Climate change is reshaping marine reef communities through long-term stressors (like ocean warming and acidification), and short-term disturbances (like heatwaves and typhoons). We used natural underwater “climate laboratories” in Japan and New Zealand to investigate how temperate reef communities respond to such pressures. We found that climate stressors fundamentally reorganise marine food web structure, which consequently dictates how they respond to- and recover from- extreme disturbance events. Persistent exposure to these stressors may result in the simplification of marine ecosystems due to losses in biodiversity, habitat complexity, and functionality. Using a novel integration of natural laboratories and disturbance experiments, my thesis captures the complexity of real reef ecosystems, providing rare insight into their vulnerability and resilience.