Most U.S. coastal wetlands are slowly disappearing underwater
A new national assessment reveals that 84 percent of U.S. coastal wetlands are currently inundating due to rising sea levels. While most wetlands are gaining elevation, only 16 percent are doing so fast enough to keep pace with the accelerating rate of water rise.
Why it matters
Coastal wetlands are critical for storm surge protection and biodiversity; their loss threatens infrastructure and environmental stability along the U.S. coastline.
Salt marshes and mangroves rim the three coasts of the contiguous United States. They are losing a slow race: sea levels are climbing, and coastal wetlands are drowning under the tide.
That race reaches well beyond the marsh. Wetlands blunt storm surge, shield roads and buildings, and shelter migratory birds and endangered species.
The first national assessment has now measured how that race is going. Across the contiguous coasts, 84 percent of wetlands are inundating , and many are headed toward open water.
Wetlands survive rising seas by rising with them. Tides deliver sediment, plants add root material, and the marsh surface builds upward year after year.
The new study finds that 89 percent of American coastal wetlands are still gaining elevation that way. However, only 16 percent are gaining it fast enough to outpace the water.
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