Kelp and other macroalgae do matter. They absorb large amounts of carbon, move organic material through the ocean, and help drive the wider marine carbon cycle. Some of that carbon ends up stored for long periods in deep water or sediments. But this is also where the inflation begins. Kelp is often sold as a clean climate fix long before the science can justify that certainty.
The safer conclusion is narrower: kelp plays an important role in marine carbon flow, but the long-term sequestration numbers remain too uncertain to sit cleanly inside formal blue-carbon accounting. That matters because blue carbon politics often stops at what is easy to market, not what is most structurally important.
The bigger issue sits below the kelp. Marine sediments are already a vast carbon store whether policy counts them properly or not. In Norway alone, researchers reported in 2024 that the upper ten centimeters of shelf sediments hold roughly 814 million tonnes of organic carbon, with around 6 million tonnes added each year. That should be enough to change how the seabed is understood.
Once that scale is clear, the political meaning changes too. Disturbing the seabed is not just habitat damage or biodiversity loss. It is also interference with a major carbon structure that is already doing climate work without being treated as climate infrastructure.
This is where the bottom-trawling debate matters. There is broad agreement that trawling disturbs sediments, damages benthic ecosystems, and disrupts marine carbon flows. There is less agreement about how much of that disturbance translates directly into atmospheric CO2. That debate is real. It is also politically convenient.
It allows governments and industries to hide behind uncertainty in the climate numbers while continuing practices whose ecological damage is already obvious. The exact emissions figure is disputed; the physical disturbance is not. In practice, uncertainty becomes a governing tool. It delays limits, softens scrutiny, and keeps extraction moving.
The same logic now appears in seabed mining. Commercial deep-sea mining is still limited, but the pressure to open the seabed to further extraction is growing faster than the knowledge needed to justify it. That is not a minor procedural problem. It shows the same pattern as trawling: disturbance is pushed forward first, while caution is deferred into endless scientific qualification.
They are one struggle over whether the seabed will be treated as living carbon infrastructure or opened further as industrial space. That is not precaution. It is industrial expansion under cover of uncertainty.
So the seabed is being forced into two roles at once: a carbon store and a sacrifice zone. Kelp is part of that story, but not the whole of it. The deeper issue is that marine sediments already perform climate work while policy still treats them as industrial space. The seabed is not background. It is carbon infrastructure under assault.
- IPCC AR6 WGII, Chapter 3 – Oceans and Coastal Ecosystems and their Services
- Krause-Jensen & Duarte (2018) – Sequestration of macroalgal carbon: the elephant in the Blue Carbon room
- McHenry et al. (2025), Nature Reviews Earth & Environment – A blueprint for national assessments of the blue carbon potential of kelp forests
- Production and fate of macroalgal carbon in the ocean (2025) – oversiktsartikkel om produksjon, eksport og sekvestrering
- Nordisk ministerråd (2020) – Nordic Blue Carbon / TemaNord 2020:541
- NIVA – Restoring Norway’s Underwater Forests
- ScienceNorway (2024) – The seabed off Norway stores six million tonnes of carbon each year
- IPCC SROCC, Chapter 5 / FAQ 5.1 – om oppvarming, forsuring og deoksygenering i havet
- IUCN (2019) – Ocean deoxygenation: Everyone’s problem
- State of the World’s Kelp Forests (2024)
- Hiddink et al. (2023) – Quantifying the carbon benefits of ending bottom trawling
- Hilborn et al. (2023) – Evaluating the sustainability and environmental impacts of seabed trawling
- Felgate et al. (2024) – Investigating the effects of mobile bottom fishing on benthic carbon
- Atwood et al. (2024) – om CO2 og forsuring fra bunntråling, med høye anslag og fortsatt debatt
- Waqas et al. (2024) – Environmental performance of seaweed cultivation
- Wu et al. (2025) – Nearshore Macroalgae Cultivation for Carbon Sequestration
- EDF / UNEP / NOAA bakgrunnskilder om blått karbon og marine økosystemer, brukt som støtte, men ikke som hovedgrunnlag for de viktigste konklusjonene