Future risks to coastal wetlands under climate change: A case study from Victoria, Australia

Despite Australia being globally recognised for its extensive coastal wetland distribution, its blue carbon ecosystems are increasingly at risk from climate and anthropogenic stressors. Without proactive management, these pressures could accelerate ecosystem degradation and loss. Yet, regionally focused, spatially explicit assessments of cumulative stressors remain scarce, limiting the development of data-driven strategies for effective conservation and management. This study quantifies the cumulative impact experienced by mangrove and saltmarsh ecosystems due to six stressors: temperature, rainfall, inundation depth, salinity, coastal erosion, and land use, under present and future scenarios (SSP2-2090, SSP5-2090) using the state of Victoria, Australia, as a case study. Using regional datasets, we classify the degree of stressor impact (low, medium, high) based on ecosystem-specific thresholds derived from literature and combine these using an equal-weight approach to estimate cumulative impact levels. Our findings suggest that both mangroves (∼98%) and saltmarshes (∼86%) are predominantly under medium cumulative impact across all scenarios. Projected future scenarios show minimal changes in mangrove impact distribution relative to present conditions, while saltmarshes exhibit marked shifts under SSP5-2090, with high-impact zone expanding up to 6.8% (∼1742 ha) indicating higher exposure to combined stressors. Regionally, ecosystems in Corner Inlet and Western Port Bay remain relatively stable, whereas Gippsland Lakes show notable escalation in stress, underscoring site-specific management priorities. The cumulative impact maps presented here highlight areas of heightened risk, providing a foundation for prioritizing future conservation and restoration actions that enhance ecosystem resilience under changing climate and land use conditions.