Fig 1.
Location of NOAA tide gauges utilized in this study.
NOAA’s National Ocean Service maintains all of the 52 tide gauges along the U.S. East and Gulf coasts used in our analysis. We chose gauges with a defined flooding threshold for minor coastal flooding and those included in NOAA’s online Inundation Analysis tool.
Table 1.
Median flood events per year for the Intermediate-High scenario by region.
Fig 2.
Flood events identified by the Inundation Analysis tool (dark blue) and those with an associated Coastal Flood Advisory (light blue) for the years 2012 and 2013.
Gauges where less than two-thirds of flood events identified by the Inundation Analysis tool had corresponding Coastal Flood Advisories were excluded from further analysis. Note that 15 gauges with three or fewer flood events during the 2012–2013 evaluation period were excluded from this correlation analysis.
Fig 3.
Comparison of local sea level rise projections for 2030.
IPCC RCP scenarios (RCP 2.6, RCP 4.5, RCP 8.5) are shown in greyscale circles [28]. National Climate Assessment scenarios (Intermediate-Low, Intermediate-High, and Highest) are shown in bluescale squares ([43]; this study). RCP data represent the 50th percentile projections [28]. Note that this is a subset of our full tide gauge set, as not all gauges included in this study were analyzed by both [28] and [43].
Fig 4.
Comparison of local sea level rise projections for 2050.
IPCC RCP scenarios (RCP 2.6, RCP 4.5, RCP 8.5) are shown in greyscale circles [28]. National Climate Assessment scenarios (Intermediate-Low, Intermediate-High, and Highest) are shown in bluescale squares ([43]; this study). RCP data represent the 50th percentile projections [28]. Note that this is a subset of our full tide gauge set, as not all gauges included in this study were analyzed by both [28] and [43].
Fig 5.
Average tidal flooding events per year for three present-day baseline periods: 2001–2005, 2006–2010, and 2011–2015.
Blue bars show averages for each 5-year period, grey bars show one standard deviation.
Fig 6.
Tidal flooding events per year for all gauges observed today, and projected for 2030, and for 2045.
Numbers shown represent annual averages and are based on localized sea level rise projections using the National Climate Assessment’s Intermediate-High scenario.
Fig 7.
Flood events per year by region.
Regions are defined as follows. Northeast: ME, MA, RI, CT; Mid-Atlantic: PA, DE, NJ, NY, VA, MD; Southeast: NC, SC, GA, FL (Atlantic Coast); Gulf Coast: FL (Gulf Coast and Keys), LA, MS, TX. Bars show median values for each region. Open circles show values for each tide gauge within the region.
Fig 8.
When sea level rise turns a minor flood into a moderate flood.
Bars show the year in which a tide that would cause only a minor flood today would cause a moderate flood based on localized sea level rise projections using the Intermediate-High scenario. The two vertical lines are at 2030 and 2045, our two time horizons for analysis.
Table 2.
Current and future average annual flood frequency at all sites for the Intermediate-High scenario.
Also shown are one standard deviation of the average for each time horizon and sea level rise projections for each site [43].
Fig 9.
Average annual number of flood events today (A), in 2030 (B), and in 2045 (C). Numbers are based on localized sea level projections using the National Climate Assessment’s Intermediate-High scenario. Circle size represents the average number of flood events per year.
Table 3.
Average local sea level rise (in cm) at the gauges utilized in this study.
Fig 10.
A) Number of sites with, on average, 24 or more minor coastal flooding events per year in 2030. B) Number of sites at which a flooding event that would cause only minor flooding today would cause moderate flooding in 2045. C) Number of “newly exposed” sites. Number of sites with fewer than 5 minor flooding events per year today that have at least 24 flooding events per year in 2045 and a 10-fold increase in the number of flood events. Numbers are based on localized projections for the Intermediate-Low (IL), Intermediate-High (IH) and Highest (H) scenarios.