When and where could rising seas cross thresholds for initiating wetland drowning across conterminous United States?

Recent data syntheses have clarified future relative sea-level rise exposure and sensitivity thresholds for drowning. We integrated these advances to estimate when and where rising sea levels could cross thresholds for initiating wetland drowning across the conterminous United States. We evaluated three sea-level rise thresholds for wetland drowning (4, 7, and 10 mm/yr). Our study area spans the coastal conterminous United States, which includes Washington, D.C. and 22 coastal states along the Pacific Ocean, Gulf of Mexico, and Atlantic Ocean. Within the study area, we created a grid of 168 1-degree resolution cells for data acquisition and analyses. We examined three alternative sea-level rise scenarios, the Intermediate-Low, Intermediate, and Intermediate-High relative sea-level rise scenarios identified by the most recent United States interagency sea-level rise technical report. These three scenarios correspond to 0.5, 1.0, and 1.5-m global mean sea-level rise levels by 2100, respectively. Our results show that there is much spatial variation in relative sea-level rise rates, which impacts the potential timing and extent of wetlands crossing thresholds. High rates of relative sea-level rise along wetland-rich parts of the Gulf of Mexico and Atlantic coasts highlight areas where wetlands are already drowning or could begin to drown within decades, including large wetland landscapes within the Mississippi River Delta, Greater Everglades, Chesapeake Bay, Texas, Georgia, and the Carolinas.