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How is climate data relevant for decision-making in California?

Topics covered in this article:

  • How is climate data relevant for decision-making?
    • California’s changing climate
    • Using climate data in adaptation planning

How is climate data relevant for decision-making?

Characterizing climate conditions is important when planning for the future in a variety of sectors, including municipal planning, natural resource stewardship, utility management, public health and safety programming, and private industry. By assessing the range of possible future conditions under a changing climate, you can plan adaptations that reduce the impacts of climate change and safeguard lives, livelihoods, and landscapes for decades to come.

California’s changing climate

The California Fourth Climate Change Assessment produced updated climate projections that provide state-of-the-art understanding of different possible climate futures for California. The science is highly certain that California (and the world) will continue to warm and experience greater impacts from climate change in the future. Projected statewide climate change trends are listed in the table below:

Climate variable Cal-Adapt symbol Projected change Scientific confidence Cal-Adapt tools
Temperature Warming Very high Annual averages, Extreme heat, Maps of projected change, Local climate change snapshot, Cooling degree days and heating degree days, Extended drought
Sea levels Rising Very high Sea level rise – CalFloD-3D Hourly projections of sea level
Snowpack Declining Very high Snowpack
Heavy precipitation events Increasing Medium high Annual averages, Maps of projected change, Local climate change snapshot, Extreme precipitation events
Drought Increasing Medium high Local climate change snapshot, Extended drought
Wildfire Increasing Medium high Local climate change snapshot, Wildfire

Table: projected climate change trends in California, from Fourth Assessment key takeaways report

These trends will vary in magnitude and impact across California, so it’s important that adaptation planning uses data that are specific to the planning location and the climate hazards of concern in that location. To explore climate projections for a specific area, check out the Cal-Adapt tools associated with each climate variable. For additional information on the impacts of climate change in California, you can explore California’s Fourth Climate Change Assessment.

Using climate data in adaptation planning

Cal-Adapt data can be used in combination with other data sources to inform a climate vulnerability assessment, which combines projections data, historical data, and other qualitative and quantitative sources to identify how specific climate-related risks will impact a community. Vulnerability assessments are commonly used to identify the populations, infrastructure, and natural systems most at risk of climate change impacts and evaluate the severity of their vulnerability and their ability to adapt. Climate change vulnerability analysis and adaptation planning methods can vary by sector. Regardless of the context, using climate change data to understand vulnerability is an important cornerstone of identifying the best adaptations to undertake to address the projected risks.

The 2020 Adaptation Planning Guide (APG) provides guidance to local governments on local adaptation and resiliency planning in California, including how to use Cal-Adapt to inform a vulnerability assessment. The APG breaks down adaptation planning into four phases:

  1. Explore, Define, and Initiate
  2. Assess Vulnerability
  3. Define Adaptation Framework and Strategies
  4. Implement, Monitor, Evaluate, and Adjust

While following this process, it is most useful to start examining climate change data from Cal-Adapt in a preliminary analysis during Phase 1 to understand the scope of the assessment you are about to undertake, and then to conduct a more thorough technical analysis as you move into Phase 2. Explore each phase, broken down into manageable smaller steps in the online Adaptation Planning Guide.

Cities and Counties in California are required to address climate adaptation and vulnerability in their safety elements. For more information on the requirements see the State's 2020 Adaptation Planning Guide, the General Plan Guidelines Chapter 4, or Government Code section 65302(g). (Senate Bill 379, Jackson, 2015).

The way that you use climate data will depend on your particular needs, risk tolerance, and planning context. To support adaptation planning, the State of California has produced guidance materials, including:

You can find a list of additional climate change adaptation planning resources on the California Adaptation Clearinghouse Resources Page and example plans and strategies by exploring the database search page, which can filter resources by the topics, climate impacts, regions, and resource types most relevant to you. Additionally, the Governor’s Office of Planning and Research regularly conducts an inventory of local adaptation efforts and related documents, which are displayed for public access on the ResilientCA Adaptation Planning Map (RAP-Map), also housed on the Adaptation Clearinghouse.