California’s Fourth Climate Change Assessment Statewide Summary Report

This statewide summary report summarizes the main findings from the Fourth Assessment. The report synthesizes these Fourth Assessment findings in the context of recent literature to provide a more complete presentation of the information available on climate change impacts and adaptation options in California. However, while the report strives to be as representative as possible, it is not a comprehensive review of the tremendous amount of research on climate change in California that has been generated since California’s Third Climate Change Assessment was released in 2012. Every attempt is made to represent uncertainty and conditions under which future climate conditions are estimated; however, the report does not include a standard methodology for conveying uncertainty.

The report begins with an overview of historical and projected climate change in California under downscaled climate scenarios (Chapter 1). Chapter 2 discusses how climate change interacts with other changing factors such as land use and demographic change, and how these factors affect the State’s people, infrastructure, and natural systems. The following section reviews adaptation strategies and how they contribute to resilience (Chapter 3). The report concludes with a discussion of research needs in Chapter 4, followed by an overview of how the findings from the Fourth Assessment and future assessments can support climate action in Chapter 5.