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
03:00 PM
The European Union Joint Programming Initiative on Blue Carbon (7544)
Tutorial/Invited: Invited
Primary Presenter: Yekaterina Astafyeva, JPI-Oceans (yekaterina.astafyeva@jpi-oceans.eu)
Europe is rich in coastal blue carbon ecosystems (CBCE), i.e., ecosystems dominated by macrophytes that capture carbon dioxide and bury it in the organic form, creating massive carbon reservoirs. With a few exceptions in the EU's outermost regions and OCTs, where mangroves are present, CBCE in Europe are represented by tidal marshes and seagrass beds. Driven by the need to reduce atmospheric CO2 to mitigate global warming, efforts to study these carbon sinks and reservoirs have grown exponentially. In order to share visions, unite efforts and agree on common strategies in this field in the Union, the Joint Programming Initiative Oceans is promoting a Joint Action on Blue Carbon (BC) to provide scientific advice and evidence to support national, EU and international environmental and climate policy objectives. The BC Expert Group (involving 15 EU Member States) has already developed a consensus vision of the field and prioritised the BC issues that require urgent attention. These include (i) integrating available information on BC in the EU, (ii) intensifying efforts to map CBCE, (iii) identifying key drivers of vulnerability of CBCE, (iv) addressing key knowledge gaps in BC science, (v) exploring opportunities for policy action, and (vi) engaging decision-makers and communities in protecting and restoring their CBCE. In this presentation, we will describe in detail the JPI Oceans action and its implementation plans, which may include joint calls, fast track activities, knowledge hubs or task forces, among others.
03:15 PM
National assessment of blue carbon in Portugal (5876)
Primary Presenter: Rui Santos, Centro de Ciências do Mar, CCMAR (rosantos@ualg.pt)
As part of the Blue Carbon project of the Calouste Gulbenkian Foundation, all available information on the temporal and spatial distribution and conservation status of the main blue carbon ecosystems (BCE) in Portugal was collected, to highlight gaps to be addressed for a reliable national assessment, to provide a base line for the design and implementation of CO2 offset projects and to contribute to the putative inclusion of BCE in the national inventory of greenhouse gas emissions. A database with all variables to estimate carbon stocks and sequestration rates was created. The main conclusions are 1) the BCE area is 85% saltmarsh and 15% seagrass, 2) data to estimate carbon stocks are scarce and outdated; the national estimate of 1 026 Gg, (89% in saltmarsh, 11% in seagrass) has low precision, 3) 88 % of the saltmarsh carbon stock is in Ria Formosa and Ria of Aveiro lagoons and in Tagus Estuary, whereas 72% of the seagrass stock is in Ria Formosa, 4) Ria Formosa is the only system where sequestration rates were measured, so the national estimate of 3 745 Mg year-1 (78% saltmarsh, 22% seagrasses) is highly unreliable, 5) most BCE are under some protection figure and the ecological state of the water bodies are mostly Reasonable (49%) and Good (32%), 6) the historical loss of BCE area was estimated at 33% for saltmarshes and 9 % for seagrasses, but this is certainly underestimated as there is anecdotal historical evidence of large seagrass areas that have not been quantified. Further BCE research is necessary for sound blue carbon policy and management in Portugal
03:30 PM
Estimating the Carbon Storage Potential of Danish Saltmarshes (5104)
Primary Presenter: Carmen Leiva Dueñas, Aarhus University (carmenld92@hotmail.com)
Saltmarshes have gained recognition as blue carbon habitats with a high capacity to act as effective sinks of organic carbon (OC) and their protection and restoration helping slow down global warming. However, regional estimates of saltmarsh OC storage are often missing, including for the Nordic region. To address this knowledge gap, we assessed OC storage and accumulation rates in 17 saltmarshes distributed along the Danish coasts and investigated main drivers of sediment OC storage. Danish saltmarsh sediments store 10 kg OC m-2 (range: 5.4-36.4) in the top meter and sequester 31.5 g OC m-2 yr-1 (range: 5-142), values at the lower end of global estimates. Grazed but also older and stable saltmarshes had higher OC stocks and accumulation rates, highlighting the significance of ecosystem stability in maximizing OC potential. Saltmarsh sediments in mesohaline settings with fine grain sizes, and high proportion of eelgrass organic material showed highest OC densities, pointing to a more efficient OC preservation under these conditions. However, the dominant source of organic matter across sites was terrestrial. Scaling up, Danish saltmarsh sediments, comprising about 1% of the country's area, have the potential to capture up to 0.13 ± 0.03% of Denmark’s annual consumption-based CO2 emissions. Our research expands the baseline data needed to advance blue carbon research and management in the Nordic region but also highlights the need for a more comprehensive approach to saltmarsh management that considers the full range of benefits and services of these important ecosystems.
03:45 PM
Impact of human interventions on sediment accretion and carbon sequestration within saltmarsh ecosystems (6740)
Primary Presenter: Inés Mazarrasa, IHCantabria (mazarrasai@unican.es)
Saltmarshes can contribute to climate change mitigation and adaptation against sea level rise in coastal areas thanks to their sediment and organic carbon (Corg) accretion capacity. Yet, vast areas of estuarine saltmarshes have been totally or partially transformed during the last century due to human interventions (e.g. tidal restriction and land reclamation), leading to changes in both the community structure and the ecological functions. Within the scope of the European project LIFE ADAPTA BLUES, we retrospectively assessed the impact of tidal restriction and/or land reclamation in estuarine saltmarshes carbon sinks and soil accretion rates. We do so by examining differences in soil accumulation rates, and organic carbon sequestration rates during the last century across saltmarshes under different levels of human transformation in the north of Spain. Soil and Corg accumulation rates since 1960 across saltmarshes examined ranged from 0.09 to 0.29 cm y-1 and from 6 to 109 g Corg m-2 y-1, respectively. The results found show that tidal restriction impacted Corg storage and the capacity of saltmarshes to adapt to sea level rise by reducing between 70 and 95 % the Corg accumulation rates and between 75 and 81% the sediment accretion rates of transformed saltmarshes, compared to non-transformed ones. This study showcases the benefits of tidal reintroduction in drained estuarine settings for climate change mitigation and adaptation, while providing baseline data for the implementation of Blue Carbon restoration projects.
04:00 PM
Complexity of offsetting carbon emissions in the voluntary market by restoring tidal marshlands in Spain (6506)
Primary Presenter: Federico Cardona Pons, Iberostar Group (fede.cardona@grupoiberostar.com)
From 2015 to 2016 the European Commission co-funded the Life Blue Natura project. The project was coordinated by the regional government of Andalucía (Spain) and designed to quantify carbon deposits and sequestration rates in seagrass meadows and tidal marsh habitats in Andalucía, to analyse the evolution of these habitats in the coming decades, and to explore and promote initiatives to finance conservation and restoration projects of blue carbon habitats-sinks with policies for the mitigation of and adaptation to climate change, with specific attention being given to voluntary carbon offset markets. Thanks to the work done in the Life Blue Natura project and the committment of the Junta de Andalucía, a group of private companies decided to team up in order to restore 365 ha. of tidal marshlands in the Parque Natural Bahía de Cádiz in order to offset up to 106.367 tones of CO2 in 50 years, being the first blue carbon project in which a regional government issues carbon credits in the voluntary market in Europe. This communication refers to the negotiation process, bureaucracy, technical issues and fears faced by the private consortium willing to restore the tidal marshland and the regional government of Andalucía.
04:15 PM
CHALLENGES FOR DEMONSTRATING ADDITIONALITY IN SEAGRASS BLUE CARBON PROJECTS (6243)
Primary Presenter: Jack Robinson, Edith Cowan University (jack.robinson@ecu.edu.au)
Globally, there is an increasing effort to incorporate seagrasses into blue carbon projects through meadow conservation or restoration. Here, we assessed the return of carbon sequestration and avoided emissions linked to the restoration of Amphibolis and Posidonia meadows in South Australia. Comparisons of organic carbon (Corg) stocks among undisturbed and restored A. antarctica (0.6±0.04 and 1.2±0.4 kg Corg m-2, respectively) and P. sinuosa (1.5±0.4 and 0.5±0.3 kg Corg m-2, respectively) meadows did not clearly show a return of Corg stocks and sequestration within 10-yrs recovery. The mixing and lack of excess 210Pb radioisotopes precluded comparing stocks over the same period of accumulation, reflecting the high hydrodynamic nature of the sites. The comparison of Corg stocks between undisturbed and lost P. sinuosa meadows showed the likely erosion of 1.58 kg Corg m-2, which could have been mitigated through restoration. Overall, the inability to robustly demonstrate Corg accumulation rats or erosion, and therefore, additionality linked to enhanced sequestration and avoided emissions, poses a major barrier to the inclusion of seagrass restoration efforts in verified carbon crediting schemes. We conclude that the selection of a depositional site known to accumulate sediment will likely be key to the success of seagrass blue carbon projects. Challenges with existing approaches for retrospectively demonstrating carbon accumulation calls for new methods to be developed to robustly demonstrate carbon abatement in seagrass restoration and recovery projects for carbon crediting.
SS093C Coastal Blue Carbon Ecosystems: Advances and Challenges
Description
Time: 3:00 PM
Date: 9/6/2023
Room: Sala Palma