Which households contribute most to climate change? To find out, take a look at this interactive map created by researchers at the University of California, Berkeley. It provides estimates for all 31,000 ZIP codes, based on everything people consume in a single year, including energy, travel, goods, and services.
A major finding of the research: suburbs account for more greenhouse gas emissions than other areas. In total, suburbs produce about 50% of household emissions, despite housing only 143 million people in total from a U.S. population of 313 million. Inner city residents tend to have lower carbon footprints, because they live in smaller homes and use more public transit. Some urban households produce 50% of the national average, while some suburban households emit double the national average.
"Metropolitan areas look like carbon footprint hurricanes, with dark green, low-carbon urban cores surrounded by red, high-carbon suburbs," says Chris Jones, a doctoral student at Berkeley's Goldman School of Public Policy, and the lead author of the paper.
The analysis, which is written up in this recent paper, is based on multiple sources of data, including census information and household travel surveys. Transportation—which is responsible for 26% to 42% of overall U.S. household emissions—is the most important factor for the difference between the suburbs and cities, with households 15 to 45 miles from city centers producing the highest emissions. Suburban transport emissions are as much as 2.5 times higher than urban ones, the researchers say.
Aside from differences between urban and suburban areas, the maps also show which regions produce the most emissions related to other factors. For example, the Midwest, non-coastal East, and most of the South have relatively high emissions from electricity generation. The West and Northwest have relatively low emissions, reflecting more low-carbon energy sources. Overall, energy accounts for 15% to 33% of total household emissions.
The researchers hope the maps will help cities create climate action plans by understanding what drives emissions in different places. The most important factors, they find, are household income, vehicle ownership and home size—all which are greater in suburbs.
Does that mean we should limit suburban development, and increase population density inside cities, if we want to cut emissions? Not necessarily. The researchers suggest this has limited benefit, and that focusing on carbon-reduction in today's neighborhoods would be better. "[Suburbs] are ideal candidates for a combination of energy efficient technologies, including whole home energy upgrades, and solar photovoltaic systems combined with electric vehicles," the study says.