Abstract

The time to act is now. Climate change is already altering the physical environment of the Sacramento–San Joaquin Delta and Suisun Marsh (Delta), and we will continue to experience its effects through hotter temperatures, more severe wildfires, and prolonged droughts. Over the long term, climate change in the Delta is expected to harm human health and safety, disrupt the economy, diminish water supply availability and usability, shift ecosystem function, compromise sensitive habitats, and increase the challenges of providing basic services. Many of these impacts will disproportionately affect vulnerable communities.

Although the exact extent and timing of these impacts is uncertain, this climate change vulnerability assessment phase of Delta Adapts will help the Delta Stewardship Council (Council) understand specific regional climate risks and vulnerabilities.

Regional, collaborative adaptation strategies rooted in science are more critical than ever. The next phase of Delta Adapts, preparing an adaptation strategy, will identify ways to address the risks and vulnerabilities.

We did not go at this alone. The Council conducted the climate change vulnerability assessment in coordination and input from a diverse group of stakeholders over the last two years. The Council worked with agency partners at the local, regional, State, and federal levels to obtain data, expand upon existing technical work, and ensure that our climate studies complement other ongoing work. The Council also coordinated with stakeholders representing various Delta interests including community-based organizations, service providers, reclamation districts, water districts, and environmental groups to gather input, to verify results, and to structure the outreach program and technical materials to reach a wider audience.

Considers a broad range of climate futures. Delta Adapts aligns with State guidance and best practices, leverages best available data sources, and conducts targeted analyses to expand our knowledge of climate impacts in the Delta. This climate change vulnerability assessment considers climate impacts at three planning horizons: 2030, 2050, and 2085. It also considers a broad range of potential hydrologic conditions including river inflows, sea level rise, storm surge, and tides.

The assessment considers climate stressors, or chronic changes in climate conditions that may stress Delta systems, including changing temperatures, precipitation and hydrologic patterns, and sea level rise. Climate hazards or acute events that may impact assets and resources include flooding, extreme heat, wildfire smoke, and drought.

Our analysis considers the most vulnerable populations. Delta Adapts defines vulnerability as the intersection of exposure to climate hazards, sensitivity to those hazards, and adaptive capacity, or the ability to recover from and adapt to climate hazards. Delta Adapts identifies the communities with the highest social vulnerability to climate hazards, meaning the communities with high sensitivity and low adaptive capacity to flooding, extreme heat, and wildfire.

Bringing it all together. While many of these findings were expected, we now know where the greatest climate impacts will occur to people, places, recreation, agriculture, and infrastructure, and we understand the respective economic impacts. This underscores the importance of future levee investments targeted to protect communities and assets. We understand where the most socially vulnerable communities are located, and where future investments should be prioritized so that climate change adaptation is equitable.

This assessment provides the data and information from our modeling efforts and equity analysis to guide how we address these vulnerabilities in the important next step of Delta Adapts, preparation of an adaptation strategy. An effective plan for adaptation in the Delta will take teamwork and require input from a diverse range of stakeholders. We invite you to join us.