Indicators of Climate Change in California

This report presents 36 indicators tracking trends in climate change and climate impacts on California's environment and people. Form the California Environmental Protection Agency (CalEPA) Office of Environmental Health Hazard Assessment (OEHHA), this third edition report updates the 2009 and 2013 version. The report is a resource intended for decision makers, scientists, educators, and the public - and brings scientific analysis to inform climate mitigation and adaptation decision-making. 

The report’s 36 indicators are grouped into four categories:

  • Human-influenced (anthropogenic) drivers of climate change, such as greenhouse gas emissions
  • Changes in the state’s climate
  • Impacts of climate change on physical systems, such as oceans, lakes and snowpack
  • Impacts of climate change on biological systems – humans, vegetation and wildlife

Every indicator has a dedicated and detailed subsection within the report.  For each indicator, the trend is illustrated using one or more graphs or maps, and the following questions are answered: • What does the indicator show? • Why is the indicator important? • What factors influence the indicator? Each indicator report includes some technical considerations (describing strengths and limitations of the data); and contact person(s) who generally are the researcher or technical expert who contributed to, or collaborated with OEHHA on, the preparation of the indicator information.

Environmental changes and trends for which the influence of climate change remains uncertain are discussed in the final section - Emerging Issues. Additional data or further analyses are needed to determine the extent by which climate change plays a role for these issues to be considered indicators. These climate related impacts include: coastal fog, Central Valley fog, lightening, forest disease and pest infestations, invasive agricultural pests, blue-tongue in livestock (a vector-borne viral disease of sheep, goats and cattle transmitted by biting midges), and harmful algal blooms.   


Publication Date: May 9, 2018

Related Organizations:

  • California Environmental Protection Agency (CalEPA)


Resource Category:

Resource Types:

  • Indicators

States Affected:


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