Influence of El Nino-Southern Oscillation (ENSO) events on the evolution of central California's shoreline

Significant sea-cliff erosion and storm damage occurred along the central c oast of California during the 1982-1983 and 1997-1998 El Nino winters. This generated interest among scientists and land-use planners in how historic El Nino-Southern Oscillation (ENSO) winters have affected the coastal clima te of central California. A relative ENSO intensity index based on oceanogr aphic and meteorologic data defines the timing and magnitude of ENSO events over the past century. The index suggests that five higher intensity (rela tive values 4-6) and 17 lower intensity (relative values 1-3) ENSO events t ook place between 1910 and 1995, The ENSO intensity index correlates with f luctuations in the time series of cyclone activity, precipitation, detrende d sea level, wave height, sea-surface temperature, and sea-level barometric pressure. Wave height, sea level, and precipitation, which are the primary external forcing parameters in sea-cliff erosion, increase nonlinearly wit h increasing relative ENSO event intensity The number of storms that caused coastal erosion or storm damage and the historic occurrence of large-scale sea-cliff erosion along the central coast also increase nonlinearly with i ncreasing relative event intensity. These correlations and the frequency di stribution of relative ENSO event intensities indicate that moderate- to hi gh-intensity ENSO events cause the most sea-cliff erosion and shoreline rec ession over the course of a century.