Study shows Sonoma County has among smallest carbon footprints in Bay Area

Sonoma County had the second smallest household greenhouse gas footprint of the nine Bay Area counties, and 11 local cities and towns accounted for carbon-related emissions below the statewide average, according to a new UC Berkeley report.

The average Sonoma County household had a footprint of 40.4 metric tons of greenhouse gas emissions per year, well below the statewide average of 45.7 tons per household and the Bay Area average of 44.3 tons, the report said.

Only San Francisco, the region's most compact city with multiple mass transit systems, had a smaller footprint at 38.7 tons of greenhouse gas emissions, while affluent Santa Clara County was tops at 48.6 tons and wealthy communities like Atherton, Piedmont and Alamo accounted for 70 to 85 tons, as income, vehicle ownership and home size contributed heavily to the regional differences.

The average U.S. household accounts for about 50 metric tons of emissions.

Read the UC Berkeley report here

See an interactive map of carbon footprints around the Bay Area here

People with larger incomes “just consume more,” said Christopher Jones, program director of UC Berkeley's CoolClimate Network and report co-author. They own larger homes which are “full of more stuff,” he said, and also travel by air more often, boosting their expenditures for transportation, which accounted for one-third of Bay Area emissions, the largest source by far.

Food is the second largest source of emissions at 19 percent, followed by goods and services (each 18 percent), heating fuels (5 percent), home construction (3 percent), electricity (2 percent) and waste (1 percent).

Rohnert Park households had the smallest footprint of the eight Sonoma County cities and three communities cited in the report at 37.7 metric tons of emissions per year, while Windsor was highest at 45.1 tons, exceeding the Bay Area average but still below the state mark.

Santa Rosa and Glen Ellen were in the middle of the pack, each at 39.5 metric tons.

Sonoma County households collectively accounted for 7.2 million metric tons of greenhouse gas emissions per year. Californians accounted for 585.5 million tons; households nationwide accounted for 5.8 billion tons of greenhouse gas emissions annually, the Berkeley report said.

Sonoma County is a “good example of low-carbon development,” Jones said, noting the absence of widespread urban sprawl along with relatively modest household income and the benefit of a cool climate that reduces home energy consumption.

The greenhouse gas inventory, produced by the CoolClimate Network and the Bay Area Air Quality Management District, calculated carbon footprints based on household consumption, no matter where the emissions occurred. If a household in Santa Rosa purchased a computer made in China, all emissions from the computer's production were allocated to the household's Santa Rosa neighborhood.

In what the report termed a “full life-cycle analysis” of emissions from products and services, motor vehicle emissions included the greenhouse gases from the manufacture of all the vehicle's parts, assembly and transportation to dealer, as well as vehicle maintenance and refining and burning of the fuel that powered it during its useful life.

The consumption-based approach found about 35 percent higher greenhouse gas emissions than the traditional territorial approach, largely due to “higher emissions from imported food and goods,” the report said.

The report also said that transitioning vehicles and heating systems from fossil fuel combustion to electricity would be a key way to meet the state's greenhouse gas reduction target. The latest goal is to reduce emissions to 80 percent below 1990 levels by 2050.

Jones said the “biggest opportunity” to reduce emissions from household consumption is to “massively scale up electrification of our vehicles and our heating,” which could reduce the Bay Area's carbon footprint by about 30 percent. Electricity is a “tiny part of the problem, but it's a huge part of the solution,” he said.

Ann Hancock, executive director and co-founder of the Santa Rosa-based Center for Climate Protection, gave the report, including its endorsement of electrification, a hearty thumbs-up.

“We have to move fast and we have to move big,” she said, regarding the campaign to curb greenhouse gas emissions, the key contributor to global warming.

Vehicle fuel, which the study said accounts for 22 percent of the Bay Area's carbon footprint, is “the 800-pound gorilla,” Hancock said.

More than 1,900 electric vehicles have been purchased in Sonoma County since 2010, offsetting about 7,000 metric tons of greenhouse gas emissions that would have been produced by traditional fuel-burning cars, her group reported last year.

Anyone considering a new vehicle purchase should “go try out an electric vehicle,” Hancock said this week.

Much smaller consumer decisions also matter, she said, noting the Berkeley report's recommendation to spend money on local services and entertainment, which typically have a lower carbon footprint than manufactured products sold at shopping malls.

The report also suggested “low-carbon diets” that reduce the amount of food consumed and wasted, as well as less meat and dairy products.

While “California cuisine” and vegetarianism are popular in the Bay Area, the report said that considering all 2.6 million households in the area “residents do appear to have substantially different diets than other cities in the western United States.”

Regarding the advent of the Sonoma-Marin Area Rail Transit Authority, scheduled to begin diesel-powered commuter train service late this year, Hancock said, “We'll probably be kicking ourselves that we didn't have an electric train.”

Still, she said, the train will “get people out of their cars” and may also focus development along the rail corridor, ultimately running from Cloverdale to Larkspur.

The report recommends development of smaller housing units in urban core areas, which Jones said matches the interest of young adults seeking affordable housing close to shopping, services and entertainment. Occupants of large suburban homes find it “pretty hard to lower their carbon footprint,” he said.

You can reach Staff Writer Guy Kovner at 521-5457 or guy.kovner@pressdemocrat.com. On Twitter @guykovner.