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Kaid Benfield’s Blog

Dramatic new maps of CO2 emissions per household

Kaid Benfield

Posted May 27, 2009

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  red areas emit the most CO2 per acre from driving (by: CNT)  red areas emit the most CO2 per household from driving (by: CNT) 

The Center for Neighborhood Technology is releasing today a new series of GIS-based maps showing where carbon emissions from driving are the highest in the nation's metro areas.  The maps demonstrate vividly that, although emissions on a per-acre basis are greatest in highly urban areas, it is in the suburbs and outlying areas where we pollute the most on a per-household basis.  This is because rates of driving are so much higher in spread-out suburbia than in places where homes, jobs, shops, and services are in more convenient proximity to each other.

Above left, for example, is the Tri-State area including and around New York City.  The map on the left shows that the areas with the highest emissions, in red, are those that are most heavily populated.  That much should not be surprising.  But the map changes dramatically when carbon emissions are plotted on a per-household basis, as shown on the right.  It is essentially a reversed image of the map on the left, showing that the most populated areas actually have the lowest pollution rates per household.

The differences show up even more dramatically in the sprawling Phoenix region:

  red areas emit the most CO2 per acre from driving (by: CNT)  red areas emit the most CO2 per household from driving (by: CNT) 

CNT is a longtime collaborator with NRDC and many other organizations, and their GIS work is superb.  I have previously written about their excellent work on the geography of home affordability (for example, here and here) and have cited an early prototype of the CO2 mapping in a post about per-capita thinking in environmental impacts management.

Transportation accounts for 28 percent of all US greenhouse gases, according to CNT, and I believe it accounts for an even higher portion of carbon dioxide emissions specifically.  According to CNT president Scott Bernstein:

"Cities are more location-efficient - meaning key destinations are closer to where people live and work They require less time, money, fuel and greenhouse gas emissions for residents to meet their everyday travel needs. People can walk, bike, car-share, take public transit. So residents of cities and compact communities generate less CO2 per household than people who live in more dispersed communities, like many suburbs and outlying areas.

"If you're deciding where to live, consider moving to an urban area. You'll help fight global warming by emitting less CO2. And you're likely to drive less, so you'll spend less on transportation, saving up to $5,000 annually."

I would add that the emissions savings come not only from a greater array of transportation mode choices but also from the shorter driving distances that are taken in more accessible locations.  And, in addition to cities, the traditional centers of well-established suburbs also can exhibit favorable per-household emissions profiles.  This is illustrated in the maps below of metro Cincinnati, where I was last week:

  red areas emit the most CO2 per acre from driving (by: CNT)  red areas emit the most CO2 per household from driving (by: CNT)

The carbon maps are part of CNT's larger Housing +Transportation Affordability Index, which includes geographic data and mapping on housing costs, transportation costs, gasoline prices, and various customized variations thereof.  You can currently access the CO2 maps for 55 US metropolitan regions, and zoom in on particular neighborhoods or local communities if you like.  Later this year CNT expects to have 330 metro areas mapped on its site. 

Kaid Benfield writes (almost) daily about community, development, and the environment.  For more posts, see his blog's home page. 


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Dave ReidMay 27 2009 11:02 AM

Great maps (well not great actually I suppose), do they have similar ones for Milwaukee, WI?

Kaid @ NRDCMay 27 2009 11:09 AM

Absolutely. Just follow the links and click on "change region."

kirstin replogleMay 27 2009 01:07 PM

one question -- is it possible to get the URL to change when you go to a different region? i'd like to share the champaign-urbana info directly, but when i go to that region the URL is still for the NY-LI-NNJ maps...

pretty cool!

Kaid @ NRDCMay 27 2009 02:22 PM

Yes, but it's a bit tricky. I was able to do it through trial and error (note the links to the images I posted). Basically, you have to go to the home page for the H+T index (the final link in my post), then choose your region from the map.

Dr. James SingmasterMay 27 2009 06:47 PM

Why are wasting time and money plotting CO2 emissions per household instead of getting action to remove some of the CO2? I have a comment #2 on the Greeninc NYTimes blog, may 22 on the useless climate bill in Congress, which has no program for removing CO2 as I outlined in the comment. Just cutting emissions even 75% (requiring an act of God) we would still have 25% adding to the growing overload of CO2.
Dr. J. Singmaster

Ray HicksMay 27 2009 08:48 PM

I'm impressed the mapping shows exactly what we have found but on a grand scale. I supply CO2 mesuring equipment to many varied applications from agriculture to indoor air quality and what is considered to be good in the city would make many in rural areas ill. It's remarkable how our bodied adapt, some of our medical customers question how quality of life is measured in these high concentration areas. What is certain the that the increses are real and steady and it will have some health concequences.
Ray Hicks

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