Climate Science and Policy

In light of anthropogenic climate change and increasing global temperatures, coastal flooding and erosion from sea level rise are becoming more prevalent. Historically, adaptation techniques to protect the coastline have focused on gray infrastructure; however, nature-based solutions (NBS) are rapidly emerging as a viable long-term approach for successful adaptation. Due to the relative novelty of the climate adaptation field as a whole and nature-based solutions specifically, barriers to their implementation include a lack of funding and general support. Thus, quantifying and communicating the benefits of NBS is crucial to their successful widespread implementation. This report addresses this issue in the specific context of NBS to sea level rise in Imperial Beach, California. It aims to create a framework that adequately quantifies the benefits of NBS to sea level rise and expresses them in a manner that allows for seamless implementation. A cost-benefit analysis is used, which consists of five steps: (1) project identification, (2) project attributes identification, (3) cost summary, (4) benefits summary, and (5) comparative analysis. The Bayshore Bikeway Resiliency Project and beach nourishment events are considered highly cost-effective solutions based on key findings. Dune restoration, however, is not considered a cost-effective method, given only the current quantitative benefits. If the broader range of additional benefits is included, the City may still designate this project as a plausible response to sea level rise. The most cost-effective method of adaptation considered in this study is beach nourishment. However, a single-project approach is not recommended in climate adaptation. A hybrid adaptation approach is usually the most effective and beneficial as there is no “one-size-fits-all” procedure to planning. Future studies may expand upon this research by utilizing a similar framework for other NBS in different jurisdictions. The City may also utilize this information to further the planning process of climate adaptation projects as they and many other cities work to build resilient communities in the presence of climate change.