Economic Effects of Storm Surge and Sea Level Rise on US Coasts

by Grace Stewart

Neumann et al. (2015) provide evidence that to properly analyze the risk climate change poses to coastal property, it is necessary to account for the effects of both sea level rise and storm surges. They conducted a study accounting for both of these phenomena in determining the economic damages to coastal regions through the year 2100 by combining three models—a tropical cyclone simulation model, storm surge model, and economic impact and adaptation model. This study seemed particularly relevant due to the recent Hurricane Sandy, which depicted the devastating effects of storm surges to infrastructure and safety of coastal residents.

The authors began by modifying the USEPA’s National Coastal Property Model (NCPM), which addresses the threat of sea level rise, to include effects of storm surge on “estimates of vulnerability, impact, adaptation response, and economic damages” (339). To do so, Neumann et al. modified NCPM in three ways to incorporate storm surge: estimating a cumulative distribution function both for location-specific storm surge and for economic damages, and adding “property elevation” as a cost-effective response option in areas of episodic flooding. The model was tested under multiple sea level rise scenarios, which included contributions from dynamic ice-sheet melting and various greenhouse gas mitigation policies. The cost of adaptation and damage from storm surge was determined for 17 multi-county study areas on the East, West, and Gulf coasts.

Results of the analysis were as follows: cumulative total undiscounted costs of adaptation to sea level rise (excluding storm surge) for the contiguous US ranged from $470 to 610 billion under ‘business as usual’ scenarios, and from $400 to 510 billion under greenhouse gas mitigation policy scenarios. When storm surge was included, cumulative total costs through 2100 ranged from $540 to 610 billion for business as usual, and from $510 to 560 billion under the policy scenarios (for the 17 modeled sites only). Costs were associated with shoreline armoring, beach nourishment, abandoned property, and elevating. Total undiscounted costs of adaptation to sea level rise and storm surge ranged from $930 billion to $1.1 trillion under business as usual, and from $840 to 980 billion under the policy scenarios. These benefits associated with mitigation policies were found not to come into effect until mid-century (2050).

Neumann et al.’s approach was limited in a few ways: damages from wind and rain that come with coastal storms were not included; impacts to infrastructure and ecosystem services were not accounted for; and post-disaster damages, like power outages, were not included. Future research can overcome these limitations by pinpointing how damages to infrastructure and ecosystems contribute to damage estimates in general. Overall, this study confirmed the need for both mitigation and adaptation strategies in the face of sea level rise and storm surges.

Neumann, J.E., Emanuel, K., Ravela, S., Ludwig, L., et al., 2015. Joint effects of storm surge and sea-level rise on US Coasts: new economic estimates of impacts, adaptation, and benefits of mitigation policy. Climatic Change 129, 337-349.



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