California Department of Transportation

Climate Change Branch

California has a complex multi-modal transportation system consisting primarily of streets and highways, rail lines, airports, sea ports, and bicycle and pedestrian facilities throughout the state.  As owner and operator of the State Highway System, Caltrans is responsible for ensuring over 50,000+ lane miles of state highway and associated infrastructure are safe and reliable for the traveling public.  A burgeoning challenge for Caltrans and other transportation agencies in maintaining transportation systems is the impacts from climate change and extreme weather events.  Potential impacts to the State Highway System include flooding, landslides, sea level rise, washouts, pavement deterioration, and increased wildfires.  In response to these impacts, the Caltrans Climate Change Branch coordinates mitigation and adaptation efforts to ensure the State Highway System is safe and efficient. 

Below is information on how the climate is changing in California, how it is impacting the transportation system and what Caltrans is doing in response. 


Climate Change Questions and Answers

flooded mountain road

burning mountain

big sur

What is the difference between weather and climate?

How is the climate in California changing?

Possible impacts of climate change and extreme weather events on the transportation system in California.

California's transportation system extends through deserts, mountains, coastal areas and floodplains and will therefore experience a range of impacts as the climate changes.  Climate change has many potential effects to our transportation networks:

  • Intense storms may cause flooding of roadways and washout of transportation infrastructure.
  • Sea level rise is already affecting some of California's roads and bridges by undermining (scouring) the supports.  Roads along the coast are also vulnerable to damage from flooding.
  • As wildfires increase, slopes near transportation networks can become more unstable and prone to landslides during rainstorms.
  • Higher temperatures and longer heat spells will likely increase the buckling and rutting of roads, warping of rails, and difficulty in maintaining and constructing roads during the day.
  • Sea ports and low lying airports (San Francisco, Oakland, and San Diego) are also susceptible to sea level rise associated with the warming climate.  Many ports and airports have begun taking action to protect against sea level rise by strengthening their barriers.

Why is Caltrans concerned with climate change?

Caltrans' responsibility for maintaining the State Highway System's 50,000+ lane miles requires continual monitoring and repair of the roads, highways, bridges and other infrastructure.  Climate change will increase the stress these facilities experience and will require more durable materials and more frequent repairs.  For example, in the San Francisco Bay, State Route 37 is currently at risk of failure due to sea level rise, while roads in Fresno are wearing more quickly due to the increase in the length and temperature of heat waves. 

Caltrans is especially concerned with extreme weather events – consecutive days of high temperature, heavy rainstorms, storm surges, and high winds.  While infrastructure is often designed to withstand certain types and frequencies of extreme weather, climate change will likely increase the severity and duration of these events thereby necessitating a State Highway System capable of withstanding harsher conditions.  Since California's economy depends on a well-functioning highway system, Caltrans is currently working to identify and strengthen areas that are vulnerable to climate change and extreme weather impacts.

What is Caltrans doing in response to climate change and extreme weather events?

At Caltrans, we are focused on doing our part to mitigate GHG emissions from our operations and adapt to the changing climate to ensure that the State Highway System is safe for the traveling public.  In 2013, Caltrans released "Caltrans Activities to Address Climate Change - Reducing Greenhouse Gas Emissions and Adapting to Impacts" – a report that highlights Caltrans' statewide actions to reduce greenhouse gases.

Caltrans recently completed a vulnerability assessment in District 1 (Humboldt, Mendocino, Del Norte, and Lake counties), and will assess eight out of the eleven remaining districts by 2017.  These assessments will identify the sections of the highway system at highest risk to extreme weather events related to climate change.  Using the results, Caltrans will prioritize sections of the highway system for adaptation planning and strengthening.  In addition, Caltrans engineers have already begun incorporating more resilient designs for long-life projects in anticipation of increased future climate stressors.  These actions will help Caltrans to reduce maintenance costs and will keep the State Highway System functioning effectively and efficiently. 

Please click here to see examples of Caltrans' climate change projects and studies.


Program Contacts

Tracey Frost
Chief, Office of Smart Mobility and Climate Change
(916) 654-8175
Reza Navai
Assistant Division Chief
(916) 654-3330
Julia Biggar
Senior Transportation Planner
(916) 654-6344

Dillon Miner
Associate Transportation Planner
(916) 653-4287


Associate Transportation Planner