Tim J. Carruthers ^1* Beaux Jones ¹ Megan K. Terrell ² Jonathan F. Scheibly ³ Brendan J. Player ⁴ Valerie A. Black ¹ Justin Ehrenwerth ¹ Patrick Biber ⁵ Rod M. Connolly ⁶ Stephen Crooks ⁷ Jason P. Curole ¹ Kelly M. Darnell ⁵ Alyssa Dausman ¹ Allison L. DeJong ¹ Shawn M. Doyle ¹ Christopher R. Esposito ¹ Daniel Friess ⁸ James W. Fourqurean ⁹ Ioannis Y. Georgiou ¹ Gabriel D. Grimsditch ¹⁰ Songjie He ¹¹ Eva R. Hillman ¹² Guerry O. Holm ¹³ Jennifer Howard ¹⁴ Hoonshin Jung ¹ Stacy Jupiter ¹⁵ Erin Kiskaddon ¹ Ken W. Krauss ¹⁶ Paul S. Lavery ¹⁷ Bingqing Liu ¹⁸ Catherine Lovelock ¹⁹ Sarah K. Mack ²⁰ Peter I. Macreadie ²¹ Karen McGlathery ²² J P. Megonigal ²³ Brian J. Roberts ²⁴ Scott Settelmyer ²⁵ Lorie Staver ²⁶ Hilary J. Stevens ²⁷ Ariana Sutton-Grier ²⁸ Jorge A. Villa ¹⁸ John R. White ¹¹ Michelle Waycott ²⁹

• ¹ The Water Institute of the Gulf, Baton Rouge, United States
• ² Plauché and Carr, LLP, Baton Rouge, United States
• ³ Stantec, 3052 Beaumont Centre Cir, Lexington, United States
• ⁴ Stantec, 150 Riverside Manor Blvd Suite 301, Fredericksburg, United States
• ⁵ School of Ocean Science and Engineering and Gulf Coast Research Laboratory, The University of Southern Mississippi, Ocean Springs, United States
• ⁶ Coastal and Marine Research Centre, Australian Rivers Institute, School of Environment and Science, Griffith University, Gold Coast, Queensland, Australia
• ⁷ Silvestrum Climate Associates, Sausalito, United States
• ⁸ Department of Earth and Environmental Sciences, School of Science and Engineering, Tulane University, New Orleans, Louisiana, United States
• ⁹ Department of Biological Sciences, College of Arts, Sciences and Education, Florida International University, Miami, Florida, United States
• ¹⁰ United Nations Environment Programme (Kenya), Nairobi, Kenya
• ¹¹ Department of Oceanography and Coastal Sciences, College of the Coast and Environment, Louisiana State University, Baton Rouge, Louisiana, United States
• ¹² Department of Biological Sciences, Southeastern Louisiana University, Hammond, LA 70402 and Science Program, Pontchartrain Conservancy, Metairie, United States
• ¹³ Jacobs Engineering, New York, United States
• ¹⁴ Conservation International, Arlington, Virginia, United States
• ¹⁵ Wildlife Conservation Society, Global Marine Program, Bronx, New York, United States
• ¹⁶ U.S. Geological Survey, Wetland and Aquatic Research Center, Lafayette, Louisiana, United States
• ¹⁷ School of Science and Centre for Marine Ecosystems Research, Edith Cowan University, Joondalup, Australia
• ¹⁸ University of Louisiana at Lafayette, Lafayette, Louisiana, United States
• ¹⁹ School of Biological Sciences, Faculty of Science, The University of Queensland, Brisbane, Queensland, Australia
• ²⁰ Tierra Resources LLC, Lafitte, United States
• ²¹ Biosciences and Food Technology Discipline, School of Science, RMIT University, Melbourne, Australia
• ²² Department of Environment Sciences, Univesity of Virginia, Charlottesville, Virginia, United States
• ²³ Smithsonian Environmental Research Center (SI), Edgewater, Maryland, United States
• ²⁴ Louisiana Universities Marine Consortium, Chauvin, Louisiana, United States
• ²⁵ TerraCarbon, Peoria, United States
• ²⁶ Laboratory of Horn Point, Center for Environmental Science, University of Maryland, College Park, Cambridge, United States
• ²⁷ Restore America's Estuaries, Arlington, United States
• ²⁸ United States Geological Survey (USGS), United States Department of the Interior, Reston, Virginia, United States
• ²⁹ School of Biological Sciences, Faculty of Sciences, Engineering and Technology, University of Adelaide, Adelaide, South Australia, Australia

One of the world's largest 'blue carbon' ecosystems, Louisiana's tidal wetlands on the US Gulf of Mexico coast, is rapidly being lost. Louisiana's strong legal, regulatory, and monitoring framework, developed for one of the world's largest tidal wetland systems, provides an opportunity for a programmatic approach to blue carbon accreditation to support restoration of these ecologically and economically important tidal wetlands. Louisiana's coastal wetlands span ~1.4 million ha and accumulate 5.5-7.3 Tg yr -1 of blue carbon (organic carbon), ~6-8% of tidal marsh blue carbon accumulation globally. Louisiana has a favorable governance framework to advance blue carbon accreditation, due to centralized restoration planning, long term coastal monitoring, and strong legal and regulatory frameworks around carbon. Restoration efforts, planned through Louisiana's Coastal Master Plan, over 50 years are projected to create, or avoid loss of, greater than 200,000 ha of wetland. Current restoration funding, primarily from Deepwater Horizon oil spill settlements, will be fully committed by the early 2030s and additional funding sources are required. Existing accreditation methodologies have not been successfully applied to coastal Louisiana's ecosystem restoration approaches or herbaceous tidal wetland types. Achieving financial viability of accreditation of these restoration and wetland types will require updates to existing blue carbon crediting methodologies, or additional methodologies (and/or standards) but is technically feasible. This study identified twenty targeted knowledge needs to address data and knowledge gaps to maximize financial viability of blue carbon accreditation of Louisiana's tidal wetlands. Knowledge needs were identified in five categories: legislative and policy, accreditation methodologies and standards, soil carbon flux, methane flux, and lateral carbon flux. Due to the large spatial scale and diversity of tidal wetlands, it is expected that progress in coastal Louisiana has high potential to be generalized to similar wetland ecosystems across the northern Gulf of Mexico and globally.