Marine carbon dioxide removal (mCDR) technologies, (e.g., alkalinity enhancement, iron fertilization, direct ocean removal) are rapidly advancing from concept to deployment. However, the environmental impact of these technologies remains poorly constrained, and there is no shared framework determining what constitutes meaningful or acceptable impacts. 

This session examines how ecological responses are evaluated across diverse mCDR pathways, including ecosystem and biogeochemical changes, risks, and co-benefits. We invite contributions that explore how impacts are defined, measured, and quantified across different project types, governance contexts, and regions, including contrasts between Global North and Global South. Contributions from terrestrial CDR communities are also welcome to encourage cross-domain comparison and synthesis.

This session aims to unify community practices, highlighting opportunities to improve consistency, transparency, and inclusivity in impact assessment. Outcomes include identification of key challenges, emerging best practices, and priorities for advancing integrated frameworks that better capture ecological, environmental, and human dimensions of mCDR.