Surging Seas Sea level rise analysis by Climate Central

South Carolina and the Surging Sea

Description: A vulnerability assessment with projections for sea level rise and coastal flood risk.
Date: July, 21 2014

Full PDF of Report

Executive Summary

Floods exceeding today’s historic records are likely to take place within the next 20-30 years in the Hilton Head and Myrtle Beach areas, about 3.5 feet above the local high tide line, under mid-range sea level rise projections. Low-range projections lead to an at least 50 percent chance of extreme floods exceeding 4 feet above the high tide line within roughly half a century, at sites across the state. Under high-range projections, there is an at least 50 percent chance of floods above 9 feet by end of century.

More than 800 square miles of land lie less than 4 feet above the high tide line in South Carolina. Some $24 billion in property value, and 54,000 homes – mostly in Charleston and Beaufort Counties – sit on this area. More than 1 in 6 homes are threatened in the city of Charleston, more than 1 in 4 on Hilton Head Island, and more than 1 in 2 on Edisto Island and in Folly Beach. Totals jump to some $60 billion and 174,000 homes on 1,400 square miles of land under 9 feet.

The state has more than 1,200 miles of road on land below 4 feet, plus 13 schools; 33 houses of worship; and 76 EPA-listed sites such as hazardous waste dumps and sewage plants. At 9 feet, these numbers grow to nearly 4,000 miles of road, plus 60 schools, 171 houses of worship, and more than 200 EPA-listed sites. More than 40 percent of the land and road miles on Parris Island, the century-old major national Marine Corps training center, lie below 4 feet.

Sea levels are rising at an accelerating rate, and the scientific community is confident that global warming is the most important cause. Higher sea levels translate to more and higher coastal floods. To forecast future risk, this analysis integrates historic local sea level trends and flood statistics with global sea level rise scenarios, developed by a multi-agency federal task force led by NOAA in support of the recent U.S. National Climate Assessment.

This report is being released as a high-level summary of findings and methods, coincident with the online launch of a Surging Seas Risk Finder tool for the state, providing much more detailed and localized findings, and accessible via http://sealevel.climatecentral.org/ssrf/south-carolina.

The tool includes:

  • Interactive local projections of sea level rise and increasing coastal flood risk from 1-10 feet by decade;
     
  • A zooming, zip-searchable map of low-lying areas threatened, plus layers showing social vulnerability, population density and property value;
     
  • Detailed assessments of populations, property, infrastructure and contamination sources exposed, for each implicated county, city, town, zip code, planning district, legislative district and more;
     
  • State- and county-wide heat maps facilitating high-level vulnerability comparisons; and
     
  • Brief customized “fast look” reports that integrate key findings from across all analyses for each locality, and provide interpretation and context.
     

Detailed knowledge of vulnerability is a critical tool for communities seeking to build resiliency to the climate challenges of today and the future.