Climate-driven changes in ocean temperature, stratification, and productivity are reshaping marine ecosystems worldwide. Detecting biological responses across large spatial and temporal scales remains challenging because in situ observations are often spatially limited and discontinuous. Satellite Earth Observation provides a synoptic and long-term perspective for monitoring ecosystem variability and identifying non-linear ecological responses to environmental change. Here, we present examples from different marine regions illustrating how satellite observations reveal abrupt shifts in ocean colour, phytoplankton dynamics, fisheries, and the expansion of warm-water non-indigenous species. These examples from the demonstrate the potential of Earth Observation to detect regime shifts, assess ecosystem resilience, and provide evidence relevant to identifying marine ecosystems approaching ecological tipping points. We highlight the growing role of satellite observations in supporting ecosystem monitoring, biodiversity conservation, and climate adaptation under a rapidly changing climate.