Underwater Drones Offer New Insights Into the Ocean’s Capacity to Store Carbon

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Advances in marine technology are beginning to reshape how scientists and investors understand the ocean’s role in absorbing and storing carbon dioxide. By mapping the seafloor in high resolution, researchers are gaining clearer evidence of how coastal ecosystems capture carbon and lock it into marine sediments, potentially strengthening the credibility of so-called blue carbon projects.

At the centre of this effort is Fujitsu Ltd, which is applying its digital and sensing expertise to one of the most difficult challenges in climate finance: measuring how much carbon coastal ecosystems actually absorb.

 

Turning the Seafloor Into Data

 

Fujitsu has developed a microwave-sized autonomous underwater vehicle that moves in a zig-zag pattern across the ocean floor, scanning vegetation and identifying plant species that absorb carbon dioxide. When these plants die, a portion of the carbon they capture is stored in sediment, potentially for centuries or longer.

Data collected by the drone is used to build digital replicas of coastal habitats. These “digital twins” allow researchers to estimate how much carbon is absorbed by living plants today and to simulate how conservation or restoration efforts could increase future carbon uptake. This approach aims to reduce one of the biggest uncertainties in blue carbon markets: measurement accuracy.

The technology has already been tested in real-world conditions. In a habitat restoration project near Uwajima on Japan’s Shikoku island, Fujitsu’s drone-based surveys supported the issuance of blue carbon credits certified by Japan’s national body in 2025.

 

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Why Blue Carbon Attracts Attention

Blue carbon refers to carbon stored by coastal and marine ecosystems such as mangroves, salt marshes and seagrass meadows. These systems are drawing growing interest because they can store significantly more carbon per unit of land than many terrestrial ecosystems, including tropical forests. They are also less exposed to risks such as wildfires and prolonged droughts.

Despite these advantages, blue carbon remains a small segment of global carbon markets. According to BloombergNEF, credits issued from ocean-based projects peaked in 2022 at the equivalent of 3.1 million tonnes of carbon dioxide. Under a base-case scenario, that figure could rise to more than 40 million tonnes by mid-century, but only if confidence in measurement and verification improves.

 

Measurement Risk and Investor Confidence

 

Investor confidence remains the primary bottleneck for scaling blue carbon. Estimating how much carbon is stored in marine sediment is technically complex, and results can vary widely depending on location and methodology. A peer-reviewed study published in 2022 found differences of several orders of magnitude between the highest and lowest estimates of carbon burial rates across salt marshes, seagrasses and mangroves.

This uncertainty has made investors cautious. Without reliable data, it is difficult to assess whether a project genuinely delivers climate benefits or whether credits risk overstating their impact. Technologies such as underwater drones, hyperspectral satellites and ocean digital twins are increasingly seen as tools to address these concerns by providing more direct, site-specific evidence.

 

Beyond Measurement: Proving Additionality

 

Another challenge is additionality, or demonstrating how much carbon an ecosystem would have absorbed without human intervention. Many restoration projects struggle to prove that their activities lead to additional carbon storage beyond what would have occurred naturally. Researchers warn that issuing credits without robust additionality risks undermining the environmental integrity of carbon markets.

Technology is beginning to play a role here as well. By tracking ecosystem changes over time and modelling counterfactual scenarios, digital monitoring tools may help distinguish between natural recovery and outcomes directly attributable to restoration efforts.

 

Lowering Costs Through Automation

 

Cost is another barrier for blue carbon projects, particularly in marine environments where restoration work is labour-intensive. San Francisco-based Ulysses Maritime Technologies Inc is addressing this by deploying underwater robots that plant seagrass seeds with high precision. In an Australian project, the company reported cost reductions of up to 90 percent compared with diver-led restoration, while completing work up to ten times faster.

Automation of this kind not only reduces costs but also improves consistency and scale, both of which are essential for attracting institutional capital.

 

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Fragile Ecosystems, High Stakes

 

While the potential is significant, blue carbon ecosystems remain fragile. Coastal development, dredging, rising sea levels, stronger storms, warming waters and ocean acidification all pose risks to long-term carbon storage. These vulnerabilities underline the importance of continuous monitoring and adaptive management, rather than one-off measurements.

For proponents of blue carbon, the goal is not to present marine ecosystems as a silver bullet for climate change. Even under optimal conditions, scientists estimate that protecting and restoring these habitats would address only a small fraction of global emissions. However, when combined with biodiversity protection, coastal resilience and community benefits, blue carbon projects can offer a compelling package of environmental value.

 

A Technology-Driven Path Forward

 

As carbon markets mature, the credibility of underlying data is becoming just as important as ambition. Underwater drones and digital modelling tools are emerging as critical infrastructure for the next phase of nature-based climate solutions. By reducing measurement risk and improving transparency, these technologies could help unlock financing for coastal restoration while ensuring that claimed climate benefits are grounded in evidence.

If successful, they may turn one of the most uncertain corners of the carbon market into one of its most scientifically robust.

 

Source: https://www.bloomberg.com/news