Seeing a City’s CO2 Emissions, Block by Block Counting carbon dioxide emissions block-by-block could enable locally tailored solutions to global warming. By Sarah Fecht Read more: Seeing a City’s CO2 Emissions, Block by Block – Popular Mechanics

By Sarah Fecht

This map shows where CO2 is emitted across the city of Indianapolis, Indiana, and combines data from sources including factories, automobiles on roadways, homes, and power plants.

When people talk about carbon emissions, it’s often on a national and international scale. The EPA reports that in 2010 the U.S. generated nearly seven billion metric tons of carbon dioxide. That number is difficult to contemplate, and for most of us, it’s hard to see how our everyday activities fit in with it.Scientists from Arizona State University wanted to study greenhouse emission not on a large scale, but down to the level of a single building or street. So they devised a way look at a city’s CO₂ emissions with extremely high resolution. The new software visualization can even model CO₂ emissions by the hour, day of the week, and season, says Kevin Gurney, an ecologist who led the study.

“We literally see the city waking up, having breakfast, and we watch the CO₂ flow along the roads, and then we watch the commercial sector light up,” he says.

The program, named Hestia after the Greek goddess of hearth and home, was announced recently in Environmental Science and Technology. This early version of Hestia models Indianapolis. The software doesn’t model real-time data: Sensors have a hard time measuring fluxes in CO₂ concentrations, and due to atmospheric mixing, they can’t tell the difference between CO₂ that’s emitted by a rhododendron versus a power plant. Instead, Hestia models emissions by combining data from air pollution sensors, roadway traffic counts, and public records on the size, age, and fuel source for every building in town.

The maps generated by Hestia reveal ribbons of CO₂ emissions along highways, and a tall black bar that towers over the entire city—that’s the Harding Street Station, a 1996 1196-MW power plant. Not surprisingly, the Indianapolis International Airport was also a big CO₂contributor.

“I think Hestia is a very powerful tool,” says Michael Steinhoff, who develops carbon accounting tools for cities through the International Council for Local Environmental Initiatives (ICLEI), and who wasn’t involved in the new research. Steinhoff says that although the data has been available for a while, Hestia “communicates this information in a new way, and ties it back to the activities that are really responsible for those emissions. People as individuals can say, ‘That’s the building I work in,’ and start to connect abstract concepts back to their own life.”

Hestia’s creators say that America’s major cities are responsible for nearly 25 percent of the world’s CO₂ emissions. And since much of those emissions arise from the daily actions of ordinary Americans, Gurney says many carbon-curbing policies should also operate on the micro-scale. He hopes the high-res software will help local politicians to make smart, low-cost decisions to cut carbon emissions. For example, he says, if a city government receives funding to increase residential insulation, Hestia could pinpoint the homes that are likely to have the greatest need for better insulation based on their disproportionate energy use. And in future versions of the software, decision-makers will be able to model the impacts of different carbon-cutting strategies, to select the most effective one.

“Every city is different, and that means that no single policy works for everybody,” Gurney says. “Solutions should be dialed in to best suit their needs and reflect what they can and can’t do,” he says. The software can be adapted to nearly any city, Gurney says, it just takes time to compile all the relevant data from the local governments.

The researchers are now modeling CO₂ emissions across Los Angeles and Phoenix. Representatives from several other cities have expressed interest in participating in the project, including reps from Cincinnati, Minneapolis, and Miami.

Hestia could have impacts on a larger scale as well. Gurney says that the U.S. has been hesitant to participate in international treaties—such as the Kyoto Protocol—because there hasn’t been a way to verify whether each country truly has reduced CO₂ emissions. He thinks that Hestia or similar software could provide an accounting system that makes international cooperation more palatable.

Still, ICLEI’s Steinhoff says that’s no guarantee that countries will cooperate more on emissions agreements. “Reasons for joining or not joining are really just political,” he says. At least on the national and international level, the effort to curb climate change seems likely to remain politics as usual.