Source: UC Berkeley CoolClimate Network, Average Annual Household Carbon Footprint (2013)
Well, we city-dwellers have known
all along that it is more environmentally beneficial to live in high density
urban areas. But now we have the
unfortunate evidence that, alas, any carbon footprint benefits accruing to
cities are more than offset by the much higher carbon footprint of our suburban
counterparts in the nearby hinterlands, and based upon a visual inspection of
the mapped data, it appears that the wealthier suburban communities are
definitely the bigger energy hogs than their poorer suburban neighbors or rural
areas. There are a series of cool
interactive maps (at http://coolclimate.berkeley.edu/maps
and thanks, Tom Paino, for sending me the link) allowing you to zoom into any
zipcode in the continental US and see how the annual household carbon footprint
has been tallied, considering transportation, housing, food, goods, and
services. My zipcode, 10033 in
Washington Heights, NYC, for example, is rather carbon thrifty, at 34.6 metric
tons of CO2 equivalent, while just across the Hudson River in 07632
Englewood Cliffs, NJ, it is nearly double at 69.5, and in Old Westbury, on Long
Island to the east of NYC, it is 95, almost triple.
Baltimore City, MD (21201) is
positively parsimonious at 25, and Baltimore shows up on the map as a green
oasis in a sea of reds and oranges, denoting the surrounding suburban household
carbon footprints double that of the inner city. There was one thing that I question on this
map and that is there is no legend, so we cannot see what the class ranges are
for each color. When you touch on each
zipcode, the stats for that zipcode pop up, but it seemed to me that the same
color represented different ranges, perhaps dependent upon the state. Therefore it is difficult to make any
consistent inferences based on the zipcode color, which obviously can be
somewhat misleading in making visual comparisons.
There are two other interactive
maps: Average annual household energy (electricity, natural gas, other) carbon
footprint by zipcode (where, again the contrast between Washington Heights in
Upper Manhattan around 6 and Old Westbury at 16 is amazing!).
The third map is average monthly
vehicle miles traveled per household by zipcode, (and of course in many parts
of NYC, households have on average as low as 0.1 vehicle per household. In other words, in many parts of the city,
only one in 10 households has a car, on average. The vehicle miles traveled is figured by
multiplying vehicle miles traveled per month by the number of vehicles per household.
I found the assumptions of this
calculation a little odd – nearly every zipcode in the country had households
driving about 1,200- 1,400 miles per month, and I think there should be much
more variation in this figure. Only in
some isolated areas in the western and northern US were households driving
1,500-1,700 miles per month, otherwise it seems that every household puts on essentially
the same mileage. I think if you live in
NYC and are crazy enough to have a car there, the last thing you would be doing
is sitting in your car racking up 1,200 miles a month. If so, that’s about all you would have time
to do traveling at the snail’s pace that is NYC traffic! That’s an average of 40 miles per day, and
virtually no one within the city would drive a 40 miles per day commute or just
go joy-riding around for 40 miles per day.
But other than those relatively
minor cavils (and knowing how difficult it is to keep a nation-wide study
consistent when there is such extreme variation across zipcodes) the maps are
fascinating and the study seems sound.
This shows how the suburban areas create a much higher carbon footprint than the cities or rural areas, from Philadelphia to New York City.
Here’s the abstract from the paper
the maps in which the maps appear:
“Which municipalities and locations within the United States
contribute the most to household greenhouse gas emissions, and what is the
effect of population density and suburbanization on emissions? Using national
household surveys, we developed econometric models of demand for energy,
transportation, food, goods, and services that were used to derive average
household carbon footprints (HCF) for U.S. zip codes, cities, counties, and
metropolitan areas. We find consistently lower HCF in urban core cities (40
tCO2e) and higher carbon footprints in outlying suburbs (50 tCO2e), with a
range from 25 to >80 tCO2e in the 50 largest metropolitan areas. Population
density exhibits a weak but positive correlation with HCF until a density
threshold is met, after which range, mean, and standard deviation of HCF
decline. While population density contributes to relatively low HCF in the
central cities of large metropolitan areas, the more extensive suburbanization
in these regions contributes to an overall net increase in HCF compared to
smaller metropolitan areas. Suburbs alone account for 50% of total U.S. HCF.
Differences in the size, composition, and location of household carbon
footprints suggest the need for tailoring of greenhouse gas mitigation efforts
to different populations.”
From:
Christopher M. Jones and Daniel M.
Kammen, Spatial Distribution of
U.S. Household Carbon Footprints Reveals Suburbanization Undermines Greenhouse
Gas Benefits of Urban Population Density. Environ.
Sci. Technol., 2013, dx.doi.org/10.1021/es4034364
Frequently asked questions about the paper (and including
limitations of the study and urban planning implications) are at: http://coolclimate.berkeley.edu/files/coolclimate/Jones-Kammen-CarbonFootprint-FAQ-EST-1-10-2014.pdf
The American Carbon
Footprint
Also, here’s another cool website with interactive maps, showing global carbon footprints
by current emissions, per capita, intensity, and cumulative emissions, going
back to 1850 at the dawn of high industrialization. Very enlightening! http://environment.nationalgeographic.com/environment/energy/great-energy-challenge/global-footprints/
And we couldn’t forget Danny Dorling’s amazing global cartograms
of CO2 emissions, from the Worldmapper team at WWW.worldmapper.org
