Transportation and Climate Change Clearinghouse
1 - Study Intent
The methodologies, uncertainties and intended uses of this study should be considered while reviewing the results. This study was designed to produce high level estimates of the net effect of sea level rise and storm surge on the national transportation network. It was designed primarily to aid policy makers at the U.S. Department of Transportation by providing estimates of these effects as they relate to roads, rails, airports and ports.
This study was meant to provide a broad, first look at potential sea level changes on the Atlantic coast, and the results should not be viewed as defining specific changes in water levels at specific points in time. The study was not intended to create a new estimate of future sea levels, or to provide a detailed view of a particular area under a given scenario. Instead, the study applied existing predictions of global sea level rise from the Intergovernmental Panel on Climate Change's (IPCC) Third and Fourth Assessment Reports1. The inherent value of this study is the broad view of the subject and the overall estimates identified.
Due to the overview aspect of this study, and systematic and value uncertainties in the involved models, this analysis appropriately considered sea level rise estimates from the IPCC reports as eustatic occurrences, in other words, as uniform sea level rise estimates, rather than estimates for a particular geographic location. The confidence stated by the IPCC in the regional distribution of sea level change is low due to significant variations in the included models; thus, it would be inappropriate to use the IPCC model series to estimate local changes. Local variations, whether caused by erosion, subsidence2 or uplift, local steric3 factors or even coastline protection, were not considered in this study.4 The effect of potential protective measures, such as building levees or sea walls, was not considered in this report.
Ultimately, the goal of this study is to provide a "first look" at areas and infrastructure that may be inundated by sea level and the resulting increase in storm activity. The areas and infrastructure identified in the maps, statistics and the qualitative report should therefore be considered for further, more detailed study.
1 IPCC's Assessment Reports http://www.ipcc.ch/ipccreports/assessments-reports.htm
2 Subsidence - this study uses the term to mean the motion of the Earth's surface as it shifts downward relative to sea level
3 Steric - this study uses this term to refer to the volumetric increase in water due to thermal expansion.
4 It is recognized that protection such as bulkheads, seawalls or other protective measures may exist or be built that could protect specific land areas but, due to the overview nature of this study, they were not included in the analysis.