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SALT LAKE CITY — Multiple carbon dioxide sensors strategically scattered throughout Salt Lake Valley reveal the impacts of urban growth and suburban sprawl on greenhouse gas emissions, offering unique insight to metropolitan planners and city leaders trying to reduce their carbon footprint.
In findings published this month in the Proceedings of the National Academy of Sciences, a University of Utah-led research team determined suburban sprawl causes more carbon dioxide emissions than an already-established urban core.
"You're taking an area that had nothing and adding something to it," said Logan Mitchell, a research associate with the U.'s Department of Atmospheric Sciences.
The U. started what is now the world's oldest network of carbon dioxide sensors in 2001, collecting a steady stream of data on greenhouse gas emissions for a decade.
The research project's first sensor went on top of the William Browning Building on campus, with more that followed in Rose Park, Murray, Sugar House and in 2004 in southwest Salt Lake County, an area dominated by open fields.
The sensor placed in the southwestern section of Salt Lake County was intended to measure greenhouse gas emissions in rural areas, but over the study period, development exploded in the area, adding another 13,000 people.
Even though Salt Lake City's metropolitan area added about the same number of people, the carbon dioxide emissions footprint was less, researchers said.
"With urban growth, you are putting more people into an existing area. They don't have to drive as far to get to their jobs. You're replacing a house with an apartment building. It is not associated with that much more carbon dioxide emissions," Mitchell said.
The southwest sensor allowed researchers to examine the effects of population growth on carbon dioxide emissions, and particularly how land use decisions might shape outcomes.
Such data will be helpful to cities trying to meet carbon emission reductions. Salt Lake City, as an example, wants to reduce carbon dioxide emissions by 80 percent by 2040.
“The hope is that we or others who use these tools can help inform where the most bang for their buck is or whether 80 percent is even realistic given the projected population growth," said John Lin, associate professor in the U.'s Department of Atmospheric Sciences.
Mitchell added that coordinated urban planning will play an even more critical role if the goal is to reduce carbon emissions.
“Salt Lake City is one entity in the valley, but it's not the only one,” Mitchell said. “If you reduce emissions by 80 percent and everyone moves out further from work and commutes in, it's not actually solving the problem.”
U. researchers now plan to collaborate with a handful of other cities with a network of carbon dioxide sensors in place: Indianapolis, San Francisco, Los Angeles, Boston and Baltimore, which is just coming online.
The hope, Mitchell said, is to develop common ground for modeling and projections based on each system, so researchers can compare information among these metropolitan regions.
Locally, they also want to look at the relationship between carbon dioxide and air quality by examining data from pollution monitors on tower sites as well mobile monitors on trains.
