Dense cities contribute less GHG
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A CoolClimate Map of the SF Bay Area's carbon footprint by zipcode tabulation area shows a pattern typical of large metropolitan areas: a small footprint (green) in the urban core but a large footprint (orange and red) in surrounding suburbs.According to a new study by Dan Kammen and graduate student Christopher Jones at UC Berkeley, population-dense cities contribute less greenhouse-gas emissions per person than other areas of the country, but these cities’ extensive suburbs essentially wipe out the climate benefits.
Dominated by emissions from cars, trucks and other forms of transportation, suburbs account for about 50 percent of all household emissions – largely carbon dioxide – in the United States.
The study uses local census, weather and other data – 37 variables in total – to approximate greenhouse gas emissions resulting from the energy, transportation, food, goods and services consumed by U.S. households, so-called household carbon footprints.
A key finding of the UC Berkeley study is that suburbs account for half of all household greenhouse gas emissions, even though they account for less than half the U.S. population. The average carbon footprint of households living in the center of large, population-dense urban cities is about 50 percent below average, while households in distant suburbs are up to twice the average.
Interactive carbon footprint maps for more than 31,000 U.S. zip codes in all 50 states are available online at http://coolclimate.berkeley.edu/maps.
A link to their paper in Environmental Science & Technology is here: Spatial distribution of U.S. household carbon footprints reveals suburbanization undermines greenhouse gas benefits of urban population density (ES&T, 2014)