Analysis of relative sea level variations and trends in the Chesapeake Bay: Is there evidence for acceleration in sea level rise?

Abstract

Over the past few decades the pace of relative sea level rise (SLR) in the Chesapeake Bay (CB) has been 2-3 times faster than that of the globally mean absolute sea level. Our study is part of ongoing research that tries to determine if this SLR trend is continuing at the same pace, slowing down (SLR deceleration) or speeding up (SLR acceleration). We introduce a new analysis method for sea level data that is based on Empirical Mode Decomposition (EMD) and Hilbert-Huang Transform (HHT); the analysis separates the SLR trend from other oscillating modes of different scales. Bootstrap calculations using thousands of iterations were used to test the robustness of the method and obtain confidence levels. The analysis shows that most sea level records in the CB have significant positive SLR acceleration, so the SLR rates today are about twice the SLR rates of 60 years ago. The acceleration rates of our calculations are larger than some past studies, but comparable to recent results [1] who show accelerated SLR “hotspots” in the coastal areas between Cape Hatteras and Cape Cod. The results have implications for projections of future SLR and the impact on flooding risks in the Hampton Roads area. The contributions to SLR from land subsidence and climate-related changes in ocean circulation need further research.