The degradation or loss of vegetated coastal ecosystems reduces carbon storage, with positive feedbacks to the climate system (high confidence).‘Seagrass meadows (high confidence) [...] will face moderate to high risk at temperature above 1.5°C global sea surface warming.’ ‘The transition from undetectable to moderate risk in salt marshes [...] takes place between 0.7°C–1.2°C of global sea surface warming (medium/high confidence), and between 0.9°C–1.8°C (medium confidence) in sandy beaches, estuaries and mangrove forests.’ ‘The ecosystems at moderate to high risk under future emission scenarios are mangrove forests (transition from moderate to high risk at 2.5°C–2.7°C of global sea surface warming), estuaries and sandy beaches (2.3°C–3.0°C) and salt marshes (transition from moderate to high risk at 1.8°C–2.7°C and from high to very high risk at 3.0°C–3.4°C) (medium confidence).’ ‘Global coastal wetlands will lose between 20–90% of their area depending on emissions scenario with impacts on their contributions to carbon sequestration and coastal protection