When the U.S. started exporting manufacturing to China and other countries in the 1990s, it cut its carbon emissions because the pollution was no longer going into our atmosphere. But, of course, those emissions were still going into someone's atmosphere, and, really, we're still responsible even if footprint calculators tend not to show it that way.
The difference with the carbon maps here is they repatriate those emissions. They show all pollution related to consumption in the San Francisco Bay Area irrespective of whether goods and services are made in Alameda or Guangzhou. The result: households have 35% higher emissions than calculated in other surveys.
The maps were created by researchers at the University of California, Berkeley and the Bay Area Air Quality Management District. Transport is the largest single source of emissions (33%), followed by food (19%), goods (18%), services (18%) heating fuels (5%), home construction (3%), electricity (2%) and waste (1%). Household emissions are slightly lower in the region than the national average: 44.3 metric tons of CO2 equivalent compared to 50 metric tons across the country.
Because they show where emissions are greatest and least, the maps indicate where actions to reduce pollution might have the most bang-for-buck. There are fivefold differences between households in different neighborhoods and differences of 2.5 times between cities. For example, in the East Bay, emissions range from 31 tCO2e per household in Emeryville to 76 tCO2e in Piedmont. In general, more suburban areas have higher footprints because people drive more, while richer households tend to fly and buy more, upping their footprints.
The latest maps follow a nationwide effort in 2014 (see all 31,000 ZIP codes here). They're based on a host of data, including electricity and natural gas consumption, fuel economy rates, and household consumption and travel surveys. The researchers claim they're the most detailed carbon maps ever produced for a metropolitan area.
Take a look for yourself here.