How do coastal wetlands respond to the impact of sea level rise?

Abstract

Coastal wetlands have the capacity to trap and store large amounts of carbon and function as efficient blue carbon sinks—an essential nature-based approach for climate change mitigation. Owing to anthropogenic activities and sea level rise (SLR), coastal wetlands located at the land–sea interface are subject to severe deterioration, transformation, and loss. Assessing coastal wetland vulnerability to SLR serves as the foundation for developing climate change adaptation solutions and is critical for maintaining the stability and sustainability of coastal ecosystems. In this paper, we provide an overview of approaches for assessing coastal wetland vulnerability and find the following: (1) The Rod Surface Elevation Table–Marker Horizon (RSET–MH) method can provide accurate and repeatable measurements of local surface elevation changes; however, contrary to Relative Sea Level Rise (RSLR) recorded by long-term tide gauges, RSETs recording the current surface elevation changes of coastal wetlands provide short-period monitoring with uneven coverage. Hence, RSET monitoring needs to be further extended to obtain long-term broad-coverage data for more accurately assessing coastal wetland vulnerability. (2) Existing vertical accretion models for coastal wetlands account for important feedback mechanisms between SLR and sediment accretion; however, they do not account for the relationship between vertical accretion and climate change, i.e., elevated atmospheric carbon dioxide concentration. This omission may lead to a shift in the SLR threshold for the survival of coastal wetlands. (3) Human activities affect the stability of wetlands, and current studies on coastal wetland vulnerability do not consider the potential impacts of human activities on these areas, resulting in an incomplete assessment of wetland risk. Incorporating the effects of human activities into biophysical models of coastal wetland evolution is a major challenge that must be addressed.