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California Natural Resources Agency Publishes State’s Fourth Climate Change Assessment

On August 27, 2018, the California Natural Resources Agency published a 132-page report entitled “California’s Fourth Climate Change Assessment” (Climate Change Assessment).


The Climate Change Assessment

The Climate Change Assessment states:


  • . . .includes over forty-four technical peer-reviewed reports that examine specific aspects of climate change in California, including projections of climate change impacts, analysis of vulnerabilities and adaptation for various sectors, and social and governance considerations for climate adaptation.

The Climate Change Assessment is intended to be used by groups ranging from the scientific research community and technical staff from local, regional, and state entities to local, regional, and state decision makers and stakeholders. The Climate Change Assessment is guided by five principles:


  • •Protection of the state’s most vulnerable populations and communities


  • Prioritization of natural infrastructure solutions


  • Promotion and prioritization of integrated climate actions


  • Coordination with local and regional governments


  • Sustained monitoring and research to increase ability to understand and manage climate change impacts


Some of the key findings from the Climate Change Assessment are highlighted below.



The Climate Change Assessment projects an average annual maximum daily temperature increase of between 5.6 degrees and 8.8 degrees by 2100. This rise in temperature has public health impacts, with an increase in mortality rates and illnesses, and significant economic impacts. For example, the Climate Change Assessment estimates approximately $1 billion in increased transportation costs (paving/asphalt) between 2040 and 2070 and approximately $1 billion per year in increased energy costs by 2050.


 Water Supply

A major source of water supply for California is its snowpack, but the Climate Change Assessment projects a two-thirds decline in water supply from California’s snowpack by 2050. Economic water shortage impacts range from a low of $100 million per year to $1 billion per year. For agricultural production, the Climate Change Assessment estimates that the snowpack supply reduction and hotter conditions could lead to water shortages of up to 16 percent in certain regions of the state.

The Climate Change Assessment notes that although technical solutions have the potential to address the projected declines in water supply, the solutions depend on a number of factors, including funding and the state’s legal and political landscape. California’s varied water management and governance system also presents a challenge because water suppliers include both public and private entities.



California suffered through more devastating wildfires in 2018. The Climate Change Assessment notes that if greenhouse gas emissions continue to rise, then, by 2100, the frequency of extreme wildfires will increase. According to the Assessment, the average area burned statewide would also increase by 77 percent. This environmental impact also has a corresponding economic impact because the Climate Change Assessment estimates an increase in wildfire insurance costs of 18 percent by 2055 in areas that have the highest fire risk. In addition, wildfires could cost utilities $47 million per year due to damages to their transmission and distribution infrastructure.


 Sea Level Rise

California’s coast is treasured by Californians and visitors alike. This makes the Assessment’s estimates on sea level rise particularly frightening. According to the Assessment, from 31 percent to 67 percent of Southern California beaches “may completely erode by 2100 without large-scale human interventions,” with conditions worsening if a 100-year costal flood event occurs. The Climate Change Assessment notes that although some areas subject to sea level rise will implement strategies to minimize the impacts from sea level rise, and by 2050, many localities may begin to consider retreat as an option, which may require an expansion of inland cities.

While the environmental impact itself is worrisome, the economic impact is also alarming. The Climate Change Assessment estimates that, by 2050, $48 billion worth of coastal properties could be impacted statewide, with economic impacts to southern California beaches ranging from $40 million to $63 million per year. In addition, inland flooding costs could total $42 billion.


Conclusion and Implications

The Climate Change Assessment is intended to serve as an informational document detailing the potential climate change impacts to California in the coming years. The Climate Change Assessment also includes information on the state’s efforts to prepare for these impacts by taking actions that will reduce the acute and long-term effects of climate change while building the state’s climate change resiliency. As a result, the Climate Change Assessment serves as a valuable reference guide for California’s ongoing efforts to meet its climate change goals. For more information, see:; and see:

(Kathryn Casey)