Contra Costa County Greenhouse Gas Emissions by Sector

Plane over freeway in San Diego, CA

By Gary Farber, member, 350CCA Climate Policy Team

Transportation accounts for the largest chunk of greenhouse gas emissions (GHG emissions) in Contra Costa County. Residential and nonresidential usages produce plenty as well. I looked at three different sources to get a fairly clear picture of the various sectors contributing GHG emissions. But first, you may be wondering what we mean by the term.

What are Greenhouse Gas Emissions?

Greenhouse gas emissions are the chemicals that society and nature put into the air, and which science has identified as responsible for the dangerous heating of the planet (affecting oceans, land, weather and living things).

Two Climate-Altering GHG Emissions

The two types of emissions identified as causing the preponderance of climate change are carbon dioxide (CO2) and methane. While both CO2 and methane are generated by naturally occurring ecological systems, the main cause of global heating is the extraordinarily large additional amount of CO2 and methane that is released into the air, and rises into the atmosphere, due to humans’ use of fossil fuels for energy.

In California, the main energy types contributing to GHG emissions are gasoline for vehicles, and natural gas for heating air and water in buildings and for generating electricity. Burning gasoline results in high CO2 emissions; natural gas produces less CO2 than gasoline per unit of energy, but consists mainly of methane.

Main GHG Emissions Sources in Contra Costa County

So what are the main sources of GHG emissions in Contra Costa County? I was unable to find a source providing data for the entire county. The three tables below show data reported by 1) the State of California, 2) the County for unincorporated areas, and 3) the city of Walnut Creek. In all three reports, transportation is the highest contributor of GHG emissions—as much as 60 percent in Walnut Creek, and 46 percent in unincorporated county.

GHG Emissions Data, by Sector, from Three Sources


Sector  %
Transportation 38
Industrial 23
Electricity Generation 16
Agriculture & Forestry 9
Residential 8
Nonresidential 6
Source: California Air Resources Board

Unincorporated Contra Costa County

Sector  % 
Transportation 46
Solid Waste 22
Residential 19
Nonresidential 11
Offroad Equipment 9
Agriculture 4
Water & Wastewater 0.5
Source: Contra Costa County Climate Action Plan Update

City of Walnut Creek

Sector  % 
Transportation 60
Residential 16
Nonresidential 16
Waste 4
Offroad Equipment 3
Water & Wastewater 0.4
Source: City of Walnut Creek Sustainability Action Plan

A big difference between the State data and the local data is that the State data includes industry and electricity generation. With the State including more sectors, the building emissions (residential and nonresidential) become a smaller percentage, as compared to what the County and Walnut Creek, with fewer sectors, report.

    Note: For the County and Walnut Creek, percentages were calculated based on reported emissions; percentages may not add to 100 due to rounding

    Photo by Soly Moses on Pexels

    Share this page