Sea Level Rise and Coastal Hazards
Washington’s climate is changing in ways that could lead to potentially profound effects on valuable infrastructure, development, and natural resources along the coast.
As global temperatures rise, the oceans warm and expand, and ice caps and glaciers melt. This causes sea levels to rise. In June 2012 the National Research Council released a report entitled Sea-Level Rise for the Coasts of California, Oregon, and Washington: Past Present, and Future. Key findings of the study include:
- Global sea level has risen about 7 inches during the 20th century and is projected to rise at a higher rate in the future.
- For the Washington, Oregon, and California coasts north of Cape Mendocino, sea level is projected to rise 24 inches over the next century. Sea level rise in this region is projected to be lower than the global average because tectonic plate movement is causing the land to rise at about 3/5 to 11/5 inches per decade.
- An earthquake magnitude 8 or greater along the Cascadia Subduction Zone would suddenly raise sea level along parts of the coast by an additional 3-7 feet over projected levels.
|Sea Level Rise Projections Relative to Year 2000|
for Washington, Oregon, and northern California
|Year ||Projection |
|2030 ||+2.6 ||-2 to +9|
|2050 ||+6.5 ||-1 to +19|
|2100 ||+24 ||+4 to +56|
- Much of the damage along the Washington coast is caused by storms — particularly from the combined effects of large waves, storm surges, and high tides during a strong El Niño. Sea-level rise will magnify the adverse impact of storm surges and high waves on the coast, and will increase the risk of coastal flooding and damage and cause increased coastal erosion and retreat of coastal cliffs, beaches, and dunes.
- Natural shoreline can provide partial protection for coastal development against sea level rise and storms.
- Impacts of sea level rise on marshes depend on local conditions. Salt marshes in areas with a high sediment supply (such as at the mouth of a major estuary) will persist in their current form.
Protecting Coastal Areas in a Changing Climate
With over 3,000 miles of marine coastline, much of Washington’s population lives, works, and thrives in coastal areas. Washington State’s Climate Change Response Strategy lays out a roadmap for state and local policymakers and planners to prepare for the risks sea level rise poses to our coastal communities, wildlife, and economy, and includes strategies to:
- Identify and map areas vulnerable to sea level rise and storm surge and help focus new investments in areas at low risk.
- Protect and restore nearshore habitat and natural processes.
- Build capacity in local communities to assess vulnerability and respond to risks by incorporating climate change considerations into land use and shoreline decisions.
- Develop tools such as a sea level rise guidebook to assist local planners.
- Consider potential climate risks and options to prevent, detect, and swiftly respond to risks in long-range programs, policies, and public investment initiatives at the state level.
Taking action now can reduce our vulnerability, ensure our investments and operations are strategic and prudent, and help keep Washington’s coastal areas vibrant and healthy under future climate conditions.
What is at risk?
Although risk levels vary by location, rising sea levels will increase the vulnerability of low-lying areas to flooding and erosion and result in losses of beaches and tidal habitats.
- Coastal communities will face increased risk of property damage to infrastructure.
- Ports, harbors and low-lying transportation networks will face increased risk of disruptions from flooding.
- Low-lying agricultural areas could be adversely affected by salt water inundation, dikes and levees will be threatened, and drainage will become more difficult.
- Beaches and nearshore areas that provide critical habitat for fish, shorebirds, shellfish, and other species could shift inland or be lost.
Sea Level Rise Science and Impacts
State and Local Adaptation Resources
- Ch. 6 Ocean and Coastlines, in Preparing for a Changing Climate: Washington State’s Integrated Climate Response Strategy, Dept. of Ecology, April 2012
Addressing Sea Level Rise in Shoreline Master Programs (pdf), Appendix A in the Shoreline Master Program Guidebook, Dept. of Ecology
- Climate Impacts Vulnerability Assessment – a report written by the WA Dept. of Transportation in fulfillment of a grant from the Federal Highway Administration (FHWA) (2011)
- Vulnerability of Major Wastewater Facilities to Flooding from Sea Level Rise, King County, WA (2008,
- Presentation - Community Update on Sea Level Rise, City of Olympia (2012)
- Technical Report - Engineered Response to Sea Level Rise, City of Olympia (2011)
- Implications of Observed Anthropogenic Changes to the Nearshore Ecosystems in Puget Sound, Puget Sound Nearshore Ecosystem Restoration Project (2011,
- Climate Change Effects and Adaptation Approaches in Marine and Coastal Ecosystems of the North Pacific Landscape Conservation Cooperative Region: A Compilation of Scientific Literature, National Wildlife Federation (2011)
- NOAA’s CAPRI project is conducting pilot climate impact assessments in four parts of the Puget Sound region of Washington State (Commencement Bay, Lower Duwamish River, Nisqually Estuary/Olympia, and Snohomish Estuary).
Coastal Climate Adaptation Resources
- Adaptation Tool Kit: Sea Level Rise and Coastal Land Use, Georgetown Climate Center (2011)
- Coastal Climate Adaptation, NOAA website
- Sea Level Rise and Coastal Flooding Impacts Viewe, NOAA website
- Incorporating Sea Level Change Scenarios at the Local Level, NOAA Coastal Services Center (2012)
- Adapting to Climate Change: A Planning Guide for State Coastal Managers, NOAA (2010)
Local Strategies for Addressing Climate Change, NOAA (2009)
- Rolling Easements Primer, U.S. EPA (2011,
- Climate Ready Estuaries, U.S. EPA website
- Synthesis of Adaptation Options for Coastal Areas, U.S. EPA Climate Ready Estuaries (2009,
- Mitigating Shoreline Erosion along Sheltered Coasts, Report Summary, National Academy of Sciences
Mapping and Visualization
- USACE’s Circular No. 2265-2-212, how to incorporate SLR in civil works programs, U.S. Army Corps of Engineers (2011, pdf)
- Final Interim Sea Level Rise Guidance Document, California Action Team Coastal and Oceans Climate Action Team Sea Level Rise Task Force (2010, pdf)
- Guidance on Incorporating Sea Level Rise: For use in the planning and development of project initiation documents, California Department of Transportation (2011, pdf)
- Sea Level Rise: Technical Guidance for Dorchester County, MD, Maryland Department of Natural Resources (2008, pdf)
- Local Land Use Response to Sea Level Rise, The Nature Conservancy (2012, pdf)
- Climate Change Adaption Guidelines for Sea Dikes and Coastal Flood Hazard Land Use, BC Ministry of Environment (2011, pdf)
- New York State Sea Level Rise Task Force Report to the Legislature (2010, pdf)