Is the Intensifying Wave Climate of the U.S. Pacific Northwest Increasing Flooding and Erosion Risk Faster Than Sea-Level Rise?

Abstract

The relative contributions of sea-level rise (SLR) and increasing extratropical storminess to the frequency with which waves attack coastal features is assessed with a simple total water level (TWL) model. For the coast of the U.S. Pacific Northwest over the period of wave-buoy observations (approximately 30 years), wave height (and period) increases have had a more significant role in the increased frequency of coastal flooding and erosion than has the rise in sea level. Where tectonic-induced vertical land motions are significant and coastlines are presently emergent relative to the mean sea level, increasing wave heights result in these stretches of coast being possibly submergent relative to the TWL. Although it is uncertain whether wave height increases will continue into the future, it is clear that this process could remain more important than, or at least as important as, SLR for the coming decades, and needs to be taken into account in terms of the increasing exposure of coastal communities and ecosystems to flooding and erosion.