Posted on February 19, 2024
Understanding the Impact of Sea-Level Rise on Coastal Marshes
A real-world experiment conducted along the Gulf Coast has provided important insights into the repercussions of accelerated sea-level rise on our coastal marshes. The study, involving more than 400 monitoring sites, discovered that a staggering 90% of these sites were unable to keep pace with the rate of water-level rise. The implications of this are severe, with researchers projecting that approximately 75% of wetland sites will be in deficit by 2070, leading to an increased rate of wetland loss. This study was generously funded by the U.S. Department of the Treasury through Louisiana’s Coastal Protection and Restoration Authority’s Center of Excellence Research Grants Program (RESTORE Act).
Drastic Changes in Coastal Ecosystems
The Gulf of Mexico, specifically the Louisiana coastal wetlands, experienced a coastal ecosystem change during 13 years of rapid sea-level rise. This rise is largely attributed to anthropogenic climate change. The findings of the study were alarming, with 87% of monitoring sites unable to adapt to the rising water levels. If this trend continues, it is forecasted that we could lose 75% of Louisiana’s coastal wetlands by 2070. These ecosystems are invaluable, and understanding the impacts of sea-level rise on them is crucial.
Sea Level Rise, Storm Surges, and Wetland Migration
Research in the Tampa Bay Estuary, Florida, USA, delved into the impact of sea level rise, storm surges, and wetland migration on intertidal native shell-bearing sites. The study emphasized the interactions between shell-bearing sites, sea level rise, storms, and migrating wetland habitats. Already, wetland encroachment is occurring at 247 archaeological sites within the Tampa Bay Estuary. About 100 additional archaeological sites provide topographic relief for migrating coastal wetlands in the future. The need for collaboration between archaeologists, estuary managers, and descendant communities to co-manage these sites has been suggested.
Coastal Marshes and Climate Change
A study by Tulane University revealed that coastal marshes in the U.S. Gulf Coast are experiencing an accelerated rate of sea-level rise, three times the global average, due to subsidence caused by natural and human factors. This rapid change in the structure and function of the marshes exposes them to conditions not expected until around 2070 under the most pessimistic projections of climate change. Therefore, the study calls for adaptive and flexible strategies to protect and restore coastal marshes in the face of climate change.
Sea-Level Rise, Storm Surges, and Coastal Forest Retreat
Long-term data of hydrological variables were analyzed to understand the impact of sea-level rise and storm surges on coastal forest retreat and salt marsh expansion. The research found that water content and groundwater electrical conductivity were the main variables responsible for the hydrological differences among the sites. Salinization and flooding events are threats for salt intolerant vegetation species and encourage ecological zonation and ecosystem transition.
Managing Tidal Wetlands
A study focusing on the impact of open-water conversion of tidal wetlands along the mainland coast of China revealed that between 1999 and 2019, about 53,000 ha of tidal wetlands were converted into open water. About 12% of the current tidal wetlands are significantly transitioning towards open water. A four-quadrant model was introduced in the study to guide tidal wetlands management in China.
Conclusion
Immediate action to reduce carbon emissions and meet Paris Agreement targets could significantly help to shift to a more sustainable climate trajectory, thereby reducing the rate of wetland loss. The rising sea levels pose a significant threat to our precious coastal ecosystems, and understanding the impact of these changes is the first step towards protecting these invaluable habitats.
