Air Quality and Climate Change

The Office of Air Quality and Climate Change (AQCC) is responsible for advancing the Department’s goals of advancing climate action and integrating climate equity considerations into all planning processes and guidance. AQCC assesses the impacts of climate change on the State’s multimodal transportation system, and leads the development of guidance and tools to support Caltrans Districts’ climate adaptation and resilience efforts. Additionally, AQCC is the Department’s lead technical advisor on air quality conformity policy and National Environmental Policy Act (NEPA) assignment, providing both regional and project-level assistance to the Districts, and to the Divisions of Environmental Analysis (DEA), Local Assistance, and Programming. AQCC consults and coordinates with local, state, and federal stakeholders to carry out air quality and climate change planning activities statewide.



Cal-Adapt is the central repository for climate data and information endorsed by the State of California, including climate projections produced for a State of California context. The data available on this site offer a view of how climate change might affect California at the local level.

 Adaptation Planning Guide

The Adaptation Planning Guide provides guidance to local governments on local adaptation and resiliency planning. A step-by-step process is presented that communities can use to plan for climate change, that is designed to be flexible and responsive to community needs, including equity and community engagement throughout. The guide also includes a summary of statewide guidance, resources, and tools for climate resilience planning

Planning & Investing for a Resilient California

This Guidebook is for State agencies, pursuant to Executive Order B-30-15. The guidance is designed to inform planning and investment processes to address the two primary elements of resilience – planning for future conditions and doing planning itself differently. This document introduces a four step process and a set of resilient decision making principles for state agencies. The Guidebook is currently being updated by OPR and the updated version will be released in 2022.

What is Transportation Conformity?

All Federal actions must further the purposes of the Clean Air Act through a regulatory process called “Conformity” (§7506(c)). Towards that goal, Federal agencies are prohibited under the Clean Air Act from approving or funding projects and plans that don't "conform" to the letter and purpose of the State Implementation Plan, which governs how each State addresses Federal air quality requirements. Under US EPA regulations (40 CFR Parts 51 and 93), recipients of Federal highway and transit funding are also subject to conformity requirements when approving non-Federal “regionally significant” highway and transit projects. For more information on transportation conformity, air quality analysis in NEPA, and roles and responsibilities, see the following fact sheet:

Statewide Conformity Working Group

The Statewide Conformity Working Group is a coordinating group for discussion and interagency agreement about transportation-related air quality and Federal Clean Air Act conformity issues in California. The public is welcome to participate, and there is a time on the agenda for public comment regarding issues not otherwise on the agenda. Actions taken by the group are not regulations; rather, they are informational in nature, or are agreements regarding procedures and interpretation of the transportation conformity regulations to be used by transportation agencies and project proponents.

Caltrans maintains an electronic mail list to forward announcements and other information to the working group. For network security reasons, the list archives are only available to list members. Go to the mailing list page to sign up.

2024 Meetings

2021 Meetings

Additional Resources


Climate Change Technical Resources, Tools and Training

Caltrans Greenhouse Gas Emissions and Mitigation Report (PDF)

The Caltrans Greenhouse Gas Emissions and Mitigation Report documents and evaluates current Caltrans procedures and activities that track and reduce greenhouse gas (GHG) emissions and identifies additional opportunities for further reducing GHG emissions from Department-controlled emission sources.

2021 Vulnerability Assessment Statewide Summary Report (PDF)

The Caltrans Vulnerability Assessment Statewide Summary Report provides an overview and synthesis of the results of the 12 District Vulnerability Assessment Summary Reports and highlights Caltrans’ planned next steps.

Adaptation Priorities Reports

Building upon the Vulnerability Assessments, Caltrans developed the Climate Change Adaptation Priorities Reports, which evaluate at-risk assets and prioritize exposed assets while exploring facility-level adaptation solutions within each district.

Climate Change Communication Guide (PDF)

The guide articulates best practices that the Department uses to educate, inform, and strengthen collaboration internally, among external partners, and with the public on the topic of climate change.

2019 Climate Change Vulnerability Assessments

The Climate Change Vulnerability Assessments identify segments of the State Highway System vulnerable to climate change impacts including precipitation, temperature, wildfire, storm surge, and sea level rise. 

Climate Adaptation Strategies for Transportation Infrastructure (PDF)

Building upon the Climate Change Emphasis Area Guidance for Corridor Planning, Caltrans developed an educational resource - Climate Adaptation Strategies for Transportation Infrastructure. This educational guide aims to assist planners by providing an initial overview of how to consider project-level strategies to adapt to climate risks.


Featured Links

California State Transportation Agency


California State Transportation Agency

Connecting State Climate Goals and VMT

CARB 2017 Scoping Plan

Connecting State Climate Goals and VMT

California Transportation Commission


California Transportation Commission