More settled science.
The media release and study abstract are below.
Marsh resilience to sea-level rise
Carbon dioxide fertilization effects may increase rates of coastal marsh soil accretion and marsh resilience to sea-level rise, according to a study. Sea-level rise endangers coastal marshes, but the rate of marsh drowning depends on rates of inorganic sediment deposition and organic soil formation, and changes to these processes under elevated carbon dioxide and climate change scenarios are poorly understood. Marco Marani and colleagues constructed a model of marsh vegetation and morphology that incorporated published observations of marsh vegetation response to elevated atmospheric carbon dioxide. The authors found that by increasing plant productivity, carbon dioxide fertilization may increase marsh resilience to an accelerating sea-level rise by increasing both above-ground soil accretion and below-ground organic soil generation. Increased below-ground productivity accelerates organic soil generation, according to the authors, and increased above-ground productivity boosts trapping of suspended inorganic sediment. In some cases, modeled increases in marsh productivity increased the threshold sea level-rise rate that could initiate marsh drowning by up to 60%. Further, the authors found that carbon dioxide fertilization effects on marshes displayed high spatial variation, suggesting that studies of point responses may be useful in elucidating some marsh processes but may fail to capture full-scale marsh responses to climate change. The results suggest that marsh ecosystems may be more resilient to sea-level rise than previously thought.