Ambition Disparity Reveals Unlocked Mitigation Potential for Blue Carbon in the Paris Agreement

The Paris Agreement aims to keep the global temperature rise under 2°C, which is implemented through National Greenhouse Gas Inventory Reports (NIRs) and Nationally Determined Contributions (NDCs). Blue carbon ecosystems, despite substantive climate change mitigation potential, remain underutilised in the Paris Agreement. We analysed over 1700 NDCs and NIRs submitted since 2015 to identify inclusion and quantify mitigation gaps in the utilisation of blue carbon ecosystems (mangroves, seagrasses, tidal marshes, and tidal flats) in the context of the Paris Agreement. 33% of the blue carbon-holding countries have incorporated them into NIRs, and 19% have set quantifiable NDC targets, with Non-Annex I Parties making much of this contribution. Only 13.4 Gt CO₂ eq of blue-carbon mitigation is currently pledged, yet Non-Annex I Parties hold nearly twice the untapped potential (68.7 Gt CO₂ eq) compared to Annex I Parties (35.5 Gt CO₂ eq), highlighting both the opportunity and the imbalance. Full protection and restoration of blue-carbon ecosystems could sequester 122.3 Gt CO₂ eq by 2050—roughly 2.5 years of global emissions from all sectors. Closing this gap would elevate blue carbon from a marginal opportunity to a core component of global mitigation, while enhancing the resilience and improving the livelihoods of coastal communities.