The system, dubbed "Hestia" after the Greek goddess of the hearth and home, provides hourly, building-by-building and street-by-street dynamics of carbon dioxide emissions.
"With Hestia, we can provide cities with a complete, three-dimensional picture of where, when and how carbon dioxide emissions are occurring," said Hestia's lead scientist Kevin Gurney, an associate professor in ASU's School of Life Sciences and senior scientist with the Global Institute of Sustainability, in a news release.
"Cities have had little information with which to guide reductions in greenhouse gas emissions -- and you can't reduce what you can't measure."
The researchers have already completed a map for Indianapolis, which they say was the first finely detailed account of an urban area's fossil fuel carbon emissions.
While there have been other studies to measure emissions, the researchers say that those attempts have covered larger geographical areas or have taken a more general approach.
To measure buildings, for example, the team accesses tax records for details such as square footage, the age of the building and what kind of fuel it uses for heating. Then the team runs individual building-energy models to estimate heat and air conditioning needs. The data are combined within a modeling system for quantifying CO2 emissions.
The Hestia team is working on maps for Los Angeles and Phoenix. Eventually the study will cover hundreds of metropolitan areas.
The Hestia model will help cities to determine precise locations of CO2 hotspots, such as energy-wasting factories or a neighborhood of older houses.
"This research, and its implications for global engagement regarding climate change, is an exciting step forward," said ASU President Michael M. Crow.
"Hestia gives us the next tool we need to help policymakers create effective greenhouse gas legislation."
Scott Bernstein, who heads up the Center for Neighborhood Technology, a Chicago firm that promotes sustainable urban communities, says it's much easier to take steps to reduce CO2 emissions from city streets and buildings rather than to change the entire nation's network of power plants, coal mines and refineries.
Previous tools to measure CO2 often weren't user-friendly.
"People look at these big giant spreadsheets in emissions accounting and their eyes glaze over badly, but if they can see a color-coded map, if they can see a flyover view, people get engaged," Bernstein told National Public Radio.
Hestia is expected to complement NASA's planned December 2013 launch of the Orbital Carbon Observatory satellite, which will measure the concentration of CO2 in the Earth's atmosphere, the university says.