Regional Sea Level Scenarios for Coastal Risk Management: Managing the Uncertainty of Future Sea Level Change and Extreme Water Levels for Department of Defense Coastal Sites Worldwide

Abstract : Global change, including climate change, poses unique challenges to the Department of Defense (DoD). In particular, coastal military sites, and their associated natural and built infrastructure, operations, and readiness capabilities, are vulnerable to the impacts of rising global sea level and local extreme water level (EWL) events. One way to assess vulnerabilities and impacts is to pose plausible and scientifically credible future conditions, or scenarios, with regard to sea level and EWLs. A multi-agency group conducted a literature synthesis and applied research effort to develop such scenarios. This report and its accompanying scenario database provide regionalized sea level and EWL scenarios for three future time horizons (2035, 2065, and 2100) for 1,774 DoD sites worldwide. The global nature of DoDs presence required a broad and comprehensive approach that to this point has been lacking in similar efforts. These regionalized scenarios were based on five global sea-level rise (SLR) scenarios. The site specific results reflect the fact that SLR is not uniform across the globe. The set of five global SLR scenarios (starting from 1992 and ranging from 0.2 meters to 2.0 meters by 2100) was developed consistent with other efforts of a similar nature that attempt to frame the plausible range of risk of concern to coastal managers. The suite of global scenarios and their associated storylines enable decision-makers to tailor their use of the scenarios to the decision under consideration and other factors. Although the scenarios extend only to the year 2100, for all global scenarios considered, sea levels will continue to rise past 2100. Decision-makers and planners with time horizons that go beyond 2100 should take this into account.