North Carolina Sea Level Rise Assessment Report - 2015 Update

This report responds to a charge from the North Carolina Coastal Resources Commission (CRC) specifying that sea level rise (SLR) projections be developed for a 30- year timeframe - and to the N.C. General Assembly Session Law 2012-202 (which prevented the CRC from taking any regulatory action before July 1, 2016). Sea level is rising along the entire coast of North Carolina, and the variation in the extent of localized sea level rise and causes of variation are described. The report describes sea level rise dynamics, the use of tide gauges, future projections of SLR in North Carolina, and how to make sense of these predictions - in an approachable fashion. Recommendations for improved sea level rise monitoring in North Carolina are included.

In addition to using a 30-year time frame for sea level rise projections as requested by the CRC, this report updates the 2010 SLR assessment and 2012 addendum with the inclusion of SLR projections from the most recent Intergovernmental Panel on Climate Change (IPCC) Report (AR5). Also, variability in relative SLR along the North Carolina coast due to geologic factors has been recognized, and estimated. Dredging effects on tide range and sea level signal are described. In addition, a range of predictions at each of the long-term tide gauges are given, which are based on a combination of local vertical land motion information and the IPCC scenarios.

A discussion of what causes sea level change variation across the state’s coast includes descriptions of:

  • Tectonic Structural Deformation Resulting in Subsidence and Uplift
  • Glacial Isostatic Adjustment
  • Other Factors Influencing Vertical Land Motion
  • Geological Zonation of the North Carolina Coastal Plain
  • Oceanographic Effects

Some of the results of the assessment are that:

  • Two main factors affect the local rate of sea level rise: (1) vertical movement of the Earth’s surface, and (2) effects of ocean dynamics (oceanographic influences).
  • Land subsidence in certain areas contributes to higher measured rates of sea level rise along the northeastern North Carolina coast.
  • At existing rates of sea level rise, over a 30-year time frame, sea level rise across the North Carolina coast would vary from a low estimate of 2.4 inches to a high estimate of 5.4 inches.
  • In a scenario with high greenhouse gas emissions, projected potential sea level rise over a 30-year time frame would vary from a low estimate of 6.8 inches to a high estimate of 8.1 inches.

 

Publication Date: March 31, 2015

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