Global seagrass carbon stock variability and potential emissions from seagrass loss

Seagrass ecosystems are recognized for their multitude of benefits to people and particular attention is being paid to their capacity to sequester and store soil carbon. There is large variability in seagrass soil organic carbon (C_org) stocks associated with plant traits and environmental conditions, making the scaled-up carbon storage and flux inferences needed to contribute to climate change mitigation highly challenging. Here, we provide estimates of carbon stocks associated with seagrass systems through analyses of a comprehensive global database including 2200+ seagrass soil cores. The median global soil C_org stock estimate is 25.2 (13.8 – 44.1) Mg C_org ha^-1 in the top 30 cm of soil, 24% lower than previous estimates. Our estimate is robust to new data addition and refines the Tier 1 soil C_org stock for places without local data. Our models of soil C_org stock correlates allow for the calculation of Tier 2 estimates by considering species traits, bioregion and geomorphic setting. We estimate that current seagrass carbon stocks at risk of degradation could emit 1,170 Tg (659 – 1757) CO₂ with a social cost of $217 billion (2020 US dollars), if no action is taken to conserve these habitats.

Presentation Preference: Oral

Primary Presenter: Johannes Krause, Florida International University (jkrause@fiu.edu)

Authors:

Johannes Krause, Florida International University  (jkrause@fiu.edu)

Clint Cameron, University of Queensland  (clintcameron1@yahoo.co.nz)

Ariane Arias-Ortiz, Universitat Autònoma de Barcelona  (ariane.arias@uab.cat)

Migueal Cifuentes-Jara, Smithsonian Environmental Research Center  (miguel.cifuentes.jara@outlook.com)

Steve Crooks, Silvestrum Climate Associates  (steve.crooks@silvestrum.com)

Martin Dahl, Södertörn University  (martin.dahl@sh.se)

Daniel Friess, Tulane University  (dfriess@tulane.edu)

Hilary Kennedy, Bangor University  (h.a.kennedy@bangor.ac.uk)

Kiah Eng Lim, National University of Singapore  (limkiaheng@gmail.com)

Catherine Lovelock, University of Queensland  (c.lovelock@uq.edu.au)

Nuria Marbà, Institut Mediterrani d’Estudis Avançats (CSIC-UIB)  (ieanmbster@gmail.com)

Karen McGlathery, University of Virginia  (kjm4k@virginia.edu)

Matthew Oreska, University of Virginia  (matthew.oreska@gmail.com)

Emily Pidgeon, Conservation International  (epidgeon@conservation.org)

Oscar Serrano, Centro de Estudios Avanzados de Blanes, Consejo Superior de Investigaciones Científicas (CEAB-CSIC)  (oserrano@ceab.csic.es)

Mathew Vanderklift, CSIRO Environment  (mat.vanderklift@csiro.au)

Lynn-Wei Wong, National University of Singapore  (wong.lynnwei@u.nus.edu)

Siti Yaakub, International Blue Carbon Institute, Conservation International  (smaryam@conservation.org)

James Fourqurean, Florida International Univeristy  (fourqure@fiu.edu)