Analysis of Global Sea Level Rise Impact and Adaptation Risk Assessments

Global sea levels currently are rising and will continue to rise far into the future. This rise engenders significant risks to life and the environment, as it creates negative physical, economic, and societal impacts across the globe. The precise magnitude of the impacts depends on a diversity of variables, e.g., the amount the sea will rise, the magnitude of storm surges, and the types of adaptation and protection measures in place to mitigate the impacts.

If the various geographic regions across the globe are to adequately prepare for the rising sea, it is necessary to conduct risk assessments to determine which specific impacts and the policy options that are necessary to mitigate those impacts. While many regions have conducted analyses and are planning adaptation measures, many have neither thoroughly assessed the impacts nor planned adequately for the risks. Additionally, some regions that have conducted analyses did not rigorously assess the impacts or a diversity of possible policy options. This may be due to lack of sufficient funding to conduct the assessment, lack of knowledge of the severity of the issue, or lack of expertise to conduct a thorough assessment.

This paper examines a diversity of risk assessments conducted by regions worldwide. It includes a range of studies that assess regions with different economic capacities, types of terrain, location, and that implement a range of different methodologies. It examines and compares the impacts and policy options included in the analyses, as well as the variable inputs and evaluation criteria that were implemented to conduct the assessments. While some previous studies have analyzed a particular risk assessment methodology for sea level rise or compared adaptation measures, no previous study has been conducted to comparatively weigh the components and results of impact and adaptation risk assessments.

Through a comparison of the components and results of a variety of risk analyses, this study provides valuable insights into the diverse impacts and possible policy options that may be selected for inclusion in future sea level rise studies. The goal of this study is to assist regions in tackling the problem of sea level rise by providing a foundation to streamline the process for future assessments.

Based on the assessed reports, the results demonstrate that the most commonly analyzed impacts are those to a region’s economy and population. Additionally, the impacts to a region’s infrastructure, particularly transportation infrastructure, and total land surface appear to be of great importance. The variable inputs that appear to be most commonly applied to assess the impacts are storm surge and a range of sea level rise scenarios, as opposed to one specific future sea level rise quantity.

The results of a comparison of reports that analyze policy options to sea level rise show that hard adaptation options (e.g., dikes, sea walls, breakwaters) are more commonly assessed than soft adaptation options (e.g., land use change, relocation). Of the hard and soft measure categories, natural barriers and resettle were included in the most reports. Additionally, it appears valuable to include the current protection activities and policies of a region in an assessment. The criteria most utilized for conducting the policy evaluations are the protection cost of a measure and its environmental impacts. While not all reports proposed an exact recommendation that the study area should pursue for mitigating sea level rise impacts, soft options were more frequently recommended at the conclusion of the reports.

The majority of the studies were conducted with quantitative methods. However, it is recommended that future assessments also include a qualitative perspective. It may be valuable to discuss the impacts of sea level rise with residents of an area to determine which impacts are considered most important to mitigate and to determine the most appropriate adaptation options to pursue in preparation for mitigating those impacts.

There is no correlation between a study region and the quantity of impacts analyzed or depth of the impacts assessed. Additionally, there is no correlation between a study region and the policy options pursued.

Lastly, omissions of variables and criteria from the reports are explored. Future impact studies should include location-specific trends in sea level rise, as opposed to assessing the impacts based on the global average future sea level rise prediction. It is also important to incorporate the speed of the rise in a dynamic analysis, as well as any uncertainties in a report’s input variables. Future policy assessments should include a criterion that accounts for the human behavior and response to the sea level rise and the implemented policy measures.