Key points

Arctic wetlands are especially susceptible to damage from climate warming impacts, including permafrost melting, erosion and storm surges; subarctic wetlands are shaped by freeze–thaw cycles and overgrazing by waterfowl; West Coast earthquakes, tsunamis and glacier surges are added stressors in subarctic marshes; temperate marshes of the mountainous West Coast are in isolated valleys, sometimes disconnected from tidal exchange; temperate East Coast marshes are extensive, but altered by farming, frequent hurricanes and ‘nor’easter’ storms; Bay of Fundy megatidal marshes sequester much carbon despite erosion by massive winter ice blocks; subtropical wetlands of Florida and Mexico have shrubby mangroves fringed by brackish water swamp cedars or desert palms and cactus scrub; microtidal Mississippi Delta marshes include floating vegetation islands; tropical mangroves have a high diversity of tall trees and shrubs, particularly in Central America.

The Arctic is warming faster than any other region on Earth, bringing dramatic reductions in sea ice extent, altered weather, and thawing permafrost. Implications of these changes include rapid coastal erosion. . . and unpredictable impacts on subsistence activities and critical social needs.