Warming and Sea‐Level Rise Transform Intertidal Sediment Thermal Dynamics

Abstract

Intertidal sediments are important hotspots in coastal ecology and biogeochemistry. Their function and ecology are strongly controlled by temperature, yet the impact of future climate warming and sea‐level rise (SLR) on their thermal dynamics remains unquantified. Here we simulate present‐day and future (2100) thermal dynamics of intertidal sediments under contrasting warming and SLR scenarios, using Oosterschelde (the Netherlands) as a representative model system. Although SLR‐induced losses in intertidal area will remain minor, emersion times will be strongly reduced, shifting the system's thermal regulation from air‐to water‐dominated. Combined with climate warming, this will lead to systematically higher but less variable sediment temperatures, with extreme warm events during summer intensifying in frequency (from 5% to up to 25%), duration, and spatial extent. This previously unrecognized restructuring of thermal regimes in intertidal sediments has important implications for benthic organisms and biogeochemical fluxes, constraining habitat suitability and impacting nutrient cycles in coastal zones.