The costs and motivations of blue carbon ecosystem restoration in Australia

Restoration of blue carbon ecosystems (BCE), such as mangroves, seagrasses and saltmarshes has the potential to support climate mitigation, adaptation and biodiversity conservation. Yet, restoration efforts remain small-scale, costly and underfunded, while limited information on restoration costs, funding sources and barriers constrains coastal management decisions on restoration planning, investment and implementation. Our study provides practitioner-reported evidence on the costs, funding sources, motivations and barriers associated with BCE restoration in Australia. We covered 29 projects implemented between 1999 and 2025, encompassing 12 seagrass, 6 saltmarsh, 6 mangrove, 4 multi-habitat, and one coastal wetland project implemented across Australia. Funding information was available for 13 of the 29 projects. Together these represented AUD 5,339,693, or a mean of AUD 410,746 ± 588,697 (SD) per project. Funding was sourced primarily from the government (n = 11), followed by private investment (n = 3) and philanthropic donations (n = 1). Seagrass projects were associated with the highest costs, whereas saltmarsh interventions generally required less investment. Implementation accounted for the largest share of seagrass budgets, while monitoring represented the largest share for saltmarsh projects. While carbon sequestration was consistently identified as a motivation of blue carbon ecosystem restoration, there was some variation between habitat types. Governance (e.g. permitting), technical and economic constraints were the key barriers to BCE restoration. These findings provide a baseline for planning and financing BCE restoration, and highlight the need for streamlined permitting, dedicated funding for long-term monitoring and standardised cost reporting.