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 scenarios estimate that in certain regions, sea level could increase by roughly up to 1 meter by 2100 and by 2 meters if Greenland ice sheet melt accelerates. SLR has the potential to affect existing coastal infrastructure critical to the Department of Defense.
Potential local effects projected by changes in sea level 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. Potential ramifications for national security are recognized in recent legislation that directs DoD to provide guidance to military planners to assess the risks of potential climate change. The 2010 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 is pursuing 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. A suite of SERDP projects are developing the 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 Projects
Effects of Near-Term Sea-Level Rise on Coastal Infrastructure – Focused on Eglin Air Force Base, the goal of this project is to quantify the potential impact from sea-level rise and the predicted increases in hurricane activity. The project is employing existing process-oriented numerical models and incorporating 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 will be 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 is to develop and demonstrate an integrated, multi-criteria, multi-hazard risk assessment framework that will be suitable for evaluating changes in risks to coastal military installation assets and mission capabilities. A comprehensive inventory of assets and mission capabilities is being developed for Hampton Roads military installations. Long-term forcing effects of increasing rates of SLR on associated risk drivers at the sites will be simulated over a 100-year period using well-established hydrologic models and methods. A water depth-frequency-damage paradigm will be used to estimate impacts on military installation assets and mission capabilities with related costs simulated using the Federal Emergency Management Agency's (FEMA) Hazards U.S. Multi-Hazard (HAZUS-MH) model. Risk assessment will characterize military 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 focuses on the impacts of the potential loss of coastal barrier islands. An integrated field and modeling approach is being 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 and wave climates. In addition, the North Carolina site also is subject to frequent nor'easter storm events. By coupling a suite of models, researchers are projecting the geomorphic response to SLR scenarios at each installation and examining how these changes alter the susceptibility of each installation to storm-induced impacts. Barrier morphology will be evolved as a result of rising sea level and storm impacts. These results will inform modeling of storm impacts under these revised conditions.
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 is to develop a military-relevant framework for assessing the impacts of local mean sea level rise and associated phenomena. Development of the framework and vulnerability assessment will consist 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
- Under joint-SLR scenarios, characterize the expected physical effects of sea level rise within the Southwest region
- Under each of the defined joint-SLR scenarios, 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
Together, these projects will provide 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 sea-level rise and associated phenomena on coastal infrastructure.
These assessment tools are intended to be in a format that is readily available to use and apply to management decisions related to coastal installations at risk from future sea-level change. Models will capture the essential underlying processes shaping the shoreline under conditions of accelerating sea-level rise. As such, strategies will be portable to other locations.
This research will assist DoD in its efforts to achieve appropriate allocations of risk management efforts, placing climate-induced risks in perspective with non-climate risks within a multi-stress environment.
The resulting military-relevant framework will be broadly useful for assessing vulnerability to SLR. The application of this framework to scientifically based-scenarios will provide a basis for future analysis including further work toward development of adaptation options.