Is California — home to Tesla, solar panels galore and gobs of scientists — the green-energy paradise it’s made out to be? A new, peer-reviewed study in the Proceedings of the National Academy of Sciences journal reinforces the idea.
Households here emit 33% less carbon than any other state, while only two other sunbelt states consume less energy, according to researchers at the University of Michigan, who analyzed the environmental impact of 78% of the nation’s housing stock (about 93 million homes), using 2015 data.
San Francisco’s household emissions were nearly three times lower than the national average — 1.03 tons of carbon dioxide per capita vs. 2.83 for the U.S. — and lower than any other major city included in the research paper. In Los Angeles, the average household contributed 2.28 tons of carbon dioxide for the year, compared to 3.64 in Oklahoma City, 3.11 in Denver and 2.69 in Boston.
One strong correlation to greenhouse gas emissions was geography.
Seven of the eight states with the lowest carbon emissions were in the Western U.S.: California (23 carbon dioxide equivalents per square meter of a house), Oregon (34), Washington (34), Utah (34), Idaho (37) and Nevada (40). All eight of the highest-emitting states were in the central and southern parts of the country: North Dakota (74), West Virginia (70), Missouri (69), Oklahoma (67), Kansas (65), Iowa (64), Mississippi (63) and Kentucky (63).
Examining data in 8,858 U.S. zip codes, researchers also found households in high-income neighborhoods contributed 25% more carbon dioxide than households in low-income neighborhoods. In the Los Angeles metro area, for example, the affluent Hollywood Hills, Brentwood and Sherman Oaks zip codes had among the most greenhouse gas emissions, while Inglewood, Fullerton and Huntington Park had some of the lowest.
“The tendency for affluence and (average floor space) to increase together is a key emissions driver for wealthier households,” researchers wrote.
While increased density, commonly associated with a smaller carbon footprint, did show some correlation, the apparent effect from the income gap was far wider.
“Variation in (greenhouse gas) intensity among the ZIP codes likely reflects differences in climate, building characteristics, and carbon intensity of the electrical grid, such that the overall relationship between density and emissions is attenuated,” researchers wrote.
Households in states with warmer climates consumed less energy, measured by kilowatt hours per square meter. The national average is 147 kilowatt hours per square meter, while Florida (97), Arizona (103) and California (109) had the lowest rates in the nation. San Francisco and Los Angeles consumed even less than the state, at kilowatt hours per square meter. and 103 kilowatt hours per square meter, respectively.
Researchers began with the goal of identifying where in the nation households are likely to need the most aggressive action to meet the 2025 and 2050 goals set forth by the Paris Climate Agreement. Residential emissions account for 20% of the total in the U.S., they said, and would by themselves be the world’s sixth-largest polluter of greenhouse gasses, on the scale of Germany.
