Greenhouse Gas Emissions

What quantity of greenhouse gases are emitted by Bay Area drivers?

Greenhouse Gas Emissions

Definition: 
Greenhouse gas emissions refer to carbon dioxide and other chemical compounds that contribute to global climate change. Vital Signs tracks greenhouse gas emissions linked to on-road motor vehicle transportation, using fuel sales to retail customers as a source of monitoring data. This measure helps track progress towards achieving our region’s per-capita greenhouse gas target under Senate Bill 375, which is focused on emissions from cars and light-duty trucks.

Climate change is one of the most significant global challenges of the 21st century, posing major risks for developed and developing countries alike. Despite our region’s commitment to environmental protection, Bay Area residents generate greenhouse gas emissions at a rate substantially higher than the global average – with nearly 40 percent of these emissions coming from the transportation sector. Reducing the carbon footprint of our transportation system has emerged as a key regional environmental priority and is one of the main objectives of Plan Bay Area, our region’s long-range transportation and land use plan.

Local Focus
Because San Francisco residents drive less, San Francisco has the lowest per-capita greenhouse gas emissions from transportation of any Bay Area county.

In 2012, combustion of gasoline and diesel fuels for use in cars and trucks resulted in approximately 23 million tons of greenhouse gas emissions – but not every county contributes equally to this regional total. Most notably, per-capita greenhouse gas emissions from fuel sales are half the regional average in San Francisco. The city’s “green” status is likely attributable to a robust public transit system, limited parking and a dense land use pattern. These factors decrease fuel consumption by shortening travel distances and making public transit, walking and bicycling more viable.

While comprising a relatively small share of the region’s greenhouse gas emissions from transportation, Solano and Napa counties lead the region in terms of the highest per-capita greenhouse gas emission rates from transportation. Given that residents in these rural and suburban communities tend to have longer trip distances, and that public transit options are limited, it’s not surprising that their greenhouse gas emissions from transportation are far above the regional average.

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Sources: 

California Energy Commission: Retail Gasoline Sales by County (2012)

California Energy Commission: Retail Diesel Sales by County (2012)

Energy Information Administration: CO2 Conversion Data (2015)

California Department of Finance: Population and Housing Estimates (2012)

Image: Flickr (Creative Commons license), Photographer: JT, https://www.flickr.com/photos/environmentblog/7190921060

Methodology Notes: 

Because the California Energy Commission changed its retail fuel survey methodology in 2012, historical data is not available for this measure. The data is based on a survey of fueling stations, the vast majority of which respond to the survey; the Energy Commission corrects for non-response bias by imputing the remaining share of fuel sales. Greenhouse gas emissions are calculated based on the gallons of gasoline and diesel sales, relying upon standardized Energy Information Administration conversion rates for E10 fuel (gasoline with 10% ethanol) and standard diesel. Per-capita greenhouse gas emissions are calculated simply by dividing emissions attributable to fuel sold in that county by the total number of county residents; there may be a slight bias in the data given that a fraction of fuel sold in a given county may be purchased by non-residents.