A new report from the Norwegian University of Science and Technology highlights significant risks associated with the rapid deployment of ocean-based carbon dioxide removal technologies. Released during the COP30 climate conference in Brazil, the findings indicate that while oceans could potentially absorb carbon dioxide to mitigate climate change, current technologies are not ready for safe large-scale implementation.
The report emphasizes that marine carbon dioxide removal methods must undergo rigorous monitoring and verification before being expanded. An expert panel under the European Marine Board has concluded that insufficient safeguards currently exist to ensure these technologies function as intended without causing additional environmental harm.
Ocean-based strategies aim to harness the natural capacity of the ocean to absorb carbon. Some methods focus on enhancing biological processes, such as promoting the growth of plankton or seaweed, which capture carbon dioxide during their lifecycle. Others employ chemical and physical techniques that extract carbon directly from seawater, with the potential to store it in deep-sea sediments or geological formations.
Helene Muri, a senior researcher at NILU, the Norwegian Institute for Air Research, led the expert group that produced the report. She stated, “This is about safeguarding the oceans for a common good. The oceans can be part of the climate solution, but we need to strengthen the way we safeguard them before we scale things up.”
As the world edges closer to the critical 1.5°C temperature threshold, the urgency for effective climate action is palpable. During his address at the COP30 Leaders’ Summit on November 6, UN Secretary-General António Guterres underscored the dire implications of unchecked climate warming, emphasizing that maintaining the 1.5°C limit is crucial for humanity.
The report advocates for immediate action on already proven methods to reduce emissions, rather than rushing into unproven marine technologies. “We know how to cut emissions, and we have lots of methods that work,” Muri remarked, stressing that emissions reduction must be the top priority.
Despite the focus on emissions cuts, some sectors present notable challenges in achieving carbon neutrality. Industries like aviation and certain manufacturing processes remain difficult to decarbonize, necessitating carbon removal strategies to balance residual emissions. Countries have set ambitious targets, aiming for net-zero emissions by 2050, which means that any emissions that cannot be eliminated must be offset by an equivalent amount of carbon removal.
To meet the 1.5°C target, experts predict that societies will need to achieve net negative emissions. Muri noted that this entails removing between 5 to 10 gigatons of CO2 annually by the end of the century, according to scenarios outlined by the Intergovernmental Panel on Climate Change (IPCC). For context, global CO2 emissions were approximately 42.4 gigatons in 2024, as reported by the CICERO Center for International Climate Research.
While various marine carbon removal techniques are in experimental stages, many are not yet ready for implementation. The report calls for establishing standards for monitoring, reporting, and verifying the effectiveness of these methods. Muri highlighted that, “If we want to be serious about figuring out if you can do marine carbon dioxide removal in responsible ways that can make meaningful contributions, then we have to get serious about the monitoring, reporting, and verification aspects.”
Furthermore, the report outlines the technical and scientific challenges associated with these technologies. Some ocean-based carbon removal approaches mirror established land-based methods, such as afforestation or the restoration of coastal ecosystems like mangroves. Others involve direct interventions, such as adding nutrients to stimulate plankton blooms, which are expected to absorb carbon and sink to the ocean’s depths.
The complexities of managing and monitoring carbon stored in the ocean present significant hurdles. Muri noted, “If you’re storing it in the ocean… it’s a lot harder to govern it and also monitor it. The ocean doesn’t stay put.” This variability complicates efforts to track the effectiveness of carbon removal initiatives and poses challenges to regulatory oversight.
As the technology matures, companies and governments may seek carbon credits for successful removal efforts. Yet, Muri cautioned that without reliable verification of the impacts, these methods cannot be deemed viable. “None of these methods are mature to use if you cannot verify impacts or where the carbon goes,” she stated.
Looking forward, Muri emphasized that marine carbon removal should not be viewed as a panacea for climate change. “Some people are really hoping to find an answer in the ocean, but in our opinion, we’re not there yet,” she concluded. The report calls for a cautious approach, advocating for clear standards and robust regulatory frameworks before scaling up ocean-based carbon removal technologies.
As the global community continues to confront the pressing challenges of climate change, the role of oceans in carbon management remains a complex and evolving issue. The findings from this report serve as a critical reminder of the need for careful consideration and thorough oversight in the pursuit of innovative climate solutions.
