Abstract

Climate change on the Washington coast will trigger significant physical and chemical stressors: (a) inundation of low-lying areas by high tides as sea level rises; (b) flooding of coasts during major storm events, especially near river mouths; (c) accelerated erosion of coastal bluffs; (d) shifting of beach profiles, moving the position of the Mean High Water line landward; (e) saltwater intrusion into coastal freshwater aquifers; and (f) increased ocean temperature and acidity. Similar forces will be working everywhere, but shore areas will respond differently depending upon substrate (sand versus bedrock), slope (shallow versus steep cliffs), and the surrounding conditions (exposed versus sheltered from storms).

We expect substantial impacts on coastal systems from bluff erosion, shifting beach berms, shoreline armoring, and inundation of coastal lands. Further, increased ocean temperatures and acidity will negatively impact shellfish aquaculture. As beaches adjust to sea level rise, coastal property lines and intertidal aquaculture leases will need to be carefully defined through modified property laws. We anticipate relatively minor impacts on coastal freshwater aquifers. Additional research is needed to develop a more comprehensive assessment of climate impacts on all coastal features in the state.