Assessing the potential long-term effects of sea-level rise on salt marsh’s coastal protective capacity under different climate pathway scenarios
Salt marsh modeling shows sea‑level rise will drive major shifts in marsh extent, with some areas gaining marsh and others losing up to 75%. As marsh loss accelerates after 2050, wave heights increase, reducing storm‑protection benefits. These results help guide climate adaptation and environmental policy.
Subject Tags
- Coastal
- Climate mitigation
- Wetlands
Abstract
Salt marshes act as natural barriers that reduce wave energy during storm events and help protect coastal communities located in low-lying areas. This ecosystem can be an important asset for climate adaptation due to its particular capability of vertically accrete to adjust to long-term changes in water levels. Therefore, understanding marsh protection benefits thresholds in the face of sea-level rise (SLR) is important for planning future climate adaptation. In this context, the main goal of this manuscript is to examine how the storm protection benefits provided by salt marshes might evolve under SLR projections with different probability levels and emission pathways. In this study, a modeling framework that employs marsh migration predictions from the Sea Level Affecting Marshes Model (SLAMM) as parameterization into a hydrodynamic and wave model (ADCIRC + SWAN) was utilized to explicitly represent wave attenuation by vegetation under storm surge conditions. SLAMM predictions indicate that the SLR scenario, a combination of probability level and emission pathways, plays a substantial role in determining future marsh migration or marsh area loss. For example, results based on the 50% probability, stabilized emissions scenario show an increase of 45% in the marsh area on Maryland’s Lower Eastern Shore by 2100, whereas Dorchester County alone could experience a 75% reduction in total salt marsh areas by 2100 under the 1% probability, growing emissions scenario. ADCIRC + SWAN results using SLAMM land cover and elevation outputs indicate that distinct temporal thresholds emerge where marsh extent sharply decreases and wave heights increase, especially after 2050, and exacerbates further after 2080. These findings can be utilized for guiding environmental policies and to aid informed decisions and actions in response to SLR-driven environmental changes.
Citation
de Souza de Lima, A., Cassalho, F., Miesse, T.W., Henke, M., Canick, M.R. and Ferreira, C.M., 2024. Assessing the potential long-term effects of sea-level rise on salt marsh’s coastal protective capacity under different climate pathway scenarios. Environmental Monitoring and Assessment, 196(9), p.817. https://doi.org/10.1007/s10661-024-12961-z
TNC Authors
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Michelle R. Canick
Director of Conservation Systems, Maryland & DC
The Nature Conservancy
Email: mcanick@tnc.org