SOUND ASSESSMENT FRAMEWORKS FOR EFFECTIVE MARINE CARBON DIOXIDE REMOVAL (SAFE-MCDR)

Without deep cuts in fossil fuel consumption, industrial emissions, and land-use changes, any supplementary carbon dioxide removal (CDR) strategies will be inadequate to mitigate continued dangerous global warming. Nevertheless, once significant emissions reductions have been achieved, CDR is expected to play an increasing role in achieving climate neutrality and is explicitly required to reach negative emissions. In recent years, various strategies for marine CDR (mCDR) have seen rapid development as potential tools for increasing the already climate-critical uptake of carbon by the oceans. However, these methods present significant uncertainties regarding not only their technical feasibility but also their ecological, socio-political, legal, and economic implications. Furthermore, any implementation of mCDR must be guided by the precautionary principle, ensuring that interventions do not compromise ocean health, biodiversity, or the livelihoods of coastal communities. The need for robust, standardised, and long-term monitoring frameworks is paramount to assess the real-world efficacy, permanence, and risks associated with mCDR. Given the ocean’s complexity—characterised by high biological and chemical variability, transboundary connectivity, and slow response times—establishing reliable and internationally coordinated monitoring systems is essential for the responsible deployment of marine-based climate interventions. As such, approaches for monitoring, reporting, and verification centred around quantifications of the additionality and durability of mCDR must be developed and standardised. These MRV tools should also help to ensure that unintended negative consequences for marine ecosystems and human communities are identified and mitigated or minimised.