Natural and engineered systems have long been used effectively to manage precipitation and wastewater safely , and maintaining and enhancing them is a key nature-based adaptation strategy for coastal communities . Estimated values of water purification and stormwater management provided by coastal ecosystems are in the hundreds to thousands of USD per hectare ; 1100-2800 USD per 0.01 km2 yr-1 from the state of Maryland, USA ; 600 USD per 0.01 km2 yr-1 in Zhuzhou City, China ]. Both wild and cultured organisms also provide filtration services. Seagrasses' ability to purify water is well recognised by coastal residents and ocean resource users in tropical and temperate locations . Globally, aquacultured shellfish remove an estimated 49,000 tonnes of nitrogen and 6000 tonnes of phosphorus from coastal waters, worth a potential 1.20 billion USD, and they may help improve existing engineered wastewater treatment systems . Climate change, especially episodic extreme rains and RSLR , is challenging management and design of wastewater and stormwater systems   and the integrity of coastal landfills . Without substantial adaptation that addresses projected wastewater management challenges and community needs , coastal water quality in many areas will decrease because of more frequent or severe releases of untreated wastes  , and this will have harmful consequences for human and
IPCC
Climate Change 2022: Impacts, Adaptation and Vulnerability
IPCC Report