Climate Change and Impacts of Sea Level Rise
Global mean sea levels are rising and are predicted to continue to rise for the foreseeable future. Because the projected rates of global mean sea-level rise (SLR) over the next century far exceed those observed in the past several thousand years, the potential exists for historically unprecedented impacts to the natural and built infrastructure occurring along coastlines. Plausible, risk-based scenarios estimate that global sea level could increase by roughly up to 2 meters by 2100 if Greenland ice sheet melt accelerates with regional and local effects adding to or subtracting from the global mean. SLR has the potential to affect existing coastal infrastructure critical to the Department of Defense (DoD).
Potential local effects projected by changes in sea level also must account for associated coastal storms, tides, and inland precipitation and runoff. Environmental effects induced by SLR are far reaching and will differ based on the geophysical setting. Local evaluation of such consequences will be essential. Potential environmental effects include the following:
- increased storm damage to coastal infrastructure
- more rapid coastal erosion
- shoreline change including the possibility for total loss of protective natural barriers
- saltwater intrusion into aquifers and surface waters
- rising water tables
- changes in tidal prism
These effects will occur over time at different rates or re-occurrence intervals. Although passive inundation is straightforward to estimate, coastal environments are dynamic and complex.
A number of DoD installations and other assets are located on the coast. These facilities are expected to experience significant changes to environmental resources and man-made infrastructure. The most recent Quadrennial Defense Review makes clear that it is a DoD priority to understand the effects of climate change on both its operations and fixed installations.
To address the information and decision support needs of DoD coastal installations under the threat of climate change, SERDP has and is continuing to pursue a number of areas of investigation. In coordination with the efforts of the other federal science providers, SERDP’s goal is to ensure DoD has the necessary science and tools to support climate change-related vulnerability and impact assessment. First, a suite of SERDP projects developed methodologies and tools needed to assess the physical effects of sea level rise and storm surge and the impacts to mission-essential infrastructure over a broad range of both geophysical settings and extant climate conditions. These settings include:
- Naval Station Norfolk and the surrounding Hampton Roads area in Virginia – a tidal basin, subject to both tropical and extratropical storms
- Eglin Air Force Base, Florida – Gulf Coast with an associated protective barrier island, subject to tropical storms
- Marine Corps Base Camp Lejeune, North Carolina – mid-Atlantic Coast also with a barrier island, subject to both tropical and extra-tropical storms
- Marine Corps Base Camp Pendleton and Naval Base Coronado, California – southwestern Pacific Coast, subject to El Niño events
Sea Level Rise Research Projects
Effects of Near-Term Sea-Level Rise on Coastal Infrastructure – Focused on Eglin Air Force Base, the goal of this project was to quantify the potential impact from sea-level rise and the predicted increases in hurricane activity. The project employed existing process-oriented numerical models and incorporated newly developed geological and historic period site-specific storm history information to quantify the effects of climate change on coastal infrastructure over the next 100 years. The models were integrated to encompass all of the components of the coastal system affecting Eglin.
Risk Quantification for Sustaining Coastal Military Installation Assets and Mission Capabilities – Focused on the Hampton Roads area, the objective of this project was to develop and demonstrate an integrated, multi-criteria, multi-hazard risk assessment framework that would be suitable for evaluating changes in risks to coastal military installation assets and mission capabilities. A comprehensive inventory of assets and mission capabilities was developed for Naval Base Norfolk. Long-term forcing effects of increasing rates of SLR on associated risk drivers at this site were simulated over a 100-year period using well-established hydrologic models and methods. A water depth-frequency-damage paradigm was used to estimate impacts on military installation assets and mission capabilities. A risk-based assessment characterized installation assets to sustain mission capabilities.
Shoreline Evolution and Coastal Resiliency at Two Military Installations: Investigating the Potential for and Impacts of Loss of Protecting Barriers – This project focused on the impacts of the potential loss of coastal barrier islands. An integrated field and modeling approach was used to conduct impact assessments for Eglin Air Force Base, Florida, and Marine Corps Base Camp Lejeune, North Carolina. Both sites are subject to relatively frequent impacts from tropical cyclones, yet they have different tidal ranges, wave climates, and barrier islands that differ geomorphologically. In addition, the North Carolina site also is subject to frequent nor'easter storm events. By coupling a suite of models, researchers projected the geomorphic response to SLR scenarios at each installation and examined how these changes alter the susceptibility of each installation to storm-induced impacts. Barrier morphology was evolved as a result of rising sea level and storm impacts. The results can inform modeling of storm impacts as environmental and barrier island conditions change.
A Methodology for Assessing the Impact of Sea Level Rise on Representative Military Installations in the Southwestern United States – Focused on Naval Base Coronado and Marine Corps Base Camp Pendleton in the southwestern United States, the objective of this project was to develop a military-relevant framework for assessing the impacts of local mean SLR and associated phenomena. Development of the framework and vulnerability assessment consisted of five primary components:
- Adapt a generalized vulnerability framework for application to coastal military installations
- Characterize and predict the strength, frequency, and probability of underlying forcing factors that control regional sea level using the predicted characteristics of these forcing factors to develop realistic assessment scenarios based on the joint probability of occurrence for a range of regional sea level conditions
- Compile critical biogeophysical and infrastructure data for each installation within a three-dimensional GIS modeling environment
- Characterize the expected physical effects of sea level rise within the Southwest region
- Develop a GIS modeling system combined with infrastructure analysis that can be used to evaluate the potential for impact to infrastructure and natural resources across the gradient of conditions present at the regional installations
Research Outcomes and Next Steps
Together, the above research projects provided a unique set of tools to DoD decision makers and the scientific community to assess vulnerabilities and impacts and devise appropriate adaptation strategies in response to SLR and associated phenomena on coastal infrastructure.
SERDP subsequently assessed common cross-cutting issues from these four projects to develop a report that provides policy-relevant questions to frame vulnerability and impact assessments for coastal military installations (SERDP Coastal Assessment Report). In addition, the report provides a set of eight technical and institutional considerations to further guide how to conduct coastal assessments. Such information will be helpful as the DoD pursues its commitment under the President's Climate Action Plan to assess the relative vulnerability of its coastal facilities under climate change.
SERDP is also continuing research to understand how coastal ecosystems and infrastructure will respond to climate change through the Defense Coastal Estuarine Research Program (DCERP) and new climate change-related research projects in the Pacific Islands. Finally, in partnership with other federal agencies, SERDP is developing methodologies for regionalizing the global SLR scenarios and estimating plausible future extreme water levels due to SLR and other contributing phenomena.
NEW! SERDP Report:
Infrastructure Damage/Fragility Models and Data Quality Issues Associated with Department of Defense Climate Vulnerability and Impact Assessment
NOAA Technical Report:
Global Sea Level Rise Scenarios for the United States National Climate Assessment
Assessing Impacts of Climate Change on Coastal Military Installations: