Runaway Climate Across the Wider Caribbean and Eastern Tropical Pacific in the Anthropocene: Threats to Coral Reef Conservation, Restoration, and Social-Ecological Resilience

Marine heatwaves are increasingly affecting tropical seas, causing coral bleaching and mortality in the wider Caribbean (WC) and eastern tropical Pacific (ETP). This leads to significant coral loss, reduced biodiversity, and impaired ecological functions. Climate models forecast a troubling future for Latin American coral reefs, but downscaled projections for the WC and ETP remain limited. Understanding future regional temperature thresholds that threaten coral reefs and res-toration efforts is critical. Our goals included analyzing historical trends in Ju-ly-August-September-October (JASO) temperature anomalies and exploring future projections at subregional and country levels. From 1940 to 2023, JASO air and ocean temperature anomalies showed significant increases. Projections indicate that even under optimistic scenario 4.5, temperatures may exceed the +1.5°C air threshold beyond pre-industrial levels by the 2040s and the +1.0°C ocean threshold beyond historical annual maximums by the 2030s, resulting in severe coral bleaching and mortality. Business-as-usual scenario 8.5 suggests conditions will become intolerable for coral conservation and restoration by 2030, with decadal warming trends largely sur-passing historical rates, under unbearable conditions for corals. Immediate development of regional and local adaptive coral reef conservation and restoration plans, along with climate change adaptation and mitigation strategies, is essential to provide time for optimistic scenarios to materialize.