Coastal Impacts, Adaptation, and Vulnerabilities - Climate ...

Vulnerability and Impacts on Natural Resources 533.1 Multiple Stressors Interact at the CoastClimate change-mediated impacts originating from terrestrial and marine sources interactat the coast to influence coastal habitats (Nicholls et al., 2007; Rosenzweig et al.,2007; Figure 3-1; Table 3-1). On the landward side, increased temperatures and alteredprecipitation patterns interact with changing land-use and land-cover practices to affectsoil moisture, ground water levels, hydrology, sediment supply, salinity, and pollutionin watersheds. On the marine side, sea-level rise, changing ocean currents, increasedwave heights, and intensification of coastal storms interact with changes in land use andland cover to exacerbate coastal erosion, flooding, and saltwater intrusion. As a result ofthese interactions, complex changes in coastal freshwater availability and water qualityare also occurring.Figure 3-1 Major physical climate forces that affect coastal regions either directly or indirectly throughexternal marine and terrestrial influences. Source: Nicholls et al., 2007.Coastal Freshwater Availability Threatened by Multi-stressor InteractionsClimatic changes to atmospheric conditions and sea-level rise interact to affect theavailability of fresh surface water in coastal regions. Cloern et al. (2011) used a seriesof linked models under two GCM scenarios to infer the impact of climatic changes onwater and habitat quality in the California San Francisco Bay-Delta estuary where wateris extracted for human use. Earlier and more extreme spring streamflow combined withreduced flows in the low-flow season as well as sea-level rise led to increased Delta salinity(Figure 3-2). These changes have important implications for decisions regardingwater releases, which will need to balance drinking and irrigation water quality withsupport for native fisheries that rely on specific water temperature and salinity rangesand flushing regimes.