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Salt marshes occur globally across climatic and coastal settings, providing key linkages between terrestrial and marine ecosystems. However, salt marsh science lacks a unifying conceptual framework; consequently, historically well‐studied locations have been used as normative benchmarks. To allow for more effective comparisons across the diversity of salt marshes, we developed an integrative salt marsh conceptual framework. We review ecosystem‐relevant drivers from global to local spatial scales, integrate these multi‐scale settings into a framework, and provide guidance on applying the framework using specific variables on 11 global examples. Overall, this framework allows for appropriate comparison of study sites by accounting for global, coastal, inter‐, and intra‐system spatial settings unique to each salt marsh. We anticipate that incorporating this framework into salt marsh science will provide a mechanism to critically evaluate research questions and a foundation for effective quantitative studies that deepen our understanding of salt marsh function across spatial scales. [ABSTRACT FROM AUTHOR]

Coastal wetlands (mangrove, tidal marsh and seagrass) sustain the highest rates of carbon sequestration per unit area of all natural systems.sup.1,2, primarily because of their comparatively high productivity and preservation of organic carbon within sedimentary substrates.sup.3. Climate change and associated relative sea-level rise (RSLR) have been proposed to increase the rate of organic-carbon burial in coastal wetlands in the first half of the twenty-first century.sup.4, but these carbon-climate feedback effects have been modelled to diminish over time as wetlands are increasingly submerged and carbon stores become compromised by erosion.sup.4,5. Here we show that tidal marshes on coastlines that experienced rapid RSLR over the past few millennia (in the late Holocene, from about 4,200 years ago to the present) have on average 1.7 to 3.7 times higher soil carbon concentrations within 20 centimetres of the surface than those subject to a long period of sea-level stability. This disparity increases with depth, with soil carbon concentrations reduced by a factor of 4.9 to 9.1 at depths of 50 to 100 centimetres. We analyse the response of a wetland exposed to recent rapid RSLR following subsidence associated with pillar collapse in an underlying mine and demonstrate that the gain in carbon accumulation and elevation is proportional to the accommodation space (that is, the space available for mineral and organic material accumulation) created by RSLR. Our results suggest that coastal wetlands characteristic of tectonically stable coastlines have lower carbon storage owing to a lack of accommodation space and that carbon sequestration increases according to the vertical and lateral accommodation space.sup.6 created by RSLR. Such wetlands will provide long-term mitigating feedback effects that are relevant to global climate-carbon modelling. Wetlands exposed to rapid sea-level rise over the late Holocene contain more soil carbon than those that experienced a long period of sea-level stability., Author(s): Kerrylee Rogers [sup.1] , Jeffrey J. Kelleway [sup.2] , Neil Saintilan [sup.2] , J. Patrick Megonigal [sup.3] , Janine B. Adams [sup.4] , James R. Holmquist [sup.3] , Meng [...]

Restoration of coastal wetlands has the potential to deliver both climate change mitigation, called blue carbon, and adaptation benefits to coastal communities, as well as supporting biodiversity and providing additional ecosystem services. Valuing carbon sequestration may incentivize restoration projects; however, it requires development of rigorous methods for quantifying blue carbon sequestered during coastal wetland restoration. We describe the development of a blue carbon accounting model (BlueCAM) used within the Tidal Restoration of Blue Carbon Ecosystems Methodology Determination 2022 of the Emissions Reduction Fund (ERF), which is Australia's voluntary carbon market scheme. The new BlueCAM uses Australian data to estimate abatement from carbon and greenhouse gas sources and sinks arising from coastal wetland restoration (via tidal restoration) and aligns with the Intergovernmental Panel for Climate Change guidelines for national greenhouse gas inventories. BlueCAM includes carbon sequestered in soils and biomass and avoided emissions from alternative land uses. A conservative modeled approach was used to provide estimates of abatement (as opposed to on‐ground measurements); and in doing so, this will reduce the costs associated with monitoring and verification for ERF projects and may increase participation in blue carbon projects by Australian landholders. BlueCAM encompasses multiple climate regions and plant communities and therefore may be useful to others outside Australia seeking to value blue carbon benefits from coastal wetland restoration. [ABSTRACT FROM AUTHOR]

Human agency is seen as a critical component of adaptive capacity concerning environmental change. This capacity may entail social actor's ability to learn from past experience, and create opportunities in the present for dealing with uncertainty and change in the future. However, it also means that actors need to be able to overturn structural barriers that impede anticipatory adaptation to climate change such as lack of political leadership, power imbalances, acceptance of climate risks and willingness to act. While scholarship around questions of structural barriers is common in environmental studies literature, there is less understanding about how future thinking could help to strengthen human agency. Harnessing the temporal and projective attributes of human agency by which social actors can exert influence over the future and create solutions may comprise a promising way forward. This paper investigates how social actors understand past social and environmental change and explores how scenario planning may help actors apply their understanding of changes over time to devise policies for climate change adaptation. The paper applies this exploratory lens to an Australian coastal local government area engaged in scenario planning and adaptation pathways planning. Findings indicate that the temporality aspect of agency applied to solving complex issues and overcoming structural barriers manifests differently from an individual to a collective perspective. This means that while scenario planning and adaptation pathways planning helps with anticipatory identification and experimentation, this may not be sufficient to overturn structural barriers to adaptation in the short‐term. [ABSTRACT FROM AUTHOR]