Mangrove Areas in the United States Likely to Be Submerged by Projected Sea Level Rise: Declines in Areal Extent, Carbon Sequestration, And Ecosystem Services

Sea level rise (SLR) threatens coastal ecosystems, which are critical for sequestering carbon (C), providing habitat, and reducing storm surge. Mangrove forests are particularly efficient in C sequestration and host a variety of dependent species. Using United States (U.S.) National Oceanic Atmospheric Administration data, we estimated future mangrove inundation from SLR at 0.3, 0.61, and 3.0 m in the U.S. By 3.0 m of SLR (around the middle of next century), we estimate mangrove area loss to be almost half of current areas, or 47.4% of the approximately 266.7 thousand ha currently present. To estimate C sequestration and ecosystem service loss, we compared scenarios where inundated mangrove areas convert to saltmarsh vs open ocean. We estimate sequestration loss to be approximately 30–199 thousand metric tons C y–1 from 3.0 m of SLR. Combined with decreases in other ecosystem services, this represents an annual loss of $5.8 billion (in USD and Int$) per meter of SLR. Migration poleward, although unlikely in areas with coastal development, may reduce some impacts in select locations. Overall, we conclude mangrove areas and their accompanying ecosystem services are likely to be greatly reduced by SLR in the future.