To what extent is coastal wetland biodiversity endangered by climate change? How can we boost the resilience of coastal ecosystems?

Global projections indicate that between 20% and 90% of current coastal wetland areas may be lost due to sea-level rise (SLR), depending on the severity of the scenario. Warming, acidification and other global change stressors such as eutrophication also show negative impacts on coastal wetlands. Such a scenario poses a dramatic threat to biodiversity, particularly in deltas and estuaries, which are vital for the conservation of coastal species and ecosystem functions. This paper summarizes the main impacts of climate change on coastal wetland biodiversity, with focus on vegetation, birds and fish. Management options to cope with climate change impacts are also summarized. Many coastal wetlands are already undergoing degradation or disappearing due to the combined impacts of climate change and other global drivers, including SLR, subsidence, sediment deficits, coastal erosion, and salt stress. Coastal squeeze, the restriction of natural habitat migration due to human infrastructure and natural constraints, also threatens these ecosystems. Enhancing the resilience of coastal wetlands involves improving hydrological connectivity, increasing sediment inputs, boosting wetland plant productivity, and allowing space for natural coastal processes. However, these efforts are highly dependent on active conservation, management and restoration policies. The future of coastal wetland biodiversity will vary significantly based on the climate scenarios that unfold, and the policies implemented. Highlights • Coastal wetland biodiversity has severely declined due to habitat loss and other aspects of global change. Remaining wetlands are endangered by climate change impacts such as sea level rise. • Salt marshes are the most endangered coastal wetlands in Europe, along with their associated flora and fauna. The Mediterranean coast may lose up to 90% of those habitats by the end of the 21 st century due to sea level rise. • Boosting coastal wetland resilience is critical to avoid biodiversity loss. To do this requires increasing the pace and scale of coastal wetland restoration, and enhancing the ecogeomorphic dynamics through the increase of hydrological connectivity and the supply of sediments to the coasts.