14.12: What Have We Learned About Local Sea Level Rise?
- Page ID
- 31704
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)In the world of sea level rise—as in the world of real estate—it’s all about location, location, location (a phrase in use since at least 1926; e.g., Safire 2009). While the average global rate of sea level rise is about 0.11 inches per year (3 mm y-1), the relative sea level rise at different locations around the world varies from 0.02 to 0.5 inches per year (0.5 to 12.5 mm y-1; e.g., Brown et al. 2012). Not everywhere experiences the same degree of sea level rise.
Among the world’s 33 megacities—defined as urban regions with more than 10 million people—at least 15 occur along coastlines (e.g., Blackburn et al. 2019; Institute for Economics & Peace 2022) Moreover, these coastal megacities include lands with an elevation of less than 10 meters—the so-called Low Elevation Coastal Zone (e.g., McGranahan et al. 2007). This is the region considered most vulnerable to impacts from sea level rise. An estimated 600 million (Neumann et al. 2015) and perhaps as many as one billion people (e.g., Kulp and Strauss 2019) live in the Low Elevation Coastal Zone.
In the United States, an estimated 3.7 million people live within one meter of mean high tide and 22.9 million within six meters, all of which may be impacted by sea level rise, especially when other factors (storm surge, waves, subsidence, etc.) are considered. The US East and Gulf Coasts face the greatest risks—especially Florida, New York, New Jersey, and Louisiana—but parts of California may also be vulnerable, especially Southern California (Strauss et al. 2012).
South of Cape Mendocino (about 200 miles north of San Francisco), tectonic-driven subsidence and human activities are causing coastlines to sink at an average rate of 0.04 inches per year (1 mm y-1). Coastlines subject to sea level rise of 0.012 inches per year (3 mm y-1) will experience 0.016 inches (4 mm) of additional sea level rise annually because the land is sinking at the same time the sea is rising. Talk about a double whammy. By 2100, relative sea level rise could exceed five to six feet for much of California (National Research Council 2012). If anyone is interested in glass bottom boat tours of sunken California cities, hit me up in 2100.