A new report takes the measure of the "carbon footprints" produced by Americans living in the nation's largest metropolitan areas. We in the Baltimore area fare rather poorly - 69th out of 100 - in the amount of carbon emitted per resident.  

The study, the first to try to quantify carbon emissions from U.S. urban centers, was produced by the Brookings Institution, in collaboration with researchers from Georgia Institute of Technology.  The report only fills in half the footprint for now, focusing on the carbon produced by driving in metro areas and by the energy used in housing.  Researchers say they hope to tally up carbon emissions from commercial and industrial activity, and from transit, by year's end.  

Densely settled regions with compact development patterns and rail transit tend to be more energy- and carbon-efficient than sprawling, car-happy metro areas, the report says. 

But per capita emissions vary widely among cities, and some, like Baltimore, still lag, despite having more transit ridership than most.  Spendthrift energy consumption to heat and chill our homes through winter and muggy summer apparently is the culprit.

Georgia Tech energy professor Marilyn Brown, a member of the Intergovernmental Panel on Climate Change, suggested that the relatively cheap electricity rates Marylanders enjoyed as a result of utility deregulation in the early part of this decade kept residents from making their homes more energy efficient.   The study only looks at energy use and carbon emissions from 2000 to 2005, before the rate caps came off and utility bills shot up by 70 percent or more.

Paying more for electricity, plus new state energy-efficiency incentives, and a push for more renewable energy could help shrink Baltimore's carbon footprint in years to come, she agreed. 

Meanwhile, Honolulu, Los Angeles and Portland, Ore. topped the list as the three regions with the smallest per capita carbon emissions, according to the study.  Cincinnati, Indianapolis and Lexington, Ky., brought up the rear with the biggest prints.  Urban areas in the West, in fact, tended to have smaller carbon outputs per resident. For more on the study, and the rankings, go here.

The report's authors say the federal government ought to do more to encourage transit and compact development, because two-thirds of Americans live in the largest metro areas, and three-quarters of all economic activity takes place in them.  The payoff to focusing on metro areas, the study says, is that the carbon footprint of an urban denizen is 14 percent smaller than for - and is increasing only half as much.