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Preparing a GHG Inventory and Developing Future Emissions Scenarios

Costa Mesa, California

Featured image for the project, Preparing a GHG Inventory and Developing Future Emissions Scenarios

Photo courtesy of Nandaro, Wikipedia.org


Nestled between the Pacific Ocean and the Santa Ana Mountains 35 miles south of Los Angeles, Costa Mesa is a vibrant small city with a population of ~113,000. The local economy is based on retail and services, generating (pre-COVID 19) tax revenue of $100 million annually. This city is home to one of the nation’s largest shopping centers, multiple arts and entertainment venues, and a wide variety of restaurants. Named one of the 2020 Healthiest Places to Live in America by Niche.com, residents can enjoy a variety of outdoor activities at public beaches, nearby hiking trails, or in one of the City’s 28 City parks and two municipal golf courses.  There are 20 public schools, three libraries, and multiple colleges within city limits. Costa Mesa also hosts the annual Orange County Fair.

Published in 2018, California’s Fourth Climate Change Assessment projects continued warming trends across the Los Angeles (LA) region in the coming decades, with average maximum temperatures increasing 4-5 °F by mid-century, and 5-8 °F by late-century. The number of extremely hot days is expected to rise from an historical average of 15 days/year above 90°F at LA International Airport (LAX) to up to 50-90 days/year above 90°F by 2100. While precipitation models predict only small changes in average rainfall, dry and wet extremes are expected to increase, making the region vulnerable to both drought and flooding. Sea level is also expected to rise by 1-2 feet by 2050, and in the most extreme scenarios, there could be 8-10 feet of sea level rise by 2100.  While the Assessment indicates there is uncertainty regarding changes in wildfire patterns, in 2020 there have been multiple, significant wildfires in the LA region. Of note, the Silverado Fire started on the west side of the Santa Ana Mountains on October 26, 5 miles from Costa Mesta, and caused the evacuation of 90,000 residents of Irvine, Costa Mesa’s neighbor.

In the last few years, there has been growing community interest and City leadership to make Costa Mesa a resilient, sustainable and inclusive leader in Orange County. The City Council demonstrated its commitment to sustainability by creating and hiring its first Energy and Sustainability Services Manager-Salem Afeworki- in early 2020. This role oversees all citywide sustainability and GHG reduction programs and initiatives, and sits in the City’s Public Services Department.

Currently, the City is developing its first Local Hazard Mitigation Plan (LHMP) in collaboration with internal and external stakeholders with the aim of having a comprehensive plan for disaster risk reduction and minimizing the negative impact of climate change. In addition, the Sustainability team is looking into developing a stand-alone Climate Action and Adaptation Plan (CAAP) in the near future. As a first step, the City is seeking subject matter expert(s) to develop a citywide GHG inventory and developing future emissions scenarios. Salem will be the Community Lead on this project, and the results of the Thriving Earth Exchange Community Science Project, as well as the outcome of LHMP, will inform the future CAAP.


The Project

The City of Costa Mesa has requested assistance with preparing a greenhouse gas (GHG) inventory that includes both municipal and community-wide emissions,  and developing future emissions scenarios (i.e., wedge analyses).  These activities are crucial components of climate action planning. This work will inform decision-makers and residents of Costa Mesa about local GHG emissions, establish baseline, and identify mitigation strategies that have the greatest impact. If timing allows, the City of Costa Mesa would also appreciate assistance with identifying appropriate GHG emissions mitigation measures.


Outputs include:

  • Developing a repeatable process for estimating emissions and monitoring changes in emissions, with written description of the strategies, formulas and data used to calculate emissions
  • Costa Mesa GHG inventory (database) and future emissions scenarios model info and results (number of scenarios to be determined in consultation with the Community Lead)
  • A written report summarizing the findings of the GHG inventory and results of future emissions scenarios
  • Recommendations for GHG emissions mitigation measures for Costa Mesa (if time permits)



Work will begin as soon as possible, with an expected project duration of 7-9 months.

About the Community

The scientist(s) will work with Salem Afeworki, the Energy and Sustainability Services Manager for the City of Costa Mesa. Salem agrees to facilitate access to data, provide input and feedback as the project progresses, and assist in overcoming local/ political/ logistical hurdles as they arise.

Project Team

Community Lead

Salem Afeworki – Energy and Sustainability Services Manager for the City of Costa Mesa
(Photo and biography coming soon!)


Community Science Fellow

Meg Thorley works at the nexus of health, equity, the built environment and climate change. A social scientist by training, she established Urban Intersect Consulting to help create and sustain healthy, resilient communities as part of the transition to a low-carbon society. The practice works with organizations and communities to build capacity in systems thinking, cross-sectoral engagement, and collective action. Developing trust and effectively collaborating with a variety of stakeholders are cornerstones of her 20+ year career working in organizations across the public, non-profit, and private sectors in over 30 countries. She earned her PhD from the University of Cambridge in the United Kingdom (UK) and holds a Master of Public Health degree from the University of North Carolina at Chapel Hill.

Scientist Wanted

Salem seeks a scientific partner to prepare the GHG inventory and create future emissions scenarios as part of a larger future process to develop a CAAP for the City of Costa Mesa. She would also welcome innovative solutions or insights regarding emissions reduction strategies that could have the most impact in the local context. She is open to having the scientific partner bring in students to support this work.


Desired skills and qualifications:

  • Background in atmospheric science or environmental science with a focus on air quality
  • Experience conducting GHG inventories, preferably using the GHG Protocol for Cities
  • Experience creating emissions scenarios
  • Experience developing Climate Action and Adaptation Plans, Sustainability Plans, Resilience Plans etc. particularly for local governments or public agencies
  • Interest in identifying science-based practical solutions to local challenges
  • Ability to effectively convey results in written form
  • Strong listening and communication skills


Thriving Earth Exchange asks all scientific partners to work with the community to help define a project with concrete local impact that they can contribute to as pro-bono volunteers and collaborators. This work can also position the scientists and communities to seek additional funding, together, for the next stage.

Interested in volunteering? Apply now!

Collaborating Organization(s)

This project is launched in collaboration with the California Strategic Growth Council.