Coastal and marine ecosystems under climate change ecological and socio-environmental impacts

Coastal and marine systems are some of the most biologically productive and economically important systems on Earth, yet they are being compromised at an accelerating pace by climate change. Ocean warming, marine heatwaves, sea-level rise, ocean acidification and deoxygenation along with increasing extreme events are interacting to change the structure, function and resilience of ecosystems among coral reefs, mangroves seagrass meadows and salt marshes. Although effort has been devoted to understanding individual ecosystem effects of climatic change, we know less about comparative mechanistic synthesis and cross-ecosystem vulnerability trajectories. This synthesis explores recent understanding of the biophysical determinants of ecosystem decline, with particular reference to thresholds, regime shifts and feedbacks that limit capacity to adapt. We explore different sensitivities among these biogenic coastal systems, and explain why coral reefs are confronted with sharp thermal and carbonate chemistry thresholds, while mangroves and tidal wetlands have threshold-based resilience contingent on sediment supply and geomorphologic setting. Beyond ecological effects, we compile social–environmental responses including fishery reduction, coastal defense loss and blue carbon release, and rising human vulnerability especially in small island and developing coastal regions. The review also examines ecosystem-based adaptation and nature-based solutions, considering their co-benefits and implementation challenges in a high-emission world. By synthesizing climate drivers, ecosystem thresholds, and social–ecological tipping points within a unified conceptual framework, this review integrates mechanisms of change and alternative stable-state transitions to improve understanding of coastal ecosystem resilience under accelerating climate change.