SW-NCA-color-FINALweb

180 assessment of climate change in the southwest united statesFigure 9.6 Coastal impacts of ocean acidification. This image depicts the aragonite saturationdepth on the continental shelf of western North America; warmer colors indicate shallower depths.Aragonite is one of the two most common forms of calcium carbonate, which forms naturally in almostall mollusk shells. Below this depth, it becomes difficult for mollusks and other species to precipitatethe calcium carbonate necessary to make shell material. Corrosive waters––those that begin to dissolvecalcium carbonate––now occur at shallower depths than in the past because the ocean is absorbingincreasing amounts of CO 2from the atmosphere. Note that in transect 5, corrosive water reaches theocean surface north of Eureka and Arcata, California. Modified from Feely et al. (2008), reprinted withpermission from the American Association for the Advancement of Science.erosion (see also sections below and Chapter 14 [for more on transportation infrastructure]and Chapter 12 [for more on power plants and energy infrastructure]). Sea-levelrise will expand the areas at risk from flooding, accelerate erosion of coastal bluffs anddunes, and, as discussed earlier, permanently inundate large areas of coastal wetlands(Heberger et al. 2009; Revell et al. 2012). Table 9.2 shows some of the current and futurevulnerabilities to both flooding and erosion related to increased exposure of the coastalbluff base to expected rise in sea level of 4.6 feet (1.4-meters) by 2100 with no additionaldevelopment along the coast beyond what existed in 2000 (Revell et al. 2012). In addition,based on a methodology that correlates bluff erosion with increased frequency ofexposure to wave attack, erosion could claim as much as nearly 9,000 acres of dunes and17,000 acres of coastal bluffs from the open ocean coast between the California-Oregonborder and Santa Barbara County (Revell et al. 2012).