While biodiversity is in crisis, it remains central to addressing climate and environmental challenges. The rich biological diversity in wetlands enables these ecosystems to adapt to environmental change, maintain productivity, and sustain critical services such as water purification, flood regulation, and fisheries—making wetland conservation a critical investment. As economist Partha Dasgupta notes in The Economics of Biodiversity (2021):
“Biodiversity enables nature to be productive, resilient and adaptable. Just as diversity within a portfolio of financial assets reduces risk and uncertainty, so diversity within a portfolio of natural assets increases nature’s resilience to shocks, reducing the risks to nature’s services. Reduce biodiversity, and nature and humanity suffer.”
Countries and communities are increasingly adopting NBS to restore wetland biodiversity and build natural capital. Evidence shows that NBS, while not universally applicable, can be integrated into most strategies and often deliver high benefit-to-cost ratios compared to traditional engineered approaches. The examples in Table 1 illustrate how NBS translate ecological restoration into measurable economic returns, with benefit–cost ratios exceeding those of conventional engineered alternatives. For example, mangrove restoration programs in coastal communities, particularly in Southeast Asia, have generated multiple co-benefits, including stronger natural coastal defenses, increased fish stocks, and improved local livelihoods, all at a fraction of the cost of hard infrastructure such as dikes and embankments.
The East Calcutta waste treatment wetlands also demonstrate how NBS can deliver cost-effective outcomes and multiple benefits compared to traditional hard engineering approaches. Instead of relying on a highly automated wastewater treatment plant, the system channels wastewater through approximately 4,000 hectares of fish ponds. These ponds complete most of their biochemical reactions with the help of solar energy. Beyond water treatment, the wetland provides about 150 tons of fresh vegetables daily and approximately 10,500 tons of table fish per year. This system sustains livelihoods for about 50,000 people directly and a similar number indirectly.
Table 1: Projects Adopting NBS to Restore Biodiversity
| Project | Location/s | Cost/Benefit Ration |
|---|---|---|
| Peatland Restoration | Scotland, Germany | 1:5 to 1:30 |
| Constructed Wetlands for Wastewater Treatment | PRC, India, Colombia, USA | 1:2 to 1:6 30-50% cheaper than conventional treatment plants |
| “Room for the River” restoration | Netherlands | 1:7 |
| Mangrove Restoration | Vietnam, Thailand, Philippines, USA | 1:3 to 1:15 |
| Urban Wetlands for Stormwater Management | Singapore, USA | 1:3 to 1:8 |