#1 COH Council RES 203-23 Integrated Climate Action Plan

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Greenhouse Gas Reduction and Climate Adaptation Actions to Integrated Climate Action Plan for the Island of Hawai'i Build Local Resilience to Climate Change CLIMATE CASCADES A climate cascade represents one component of the cascading effects and interactions of climate change. Using the climate action framework, five climate cascades were developed to address the three goals of the ICAP. All actions and plan implementation seek to address Goal 1, to increase the County capacity to address climate change. Actions in Cascades 1 and 2 address Goal 2, to reduce GHG emissions. Actions in Cascades 3, 4 and 5 address Goal 3 to increase resilience of County infrastructure and services to climate change impacts. • Climate Cascade 1 — Greenhouse Gas Emissions caused by human activities are the key drivers of human-induced climate change. This climate cascade establishes a baseline for greenhouse gas emissions for the Island of Hawaii from which to develop climate mitigation interventions to reduce Hawaii County contributions to global climate change. • Climate Cascade 2 —Air and Sea Surface Temperature are directly influenced by greenhouse gas emissions. These climate change indicators have direct impacts on human and native ecosystem health. • Climate Cascade 3 — Draught and Severe Rainfall Events are among the climate hazards resulting from increasing air and sea surface temperature and climate variability. Drought and severe rainfall impacts to community systems are exacerbated by the compounding hazards of wildfire, landslides, windstorms, and riverine flooding. • Climate Cascade 4— Sea Level Rise is a climate hazard with slowly emerging impacts on community systems, compounded by coastal and riverine flooding and landslides. • Climate Cascade 5— Tropical Cyclones and Storm Surge are climate hazards with extreme impacts on community systems. A graphic and narratives were developed for each cascade based on the current state of knowledge and experience gleaned from global, regional, and local information and data. The ICAP analyzes exposure and risk associated with each climate cascade using a geospatial overlay of climate hazards on County assets and a social vulnerability analysis of the population. County actions for climate change mitigation and adaptation were identified for key intervention points within each climate cascade. Co-benefits of climate action were identified to highlight opportunities to build climate resilience action by action. A summary of the cascading effects is depicted in Figure 5. Key climate change drivers, indicators, climate hazards, and compounding hazards used to develop the climate cascades were identified from the County of Hawaii Hazard Mitigation Plan 2020, the Hawaii State Climate Summary, the 4th National Climate Assessment, and other relevant literature. A closer look at the climate hazards can be found in Appendix A. Community systems were defined as physical, social, economic, cultural, native ecosystem, and governance assets and services. County assets and services were identified within these community systems as the focus for action in this plan. Climate cascades are intended as a starting point in describing the complexities of climate change impacts in order to better anticipate feedback loops and avoid maladaptation. These cascades will be reviewed, revised, and expanded as new research becomes available and conditions change. Climate Cascades 7