A catchy name and an apparently easy translation into economical terms has made Blue Carbon (BC) research an unstoppable phenomenon. The capacity of coastal BC ecosystems (CBCE) to capture and store organic carbon in sediments over hundreds or thousands of years is granting these habitats a purportedly relevant place in the context of biospheric sinks and, whether good, bad or both, in carbon trading schemes. Even though mangrove forests, tidal marshes, and seagrass meadows are already recognized in the major climate conventions and frameworks as potentially valuable contributors to climate change mitigation and adaptation, we are still a long way from having the necessary evidence to rigorously assess that potential. Major knowledge gaps are as fundamental as knowing the past and present size of these CBCEs (mapping) and their associated carbon stocks (plant biomass and soil), associated carbon fluxes (through accretion rates), conservation status, restoration potential, and vulnerability (and risk) from ongoing climate and anthropogenic pressures (e.g., global warming, eutrophication, or habitat mechanical destruction). Other key knowledge gaps challenge the very heart of the BC concept, such as whether or not to include algal forests into the BC family, quantifying and adding or not the BC-derived “off-site” stocks, resolving the controversy of a possible double accounting, or the long-standing critical debate on the role of carbonates, and the quantification of non-CO 2 GHG emissions from CBCEs. Technical challenges remain, including the lack of consensus on the application of standardized methodologies. Together with the complexity of the certification procedures and the lack of clear policies at regional, national, and international scales, these knowledge gaps pose significant barriers for BC projects to readily access the voluntary and, additionally, the regulated carbon markets. The challenges above have been identified during the first scoping meeting of the Blue Carbon group of the Joint Programming Initiative Healthy and Productive Seas and Oceans (JPI Oceans), a pan-European intergovernmental platform that increases the efficiency and impact of research and innovation for sustainably healthy and productive seas and oceans. The session welcomes contributions reporting advances which will help to close these knowledge gaps; we equally welcome contributions which challenge the actual soundness of CBCEs as relevant global carbon sinks. Contributions presenting successful or unsuccessful examples of carbon offset projects based on BC ecosystems, as well as initiatives to incorporate other ecosystem services alongside BC would be welcome. New perspectives from modern economics, marketing, or social science approaches are also welcomed. Those contributions with a special emphasis on the leitmotiv of this year’s ASLO ASM, i.e., resilience and recovery, will be prioritized.
Lead Organizer: Miguel-Ángel Mateo, Consejo Superior de Investigaciones Científicas (mateo@ceab.csic.es)
Co-organizers:
William Austin, University of St. Andrews (wena@st-andrews.ac.uk)
Grace Cott, University College Dublin (grace.cott@ucd.ie)
Paul Steven Lavery, Edith Cowan University (p.lavery@ecu.edu.au)
Presentations
08:30 AM
Recommendations for strengthening Blue Carbon research (4868)
Tutorial/Invited: Tutorial
Primary Presenter: Martin Dahl, Södertörn University (martin.dahl@sh.se)
Coastal ecosystems (i.e., mangroves, tidal marshes and seagrasses) are globally important CO2 sinks, yet they rank among the most threatened ecosystems on Earth. Extensive research over the last decade has quantified blue carbon (BC) storage across these habitats to obtain national and global estimates and evaluated the climate benefits linked to conservation and restoration actions. However, to include BC ecosystems in national inventories, nationally determined contributions or carbon-trading schemes, reproducible and holistic assessments of carbon storage and greenhouse gas (GHG) fluxes are needed. Here we identified 15 common research procedures that can be improved to strengthen BC science and suggest best practices to align BC research with policy and management. Recommendations are provided for: (1) planning and field practices, including technical (e.g. minimum sample size required for reducing uncertainties) and ethical (i.e. avoiding helicopter research) aspects; (2) analytical procedures, which include handling of coarse plant material within the soil and modelling of carbon burial rates; and (3) the interpretation and upscaling of results, e.g., that large carbon stocks do not necessarily reflect high carbon sequestration rate, and that all GHG fluxes influence the net CO2 sink capacity of BC habitats. We conclude that improved BC practices will help generate high-quality carbon credits and inventories based on credible and conservative calculations of baselines, additionality, leakage and permanence, moving us towards the uptake of large-scale BC projects.
08:45 AM
ASSESSING SAV BLUE CARBON IN THE CHESPEAKE BAY FROM HIGH RESOLUTION SATELLITE IMAGERY (6657)
Primary Presenter: Richard Zimmerman, Old Dominion University (rzimmerm@odu.edu)
Blue Carbon emphasizes the role of aquatic plants in the carbon cycle. However, the global importance of submerged aquatic vegetation (SAV) is highly uncertain, as <10% of this resource has been mapped. Satellite technology now provides daily coverage of the global coastal environment at 3 m resolution, enabling the mapping of Blue Carbon system dynamics at spatial and temporal scales not previously attainable. We employed satellite imagery from the Planet/Dove constellation to quantify the monthly dynamics of SAV Blue Carbon potential at five locations in the Chesapeake Bay ranging from the upper Bay dominated by freshwater SAV to the oceanic coastal lagoons exclusively vegetated by eelgrass (Zostera marina L.). We employed machine learning to classify the images and a physics-based model of reflectance to quantify Blue Carbon abundance. Since 2018, the SAV meadows occupying the oceanic coastal lagoons were temporally stable, supporting a mean above-ground biomass of 40 g C m-2. Meadows in the polyhaline lower Bay supported less biomass (~34 g C m-2) with a seasonal amplitude characterized by winter declines and summer re-growth. SAV meadows covered extensive mudflats in the freshwater uppermost portion of the Bay at extremely high density (>40 g C m-2) in summer but disappear almost completely during winter. Our efforts to quantify the seasonal dynamics of SAV from satellite imagery will improve the assessment of Blue Carbon in the Chesapeake Bay and provide an automated workflow environment that can be scaled to routine assessment of SAV dynamics across the globe.
09:00 AM
THE GLOBAL SEAGRASS WATCH SERVICE: BLUE CARBON ACCOUNTING THROUGH SCALABLE EARTH OBSERVATION ANALYTICS (4906)
Primary Presenter: Dimosthenis Traganos, German Aerospace Agency (DLR) (dimosthenis.traganos@dlr.de)
Blue carbon ecosystems provide globally significant yet vastly underestimated and impacted ecosystem services to humans, biodiversity and economies. Accelerating climate change, biodiversity loss, uneven levels of protection, and infancy in pertinent data and frameworks are all significantly stressing the benefits of coastal ecosystems, necessitating scalable contemporary technologies. Here, we present the novel coastal ecosystem accounting framework of the Global Seagrass Watch service. Our developed scalable framework blends modern Earth Observation advances with high-quality field data, across multi-national and multi-annual scales. We showcase the scalability and confidence of our framework through its recent applications across both tropical and temperate coastal biomes. Leveraging our framework, we nationally aggregate high-resolution analysis-ready mosaics using the open Sentinel-2 and PlanetScope image archives. These analysis-ready image pixels are transformed into seagrass extent, condition and blue carbon accounts. Our national seagrass accounts to date cover more than 76,000 km2 of extent across around 74,000 km of coastline in 28 countries and 3 seagrass bioregions. We discuss the real-world impact of our technology on climate change mitigation in a recent blueprint project for the Seychelles. We also articulate current technological challenges, respective solutions, and near-future opportunities and applications of Earth Observation for transparent and effective coastal ecosystem accounting, decision making, financing and resilience—within the 21st century.
09:15 AM
A NEXT-GENERATION HIGH-RESOLUTION GLOBAL MANGROVE CARBON MAP (7048)
Primary Presenter: Atticus Stovall, NASA Goddard Space Flight Center / University of Maryland (atticus@umd.edu)
Mangrove forests are vital components of coastal ecosystems while being one of the highest carbon density ecosystems on the planet, but global maps of mangrove carbon are either too coarse for forest management or use decades old data - limiting their applicability for climate mitigation strategies. Now, global measurements of mangroves are available from the NASA Global Ecosystem Dynamics Investigation (GEDI) LiDAR and TanDEM-X SAR instruments, enabling us to develop next-generation maps of mangrove forest structure. Here, we present the first high-resolution (~12 to 30 m) global mangrove forest carbon stock map developed by fusing LiDAR and SAR. We merge two critical datasets: [1] a GEDI-calibrated ~12 m TanDEM-X global mangrove canopy height map and [2] 4520 mangrove forest biomass field plots. By linking mangrove biomass field plots to our canopy height map, we create a global high-resolution carbon map, refining broad- and regional-scale allometric relationships between mangrove forest height and carbon storage, while accounting for uncertainty. We also independently develop GEDI predictions of mangrove carbon storage, applying them to nearly three million GEDI measurements globally. Finally, we use our global maps of mangrove forest carbon to show the sensitivity of these forests to a suite of environmental factors (e.g. stand density, temperature, salinity, etc.). This updated global map provides a more current and comprehensive understanding of mangrove carbon stocks, with direct implications for carbon accounting and mangrove habitat conservation.
09:30 AM
A SEASCAPE APPROACH TO UNDERSTAND COASTAL BLUE CARBON DYNAMICS (7140)
Primary Presenter: Martin Gullström, Södertörn University (martin.gullstrom@sh.se)
With today’s rapid decline of shallow coastal habitats and high competition for space in the coastal seascape, appropriate spatial conservation prioritization of natural carbon sinks is of vital importance for sustainable climate governance. Coastal conservation planners and decision makers therefore call for large-scale ecosystem-based management approaches to maximize the effect of the critical blue carbon ecosystem service. Typically, the discipline of landscape ecology provides an efficient spatially oriented conceptual framework to assess the influence of seascape configuration and connectivity on blue carbon sink capacity within coastal seascapes. With focus on multiscale seascape ecology concepts, we synthesized lessons learned from blue carbon research in tropical western Indian Ocean and temperate northern Europe. Insights from this research indicate that blue carbon hotspots have been identified within seascapes comprised of large continuous blue forest ecosystems (such as extensive seagrass meadows and mangroves). Strong land-to-sea gradients generate distinct patterns in blue carbon stock dynamics and source compositions. Land-use changes (urban development, deforestation, and habitat degradation) in the land-sea interface alter the supply and movement patterns of blue carbon in coastal seascapes. Our research clearly demonstrates benefits of using a seascape approach to understand coastal blue carbon dynamics and to maximize climate change mitigation capacity from natural blue forest ecosystems.
09:45 AM
Blue carbon stocks in intertidal seagrass and saltmarsh habitats of the Ria Formosa lagoon (south Portugal): accounting for spatial variability (7360)
Primary Presenter: Carmen Barrena de los Santos, Centre of Marine Sciences of Algarve (cbsantos@ualg.pt)
Tidal coastal wetlands, common home to seagrasses and salt marshes, are relevant carbon sinks due to their high capacity to sequester and store organic carbon (OC) in their sediments. Recent studies demonstrated that the spatial variability of the OC stocks and sequestration rates within the same wetland system can be significant. Some of the environmental drivers of this spatial variability remain understudied and their specific importance can be site dependent. Here we investigated the role of bed elevation, hydrodynamics (e.g., current velocity), and vegetation habitat type (salt marshes and seagrasses) on the sedimentary OC stocks at the mesotidal wetland of the Ria Formosa coastal lagoon, in South Portugal. Results showed that two vectors of spatial variation need to be considered to obtain accurate blue carbon maps: (1) the bed elevation that imposes a decrease of the hydroperiod and thus the zonation of vegetation species and habitats, and (2) the spatial variation along the channels of the lagoon, which imposes a gradient in the current flow velocity magnitude. This allowed us to create the first blue carbon map of the Ria Formosa lagoon by combining site-specific hydrodynamic datasets, wetland habitat distribution, and sediment geochemical data (OC stocks and sequestration rates) for intertidal seagrasses and saltmarshes. Our study emphasizes the importance of considering multiple environmental drivers and spatial variability for regional estimations of blue carbon stocks in wetlands.
SS093A Coastal Blue Carbon Ecosystems: Advances and Challenges
Description
Time: 8:30 AM
Date: 9/6/2023
Room: Sala Palma