Opportunities for coastal wetland restoration for blue carbon with co-benefits for biodiversity, coastal fisheries, and water quality

Coastal wetlands are known to sequester significant amounts of carbon dioxide, while also providing valuable ecosystem services. We assessed the economic feasibility of restoring coastal wetlands for climate change mitigation by reinstating tidal flows on floodplain, agricultural land of the Wet Tropics catchments in Queensland, Australia. We assessed whether potential carbon credits would be sufficient to incentivise conversion of the land, or whether additional ecosystem service payments would be required. We explored the co-benefits for biodiversity, fisheries, and nitrogen removal using a prioritisation approach to identify profitable restoration solutions that maximise these benefits. We identified 5,046 ha of potential restorable area that could abate 221,006 tonnes of carbon dioxide-equivalent (CO2-e) annually from carbon sequestration in vegetation and soils and avoided greenhouse gas emissions. Cost-benefit analysis over 25 years demonstrate that 3,399 ha (67%) would be profitable under conventional farm management practice using the current Australian carbon price ($13.85 per tonne CO2-e), which increased to 4,534 ha (90%) at a higher carbon price ($25 per tonne CO2-e). The profitability of coastal wetland restoration was enhanced by a higher carbon price, which can be achieved by bundling ecosystem services, or through stacking ecosystem service payments. Prioritising restoration sites by cost-effectiveness and co-benefits can achieve multiple ecosystem services for a substantial profit.