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  6. Chapter 16 - Climate Change

Chapter 16 - Climate Change

16.1 What Does This Topic Include?

This topic covers the regulatory framework, an overview and background for general climate change (greenhouse gas [GHG] emissions and adaptation) and recommended procedures for conducting climate change analysis. This topic also covers evaluation for projects on the State Highway System for which Caltrans is the lead agency under the California Environmental Quality Act (CEQA). The primary GHG emissions associated with transportation projects are discussed as well as anticipated changes in future climate conditions. Preparation of the climate change section of the environmental document, including analysis requirements, is discussed in detail. There is also guidance on making determinations for the CEQA checklist GHG questions and addressing sea level rise and other climate change considerations for projects.

16.2 Definitions

The following terms are commonly used in the discussion and analysis of climate change and adaptation. Several definitions are adopted from California's Fourth Climate Change Assessment (2018), Paying it Forward: The Path Toward Climate-Safe Infrastructure in California (2018), and Planning and Investing for a Resilient California: A Guidebook for State Agencies (2017).

Term Definition
Adaptation Adjustment in natural or human systems in response to actual or expected climatic stimuli or their effects, which moderates harm or exploits beneficial opportunities. Planning for and responding to impacts to reduce vulnerability and increase resilience. Adaption strategies may include protect, accommodate, or retreat.
Adaptive Capacity The combination of the strengths, attributes, and resources available to an individual, community, society, or organization that can be used to prepare for and undertake actions to reduce adverse impacts, moderate harm, or exploit beneficial opportunities.” Notably, disadvantaged communities have fewer resources and face socioeconomic disadvantages compared to affluent communities which presents unique challenges for these communities when adjusting to changing conditions, responding to challenges, and recovering from disruptions.
Anthropogenic The term "anthropogenic" in the context of GHG inventories, refers to GHG emissions that are a direct result of human activities or are the result of natural processes that have been affected by human activities.
Avoidance and minimization measures Actions to further reduce effects (National Environmental Policy Act [NEPA]) or less-than-significant impacts (CEQA).
CEQA mitigation Actions to reduce significant impacts under CEQA to less than significant.
Climate change Atmospheric changes caused by global warming (or cooling) including changes in hot and cold weather, average sea level, ocean water composition, and amounts and timing of rain and snow.
Climate change mitigation The act of reducing or preventing the release of GHG into the atmosphere, with the goal of making the effects of climate change less severe.
Climate-safe infrastructure Infrastructure that is sustainable, adaptive, and meets design criteria to enhance resilience in response to current and future conditions of disruptive climate-related stressors.
Exposure The presence of people, infrastructure, natural systems, and economic, cultural, and social resources in areas that are subject to harm.
Global warming An increase in average global temperature that results from increasing GHG emissions, mostly from human activities.
Greenhouse effect Warming of the Earth caused by excess accumulation of GHGs that slow the rate at which energy escapes to space, like a blanket insulating the planet.
GHGs Gases in the atmosphere that absorb the sun's energy to moderate the temperature of the atmosphere. GHGs include carbon dioxide, methane, nitrous oxide, water vapor, and fluorinated gases. Each gas has a different capacity to trap heat.
Resilience The capacity of any entity—an individual, a community, an organization, or a natural system—to prepare for disruptions, to recover from shocks and stresses, and to adapt and grow from a disruptive experience. Adaptation actions contribute to increasing resilience, which is a desired outcome or state of being.
Sensitivity The level to which a species, natural system, or community, government, etc., would be affected by changing climate conditions.
Vulnerability The susceptibility to harm from exposure to stresses associated with environmental and social change and from the absence of capacity to adapt. Vulnerability can increase because of physical (built and environmental), social, political, and/or economic factor(s). These factors include, but are not limited to ethnicity, class, sexual orientation and identification, national origin, and income inequality. Vulnerability is often defined as the combination of sensitivity and adaptive capacity as affected by the level of exposure to a changing climate.

16.3 Background

16.3.1 Climate Change Basics

Climate change refers to long-term changes in temperature, precipitation, wind patterns, and other elements of the Earth's climate system. The research of the Intergovernmental Panel on Climate Change and other scientists over recent decades has unequivocally attributed an accelerated rate of climatological changes over the past 150 years to GHG emissions generated from the production and use of fossil fuels. Human activities generate GHGs consisting primarily of carbon dioxide, methane, nitrous oxide, tetrafluoromethane, hexafluoroethane, sulfur hexafluoride, and various hydrofluorocarbons. Carbon dioxide is the most abundant GHG; while it is a naturally occurring and necessary component of Earth's atmosphere, fossil-fuel combustion is the main source of additional, human-generated carbon dioxide that is the main driver of climate change. In the United States (U.S.) and in California, transportation is the largest source of GHG emissions, consisting mostly of carbon dioxide.

In California and elsewhere, the impacts of climate change are already being observed in the form of sea level rise, drought, extended and increasingly severe fire seasons, and historic flooding from changing storm patterns. The most important strategy to address climate change is to reduce GHG emissions. California has been innovative and proactive in addressing GHG emissions and climate change by passing multiple senate and assembly bills and executive orders. To comply with legislation and policies, Caltrans must demonstrate how projects will be adapted or resilient to climate change effects. Addressing vulnerabilities in the transportation system involves long-term planning and risk management. This process must begin in the earliest stages of system planning and project initiation.

16.3.2 State and National GHG Emissions Inventories

The California Air Resources Board (CARB) collects GHG emissions data for transportation, electricity, commercial/residential, industrial, agricultural, and waste management sectors each year. It then summarizes and highlights major annual changes and trends to demonstrate the state's progress in meeting its GHG reduction goals, and posts annual reports and data on its California Greenhouse Gas Emission Inventory Program webpages.

Assembly Bill (AB) 32 required CARB to develop a Scoping Plan that describes the approach California will take to achieve the goal of reducing GHG emissions to 1990 levels by 2020, and to update it every 5 years. CARB adopted the first scoping plan in 2008. The second updated plan, California's 2017 Climate Change Scoping Plan, adopted on December 14, 2017, reflects the 2030 target established in Executive Order (EO) B-30-15 and Senate Bill (SB) 32. The third updated plan, 2022 Scoping Plan for Achieving Carbon Neutrality, identifies a technologically feasible, cost-effective path to achieve carbon neutrality by 2045 and a reduction in anthropogenic emissions by 85 percent below 1990 levels, per AB 1279. The AB 32 Scoping Plan and the subsequent updates contain the main strategies California will use to reduce GHG emissions.

The U.S. Environmental Protection Agency (U.S. EPA) conducts nationwide GHG data collection and publishes an annual Inventory of U.S. Greenhouse Gas Emissions and Sinks.

When preparing the GHG analysis for environmental documents, check both the CARB and U.S. EPA sites against the Caltrans Climate Change Annotated Outlines on the SER Forms and Templates page to ensure you are presenting the latest information.

According to the Intergovernmental Panel on Climate Changes' Sixth Assessment in Climate Change 2023 Synthesis Report: Summary for Policymakers, human activities have unequivocally caused global warming, mainly due to the emissions of GHGs. Global average air and ocean temperatures as well as global average sea level have risen, while amounts of snow and ice have decreased. The Intergovernmental Panel on Climate Change's Sixth Assessment concludes with high confidence that “global surface temperature has increased faster since 1970 than in any other 50-year period over at least the last 2,000 years.” Additionally, the Sixth Assessment states that global surface temperature has very likely increased 1.1 degrees Celsius above 1850–1900 in 2011–2020. Further, global net anthropogenic GHG emissions in 2019 were estimated to be about 12% higher than in 2010 and 54% higher than in 1990, “with the largest share and growth in total GHG emissions occurring in CO2 [carbon dioxide] from fossil fuels combustion and industrial processes” as stated in the Sixth Assessment.

In the 2018 California Fourth Climate Change Assessment, similar effects are described. Based on projections using state-of-the-art climate modeling, temperatures are expected to rise between 5.6- and 8.8-degrees Fahrenheit by the end of the century, depending on the level of GHG emissions. In addition, the report projects up to a two-third decline in water supply from snowpack resulting in water shortages; a 77% increase in average area burned by wildfire; and large-scale erosion of up to 67% of Southern California beaches due to sea level rise. Sea level rise is a particular concern for transportation infrastructure in California's coastal zone. According to recent modeling in the Fourth Assessment, by the year 2100, roughly 370 miles of coastal highways will be vulnerable to flooding in a 100-year storm event, and roughly 3,780 miles could be exposed to temporary flooding. The Fourth Assessment's findings highlight the need for proactive action to address these current and future impacts of climate change. The report states that these temperature increases will have negative impacts on public health, water supply, agriculture, plant and animal species, and the coastline. The Fifth Assessment is underway and the update will be finalized in 2026.

According to the California Climate Change Center, Our Changing Climate: Assessing the Risks to California, climate change is also expected to decrease snowfall and winter snowpack; change precipitation patterns and increase the frequency, intensity, and duration of extreme storms; and increase extreme heat conditions. These changes can affect California's transportation system by leading to increased risk of flooding, slope failure, and landslides that block roadways; cause heat damage to roads, railroad tracks, and bridge joints; and result in system disruptions from washouts and wildfire.

Climate change may also exacerbate the indirect effects of projects on resources. For instance, when a project reduces the area of important habitat, remaining habitat may be further impaired by warming or reduced precipitation.

16.3.3 Project Impacts on Climate Change

Projects affect climate change by directly and indirectly generating GHG emissions. GHG emissions from transportation projects can be divided into those produced during operation and use of the State Highway System (operational emissions) and those produced during construction. The primary GHGs produced by the transportation sector are carbon dioxide, methane, nitrous oxide, and hydrofluorocarbons. Carbon dioxide emissions are a product of burning gasoline or diesel fuel in internal combustion engines, along with relatively small amounts of methane and nitrous oxide. A small amount of hydrofluorocarbon emissions related to refrigeration is also included in the transportation sector.

CEQA Guidelines generally address GHG emissions as a cumulative impact due to the global nature of climate change (Public Resources Code, § 21083[b][2]). As the California Supreme Court explained in Cleveland National Forest Foundation v. San Diego Assn. of Governments (2017), “because of the global scale of climate change, any one project's contribution is unlikely to be significant by itself.”

16.3.4 Adaptation

Reducing GHG emissions is only one part of an approach to addressing climate change. The state must plan for the effects of climate change on the state's transportation infrastructure and strengthen or protect transportation facilities from damage. Projects must plan for and address threats to transportation assets from sea level rise, precipitation and riverine flooding, wildfire, and temperature.

Climate change is expected to produce increased variability in precipitation, rising temperatures, rising sea levels, variability in storm surges and their intensity, and in wildfire frequency and intensity. Flooding and erosion can damage or wash out roads; longer periods of intense heat can buckle pavement and railroad tracks; storm surges combined with a rising sea level can inundate highways. Wildfire can directly burn facilities and indirectly cause damage when rain falls on denuded slopes that landslide after a fire. Effects will vary by location and may, in the most extreme cases, require that a facility be relocated or redesigned. Furthermore, the combined effects of transportation projects and climate stressors can exacerbate the impacts of both on vulnerable communities in a project area. Accordingly, Caltrans must consider these types of climate stressors in how highways are planned, designed, built, operated, and maintained.

Climate change adaptation for transportation infrastructure involves long-term planning and risk management to address vulnerabilities in the transportation system. California's Fourth Climate Change Assessment (2018) is the state's effort to “translate the state of climate science into useful information for action” in a variety of sectors at both statewide and local scales.

16.3.5 Key Case Law Decisions

16.4 Laws, Regulations, and Guidance Related to Climate Change (GHG and Adaptation)

See also SER, Chapter 1, "Federal Requirements" and Chapter 2, "State Requirements" for laws and regulations that apply to all environmental analysis activities.

The primary laws and guidance related to GHG emissions and climate change stem from California state legislation, like AB 32, SB 32, and AB 1279. Additionally, the U.S. EPA and National Highway Traffic Safety Administration implement fuel efficiency standards that directly affect GHG emissions. The U.S. has also submitted a Nationally Determined Contribution under the Paris Agreement, aiming to reduce national GHG emissions by 50 to 52 percent by 2030 from 2005 levels.

Under state law, CEQA mandates an analysis of project-generated GHG emissions, including cumulative impacts due to the global nature of climate change (Public Resources Code, § 21083[b][2]). The California Supreme Court in Cleveland National Forest Foundation v. San Diego Assn. of Governments (2017) has noted that due to the global scale of climate change, any single project's contribution is unlikely to be significant by itself. In assessing cumulative impacts, it must be determined if a project's incremental effect is “cumulatively considerable” (CEQA Guidelines Sections 15064[h][1]) and 15130). To make this determination, the incremental impacts of the project must be compared with the effects of past, current, and probable future projects. Although climate change is ultimately a cumulative impact, not every individual project that emits GHGs must necessarily be found to contribute to a significant cumulative impact on the environment.

Analysis of GHG emissions can be described as the impact of the transportation system on the environment, while impacts related to climate stressors may be considered the impact of the environment on the project. At this time, analysis of potential climate change impacts to the project is not explicitly required under CEQA, unless the project will exacerbate the impacts of those stressors. However, state agencies are required to consider climate change in all planning and investment decisions, pursuant to EO B-30-15 and subsequent policies.

The following laws, regulations, orders, and guidance are relevant to the analysis of GHG emission and climate change impacts. Additional regulatory information is provided below under Regulatory Setting.

16.4.1 Federal Laws, Regulations, and Orders

16.4.1.1 GHG Emissions

16.4.1.2 Adaptation and Climate Change

16.4.2 State Laws, Regulations, and Orders

16.4.2.1 GHG Emissions

  • EO S-3-05 (2005) – Established a GHG emission reduction target for California to reduce GHG emissions to 80 percent below 1990 levels by 2050.
  • AB 32 (2006) –Set a target for 2020 GHG levels to be reduced to 1990 levels.
  • EO S-20-06 (2006) – Directs state departments to implement a cap-and-trade program.
  • SB 97 (2007) – Requires the Governor’s Office of Land Use and Climate Innovation (formerly the Governor's Office of Planning and Research) to prepare CEQA guidelines for the mitigation of GHG emissions, including, but not limited to, effects associated with transportation or energy consumption.
  • EO S-01-07 (2007) – Formally established the Low Carbon Fuel Standard and directs CARB to determine if a Low Carbon Fuel Standard can be adopted pursuant to AB 32. In 2009, CARB introduced the Low Carbon Fuel Standard, and it took effect in 2011.
  • EO B-18-12 (2012) – Directs state agencies, through green building practices, to use energy, water, and materials efficiently throughout the building life cycle, and enhance indoor and outdoor air quality.
  • EO B-30-15 (2015) – Established a new interim GHG reduction target of 40 percent below 1990 levels and directed state agencies to take additional actions to prepare for the impacts of climate change. EO B-30-15 also recognizes that effects of climate change threaten California's infrastructure and requires state agencies to factor climate change into all planning and investment decisions. Under this EO, the Governor's Office of Land Use and Climate Innovation (formerly the Governor's Office of Planning and Research) published Planning and Investing for a Resilient California: A Guidebook for State Agencies, to encourage a uniform and systematic approach to building resilience.
  • SB 32 (2016) – Increased and extended the emission reduction mandate to 40 percent below 1990 levels by 2030.
  • AB 134 (2017) – Takes $900 million of funds derived from auctioning off carbon allowances and puts it into incentives for reducing emissions from cars, trucks, buses, and other engines.
  • EO B-55-18 (2018) – Set a statewide target to achieve carbon neutrality no later than 2045.
  • EO N-19-19 (2019) – Requires every aspect of state government redouble its efforts to reduce GHG emissions and mitigate the impacts of climate change while building a sustainable, inclusive economy.
  • AB 1279 (2022) – The California Climate Crisis Act: Mandates carbon neutrality by 2045. Solidifies a goal included in EO B-55-18. Requires the state board to work with relevant state agencies to ensure that updates to the scoping plan identify and recommend measures to achieve these policy goals and to identify and implement a variety of policies and strategies that enable carbon dioxide removal solutions and carbon capture, utilization, and storage technologies in California, as specified.
  • AB 1493 (2022) – Directs CARB to set carbon-dioxide emission standards from vehicle exhaust to "achieve the maximum feasible reduction of greenhouse gases" from cars, light-duty trucks, and other non-commercial vehicles.

16.4.2.2 Adaptation and Climate Change

  • McAteer-Petris Act (1965), Government Code Title 7.2 – The San Francisco Bay Conservation and Development Commission (BCDC) administers permits for projects in the coastal zone which includes most transportation projects along the Bay's nine-county shoreline wherein projects must demonstrate consistency with the Bay Plan's 8 Policies; expectations for climate change including sea level rise is provided in the 2021 Guidance on the Bay Plan policies on climate change. BCDC also coordinates with local governments, regional councils of government, and other agencies and interested parties in development of regional climate change adaptation strategies as part of the Adapting to Rising Tides program.
  • Porter-Cologne Water Quality Control Act (1969), Water Code Division 7 and Related Sections – For sea level rise, as part of the Bay Area Basin Plan Amendment adopted in July 2022, Signed Resolution R2-2022-0027 contains a set of questions to support climate change and adaptation considerations that minimize adverse impacts to the aquatic ecosystem in permitting necessary for fill or dredge activities.
  • California Coastal Act (1976), Public Resources Code Division 20 – The primary law governing coastal management, land use and development, public access and recreation, and protection of coastal resources in the Coastal Zone. The California Coastal Commission and local agencies with certified Local Coastal Programs will evaluate how sea level rise was analyzed throughout the Caltrans project development process when Coastal Development Permits are required for Caltrans projects (Sections 30001.5[f] and 30421). The Coastal Commission bases its standard of review for Coastal Development Permits on the Chapter 3 policies, Sections 30235, 30236, and 30253 focus on coastal hazards and shoreline development. Specific to transportation, section 30253(d) requires that vehicle miles traveled (VMT) be minimized.
  • SB 375 (2008) – Gave CARB authority over sources of GHG emissions, including cars and light trucks and directed CARB to set regional targets for reducing GHG emissions.
  • EO S-13-08 (2008) – Directs state agencies to consider sea level rise scenarios for 2050 and 2100 during planning to assess project vulnerabilities, reduce risks, and increase resilience to sea level rise. It gave rise to the 2009 California Climate Adaptation Strategy, the Safeguarding California Plan, and a series of technical reports on statewide sea level rise projections and risks. The reports addressed the full range of climate change impacts and recommended adaptation strategies. The current California Climate Adaptation Strategy incorporates key elements of the latest sector-specific plans such as the Natural and Working Lands Climate Smart Strategy, Wildfire and Forest Resilience Action Plan, Water Resilience Portfolio, and the California State Transportation Agency's Climate Action Plan for Transportation Infrastructure.
  • SB 391 (2009) – Required Caltrans to update the California Transportation Plan by December 31, 2015, and every 5 years thereafter. The bill required the plan to address how the state will achieve maximum feasible emissions reductions in order to attain a statewide reduction of GHG emissions to 1990 levels by 2020 and 80% below 1990 levels by 2050.
  • EO B-16-12 (2012) – Directed state government to help accelerate the market for zero-emission vehicles in California and calling for 1.5 million zero-emission vehicles in California by 2025.
  • SB 743 (2013) – Requires the amount of driving and length of trips – as measured by VMT (instead of being based on the potential increase in traffic) – be used to assess transportation impacts on the environment for CEQA review. 
  • AB 1482 (2015) – Requires state agencies to maximize specified objectives, including, among others, promoting the use of the climate adaptation strategy to inform planning decisions and ensure that state investments consider climate change impacts, as well as promote the use of natural systems and natural infrastructure, as defined, when developing physical infrastructure to address adaptation.
  • SB 379 (2015) – Requires local General Plans to include climate change vulnerability assessments, measures to address vulnerabilities, and a comprehensive hazard mitigation and emergency response strategy.
  • SB 1386 (2016) – Declares it to be state policy that protecting and managing natural and working lands is key to meeting California's climate change goals and directs all relevant state agencies to consider this policy when conducting their work.
  • AB 2800 (2016) – Requires state agencies to take into account the current and future impacts of climate change when planning, designing, building, operating, maintaining, and investing in state infrastructure.
  • SB 150 (2017) – Requires CARB to prepare a report to the Legislature starting in 2018, and every four years thereafter, to discuss progress related to the Sustainable Communities Act, or SB 375, implementation. This progress report uses data-supported metrics to assess progress on transportation, housing, and land use strategies, identifies best practices and challenges to achieving greater reductions, and discusses the impact of state policies and funding.
  • SB 1 Transportation Funding (2017) – To the extent deemed cost effective, and where feasible, in the context of both the project scope and the risk level for the asset due to global climate change, Caltrans and cities and counties receiving funds under the program shall include features in the projects funded by the program to better adapt the asset to withstand the negative effects of climate change and make the asset more resilient to impacts such as fires, floods, and sea level rise.
  • EO B-52-18 (2018) – Establishes a goal of treating 500,000 acres of vegetation per year to reduce wildfire risk.
  • EO N-82-20 (2020) – Directs the State to accelerate and expand use of nature-based solutions while mitigating GHG emissions to adapt and become more resilient to the impacts of climate change through conserving 30 percent of California's land and coastal waters by 2030.
  • SB 1 Coastal Resources: Sea Level Rise (2021) – Declared that the impacts of sea level rise are both environmental and economic, including losses to publicly owned infrastructure, such as airports, rail lines, streets and highways, pipelines, wastewater treatment plants, schools, hospitals, and other facilities. The purpose of the declaration is to establish new planning, assessment, funding, and mitigation tools for California to address and respond to sea level rise. As the legislation directed, the California Ocean Protection Council collaborated with 17 state planning and coastal management agencies to develop the State Agency Sea-Level Rise Action Plan for California in February 2024. The California Ocean Protection Council and scientific partners have also published the State of California Sea-Level Rise Guidance every 5 years since 2010, to provide the best available sea-level rise science for state and local decision-making.

16.4.3 Caltrans Climate Change Policies

16.4.3.1 Climate Action Plan for Transportation Infrastructure

The California Action Plan for Transportation Infrastructure (CAPTI) builds on EOs signed by Governor Newsom in 2019 and 2020 targeted at reducing GHG emissions in transportation, which account for more than 40 percent of all polluting emissions, to reach the state's climate goals. Under CAPTI 2.0, where feasible and within existing funding program structures, the state will invest discretionary transportation funds in sustainable infrastructure projects that align with its climate, health, and social equity goals. It includes a commitment to working towards VMT/GHG neutrality in key state transportation programs.

16.4.3.2 California Transportation Plan

The California Transportation Plan (CTP) 2050 is a statewide, long-range transportation plan to meet our future mobility needs and reduce GHG emissions. It serves as an umbrella document for all the other statewide transportation planning documents. The CTP 2050 presents a vision of a safe, resilient, and universally accessible transportation system that supports vibrant communities, advances racial and economic justice, and improves public and environmental health. The plan's climate goal is to achieve statewide GHG emissions reduction targets and increase resilience to climate change. It demonstrates how GHG emissions from the transportation sector can be reduced through advancements in clean fuel technologies; continued shifts toward active travel, transit, and shared mobility; more efficient land use and development practices; and continued shifts to telework.

SB 391 requires the CTP to meet California's climate change goals under AB 32. Accordingly, the CTP identifies the statewide transportation system needed to achieve maximum feasible GHG emission reductions while meeting the state's transportation needs. While Metropolitan Planning Organizations have primary responsibility for identifying land use patterns to help reduce GHG emissions, the CTP identifies additional strategies.

16.4.3.3 Caltrans Strategic Plan

The Caltrans 2024–2028 Strategic Plan outlines goals centered on safety, climate action, equity, and stewardship. Climate-related strategies include implementing the Caltrans Climate Action Plan; expanding climate education, training, and outreach; strengthening partnerships to support climate resilience; promoting sustainable transportation solutions that reduce emissions; and continuing to engage underserved and disproportionately impacted communities in climate planning and implementation.

16.4.3.4 Funding and Technical Assistance Programs

In addition to developing plans and performance targets to reduce GHG emissions, Caltrans also administers several Sustainable Transportation Planning Grants. These grants encourage and support projects that improve local and statewide infrastructure climate resiliency along with the development of multimodal transportation and other adaptation strategies. This also includes technical assistance projects for under-resourced and climate vulnerable communities to perform climate adaptation planning.

16.4.3.5 Caltrans Policy Directives and Other Initiatives

Caltrans Director's Policy 30 (DP-30) Climate Change (June 22, 2012) established a Caltrans policy to ensure coordinated efforts to incorporate climate change into Caltrans' decisions and activities.

The Caltrans Greenhouse Gas Emissions and Mitigation Report (2020), (found under the Technical Resources, Tools and Training tab) provides a comprehensive overview of Caltrans' emissions. The report documents and evaluates current Caltrans procedures and activities that track and reduce GHG emissions and identifies additional opportunities for further reducing GHG emissions from Caltrans-controlled emission sources, in support of Caltrans and state goals.

16.4.3.6 Caltrans Climate Change Vulnerability Assessments

Caltrans conducted climate change vulnerability assessments to identify segments of the State Highway System vulnerable to climate change effects including precipitation, temperature, wildfire, storm surge, and sea level rise. The approach to the vulnerability assessments was tailored to the practices of a transportation agency, and involves the following concepts and actions:

  • Exposure – Identify Caltrans assets exposed to damage or reduced service life from expected future conditions.
  • Consequence – Determine what might occur to system assets in terms of loss of use or costs of repair.
  • Prioritization – Develop a method for making capital programming decisions to address identified risks, including considerations of system use and/or timing of expected exposure.

The climate change data in the assessments were developed in coordination with climate change scientists and experts at federal, state, and regional organizations at the forefront of climate science. The findings of the vulnerability assessments will guide analysis of at-risk assets and development of adaptation plans to reduce the likelihood of damage to the State Highway System, allowing Caltrans to both reduce the costs of storm damage and to provide and maintain transportation that meets the needs of all Californians. The Caltrans Vulnerability Assessments accompanying interactive maps for each district are posted on the 2019 Climate Change Vulnerability Assessments page.  

16.4.3.7 District-specific Adaptation Priorities Reports

The District Adaptation Priorities Reports (2020) were the next phase in addressing climate change after the Vulnerability Assessment was completed. This report aims to prioritize District assets that will be exposed to climate hazards through a detailed asset-level climate assessment. The climate hazards used in this report's prioritization methodology are temperature, riverine flooding, wildfire, sea level rise, storm surge, and cliff retreat. Priority scores were generated for each potentially exposed asset, ranging from 1 through 5. The higher the score, the greater the adaptation priority of the asset. This report focused on bridges, large culverts, small culverts, and roadways. District-specific Adaptation Priorities Reports were prepared in 2020 and can be found on the Division of Transportation Planning's page.

16.5 Information Needed for Project Delivery

16.5.1 Regional Transportation Plan

The Regional Transportation Plan (RTP) and corresponding environmental document prepared by the Metropolitan Planning Organization or Regional Transportation Planning Agency provide information that should inform the project's climate change analysis and serve as a building block in subsequent decision making.

  • The RTP establishes a purpose and need for regionally significant projects.
  • Identify if your project is included in a current or prior RTP.
  • The RTP or its Environmental Impact Report (EIR) may provide recommendations of project-level mitigation measures for GHGs and for other resources that could co-benefit GHG reduction. These measures should be considered and adapted for inclusion in your project and listed in the Project-Level GHG Reduction Strategies section of the climate change chapter and in the environmental commitments record.

16.5.2 Early Coordination with the Project Development Team

Consideration of potential GHG and climate change impacts should begin as early in the project development process as possible. The district Environmental Generalist should bring climate change issues to the attention of the Project Development Team at the first team meeting. Considerations include ensuring the appropriate level of analysis of GHG emissions for the project (quantitative or qualitative) and screening for and addressing the impacts of climate change (e.g., sea level rise, changing precipitation, wildfire risk). Changes in design, materials, project features, and other adaptive or preventive measures that would protect the asset and the environment, including potential for location change, are best scoped into the project at the earliest planning stages. Hydraulics, traffic, construction, landscape, and maintenance functions may need to augment their analysis and reporting methods to address climate change concerns, which could require additional resources. Necessary resources should be accounted for in the Project Initiation Document (PID), Preliminary Environmental Analysis Report (PEAR) or Mini-PEAR, and Transportation Planning Scoping Information Sheets. Appropriate resource-specific best management practices and specifications that help reduce GHG emissions or promote resilience should also be scoped at this stage.

16.5.3 Early Coordination with Regulatory Agencies

Caltrans coordinates with other state agencies to obtain various permits for Caltrans projects that may have an impact on the environment. Under AB 1282, Caltrans participated in a multi-agency Transportation Permitting Task Force to develop a structured coordination process for early engagement with permitting agencies to streamline the processing of permit applications for transportation projects. “Early” is defined as the period from the planning/scoping phase of an individual project (e.g., PID or Preliminary Environmental Study (PES) process) through the completion of the draft environmental document or prior to issuing a CEQA exemption. For simple projects or those that do not require permits, early coordination is optional. It is, however, advisable for all projects to consult with both state and local agencies with jurisdiction in a project area to coordinate with regional or local climate change adaptation plans and efforts as well as to ensure Caltrans' documentation will meet permitting requirements. For further guidance on coordination, please see the Caltrans Coastal Program webpage and the AB 1282 Transportation Permitting Task Force 2019 Final Report.

16.5.4 Interagency Coordination

16.5.4.1 GHG Emissions

With respect to GHG emissions, Caltrans has the primary responsibility for the climate change/GHG analysis and oversight (advisory) responsibility for Caltrans projects on the State Highway System. No interagency coordination on GHG analysis specifically is required by state or federal regulations.

16.5.4.2 Adaptation

California legislation and EOs such as those listed in the Laws, Regulations, and Guidance section above direct state agencies to consider climate change in general and sea level rise in their planning and investment decisions. Accordingly, Caltrans has implemented policies to consider and report the potential effects of climate change on projects and must endeavor to design assets to be protected from or resilient to climate-related impacts.

16.5.5 Reporting

16.5.5.1 GHG Emissions

No technical reports for GHG emissions are mandated by state or federal law. For projects that increase capacity or are highly controversial, Caltrans requires a quantitative analysis of changes in operational GHG emissions. It should generally be presented in the body of the environmental document, but a complex or lengthy analysis may also be prepared as a separate technical report or memo using the GHG analysis section of the Climate Change Annotated Outline as a guide. If creating a standalone document, include a summary project description to provide context for the climate change analysis. The results may then be summarized in the environmental document to support the CEQA significance determination.

All projects must report construction GHG emissions in the environmental document, including CEQA exemptions (CE). GHG emissions are generally calculated at the PID phase or in the air quality report or memo or can be requested from the project's air quality specialist. Include the results in the CE along with any Standard Specifications and project avoidance and minimization measures that co-benefit GHG emissions. Preserve the air quality report or memo in the project file. Additional information on analysis methods is presented below under Information Needed for Environmental Document.

16.5.5.2 Adaptation

All projects must conduct a project-level adaptation analysis to demonstrate the project's resilience to future climate change effects. For projects within the Coastal Zone (requiring approval of a coastal development permit, Local Coastal Program amendment); requiring approval from BCDC; or in a location subject to sea level rise (e.g., within the Sacramento-San Joaquin River Delta region), a sea level rise analysis is required. Environmental documents must include a discussion of sea level rise risks and adaptation measures, as instructed in the Climate Change Annotated Outlines. The sea level rise risk assessment and analysis should be developed in phases from the earliest planning stages, and the decision-making process and conclusions reported in the environmental document. For projects requiring specialized studies such as wave run-up or other risk factors, a separate sea level rise technical report may be warranted. Consult the Caltrans Sea-Level Rise Guidance Update (in preparation) for detailed guidance on sea level rise analysis.

16.5.6 Processing and Approval of Technical Reports

Submit the climate change chapter of the environmental document, the separate GHG and/or sea level rise technical reports if applicable, and other supporting documents to the district climate change reviewer. Technical reports may be submitted for review prior to or concurrent with preparation of the environmental document.

16.5.7 Project Initiation Document

The following information should be included in the Energy and Climate Change section of the PEAR prepared as part of the PID.

  • Acknowledge the potential for construction activities or operations to result in GHG emissions and identify potential GHG reduction strategies.
  • Determine the need for a quantitative operational GHG analysis. Scope time and resources needed.
  • Identify if the project is within the Coastal Zone or in a location subject to sea level rise, and therefore will require a sea level rise analysis. Scope necessary time and resources.
  • Identify if the project/project limits will be at risk due to projected climate stressors. Risks and proposed adaptation measures should be included in the PID.
  • Plan and resource any needed early coordination meetings.

16.5.8 Draft Project Report

This is the stage where the bulk of GHG/climate change analysis is done. Detailed analyses for all viable alternatives and the no-build alternative are completed. If a sea level rise analysis is required, it would be completed and or refined at this stage. The following information should be included in the draft environmental document (DED) or used as supporting documentation for a CE, as appropriate.

  • Identify project-level strategies that will be implemented to reduce GHG emissions and adapt to future anticipated climate change impacts in the draft project report. Summarize information that has been identified within the environmental document. 

16.5.9 Draft and Final Environmental Document

Refer to “Information Needed for Environmental Document” section below.

16.5.10 Project Report

The climate change section may be revised after circulation and public comment on the DED. To the extent that potential impacts or GHG reduction or adaptation strategies change, that information should be reflected in the final environmental document (FED) and final project report.

16.5.11 Environmental Re-evaluation

GHG and climate changes issues should be re-examined and updated as necessary whenever an environmental re-validation is done. This is especially critical for projects that did not include GHG analysis or adaptation discussions in the original environmental document.

16.5.12 Environmental Commitments

The Resident Engineer is responsible for ensuring all environmental commitments are implemented. An Environmental Commitment is a measure that Caltrans or a local agency commits to implement to avoid, minimize and/or mitigate a real or potential environmental impact. It can be identified as early as the planning and scoping stages, during the environmental document or design processes, or as late as construction or maintenance of a project. These commitments may include permit conditions along with project specific GHG reduction measures. These are listed in the Environmental Commitments Record.

Typical environmental commitments related to Climate Change include:

  • According to the Caltrans's Standard Specifications, the contractor must comply with all local Air Quality Management District rules, ordinances, and regulations for air quality restrictions.
  • The contractor will use diesel construction equipment meeting CARB's Tier 2 certified engines or cleaner off-road heavy-duty diesel engines and comply with the State Off-Road Regulation.
  • The contractor will use on-road heavy-duty trucks that meet CARB's 2007 or cleaner certification standard for on-road heavy duty diesel engines and comply with the State Off-Road Regulation.
  • All on and off-road diesel equipment shall not idle for more than 5 minutes. Signs shall be posted in the designated queuing areas and or job sites to remind drivers and operators of the 5-minute idling limit.
  • The contractor shall use electric equipment in place of diesel-powered equipment, where feasible.
  • The contractor will substitute gasoline-powered in place of diesel-powered equipment, where feasible.
  • The contractor shall use alternatively fueled construction equipment onsite where feasible, such as compressed natural gas, liquefied natural gas, propane or biodiesel.
  • Incorporate complete streets elements such as pedestrian and bicycle facilities.
  • Incorporate the use of energy-efficient lighting, such as LED traffic signals. LED bulbs cost $60 to $70 each, but last five to six years, compared to the one-year average lifespan of the incandescent bulbs previously used. The LED bulbs themselves consume 10 percent of the electricity of traditional lights, which will also help reduce the project's carbon dioxide emissions.

16.6 Information Needed for Environmental Document

16.6.1 Content and Recommended Format

Caltrans uses a standard format for impact discussions in its environmental documents. See the SER Forms and Templates page for annotated outlines that include Caltrans-approved content and recommended format for the climate change section.

The climate change annotated outline should be used to complete the Climate Change section within the CEQA chapter of documents.

The Climate Change section should discuss the following items, as indicated in the annotated outlines.

  • Regulatory Setting (optional)
  • Environmental Setting
  • Project Analysis
  • Greenhouse Gas Reduction Strategies
  • Adaptation

The two-climate change annotated outlines include the same standard language for all sections except Project Analysis. The content for Project Analysis is different for capacity increasing projects and non-capacity increasing projects, as discussed further below.

16.6.2 Regulatory Setting (optional)

The Climate Change Annotated Outlines include boilerplate language and a brief discussion of the regulatory framework for the analysis, including local, state, and federal laws. A comprehensive list of relevant laws, regulations, and guidance is provided in the Laws, Regulations, and Guidance section above.

16.6.3 Environmental Setting

Describe the project location in general terms, from the perspective of factors that affect transportation GHG emissions, such as urban or rural setting, land uses, development density, traffic congestion, and economy. Identify the transportation agency or regional transportation plan that guides transportation development and addresses GHG emissions in the project area. Recognize that some locations are subject to policies in both metropolitan planning organizations and local regional transportation planning agencies. General and state plan elements may also address GHGs in the project area.

  • Use the standard language in the approved annotated outline to describe current national and state GHG inventories, including figures and statistics. Check the CARB and U.S. EPA GHG emission inventory websites to make sure the information is up to date.
  • Discuss relevant regional plans and their GHG reduction policies or strategies under the Regional Plans subheading. Include, as appropriate, regional or metropolitan transportation plans, climate action plans, general plan elements, and active transportation or bicycle plans.

16.6.4 Project Analysis

Under CEQA (Section 15064.4), the lead agency “should make a good faith effort, based to the extent possible on scientific and factual data, to describe, calculate or estimate the amount of GHG emissions resulting from a project.” The lead agency has the discretion to address GHG emissions from a project through either qualitative or quantitative methods. Under Section 15064.4, the lead agency should also consider 1) the extent to which the project may increase or reduce GHG emissions relative to the existing environmental setting; 2) whether the project emissions exceed a threshold of significance that the lead agency determines applies to the project and 3) the extent to which the project complies with regulations or requirements adopted to implement a statewide, regional, or local plan for the reduction or mitigation of GHG emissions. Note that Caltrans has not established a GHG emissions threshold of significance for Caltrans projects.

Use the following decision tree to assess whether a project requires a quantitative or qualitative GHG analysis.

GHG Analysis Methodology Overview (PDF) | GHG Analysis Methodology Overview (ADA version)

Refer to the Interim Guidance: Determining CEQA Significance for Greenhouse Gas Emissions for Projects on the State Highway System for further instruction on completing the analysis, incorporating GHG reduction measures, and making the CEQA impact determination.

16.6.5 Recommended Methodologies

16.6.5.1 Construction GHG Emissions

GHG emissions related to anticipated construction activities must be calculated for all projects. Use a readily available model such as the California Emissions Estimator Model (CalEEMod) OR the Caltrans Construction Emissions Tool (CAL-CET). Emissions estimates are generally prepared by the project air quality specialist. Include the calculation results in a brief sentence or two stating the expected construction duration and the total expected GHG emissions for the construction period.

Discuss any additional specifications or construction measures included in the project that will further contribute to reducing construction GHG emissions.

16.6.5.2 Operational GHG Emissions

Capacity-Increasing Projects

Capacity-increasing projects require a quantitative analysis using Emission FACtor (CT-EMFAC) and VMT data to estimate operational GHG emissions. Ensure the VMT data in the climate change section are consistent with VMT presented in the traffic and air quality analyses and cite accordingly. Conduct separate model runs for existing/baseline conditions and the horizon/design-year for both the build and no-build alternatives. It is also helpful to include an intermediate year such as the open-to-traffic year. In the discussion, compare the GHG emissions numbers for the alternatives (including the no-build alternative) in the opening year and design-year to existing/baseline emissions. The comparison of design-year to baseline GHG emissions will be the basis of the CEQA impact determination. Also compare the design-year build alternative to the design-year no-build alternative. Reporting VMT here also provides context for discussing whether changes in GHG emissions can be attributed to the project. Revise the table's footnotes as needed. VMT is used in this section as an input for the calculation of GHG emissions. Reporting VMT here also provides context for discussing whether changes in GHG emissions can be attributed to the project. Note that the VMT analysis and discussion of induced travel should be presented in the Traffic/Transportation section, not in the climate change section.

Identify the applicable RTP/Sustainable Communities Strategy that applies to the region in which the proposed project is located. Discuss how the project is designed to reduce VMT, reduce congestion, and/or reduce vehicle time delays, and provide the supporting data. Provide a discussion of the early planning aspects of the project and how the modal choice was made.

Note that CARB has released the latest EMFAC model update, EMFAC2021.

Refer to the Climate Change Capacity Increasing Annotated Outline.

Non-Capacity-Increasing Projects

For non-capacity-increasing projects, provide a qualitative discussion about the operation of the project and the low to no potential for an increase in operational GHG emissions. If the project is a ramp metering or signalization project, provide a discussion of what traffic-smoothing effects the project will have; to the extent that the signal or meter provides a smoother traffic flow, there will likely be an overall reduction in GHGs emitted. If the backup at the ramp meters or signals will be lengthy, then conduct a quantitative analysis using EMFAC as described above for congestion relief/capacity-increasing projects.

Refer to the Climate Change Non-Capacity Increasing Annotated Outline.

Considerations for Maintenance of Roadway Facilities

Project maintenance and owner-operator activities are likely to generate GHG emissions from the operation of fossil-fueled maintenance vehicles and equipment, as well as indirect emissions through electricity generation for any electrical equipment onsite, such as lighting or cameras. Vehicle trips used for maintenance purposes would be temporary, and any generated VMT would generally be minor and limited to maintenance equipment and personnel and would not result in long-term trip generation. There are currently no regulations that require monitoring of GHGs emitted during maintenance or traffic management activities.

16.6.6 CEQA Conclusion

All Caltrans CEQA documents above a CE must make a determination for the two CEQA Appendix G checklist questions for GHGs:

  1. Would the project generate greenhouse gas emissions, either directly or indirectly, that may have a significant impact on the environment?
  2. Would the project conflict with an applicable plan, policy, or regulation adopted for the purpose of reducing the emissions of greenhouse gas?

Refer to the Interim Guidance: Determining CEQA Significance for Greenhouse Gas Emissions for Projects on the State Highway System for step-by-step guidance on making a CEQA significance determination.

16.7 Project-Level GHG Reduction Strategies

Identify and list all feasible measures to reduce project-level GHG emissions from operations and construction. These can include Standard Specifications, Standard Special Provisions, Nonstandard Special Provisions, requirements of the air quality management district, project-specific construction-emissions reduction measures, and measures intended to reduce effects to other environmental resources. The strategies listed in the section are environmental commitments. Accordingly, they must be written as actions with responsible parties (“biddable and buildable”) and recorded in the Environmental Commitments Record or District equivalent. Strategies may come from other resource topics, such as air quality and traffic; and from the relevant RTP, climate action plan, and air quality management district rules or recommendations. Revise them as necessary to read as specific actions that are within Caltrans' control; Caltrans must be able to verify they were implemented at project close-out. (Measures listed under Construction Emissions may be repeated in this section.)

Refer to the Interim Guidance: Determining CEQA Significance for Greenhouse Gas Emissions for Projects on the State Highway System, GHG Reduction Measures Toolbox for Internal Use in Caltrans Project Development, and the Caltrans Greenhouse Gas Emissions and Mitigation Report for potential reduction strategies.

16.8 Project Adaptation Analysis

All Caltrans projects must conduct a project-level adaptation analysis. The environmental document should specifically consider future climate impacts from sea level rise, changes in precipitation and riverine flood risk, changes in high and low temperatures, and increased wildfire risk, as applicable to your District. If your District has a completed a Climate Change Vulnerability Assessment (2019), you may use that information to assess which climate change effects are most likely to occur in your project area. Consult the additional resources and guidance in the Climate Change Annotated Outlines.

Discussion of adaptation measures should also describe environmental resources present in the project location that may benefit from, or be adversely impacted by, project adaptation features or alternatives. Environmental resources could include riparian or tidal wetlands, environmentally sensitive habitat areas, habitat areas for listed or endangered species.

Note that if the project is within the Coastal Zone (requiring approval of a coastal development permit, Local Coastal Program amendment); requires approval from BCDC; or is in a location subject to sea level rise (e.g., within the Sacramento-San Joaquin River Delta region), a sea level rise analysis is required. Use the tools and guidance in the Climate Change Annotated Outlines and the latest Caltrans sea level rise guidance to identify any potential sea level rise impacts that may occur.

For projects specifically within the coastal zone, review SER Volume 5: Coastal Requirements to identify and address typical use restrictions, common concerns addressed through coastal development review, and common technical study requirements. Early coordination with the California Coastal Commission or local coastal program is critical to determine the appropriate level of study and to avoid lengthy project delays. Coordination and analysis of sea level rise should begin in the earliest project planning phase so that the PID and PEAR adequately consider adaptation options/alternatives and account for time and resources needed to complete studies before Project Approval and Environmental Document (PA&ED). Consult with your district transportation planners for help identifying any relevant adaptation studies, feasibility studies, agency coordination efforts, and corridor plans which may include and/or impact the project area.

16.9 Statewide and Caltrans Climate Change Efforts

16.9.1 GHG Reduction Strategies

The following discussion outlines statewide and Caltrans efforts to reduce GHG emissions from transportation projects and should be referenced in the environmental document.

16.9.1.1 Statewide Efforts

In response to AB 32, CARB is implementing the 2022 Scoping Plan for Achieving Carbon Neutrality, which includes measures to achieve emission reductions of GHGs that cause climate change. Climate change programs in California are effectively reducing GHG emissions from all sectors of the economy. These programs include regulations, market programs, and incentives that will transform transportation, industry, fuels, and other sectors to take California into a sustainable, cleaner, low-carbon future, while maintaining a robust economy.

Major sectors of the California economy, including transportation, will need to reduce emissions to meet 2030 and 2050 GHG emissions targets. The Governor's Office of Land Use and Climate Innovation (formerly the Governor's Office of Planning and Research) identified five sustainability pillars in the A Strategy for California @ 50 Million report: (1) Increasing the share of renewable energy in the state's energy mix to at least 50 percent by 2030; (2) Reducing petroleum use by up to 50 percent by 2030; (3) Increasing the energy efficiency of existing buildings by 50 percent by 2030; (4) Reducing emissions of short-lived climate pollutants; and (5) Stewarding natural resources, including forests, working lands, and wetlands, to ensure that they store carbon, are resilient, and enhance other environmental benefits.

The transportation sector is integral to the people and economy of California. As stated in the 2015 California Environmental Protection Agency Environmental Compliance and Enforcement Report, to achieve GHG emission reduction goals, it is vital that the state build on past successes in reducing criteria and toxic air pollutants from transportation and goods movement. GHG emission reductions will come from cleaner vehicle technologies, lower-carbon fuels, and reduction of VMT. Reducing today's petroleum use in cars and trucks is a key state goal for reducing GHG emissions by 2030.

In addition, SB 1386 established as state policy the protection and management of natural and working lands and requires state agencies to consider that policy in their own decision making. Trees and vegetation on forests, rangelands, farms, and wetlands remove carbon dioxide from the atmosphere through biological processes and sequester the carbon in above- and below-ground matter.

Subsequently, Governor Gavin Newsom issued EO N-82-20 to combat the crises in climate change and biodiversity. It establishes a state goal of conserving 30% of California's lands and coastal waters by 2030 – known as 30x30. This 30x30 goal instructs state agencies to use existing authorities and resources to identify and implement near- and long-term actions to accelerate natural removal of carbon and build climate resilience in our forests, wetlands, urban greenspaces, agricultural soils, and land conservation activities in ways that serve all communities and in particular low-income, disadvantaged, and vulnerable communities. To support this order, the California Natural Resources Agency released the Natural and Working Lands Climate Smart Strategy.

16.9.1.2 Caltrans Efforts

Caltrans continues to be involved on the Governor's Climate Action Team as CARB works to implement EOs S-3-05 and S-01-07 and help achieve the targets set forth in AB 32, EO B-30-15, issued in April 2015, and SB 32 (2016), that set an interim target to cut GHG emissions to 40 percent below 1990 levels by 2030. The following major initiatives are underway at Caltrans to help meet these targets.

The California Action Plan for Transportation Infrastructure 2.0 (CAPTI 2.0) builds on EOs signed by Governor Newsom in 2019 and 2020 targeted at reducing GHG emissions in transportation, which account for more than 40 percent of all polluting emissions, to reach the state's climate goals. Under CAPTI 2.0, where feasible and within existing funding program structures, the state will invest discretionary transportation funds in sustainable infrastructure projects that align with its climate, health, and social equity goals. It includes a commitment to working towards VMT/GHG neutrality in key state transportation programs.

The California Transportation Plan (CTP) 2050 is a statewide, long-range transportation plan to meet our future mobility needs and reduce GHG emissions. It serves as an umbrella document for all the other statewide transportation planning documents. The CTP 2050 presents a vision of a safe, resilient, and universally accessible transportation system that supports vibrant communities, advances racial and economic justice, and improves public and environmental health. The plan's climate goal is to achieve statewide GHG emissions reduction targets and increase resilience to climate change. It demonstrates how GHG emissions from the transportation sector can be reduced through advancements in clean fuel technologies; continued shifts toward active travel, transit, and shared mobility; more efficient land use and development practices; and continued shifts to telework.

The Caltrans 2024–2028 Strategic Plan outlines goals centered on safety, climate action, equity, and stewardship. Climate-related strategies include implementing the Caltrans Climate Action Plan; expanding climate education, training, and outreach; strengthening partnerships to support climate resilience; promoting sustainable transportation solutions that reduce emissions; and continuing to engage underserved and disproportionately impacted communities in climate planning and implementation.

Caltrans Director's Policy 30 (DP-30) Climate Change (June 22, 2012) established a policy to ensure coordinated efforts to incorporate climate change into Caltrans decisions and activities. Other Director's policies promote energy efficiency, conservation, and climate change, and commit Caltrans to sustainability practices in all planning, maintenance, and operations.

The Caltrans Greenhouse Gas Emissions and Mitigation Report provides a comprehensive overview of Caltrans' emissions and current Caltrans procedures and activities that track and reduce GHG emissions. It identifies additional opportunities for further reducing GHG emissions from Department-controlled emission sources, in support of Caltrans and State goals.

16.9.2 Adaptation

The following discussion outlines federal, statewide, and Caltrans climate change adaptation efforts for transportation projects and should be referenced in the environmental document.

16.9.2.1 Federal Efforts

Under NEPA Assignment, Caltrans is obligated to comply with all applicable federal environmental laws and FHWA NEPA regulations, policies, and guidance. The Fifth National Climate Assessment presents the most recent science and “analyzes the effects of global change on the natural environment, agriculture, energy production and use, land and water resources, transportation, human health and welfare, human social systems, and biological diversity; [It] analyzes current trends in global change, both human-induced and natural, and projects major trends for the subsequent 25 to 100 years … to support informed decision-making across the United States.” Building on previous assessments, it continues to advance “an inclusive, diverse, and sustained process for assessing and communicating scientific knowledge on the impacts, risks, and vulnerabilities associated with a changing global climate.” The report, released on November 14, 2023, by the U.S. Global Change Research Program, was developed through a partnership with 14 federal agencies.

The National Oceanic and Atmospheric Administration (NOAA) provides sea level rise projections for all U.S. coastal waters to help communities and decision makers assess their risk from sea level rise. Updated projections through 2150 were released in 2022 in a report and online tool called the Sea Level Rise Viewer.

16.9.2.2 State Efforts

Climate change adaptation for transportation infrastructure involves long-term planning and risk management to address vulnerabilities in the transportation system. A number of state policies and tools have been developed to guide adaptation efforts.

California's Fourth Climate Change Assessment provides information to help decision makers across sectors and at state, regional, and local scales protect and build the resilience of the state's people, infrastructure, natural systems, working lands, and waters. The Fourth Assessment reported that if no measures are taken to reduce GHG emissions by 2021 or sooner, the state is projected to experience an up to 8.8 degrees Fahrenheit increase in average annual maximum daily temperatures; a two-thirds decline in water supply from snowpack resulting in water shortages; a 77% increase in average area burned by wildfire; and large-scale erosion of up to 67% of Southern California beaches due to sea level rise. These effects will have profound impacts on infrastructure, agriculture, energy demand, natural systems, communities, and public health.

According to findings outlined in the Fourth Assessment, without implementation of protective measures critical infrastructure will be impacted by climate change. The Assessment mentions airports in major urban areas such as San Francisco, Oakland, and San Diego could be susceptible to major flooding from a combination of sea-level rise and storm surge by 2040-2080. The Fifth Assessment is underway and the update will be finalized in 2026.

To help communicate the findings of California's Fourth Climate Change Assessment, AB 2800's multidisciplinary Climate-Safe Infrastructure Working Group published Paying it Forward: The Path Toward Climate-Safe Infrastructure in California. This report provides guidance on assessing risk in the face of inherent uncertainties still posed by the best available climate change science. It also examines how state agencies can use infrastructure planning, design, and implementation processes to respond to the observed and anticipated climate change impacts.

EO S-13-08, issued in 2008, directed state agencies to consider sea level rise scenarios for 2050 and 2100 during planning to assess project vulnerabilities, reduce risks, and increase resilience to sea level rise. It gave rise to the 2009 California Climate Adaptation Strategy, the Safeguarding California Plan, and a series of technical reports on statewide sea level rise projections and risks, including the State of California Sea Level Rise Guidance 2024 Science & Policy Update. The reports addressed the full range of climate change impacts and recommended adaptation strategies. The current 2023 California Climate Adaptation Strategy incorporates key elements of the latest sector-specific plans such as the Natural and Working Lands Climate Smart Strategy, Wildfire and Forest Resilience Action Plan, Water Resilience Portfolio, and the CAPTI 2.0 (described above). Priorities in the 2023 California Climate Adaptation Strategy include acting in partnership with California Native American Tribes, strengthening protections for climate-vulnerable communities that lack capacity and resources, implementing nature-based climate solutions, using best available climate science, and partnering and collaboration to best leverage resources.

EO B-30-15 recognizes that effects of climate change threaten California's infrastructure and requires state agencies to factor climate change into all planning and investment decisions. Under this EO, the Governor's Office of Land Use and Climate Innovation (formerly the Governor's Office of Planning and Research) published Planning and Investing for a Resilient California: A Guidebook for State Agencies, to encourage a uniform and systematic approach to building resilience.

SB 1 Coastal Resources: Sea Level Rise established statewide goals to “anticipate, assess, plan for, and, to the extent feasible, avoid, minimize, and mitigate the adverse environmental and economic effects of sea level rise within the coastal zone.” As the legislation directed, the Ocean Protection Council collaborated with 17 state planning and coastal management agencies to develop the State Agency Sea-Level Rise Action Plan for California in February 2024. This plan promotes coordinated actions by state agencies to enhance California's resilience to the impacts of sea level rise.

16.9.2.3 Caltrans Adaptation Efforts

Caltrans completed Climate Change Vulnerability Assessments (2019) to identify segments of the State Highway System vulnerable to climate change effects of precipitation, temperature, wildfire, storm surge, and sea level rise.

The climate change data in the assessments were developed in coordination with climate change scientists and experts at federal, state, and regional organizations at the forefront of climate science. The findings of the vulnerability assessments guided analysis of at-risk assets and the development of the Caltrans 2020 Adaptation Priorities Reports as a method to make capital programming decisions to address identified risks.

The Director's Office of Sustainability supports implementation of sustainable practices at Caltrans. The 2023 Sustainability Roadmap is a periodic progress report and plan for meeting the Governor's sustainability goals related to EOs B-16-12, B-18-12, and B-30-15. The Roadmap includes designing new buildings for climate change resilience and zero-net energy and replacing fleet vehicles with zero-emission vehicles.

16.10 Resources

For additional resources, please see the Laws, Regulations, and Guidance section above.

California Air Resources Board

California Climate Change Center

Caltrans

California Environmental Protection Agency

California Natural Resources Agency

California Ocean Protection Council

California State Transportation Agency (CalSTA)

California's Climate-Safe Infrastructure Working Group (CSIWG)

Federal Highway Administration (FHWA)

Governor's Office of Land Use and Climate Innovation

Intergovernmental Panel on Climate Change

National Oceanic and Atmospheric Administration (NOAA) Office for Coastal Management

State of California

U.S. Department of Transportation

U.S. EPA

U.S. Global Change Research Program

(Last content update: 06/30/2025, JC)