Effects of climate change on tidal marshes along a latitudinal gradient in California

Open-File Report 2016-1125

Prepared in cooperation with the Southwest Climate Science Center
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Public Summary

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 sea-level rise (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.

Suggested Citation

Thorne, K.M., MacDonald, G.M., Ambrose, R.F., Buffington, K.J., Freeman, C.M., Janousek, C.N., Brown, L.N., Holmquist, J.R., Guntenspergen, G.R., Powelson, K.W., Barnard, P.L., and Takekawa, J.Y., 2016, Effects of climate change on tidal marshes along a latitudinal gradient in California: U.S. Geological Survey Open-File Report 2016-1125, 75 p.,

ISSN: 2331-1258 (online)

Study Area

Table of Contents

  • Section 1—Public Summary
  • Section 2—Technical Summary
  • Section 3—Purpose and Objectives
  • Section 4—Organization and Approach
  • Section 5—Project Results
  • Section 6—Analysis and Findings
  • Section 7—Conclusions and Recommendations
  • Section 8—Outreach 
  • Acknowledgments
  • References Cited
  • Appendixes. Detailed Site-Specific Results

Additional publication details

Publication type:
Publication Subtype:
USGS Numbered Series
Effects of climate change on tidal marshes along a latitudinal gradient in California
Series title:
Open-File Report
Series number:
Year Published:
U.S. Geological Survey
Publisher location:
Reston, VA
Contributing office(s):
Western Ecological Research Center
Report: viii, 75 p.; Appendixes
United States
Online Only (Y/N):
Additional Online Files (Y/N):