project). This is reflected in the 2026 Criteria with a requirement that ARR projects, with the exception of agroforestry projects, use dynamic baselines with statistically matched controls.

What’s Next?

The 2026 Criteria create a clear, science-driven framework for both designing and delivering measurable, just, and durable carbon removal. However, the Criteria cannot ensure high-quality tonnes reach the market on its own; good criteria do not replace robust diligence. To put these criteria into practice, we encourage developers, standard-setting bodies, buyers, investors, and policymakers to consider how the Criteria can be used to inform their role in enabling the carbon market to deliver high-quality tonnes and to engage in deep diligence and ongoing monitoring over the life of a project.

This edition of the Criteria reflects what we have learned over the past year, but our work is not done. We will continue to update it so that it remains a living document that evolves with the science and the market. To do so effectively, it must be a collaborative effort; we welcome input from carbon market actors, academia, and communities.

Frequently Asked Questions

Who publishes the Criteria for High-Quality Carbon Dioxide Removal, and how often is it updated?

Relae (formerly Carbon Direct) first published the Criteria for High-Quality Carbon Dioxide Removal with Microsoft in 2021 and have updated it every year since. The 2026 edition reflects six years of lessons from real-world project diligence and advances in climate science.

What are the six principles of the Criteria for High-Quality Carbon Dioxide Removal?

The Criteria define six science-based principles that apply across all CDR pathways: social harms, benefits, and environmental justice; environmental harms and benefits; additionality and baselines; measurement, monitoring, reporting, and verification (MMRV); durability; and leakage.

What CDR pathways does the Criteria cover?

The Criteria include pathway-specific criteria across nine CDR pathways: afforestation, reforestation, and revegetation (ARR); mangrove forestation; improved forest management (IFM); soil carbon; enhanced rock weathering (ERW) in croplands; biomass carbon removal and storage (BiCRS); abiotic marine CDR; carbon mineralization; and direct air capture (DAC).

What is delivery risk in carbon removal?

Delivery risk is the likelihood that a project generates credits on the timeline and at the quantity committed to buyers. It's a distinct concern from credit quality: even a high-quality project can fail to deliver as planned because of technical, economic, commercial, organizational, or political risk, the five categories the Criteria's TECOP framework evaluates. The 2026 Criteria's new Delivery Risk Appendix gives developers, investors, and buyers a shared benchmark for identifying and managing these risks before they derail a project.

What's the relationship between carbon removal credit quality and delivery risk?

Credit quality and delivery risk are distinct but interrelated. A project that fails to deliver credits as planned reduces the availability of high-quality CDR tonnes in the market, and weaknesses in credit quality can themselves increase delivery risk by creating buyer uncertainty or limiting access to project financing. The 2026 Criteria provides a framework for evaluating both quality and delivery risk.

Key Takeaways

• Trust in carbon credits remains low. In part, this is because many mistakenly treat every credit type as interchangeable.
• Reduction, removal, and avoidance credits are verified against fundamentally different baselines, so credit quality must be judged based on type and project specifics, never with one blanket standard.
• The Integrity Council for the Voluntary Carbon Market's Core Carbon Principles now give buyers an independent bar to check against, including 44 methodologies approved across 13 eligible crediting programs, as of August 2026.
• Removal credits still make up only 5–6% of the market, even as compliance-driven demand accelerates, per our 2026 State of the Voluntary Carbon Market report.

Three Types of Carbon Credits: Reduction, Removal, and Avoidance

A carbon credit is a mechanism that allows one party to compensate another for their carbon mitigation activities. Based on their net emissions impact, there are three types of carbon credits: reduction, removal, and avoidance. 

1. Reduction credits reflect activities that decrease greenhouse gas emissions, compared to prior practices. 
2. Removal credits reflect activities that remove carbon dioxide already present in the atmosphere and oceans and lock it away for decades, centuries, or millennia.
3. Avoidance credits reflect activities that prevent greenhouse gases from being emitted in the first place. For all three types, credits are assessed and issued by measuring or estimating how much carbon is reduced, removed, or avoided as a result of a credit purchase and its associated activities.

While credits are assessed in different ways depending on the type, one of the most important indicators of quality is a project's baseline - the emissions that would be present in a business-as-usual scenario, without action being taken to reduce, remove, or avoid them. Project developers use baselines as a means of comparison to assess the net emissions impact of a project. 

• Baselines must be accurately set and data-driven. 
• Emissions impacts of a project must be correctly calculated against its baseline. 

Reduction, removal, and avoidance projects involve very different activities and, for some types of projects, it may be more challenging to establish an accurate baseline. However, without accurate baselines, climate impacts cannot be reliably determined.

Across the voluntary carbon market, Reduction credits represent roughly 20% of the purchases. Removal credits represent roughly 5% of the purchases. The remainder, roughly 75%, are avoidance credits.

Carbon Reduction Credits

Carbon reduction must drive the majority of our push to net zero, but translating carbon reduction activities into carbon credits that can be purchased is challenging. Examples of activities represented by carbon reduction credits include reducing fossil fuel use by improving fuel efficiency, or programs that reduce the methane that is generated from farms or municipal waste processing. 

Reduction credits are measured and quantified against the baseline emissions of an existing technology or process. Some reduction credits are easy to track and measure, such as efficiency investments or destruction of fugitive methane. Other projects are more complex. For example, low-emission cookstove projects in developing regions rely on tracking patterns of cookstove use and quantifying emission factors for various fuel and stove combinations, both of which are hard to do. The result, as studies have shown, sometimes leads to overcrediting in reduction projects. 

Superpollutant Credits

One class of reduction credit, superpollutant credits, has garnered recent attention. These credits involve the reduction of non-CO2 greenhouse gases with very strong radiative forcing, such as methane, nitrous oxides, or fluorinated gases like chlorofluorocarbons. These are not a substitute for CO2 removal, but can provide rapid and profound reductions at modest cost. Many different kinds of superpollutants exist in today’s market, worth roughly $60M today. Recent purchases by tech companies and others have highlighted the potential of these reduction credits.

Another class of reduction credit, transition credits, involves the deliberate early closure of emitting assets like coal-fired power plants or heavy manufacturing facilities. Early efforts by governments, banks, and companies around the world under the Just Energy Transition Partnership agreement jump-started transition credits as a concept at COP26. The Kinetic Coalition, in partnership with many groups including Relae, has launched work to bring transition credits to market with several pilot efforts, including closing a coal plant in the Philippines 10 years early. 

Carbon Removal Credits

Projects that remove carbon come from a diverse set of solutions, from nature-based solutions like reforestation, to hybrid solutions like biochar, to engineered solutions such as direct air capture and storage. Roughly 5–6% of credits on the voluntary carbon market today are classified as removals, up from roughly 3% a few years ago.

Carbon removal baselines are determined differently depending on whether a project uses an engineered, hybrid, or nature-based solution. For engineered removals, the baseline is zero, because no carbon removal was occurring in the absence of the project. The credited removal will be the difference between the quantity of carbon removed and any emissions that occur to facilitate the removal (determined through a carbon credit life cycle assessment). Baselines for hybrid and nature-based removals can be more challenging. In natural systems, changes in carbon stocks created by removals must be measured and approximated over time, and creditable removals represent the additional carbon removed by the intervention relative to the baseline (e.g., fallow land versus a reforestation project).

Another important consideration for carbon removal credits is project durability, a measure of the likely duration of carbon storage. Stored carbon can re-enter the atmosphere either through deliberate actions (e.g., deforestation) or accidental ones (e.g., wildfires). Nature-based removals are especially vulnerable to being re-released and are usually considered less durable (i.e., stored for less than 50 years). In contrast, engineered solutions offer high durability (i.e., stored for hundreds to thousands of years), and hybrid removals also offer durability periods that are typically longer than those of nature-based removals.

While less durable, nature-based solutions are effective, cost-effective, and widely available today. They made up over 95% of all carbon removal credits issued in 2025. Engineered and hybrid solutions are more expensive and scarce but offer longer durability. Prices of engineered carbon removal are likely to fall with innovation and increased market participation, but are currently much higher than most nature-based credits. With SBTi's finalized Corporate Net-Zero Standard V2.0, this balance is likely to shift. Large companies must now purchase removal credits covering 1–100% of scope 1, scope 2, and scope 3 emissions between 2035 and their net-zero year, with an explicit focus on more durable CO2 removal credits.

Carbon Avoidance Credits

Examples of carbon avoidance include avoiding deforestation that would result in the release of carbon dioxide into the atmosphere or clean energy projects that avoid the release of emissions from burning fossil fuels in possible facilities. This can be confusing, since many avoided credits are called reduction credits, as is the case with projects under the Reducing Emissions from Deforestation and Forest Degradation (REDD+) framework. Avoidance credits make up roughly 75% of certified credits on the voluntary carbon market today - an overwhelming majority - in part due to high availability and low price. 

Avoiding emissions is an important goal with numerous environmental, climate, community, and other benefits. Relae works with clients and customers across industries on developing and implementing strategies to avoid emissions within their value chain. However, there are significant challenges with the way that many carbon avoidance credits are created.

• Carbon avoidance credits are based on an estimate of the emissions that might have existed had a project not been funded. Because it is impossible to observe what might have happened in the absence of a project, carbon avoidance estimates are determined by considering historic data and contextual information. Statistical models can be used to create a presumed baseline that represents what would have happened in the absence of the project.

• Because the baseline is not observed in an avoided emissions project, there is uncertainty in calculating the number of carbon credits it produces. If the baseline is not set accurately, a project can overcredit. While the lack of a directly observed and measured baseline means avoidance credits will always have some degree of uncertainty, high-quality avoidance projects present compelling evidence to support their baselines, greatly reducing uncertainty. 

New datasets, statistical techniques, and methodologies are providing opportunities for developing avoidance credits with more certainty. Three REDD+ methodologies have now cleared the Integrity Council for the Voluntary Carbon Market (ICVCM) assessment for its Core Carbon Principles (CCPs), a concrete sign that credit quality standards for avoidance projects are maturing.

Defining and Standardizing Quality in the Voluntary Carbon Market

Carbon credits are intended to reduce, remove, or avoid emissions. They pay for an environmental service that must be delivered. Companies working to generate climate benefits through credit purchases must grapple with the differences and uncertainties of credit quality to ensure that the intended benefits are realized. 

While high-quality credits exist for all types of projects, a rich understanding of the differences in methodologies, geographies, physics, and ecology is required to identify high-quality projects and understand varied certainty, durability, and risk terms. Identifying high-quality carbon projects demands extensive and project-specific diligence beyond carbon market certification.

Our own diligence work reveals that high-quality projects can be hard to find. Fewer than 10% of the carbon removal projects we assessed for our 2026 State of the Voluntary Carbon Market report met our quality criteria. This diligence work now has an additional, independent backstop. As of August 2026, the ICVCM has approved 44 methodologies across 13 programs, as eligible for its CCP label, including ACR, Gold Standard, and VCS. For buyers, considering projects that are CCP-eligible should be used as a first filter—not a substitute for project-level diligence, but representing a legitimate floor.

While realized emissions impacts may be difficult to prove in some cases, it is important to remember that some projects provide additional co-benefits. REDD+ projects, for example, may have a positive impact on conservation and biodiversity, and cookstove projects may offer clear human health and social welfare benefits. However, these benefits should be assessed separately from carbon reduction, removal, or avoidance benefits.

Frequently Asked Questions

What's the difference between a carbon credit and a carbon offset? 

A carbon credit represents one verified tonne of emissions reduced, removed, or avoided. A  carbon offset describes how a buyer uses that credit, typically to counterbalance emissions it has not yet accounted for. The credit itself does not change type based on how it's claimed.

Which type of carbon credit—reduction, removal, or avoidance—is highest quality? 

No single type is inherently highest quality. Each project, regardless of type, is verified against a defined baseline. Quality depends on how rigorously that specific baseline was set and how well the project meets other quality criteria. Removal credits from engineered sources have the most straightforward baseline (zero), and avoidance credits carry the most baseline uncertainty by design, but these are only one determinant of credit quality.

Do carbon removal credits automatically meet the ICVCM’s Core Carbon Principles? 

No. The ICVCM assesses methodologies and programs, not individual projects. If a project uses a methodology that is eligible for the CCP label, this can be a useful floor but is not a guarantee of high quality.

How does SBTi's near-term removal mandate change which credits I should buy now?

SBTi's finalized Corporate Net-Zero Standard V2.0 doesn't require removal purchases until 2035, but it sets the ramp now (i.e., 1% of scope 1, scope 2, and scope 3 emissions in 2035, scaling to 100% by the net-zero year). This means the highest-durability removal supply that is scarcest and most in demand today is the same supply that many companies will need later. The SBTi guidelines are still changing, so buyers and project developers must track them closely.