An assessment of the suitability of current evidence on European wild seaweed ecosystems for blue carbon accounting.

Authors

Ana Julieth Calderón Márquez, Beatrice Smyth, Dan A Smale, Michele Stanley, Pamela Walsh

Published in

Annals of botany. Aug 17, 2026. Epub Aug 17, 2026.

Abstract

Blue carbon has become an important component of climate mitigation policy, integrating selected coastal ecosystems into greenhouse gas accounting frameworks. With their high productivity and large spatial extent, seaweed ecosystems have recently entered this debate, particularly in Europe where interest in seaweed-based climate strategies is expanding. However, it remains uncertain whether the evidence currently available for wild seaweed ecosystems meets the standards required for inclusion in formal blue carbon accounting.
This review systematically assesses empirical evidence from European wild seaweed ecosystems. Sixteen empirical studies were evaluated using a structured classification framework based on three accounting-relevant pillars: permanence, defined as carbon storage exceeding 100 years; the feasibility of monitoring, reporting, and verification; and demonstrable net climate benefit after accounting for losses and variability. Review and policy literature were examined to contextualise these findings.
No current wild seaweed ecosystem evidence consistently satisfied all three pillars for policy-grade accounting. Evidence for durable carbon storage was limited and highly context-specific. Monitoring approaches were generally site-based and not readily scalable to inventory-level reporting, while net climate benefit was frequently reduced or offset by greenhouse gas emissions and temporal variability. These findings highlight a mismatch between seaweed carbon dynamics, the current evidence base, and accounting requirements. The findings support a precautionary policy approach that prioritises conservation-led management of wild seaweed ecosystems. Current evidence does not yet support their inclusion in blue carbon accounting frameworks and indicates that future research should address permanence, monitoring, reporting and verification feasibility, and net climate benefit.

PMID:
42605909
Bibliographic data and abstract were imported from PubMed on 17 Aug 2026.

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