Climate Risks

As scientists refine global climate models to create projections of future conditions at the local level, it becomes clear that Sonoma County’s future climate will include more very hot days, less predictable rain, more extreme weather events, and higher ocean levels.


Using historic data to predict future conditions is no longer adequate for long-term policy planning and decision-making, as local leaders work to protect the long-term vision for a vibrant Sonoma County.

So the RCPA has teamed with scientists to develop a local assessment of climate risks: Climate Ready Sonoma County: Climate Hazards and Vulnerabilities.

The risks, uncertainties, and volatility associated with climate change pose potentially high costs to communities in terms of public health, safety, economic vitality, security, and quality of life. While some uncertainty remains in the timing of changes – especially due to uncertainty regarding future global greenhouse gas (GHG) emissions scenarios – there is enough confidence in projected trends to begin the work of preparing for climate hazards now. Preparing now will yield more cost-effective and flexible strategies than delaying action until responding to unprecedented conditions.

The first step to respond to climate change locally is to assess our exposure to climate hazards. Across all four of the representative climate futures Sonoma County can expect to experience:

Hotter, drier weather with longer summers

More extreme heat events

Longer and more frequent droughts

Greater frequency and intensity of wildfires

Fewer winter nights that freeze

More variable rain

Bigger, more variable floods

Sea level rise

Higher sea level and storm surge

Projected future changes in air temperatures vary across the county. In Figure 6, the map shows the geographic distribution of changing temperatures using the “hot/dry” future scenario, which is a conservative scenario to use when planning for heat-related hazards. Inland valleys and mountain ridges are most affected, and some regions experience no change.

hazards_chart_1

hazards_chart_2

Whether the North Bay region experiences more or less rainfall over the year, our land and watersheds will be hotter and drier overall due to rising temperatures and increased evapotranspiration (the process of transferring moisture from the earth to the atmosphere by evaporation of water and transpiration from plants). Climatic water deficit (CWD) is a numeric measure of drought stress which quantifies plants’ need for water that exceeds moisture available in the soil. CWD is projected to increase over this century, producing 10-20% drier conditions in the Summer months, leaving less water available for recharge and runoff.