NbS Triple Win Toolkit: Economics and Finance 75 Benefit-cost ratios and cost effectiveness evidence There was little evidence found in the case study review of thecost-effectiveness of wetland restoration, with only a handful of case studies reporting benefit-cost ratios between 1.2 and 2.4. In the global analysis, inland wetlands are considered to have large ranges between 1 and 1192, but wider literature analysing the total economic value of wetlands reports a median economic value range (USD per hectare per year) of between $145 and $374, with the majority of value residing in amenity and recreation, flood control services, recreational fishing and water filtering108. The largest areas of wetlands are in North and Latin America, but the greatest value wetlands are in Asia (53% of total economic value), likely due to the intensity of the use and dense populations relying on their services108. Finally, wetlands, whilst less expansive than forests, hold the highest carbon stocks (per unit area) and significant potential for hydrological ecosystem services70. Froma country perspective, Indonesia holds 76% of the total worldwidecost-effective potential for carbon mitigation from wetlands65. Non-monetised benefits Increased food and water security Supports climate regulation Further discussion Restoration of wetland ecosystems can include non-tidal wetlands – predominately freshwater (e.g., riverine, vernal pools) though also brackish – and tidal wetlands – predominately coastal (e.g., saltmarsh) which may be freshwater, brackish, or saline. In this consideration, mangroves/mangrove restoration and peatlands/peat restoration were treated as separate ecosystems and intervention types (see Methods). Evaluations of the cost-effectiveness of wetland restoration compared to grey or hardened infrastructure can be found throughout the literature109. They are often an ecosystem of interest as wetlands are inherently tied to human development; generally human settlements cluster around water sources for the direct services they provide in the form of water and water quality, subsistence in the form of fisheries and other food products107. Benefits from wetlands are therefore inherentlyor easily monetisable. Increasing human settlement and density especially in urban areas, however, directly threatens the benefits wetlands provide. Human settlements and assets alongside bodies of water are often at risk from increasing floods, mudslides, erosion, encroaching salinity, or sea level rise109. Wetland restoration must be planned carefully to avoid unintended negative impacts to social, cultural, or climate goals. Wetlands may provide vectors for disease from stagnant waters or zoonotic vectors (i.e., mosquitos carrying malaria) – though increases in transmission of disease has been tied to a loss of biodiversity and degraded wetlands110. Cultural and social values may lead to the perception of wetlands as dangerous ecosystems with pressure to turn land over to production or development, thereby generating high opportunity costs111,112. Wetlands can be an incredibly efficient sink for greenhouse gases (GHG) in the long-term in the form of carbon dioxide stored in soil and plant matter but in the short-term, some wetlands may be net GHG emitters through methane and nitrous oxide release113,114. These emissions can be mitigated through maintenance of soil conditions and different restoration practices115,116. If managed in keeping with ecological and biogeochemical processes healthy wetlands canprovide a range of important services and functions.