Rising Sea Levels: Helping Decision-Makers Confront the Inevitable

Abstract

Sea-level rise (SLR) is not just a future trend; it is occurring now in most coastal regions across the globe. It thus impacts not only long-range planning in coastal environments, but also emergency preparedness. Its inevitability and irreversibility on long time scales, in addition to its spatial non-uniformity, uncertain magnitude and timing, and capacity to drive non-stationarity in coastal flooding on planning and engineering timescales, create unique challenges for coastal risk-management decision processes. This review assesses past United States federal efforts to synthesize evolving SLR science in support of coastal risk management. In particular, it outlines the: (1) evolution in global SLR scenarios to those using a risk-based perspective that also considers low-probability but high-consequence outcomes, (2) regionalization of the global scenarios, and (3) use of probabilistic approaches. It also describes efforts to further contextualize regional scenarios by combining local mean sea-level changes with extreme water level projections. Finally, it offers perspectives on key issues relevant to the future uptake, interpretation, and application of sea-level change scenarios in decision-making. These perspectives have utility for efforts to craft standards and guidance for preparedness and resilience measures to reduce the risk of coastal flooding and other impacts related to SLR.

Keywords:

• coastal risk management
• extreme water levels
• managing uncertainty
• regional/local sea-level rise scenarios
• risk-based approach

Acknowledgments

The views expressed are those of the authors and do not represent the policies or opinions of any US government or state agency. The authors thank Kimberly Gotwals and Erik Tucker for their assistance with figure preparation. The manuscript was improved by the comments of Andy Miller, Marissa Liang, and an anonymous reviewer. The authors dedicate this article to the memory and career of Margaret A. Davidson: colleague, friend, and champion of enduring coastal management.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

R.E.K. was supported in part by a grant from the Rhodium Group (for whom he has previously worked as a consultant), as part of the Climate Impact Lab consortium, as well as by grants from the National Science Foundation (ICER-1663807) and National Aeronautics and Space Administration (80NSSC17K0698).