Sea Level Rising in the Lowcountry

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With the current King Tides upon us the following synopsis of Doug Marcy’s presentation on Earth Day at the Lake House is more than appropriate. Located at the Charleston NOAA office, Dr. Marcy is a national expert on sea level rise (SLR).

Island resident Dr. Barry Shedrow, our local Environmental Scientist took the time to interpret Marcy’s presentation into layman’s language and to add references for pertinent educational sites. Whether you heard the presentation or not, this easy to understand version is worth reading.

Ten indicators of global warming:

• Rising air temperatures over land and sea.
• Rising atmospheric water vapor content.
• Rising sea surface water temperatures.
• Rising ocean heat content.
• Rising sea level.
• Diminishing sea ice.
• Diminishing glaciers, ice sheets, and snow cover.
• Increasing frequency of very heavy precipitation events.
– 27% increase in southeast US (1958 to 2012).

Change in sea level is due to:

• Storm surges.
• Surface and deep sea circulation changes.
• Ocean warming (expansion of water).
• Melting of land-based glaciers and ice sheets.
• Land subsidence and tectonic displacements.
• Terrestrial water storage.

Sea level rise (SLR)

• Rising sea level trend at Charleston is 3.15 mm/yr (approx. 1 ft/century).
• SLR scenarios for Charleston in 2100 range from minor to catastrophic .
– Lowest: 0.25 m (0.82 ft) (based on extrapolation of current trend).
– Intermediate low: 0.55 m (1.81 ft) (driven by ocean warming).
– Intermediate high: 1.22 m (4.0 ft) (driven by moderate ice melt).
– Highest: 1.98 m (6.61 ft) (driven by major ice melt) .
• Greenland and East Antarctic ice sheets are greatest sources of uncertainty.

Nuisance flooding

• Has increased due to SLR, land subsidence, and loss of natural coastal barriers.
• Impacts include road closures, overwhelmed storm drainage systems and deterioration of infrastructure (i.e., roads, rail).
• Nuisance flooding is exacerbated by heavy precipitation events.
• By 2045, Charleston is projected to experience 180 tidal flooding event days/yr (vs current average of 23 tidal flooding event days/yr).

City of Charleston SLR planning strategy

• Implement systems that prevent/reduce the impacts of SLR and significant precipitation.
• Ensure public safety and community economic viability and recovery against flooding potential.

Selected Reference Documents and Web Sites:

• MyCoast: South Carolina (http://mycoast.org/sc)
Portal for SCDHEC to collect and anlyze pictures and data relating to coastal events (e.g., documenting King Tides)

• US Climate Resilience Toolkit (https://toolkit.climate.gov)
Climate Explorer lets user access map overlays of climate stressors and impacts (i.e., sea level rise and coastal flood web tools)

• SLR and Coastal Flooding Impacts Viewer (https://coast.noaa.gov/digitalcoast/tools/slr)
Allows user to visualize community-level impacts from coastal flooding or sea level rise.

• Sea Level Rise Strategy Charleston South Carolina (December 2015) (www.charleston-sc.gov/DocumentCenter/View/10089)

• Global Sea Level Rise Scenarios for the United States National Climate Assessment (December 6, 2012) http://cpo.noaa.gov/sites/cpo/Reports/2012/NOAA_SLR_r3.pdf

• Response to Climate Change (http://www.corpsclimate.us/ccaceslcurves.cfm)
USCOE site which provides a suite of web accessible tools to support climate preparedness and resilience planning and engineering design (i.e., sea-level change calculator.

• Climate Change 2013: The Physical Science Basis (www.climatechange2013.org/report/)
Document provides a comprehensive assessment of the physical science basis of climate

Author: Barry Shedrow,  SIPOA Environmental Committee

Submitted by: Jane Marvin

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