California's Fourth Climate Change Assessment

California’s statewide assessment of climate change impacts utilizes updated climate science to investigate vulnerability at the local scale and inform adaptation and resilience planning. The fourth climate change assessment includes 44 technical reports on projected impacts to specific sectors and potential responses, 30 summary reports, 9 regional reports, and 3 statewide topical reports on oceans and coasts, tribal and indigenous communities, and environmental justice impacts of climate change. The assessment’s Statewide Summary Report provides an overview of the main findings, and makes the climate science more accessible. This report includes adaptation strategies for primary impacts and determines priority research needs.

The technical reports include projections of climate change impacts, analysis of vulnerabilities and adaptation for various sectors, and social and governance considerations for climate adaptation (see Appendix A for a full list of technical reports).

Summary reports for regions and communities provide a "state of the science” for nine regions, the ocean and coast, tribal communities, and climate justice in California.

The CA Climate Assessment for the first time includes synthesis reports on Tribal and Indigenous communities and on Climate Justice. The summary report describes existing equity programs focused on increased climate resiliency for vulnerable populations in California. Impacts on vulnerable populations and tribes, as well as areas of research are discussed that can improve equitable climate adaptation and promote climate justice.

Suggested research and strategies include, for example, enhanced tools, indices, maps, and metrics for identifying and quantifying resilience in vulnerable communities; establishing a just transition to a low carbon economy; and methods to ensure community engagement in climate adaptation planning.

Original academic research is available that provides detailed results on climate impacts, risk and adaptive capacity to climate change - to help inform policymaking and strategic action.

The Assessment Foundation report includes updated climate change projections, data and ecosystem models used and shared by assessment authors to incorporate a range of future climate conditions and permit cross-comparability of assessment results.

The Statewide Summary report describes both historical and projected climate change in California under downscaled climate scenarios - including the climate change effects on the state’s: Temperature, Sea Levels, Snowpack, Annual Precipitation, Intensity of heavy precipitation events, Frequency of Drought, Frequency and intensity of Santa Ana Winds, Marine Layer Clouds, and Acres Burned by Wildfire.  Chapter 2 discusses how these and other major climate change impacts affect land use, natural systems, and demographic change, and further details projected impacts and vulnerabilities related to Sea-level rise and Wildfire.

Key Findings and impacts are detailed for the following focal sectors:

  • Land Use and Development
  • Public Health
  • Economic Impacts
  • Emergency Management
  • Tribal and Indigenous Communities
  • Climate Justice
  • Energy Infrastructure
  • Transportation Infrastructure
  • Water Infrastructure and Supply
  • Delta Levees and Infrastructure
  • Agriculture
  • Biodiversity and Ecosystems
  • Forest Health
  • Oceans and Coast

The website that overviews the Assessment is visually dynamic while designed to present scientific findings in a way that can be easily understood. The major climate impacts as displayed in Key Findings, for example, are succinct and memorable - like this graphic on the state's water supply: 

Adaptation strategies and how to incorporate these actions to establish resilient systems are discussed in Chapter 3 of the Summary Report. The analyses and strategies for adaptation are presented for these communities, infrastructure, and natural systems, along with cross-cutting resilience strategies for governance, financing, and planning. Adaptation and resilience strategies are described for each of the focal sectors listed above (agriculture, forests, public health etc.) - in terms of what has been found to be the most holistic and effective strategies for climate resilience in that sector from recent studies or practices.


Publication Date: August 27, 2018

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Resource Types:

  • Assessment
  • Monitoring
  • Policy analysis/recommendations

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