Beneath the Waves: The Essential Role of Blue Carbon Projects in Climate Change Mitigation

When we think of carbon sequestration, forests and trees often come to mind first. Yet in reality, the Earth’s largest carbon sink is the ocean, which plays a critical role in regulating the global climate. It stores an estimated 38,000 gigatons of carbon—almost 50 times more than the atmosphere—and has already absorbed 25–30% of human-generated CO₂ emissions since the industrial era began.

Carbon enters the ocean through two primary processes:

• The physical pump involves CO₂ dissolving in cold surface waters, especially in polar regions. These denser waters then sink and transport carbon into the deep ocean, driven by slow-moving but powerful currents.

• The biological pump involves phytoplankton (marine algae)—microscopic plant-like organisms—absorbing CO₂ through photosynthesis. When they die, some of the carbon they contain sinks to the seafloor and becomes trapped in sediments for thousands of years.

The ocean’s ability to absorb carbon makes it a powerful buffer against climate change. However, this buffering capacity is not unlimited. As atmospheric CO₂ levels continue to rise, the ocean’s ability to absorb additional emissions diminishes.

One of the most dramatic consequences of human activity is ocean acidification. As more CO₂ dissolves into seawater, it lowers the pH, making the ocean more acidic. This shift threatens marine life—especially corals, shellfish, and other organisms that rely on stable pH levels to build their shells and skeletons. Warming oceans and increased stratification (reduced mixing between surface and deeper layers) further limit the ocean’s carbon uptake and disrupt vital biological processes.

To effectively combat climate change, we must not only reduce emissions but also work to reverse ocean acidification. Protecting the ocean’s health is essential to maintaining its carbon sink function and safeguarding the ecosystems that billions of people and countless marine species depend on.

This is where the concept of blue carbon comes into play.

What Is Blue Carbon?

Blue carbon refers to the carbon captured and stored by coastal and marine ecosystems. These systems are vital for regulating the Earth’s climate by removing CO₂ from the atmosphere. Blue carbon is generally categorized into two main types:

Coastal Blue Carbon

This includes mangroves, tidal marshes, and seagrasses—often referred to as "blue forests." These habitats are among the most efficient carbon sinks on Earth, capable of sequestering two to four times more carbon than terrestrial forests per unit area. They store carbon in both their plant biomass and the sediment below.

Beyond carbon storage, coastal blue carbon ecosystems:

• Protect shorelines from erosion and storm surges

• Filter water and improve its quality

• Sustain fisheries and marine biodiversity

• Enhance food security for coastal communities

  
  

Deep Blue Carbon

This refers to carbon stored in deep ocean waters and sediments beyond coastal zones. While it accounts for roughly 90% of oceanic carbon storage, deep blue carbon is difficult to monitor and manage due to data and technology challenges.

Expanding the Concept of Blue Carbon

Traditionally, blue carbon focused on natural coastal ecosystems like mangroves and seagrasses. However, the concept is evolving to include engineered approaches that enhance carbon removal in the open ocean.

Some refer to this expanded view as "enhanced blue carbon" or "marine carbon dioxide removal (CDR)." There is ongoing debate over how these new interventions should be categorized, but the goal remains the same: to leverage the ocean’s potential in the fight against climate change.

Breakdown of Blue Carbon Approaches

Traditional Blue Carbon

• Nature-based: Involves natural carbon storage in vegetated coastal ecosystems.

• Proven and well-understood: These systems have been extensively studied and form the foundation of most current blue carbon projects.

  
  

Engineered Ocean CDR Solutions

Emerging technologies aim to amplify the ocean’s natural carbon removal capacity and include:

• Direct Ocean Capture: Extracting CO₂ directly from seawater

• Ocean Alkalinity Enhancement: Adding alkaline minerals to increase CO₂ absorption

• Biomass Cultivation and Sinking: Growing seaweed or algae and sinking it into the deep sea

• Enhanced Weathering: Spreading reactive minerals along coastlines to bind CO₂ into stable carbonates

These solutions address the need for scalable and high-impact carbon removal strategies to meet global climate goals. Given the ocean's vast capacity as a carbon sink, new methodologies could significantly accelerate its carbon uptake processes.

Real-World Examples

Traditional approach: Mangrove Reforestation In Myanmar

Led by local stakeholders and aligned with international climate standards, this large-scale blue carbon project is restoring over 2,000 hectares of degraded mangrove forests in Myanmar’s Ayeyarwady Division. Spanning from 2015 to 2035, the initiative is designed to mitigate climate change, reduce coastal disaster risks, and strengthen the livelihoods of vulnerable coastal communities.

At the core of this project is the replanting of native mangrove species—such as Rhizophora mucronata and Bruguiera gymnorrhiza—under the Verified Carbon Standard (VCS), in line with Afforestation, Reforestation, and Revegetation (ARR) and Wetlands Restoration and Conservation (WRC) requirements. These restored mangrove ecosystems will serve as powerful carbon sinks, protect against storm surges, and support biodiversity.

Myanmar is home to some of the world’s richest mangrove ecosystems, yet it faces one of the highest rates of mangrove loss globally due to unsustainable agriculture, industrial expansion, and widespread poverty. With only 5% of mangroves legally protected, the urgency for restoration is clear. This project addresses not only environmental degradation but also the social and economic vulnerabilities of coastal regions.

Community engagement is central to the project’s success. Through participatory planning, regular stakeholder meetings, and a transparent grievance mechanism, local voices help shape and guide every phase of implementation. This inclusive approach fosters long-term ownership, awareness, and commitment to conservation.

Engineering Approach: Limenet from Italy

Limenet, an Italian climate tech company, is pioneering ocean-based carbon removal through its patented pH-equilibrated Ocean Alkalinization technology. By mimicking and accelerating natural geochemical processes, the company currently uses CO₂ captured from industrial sources, converting it into stable calcium bicarbonates that are safely stored in seawater for over 10,000 years.

Launched in 2023, Limenet’s pilot plant in Augusta, Sicily, is the world’s largest facility for ocean-based CO₂ storage. It currently processes 800 tonnes of CO₂ per year, with plans to scale up to 100,000 tonnes annually by 2028. In addition to permanent carbon sequestration, the process increases ocean alkalinity, helping reverse acidification and restore marine ecosystems—particularly benefiting pH-sensitive species such as corals, plankton, and mollusks.

As part of a broader blue carbon strategy, Limenet’s approach not only removes carbon but also contributes to the health and resilience of marine environments. The technology is backed by leading scientific institutions such as Politecnico di Milano and Università Milano-Bicocca, and has been independently verified by RINA under ISO 14064-2 standards.

Limenet also ensures full transparency through a robust digital MRV system, which enables blockchain-based issuance and tracking of carbon credits via Carbonmark Direct. By combining technological innovation, environmental co-benefits, and digital accountability, Limenet is setting a new benchmark for scalable, ocean-based carbon removal within the evolving blue carbon framework.

Carbonmark: Scaling Blue Carbon Solutions

As the world turns to the ocean for scalable climate solutions, blue carbon is emerging as a powerful frontier for carbon removal and ecosystem restoration.

At Carbonmark, we make it easy for businesses to support blue carbon projects and create meaningful climate impact. Through our open blockchain-enabled marketplace, you can discover, purchase, and instantly retire high-integrity blue carbon credits. For automated carbon offsetting, our API can be seamlessly embedded into any workflow or software platform. Whether you're building a sustainability solution or automating internal offsetting, Carbonmark facilitates effortless access to verified blue carbon credits. Check our page for Buyers to learn more.

For developers and innovators advancing the next generation of blue carbon methodologies, Carbonmark Direct provides a transparent and efficient pathway to issue, manage, and monetize your credits. With blockchain-based infrastructure, dMRV compatibility, and direct marketplace access, we streamline the journey from project design to credit retirement.

Whether you're leveraging the ocean’s carbon-capturing power as a buyer or developing cutting-edge blue carbon projects, Carbonmark equips you with the technological infrastructure layer to lead. Explore our offerings at carbonmark.com.