1. Storminess and Extreme Coastal Water Levels: Historical Observations and Future Projections for the California Coast Patrick Barnard USGS Coastal and Marine Geology Program USGS Coastal and Marine Geology Program Pacific Coastal and Marine Science Center, Santa Cruz, CA

2. Sea Level Rise Rate of global SLR has increased by 50% over last two decadesRate of global SLR has increased by 50% over last two decades The global sea level rise signal is NOT spatially uniform due to variations in prevailing wind patterns, ocean temperature and salinity (‘steric effect’), and gravitational forcesThe global sea level rise signal is NOT spatially uniform due to variations in prevailing wind patterns, ocean temperature and salinity (‘steric effect’), and gravitational forces West Coast sea level rise has been suppressed for the last thirty years due to prevailing wind patterns in the Eastern PacificWest Coast sea level rise has been suppressed for the last thirty years due to prevailing wind patterns in the Eastern Pacific The current cold phase of the PDO may continue to suppress sea levels for a decade or moreThe current cold phase of the PDO may continue to suppress sea levels for a decade or more Bromirski et al., JGR 2011 NOAA, 2011

3. Coastal Water Level Factors for California Regional:Regional: Ocean circulation and wind patternsOcean circulation and wind patterns Storminess*Storminess* Tectonics (large-scale)Tectonics (large-scale) Local:Local: SubsidenceSubsidence Local tectonic deformationLocal tectonic deformation Fluvial discharge AND sediment supply changesFluvial discharge AND sediment supply changes Poland and Ireland, 1988 Subsidence in San Jose (1933-1969) National Research Council study (due Summer 2012) will provide guidance on West Coast SLR, including relative land movement, ocean circulation, and storminess.

4. What is an extreme storm? Difficult to defineDifficult to define Wave height/energyWave height/energy Wind speed/directionWind speed/direction Atmospheric pressureAtmospheric pressure Wave directionWave direction Storm durationStorm duration Beach stateBeach state Water levelWater level Largest waves = ~10 m (mean of the highest 1/3, 1 in 100 = ~15 m)Largest waves = ~10 m (mean of the highest 1/3, 1 in 100 = ~15 m) Elevated water levelsElevated water levels Tide level (~2 m variation)Tide level (~2 m variation) Seasonal variations (up to ~30 cm)Seasonal variations (up to ~30 cm) Surge (up to ~1 m)Surge (up to ~1 m) Wave set-up (up to ~1.7 m)Wave set-up (up to ~1.7 m) Worst case = ~5 m static water level increase on local beachesWorst case = ~5 m static water level increase on local beaches Wave run-up can add an additional 5 m!Wave run-up can add an additional 5 m! Capitola, January 2008

5. Components of Total Water Level Predictions MSL (datum) h slr H br d br beach slope tan  waves increase in height towards breaking zone (shoaling) breaker zone H decreases rapidly due to breaking swash zone hRhR h wv h wn hphp h tide sea level rise tide difference barometric set-up wind set-up wave set-up wave run-up (adapted from Frisby and Goldberg, 1981) Bolinas Lagoon Bathtub model (SLR + MHHW) Physics included (SLR + Extreme Event)

6. Historical Trends in Storminess The frequency and intensity of extreme storms in the North Pacific increased over the latter half of the 20 th centuryThe frequency and intensity of extreme storms in the North Pacific increased over the latter half of the 20 th century Trends of increased average summer, winter and extreme wave energy for much of U.S. West CoastTrends of increased average summer, winter and extreme wave energy for much of U.S. West Coast Allan and Komar, JCR 2006 Graham and Diaz, 2001

7. Changing El Niño Styles Changing El Niño Styles Two types of El NiñosTwo types of El Niños –Classic/EP-El Niño –El Niño Modoki/CP-El Niño High sea levels tempered during CP-El Niño but waves equally powerfulHigh sea levels tempered during CP-El Niño but waves equally powerful The intensity of CP-El Niños has increased over last three decades- linked to global climate changeThe intensity of CP-El Niños has increased over last three decades- linked to global climate change California had extreme beach erosion in 2009-10California had extreme beach erosion in 2009-10 Lee and McPhaden, GRL 2010 CPEP CP-El Niño Intensity EP-El Niño Intensity

8. Future Projections for the CA Coast Intergovernmental Panel on Climate Change (IPCC) recently confirmed link between climate change and frequency of extreme stormsIntergovernmental Panel on Climate Change (IPCC) recently confirmed link between climate change and frequency of extreme storms National Research Council study will provide guidance on West Coast SLRNational Research Council study will provide guidance on West Coast SLR Most recent suite of climate models show no clear trend in extreme events for the CA coastMost recent suite of climate models show no clear trend in extreme events for the CA coast

9. Assessing California’s Coastal Vulnerability to Climate Change (SLR + Storms) Process-based models that account for all aspects of future coastal water levels, especially due to extreme stormsProcess-based models that account for all aspects of future coastal water levels, especially due to extreme storms Models driven by output from the latest Climate Models, with downscaled winds and pressure fieldsModels driven by output from the latest Climate Models, with downscaled winds and pressure fields Inclusion of regional and local sea level rise factors that affect coastal vulnerabilityInclusion of regional and local sea level rise factors that affect coastal vulnerability State-wide, systematic approach to assess the impact of climate change, including sea level rise AND stormsState-wide, systematic approach to assess the impact of climate change, including sea level rise AND storms State-wide, comprehensive monitoring of waves, water levels and coastal changeState-wide, comprehensive monitoring of waves, water levels and coastal change For more information, contact Patrick Barnard: pbarnard@usgs.gov