The coastal region of California supports a wealth of ecosystem services including habitat provision for
wildlife and fisheries. Tidal marshes, mudflats, and shallow bays within coastal estuaries link marine,
freshwater and terrestrial habitats, and provide economic and recreational benefits to local communities.
Climate change effects such as sealevelrise (SLR) are altering these habitats, but we know little about
how these areas will change over the next 50–100 years. Our study examined the projected effects of three
recent SLR scenarios produced for the West Coast of North America on tidal marshes in California. We
compiled physical and biological data, including coastal topography, tidal inundation, plant composition,
and sediment accretion to project how SLR may alter these ecosystems in the future. The goal of our
research was to provide results that support coastal management and conservation efforts across
California. Under a low SLR scenario, all study sites remained vegetated tidal wetlands, with most sites
showing little elevation and vegetation change relative to sea level. At most sites, mid SLR projections led
to increases in low marsh habitat at the expense of middle and high marsh habitat. Marshes at Morro Bay
and Tijuana River Estuary were the most vulnerable to mid SLR with many areas becoming intertidal
mudflat. Under a high SLR scenario, most sites were projected to lose vegetated habitat, eventually
converting to intertidal mudflats. Our results suggest that California marshes are vulnerable to major
habitat shifts under mid or high rates of SLR, especially in the latter part of the century. Loss of vegetated
tidal marshes in California due to SLR is expected to impact ecosystem services that are dependent on
coastal wetlands such as wildlife habitat, carbon sequestration, improved water quality, and coastal
protection from storms.
