NbS Triple Win Toolkit: Economics and Finance 74 interventions. These factors impact the accuracy of cost estimates, since low growth rates and survival may require a repetition of restoration activities, and on the delivery of other ecosystem services associated with the restored habitat. In the early years of protection projects, grey infrastructure may be more effective in protecting local populations and a combination of green and grey infrastructure isoften proposed as especially cost-effective102. Where monetisation is based on damage to economic assets on the coastline, a large number of assumptions are required to value the expected damage or replacement costs required, including the probability of different types of extreme weather events and the damage that this is expected to cause with and without ecological infrastructure. Since the timing of benefits and costs are variablebased on the success of the intervention, it follows that the discount rate and carbon prices are of particularly importance. Of the NbS projects noted, the upfront costs of restoration are estimated to be much higher than ongoing maintenance and can be variable. As the benefits begin to increase, both absolutely and relative to the ongoing maintenance costs, the weighting placed on these future benefits by the discount rate impacts on the benefit cost ratios and therefore economic efficiency of the project in comparison with other interventions. Similarly, the inclusion of the carbon benefits is notedto increase the benefit-cost ratios of mangrove restoration by up tosix times (assuming a price of $25/tCO2e[USD]) 103,104. Wetland restoration Description of intervention Wetland ecosystems face numerous threats which have resulted in the ecosystem becoming severely degraded or lost entirely. The primary threats which wetland ecosystems face are climate change (shifting rainfall patterns, extreme weather events, droughts and floods), pollution, unsustainable development (i.e. habitat conversion and loss from the development of homes, industry or agriculture) and invasive species105,106. Restoring wetland ecosystems predominantly involves the manipulation of a formerly degraded wetland’s physical, chemical, hydrological or biological characteristics to return to its natural functions through the regeneration of the wetland itself107. Monetised benefits Increased sustainability and provision of timber and forest products Supports local fisheries through providing habitats for commercially important fish species Carbon sequestration, storage or carbon markets Provides coastal protection and shoreline stabilisation by decreasing the exposure to storms and flooding Supports water quality maintenance Improved water storage for domestic livestock and agricultural use