Presenter: Patrick Barnard (United States Geological Survey)

Description:
The interaction of accelerating sea level rise (SLR) and storms with confining coastal infrastructure over the next century will place greater stresses on physical, ecological, and human systems along the ocean-land margin. Many of these valued coastal systems could reach “tipping points,” at which hazard exposure substantially increases and threatens the present-day form, function, and viability of communities, infrastructure, and ecosystems. Determining the timing and nature of these tipping points is essential for effective climate adaptation planning. In practice the response of a given component is often analyzed in isolation, and therefore climate adaptation decisions are based on a limited understanding of the entire system. Here we assess responses of multiple components of a coastal environment to climate change from a case study in Santa Barbara, CA (USA) that integrates numerical and statistical models of the climate, ocean water levels, beach and cliff evolution, and two soft sediment ecosystems, sandy beaches and tidal wetlands. We demonstrate that degradation of key habitats of beaches and tidal wetlands occurs with just 0.25 m (~2050) of SLR or less, while the more pronounced flooding of the adjoining communities are not anticipated until SLR exceeds 0.75 m for daily flooding and 1.5 m for storm-driven flooding (~2100 or later). This research indicates assessing the tipping points of multiple components of the environment is critical for informed decision making. The interconnection of natural and human-built systems is such that the loss of natural system function could negatively impact the quality of life of residents and disrupt the local economy, resulting in indirect socioeconomic impacts long before built infrastructure is directly impacted by flooding.