Redefining blue carbon with adaptive valuation for global policy

Abstract

Blue carbon has multiple definitions but is mostly defined, by criteria, as specific habitats or species: seagrass, saltmarsh, and mangrove. These qualifying criteria include significant capacity of carbon, long-term storage of carbon, feasibility of conservation to support carbon sequestration, and other criteria depending on the definition used. If ‘blue carbon’ habitats and species may change given new data, however, blue carbon will never fit a constant definition. As such, this approach underpins uncertainty in the blue carbon definition and impedes policy integration; policy frameworks require clear and unambiguous definitions.Global policy considers blue carbon for climate change mitigation through carbon trading. As such, the requirements for blue carbon inclusion in policy mechanisms are functionally determined by carbon trading verification agencies - Standard Setting Organisations (SSOs). In practice then, accreditation criteria override and make redundant the conditions used in criteria-based definitions of blue carbon. The definition of blue carbon would therefore be more effective in policy if simply aligned to the SSO's five criteria: an established baseline, additionality, permanence, leakage, and co-benefits.This paper presents a redefinition of blue carbon that is better aligned to policy application, accreditation criteria, and research agendas:•Blue carbon – all forms of marine, intertidal, and estuarine carbon.This may include sedimentary stocks in addition to carbon stored in living biomass, which may be essential to protecting or maintaining sedimentary stocks of carbon, and with potential to be increased through protection and/or restoration. Alongside other recommendations, including a novel approach for adaptive accreditation and valuation, this paper explores how this redefinition of blue carbon would work in practice to support climate change mitigation, climate change adaptation, and biodiversity conservation.