The expected impact of sea level rise on the coast of Washington due to climate change includes several significant challenges and changes to the coastal environment, infrastructure, ecosystems, and communities. Washington’s coastline, which includes both the Pacific Ocean and the Puget Sound, is diverse, featuring urban areas, ports, tribal lands, natural reserves, and agricultural lands. The impacts of sea level rise are varied across these areas but generally include:

1. Increased Flooding and Erosion: Rising sea levels will lead to more frequent and severe coastal flooding, especially during storm surges and high tides. This can exacerbate coastal erosion, threatening natural habitats, homes, businesses, and critical infrastructure close to the shoreline.
2. Habitat Loss: Important coastal habitats, such as marshes, beaches, and estuaries, are at risk from sea level rise. These ecosystems are crucial for wildlife, including migratory birds, fish, and marine mammals. As sea levels rise, these habitats may be submerged or become too saline for freshwater species, leading to loss of biodiversity and impacts on fisheries and recreation.
3. Saltwater Intrusion: Rising sea levels can lead to saltwater intrusion into freshwater aquifers, impacting drinking water supplies and agricultural lands, particularly in the Puget Sound region. This can compromise the quality of freshwater resources and affect agricultural productivity.
4. Infrastructure and Property Damage: Critical infrastructure, including roads, bridges, wastewater treatment plants, and stormwater systems, is at risk from flooding and erosion caused by sea level rise. The costs of repairing or relocating infrastructure, as well as potential property damage and loss, could be substantial.
5. Socioeconomic Impacts: Communities along the Washington coast, including vulnerable populations and indigenous tribes, may face significant socioeconomic challenges due to sea level rise. These include displacement, loss of cultural and historical sites, and economic impacts on industries reliant on coastal and marine environments, such as tourism, fishing, and shellfishing.
6. Adaptation and Mitigation Efforts: The state of Washington and local communities are actively planning for sea level rise by implementing adaptation and mitigation strategies. These include updating shoreline management plans, investing in green infrastructure to manage flood risk, restoring natural coastal habitats to act as buffers against sea level rise, and revising building codes and land use policies to reduce vulnerability.

The extent and severity of these impacts will depend on future greenhouse gas emission scenarios, with more significant impacts expected under higher emissions scenarios. Sea level rise predictions for the Washington coast vary, but projections suggest that by the end of the century, sea levels could rise by several feet, significantly altering the coastline and impacting the region’s ecology, economy, and way of life. Planning and proactive adaptation measures are critical to reducing the vulnerability of coastal communities and natural ecosystems to these expected changes.