Salted Peat: The Forgotten Casualty of Rising Sea Level in Freshwater Coastal Tropical Peatlands

ABSTRACT Coastal tropical peatlands store vast carbon reserves now threatened by accelerating sea level rise. We synthesize emerging evidence showing that seawater intrusion may be triggering an overlooked Earth system feedback: the transformation of freshwater peatlands into saline, carbon‐emitting landscapes. This process, which we frame as “salted collapse”, could trigger vegetation dieback, oxidation, and fire risk, converting long‐term carbon sinks into persistent greenhouse gas sources. The biogeochemical transition may also cascade into social systems, undermining coastal agriculture, food security, and adaptation capacity across low‐lying tropical regions. Yet current global climate models and IPCC accounting frameworks omit this feedback, risking underestimating coastal carbon fluxes and associated human vulnerability. Recognizing salinization as a coupled geophysical and socio‐ecological tipping process is essential for closing the coastal carbon budget and integrating these landscapes into global climate models, accounting frameworks, and adaptation strategies.