The Blue Carbon Cost Tool – understanding market potential and investment requirements for high-quality coastal wetland projects

Stefanie Simpson^1*Lindsey Smart^1,2Emily Landis¹Stephanie vanLaere¹Abu SMG Kibria³Olya Albot^4,5,6Mark Beeston⁷Catherine Lovelock⁸Robert Ian Mcdonald^10,11,9Ryan P Moyer¹²Thomas Worthington¹³Tania L Maxwell¹⁴Phoebe Stewart-Sinclair¹⁵Mark Spalding^1,13

• ¹The Nature Conservancy, Arlington, United States
• ²North Carolina State, Raleigh, United States
• ³Michigan State University, East Lansing, United States
• ⁴The Nature Conservancy in Aotearo, Wellington, New Zealand
• ⁵The Nature Conservancy in Aotearoa, Wellington, New Zealand
• ⁶Victoria University of Wellington, Kelburn, New Zealand
• ⁷Conservation International, Arlington, United States
• ⁸University of Queensland, St Lucia, Australia
• ⁹The Nature Conservancy in Europe, Berlin, Germany
• ¹⁰City University of New York, New York, United States
• ¹¹Humboldt University, Berlin, Germany
• ¹²TerraCarbon LLC, Peoria, United States
• ¹³University of Cambridge, Cambridge, United Kingdom
• ¹⁴International Institute for Applied Systems Analysis, Laxenburg, Austria
• ¹⁵National Institute of Water and Atmospheric Research, Auckland, New Zealand

Blue carbon ecosystems, such as mangroves, tidal marshes, and seagrasses, are important for climate mitigation. As carbon sinks, they often exhibit higher per hectare carbon storage capacity and sequestration rates than terrestrial systems. These ecosystems provide additional benefits, including enhancing water quality, sustaining biodiversity, and maintaining coastal resilience to climate change impacts. The widespread loss of blue carbon ecosystems due to anthropogenic activities can contribute to increasing carbon emissions globally. Monetizing blue carbon through carbon credits offers an avenue to generate revenue and incentivize conservation and restoration efforts. However, limited data on project costs and carbon benefits make prioritization of blue carbon projects challenging. To address these challenges, we have developed, in collaboration with blue carbon experts, the Blue Carbon Cost Tool. This is a user-friendly interface enabling comparison of three core market project components – 1) carbon credit estimation, 2) project cost estimation, and 3) a qualitative, non-economic feasibility assessment – to assess and compare potential for blue carbon projects. Tool simulations with data available from nine countries demonstrate (a) how factors such as country, ecosystem type and project scale drive variability, (b) the need for local or project-specific data to enhance accuracy and reduce uncertainty, particularly in tidal marsh and seagrass systems, and (c) that higher price tolerance or upfront capital is needed to bridge implementation and maintenance cost gaps. The Blue Carbon Cost Tool can aid project developers and investors to better understand market opportunity and the resources needed to develop high quality blue carbon market projects.