Lessons learned on the feasibility of coastal wetland restoration for blue carbon and co-benefits in Australia.

Diverse types of saline coastal wetlands contribute significantly to global biodiversity, carbon stocks, and ecosystem functions. Opportunities to incentivise coastal wetland restoration from carbon markets is growing across the world. However, little is known of the economic feasibility of blue carbon restoration across different regions, or the quantities of ecological and social co-benefits that accompany restoration. We explored the opportunities for tidal restoration of coastal wetlands for blue carbon projects in three regions across Australia. We identified biophysically suitable potential restoration sites for mangroves, saltmarshes and supratidal forests, estimated their carbon abatement over 25 years, and undertook a cost-benefit analysis under the carbon market. Potential co-benefits of restoration sites for biodiversity, fisheries, water quality and coastal protection were measured to identify economically feasible sites that maximise the provision of co-benefits. Cultural benefits were identified as the potential for leadership and collaboration by Traditional Custodians at sites. We found that the extent of restoration opportunities varied among regions, with variation in tidal range, extent of agricultural land-use, and the type of hydrological modifications influencing carbon abatement forecasts. The presence of threatened species in hydrologically modified wetlands reduced the amount of land available for restoration, however the restoration of remaining areas could produce rich ecological and cultural benefits. A high carbon price was needed to make blue carbon restoration profitable on land used for beef production. We found sites where carbon credits can be bundled with co-benefits to possibly attain higher carbon prices. Traditional Custodians were interested in leading blue carbon projects, however the opportunity is dependent on Native Title rights. Through comparison of case studies, we developed a regional approach to identify coastal wetland restoration sites for blue carbon and co-benefits that can incorporate local knowledge and data availability, engage with Traditional Custodians, and adapt to the unique characteristics of regions.