Sea level rise threatens plant life in estuaries and salt marshes

Rising sea level is among the many effects of global climate change. Familiar dangerous consequences include increased flooding and damage from tropical storms.

Yet, rising sea level can also upend plant life in estuaries and salt marshes due to increasing salinity, as salty ocean water floods farther inland and up tidal estuaries. The US Fish and Wildlife Service has released an online tool, developed by scientist Chris Craft and colleagues, simulating how sea level rise could affect coastlines and marshes in locations from the Chesapeake Bay area, south to Georgia and in the Pacific Northwest.  Marshes may be able to migrate inland to keep pace with sea level rise and changing salinity, but they may also encounter obstacles such as hills, or roads or other development. Estuaries and marshes support ocean life and seafood supply, and provide other functions such as waste treatment and storm buffering.[[Craft, C., J. Clough, J. Ehman, S. Joye, R. Park, S. Pennings, H. Guo, and M. Machmuller. “Forecasting the effects of accelerated sea-level rise on tidal marsh ecosystem services.” (Abstract) Frontiers in Ecology and the Environment 7(2) (2009): 73-78.]]

Salinity effects also extend to trees. Increasing salinity in estuaries can make marsh soil saltier. Trees have to work harder to pull water out of salty soil; as a result, their growth can be stunted — and if the soil is salty enough, they will die, a common sign of sea level rise.[[Intergovernmental Panel on Climate Change. “Regional Impacts of Climate Change,” Section, November 2000.]] Even trees that are especially suited to salty soil can’t survive repeated flooding by seawater.[[Perry, L., and K. Williams, “Effects of salinity and flooding on seedlings of cabbage palm (Sabal palmetto).” (Abstract) Oecologia 105 (1996): 428-434.]]