Ranking the risk of CO2 emissions from seagrass soil carbon stocks under global change threats. (January 2023)

• Record Type: Journal Article
• Authors: Dahl, Martin; McMahon, Kathryn; Lavery, Paul S.; Hamilton, Serena H.; Lovelock, Catherine E.; Serrano, Oscar
• Is Part Of: Global environmental change. Volume 78(2023)
• Publication Date: 2023-01
• Subjects: Blue carbon -- Climate change mitigation -- Anthropogenic activities -- Ecosystem service -- Policy -- Coastal management; Environmental policy -- Periodicals; Human ecology -- Periodicals; Nature -- Effect of human beings on -- Periodicals; Environment -- Periodicals; Environnement -- Politique gouvernementale -- Périodiques; Écologie humaine -- Périodiques; Homme -- Influence sur la nature -- Périodiques; Environmental policy; Human ecology; Nature -- Effect of human beings on; Periodicals; Electronic journals; 333.7
• DOI: 10.1016/j.gloenvcha.2022.102632
• Languages: English
• ISSNs: 0959-3780

Abstract

Highlights: Climate change was identified as the main threat for seagrass soil CO2 emissions. Direct threats have the highest potential risk for CO2 emissions at a local scale. Empirical data on seagrass CO2 emissions following disturbance is scarce. Ranking of threats for seagrass CO2 emissions can aid management and policy. Abstract: Seagrass meadows are natural carbon storage hotspots at risk from global change threats, and their loss can result in the remineralization of soil carbon stocks and CO2 emissions fueling climate change. Here we used expert elicitation and empirical evidence to assess the risk of CO2 emissions from seagrass soils caused by multiple human-induced, biological and climate change threats. Judgments from 41 experts were synthesized into a seagrass CO2 emission risk score based on vulnerability factors (i.e., spatial scale, frequency, magnitude, resistance and recovery) to seagrass soil organic carbon stocks. Experts perceived that climate change threats (e.g., gradual ocean warming and increased storminess) have the highest risk for CO2 emissions at global spatial scales, while direct threats (i.e., dredging and building of a marina or jetty) have the largest CO2 emission risks at local spatial scales. A review of existing peer-reviewed literature showed a scarcity of studies assessing CO2 emissions following seagrass disturbance, but the limited empirical evidence partly confirmed the opinion of experts. The literature review indicated that direct and long-term disturbances have the greatest negative impact on soil carbon stocks per unit area, highlighting that immediate management actions after disturbances to recover the seagrass canopy can significantly reduce soil CO2 emissions. We conclude that further empirical evidence assessing global change threats on the seagrass carbon sink capacity is required to aid broader uptake of seagrass into blue carbon policy frameworks. The preliminary findings from this study can be used to estimate the potential risk of CO2 emissions from seagrass habitats under threat and guide nature-based solutions for climate change mitigation.