Monitoring, reporting, and verification of marine carbon dioxide removal: Exploring scientific consensus and divergences across continents

Marine Carbon Dioxide Removal (mCDR) approaches are increasingly considered for climate change mitigation as a supplement to rapid emissions reduction. However, it is still unclear if mCDR approaches could be effective, safe, and accountable. A critical requirement for mCDR to work, potentially, is robust monitoring, reporting, and verification (MRV) of greenhouse gas(es) removed through mCDR activities. MRV frameworks and protocols are currently developed in a scattered manner by individual stakeholders, so that the principles they are built upon may or may not appeal to the broader international community that is interested in the ocean commons. International agreement and consolidation on MRV for mCDR seem crucial to legitimize and validate mCDR, considering that the ocean is a globally interconnected fluid and that activities by some may affect many others. Here, we undertake a step toward consolidation of MRV by consulting the international scientific community. We established a global network of scientists organized into 6 “continental” nodes, each of which addressed the same set of MRV-related questions and whose thoughts were equally weighted in the synthesis. Our consultation shows that while there are many converging views on MRV (e.g., the importance of modeling for MRV), there are also differences in the regional MRV priorities (e.g., the importance of regional vs global models). The areas of consensus and divergence identified herein may be instrumental in the design of more widely accepted MRV frameworks, informed equally by scientists from 6 continents.