Interannual wave-driven shoreline change on the California coast

The important role of wave climate variability in driving shoreline evolution has been demonstrated recently with improved satellite-derived shoreline detection algorithms, wave buoy records, and wave reanalysis and hindcast models. While severe beach erosion with extreme El Niño waves is well documented on Pacific coastlines, less clear is the broader link between interannual wave energy and shoreline response. Here, we show half of California's interannual Landsat shoreline change is a coherent response to wave power anomalies originating from a specific central North Pacific swell generation region, which in turn is only weakly correlated with the Niño3.4 index. Positive wave power anomalies (beach narrowing) are strongly associated with El Niños, but the negative anomalies (beach widening) are not similarly tied to La Niñas. The North Pacific wave climate modulation of beach width narrowing and widening over interannual to multi-decadal time scales has implications for long-term coastal resilience planning.