The above picture is a snapshot of the city of Indianapolis, as seen through its greenhouse gas emissions. All those glowing green patches of land – those are individual residences contributing to the city’s carbon footprint thanks to home heating, lighting and appliances. The tall red towers illustrate the emissions coming from commercial properties and industry. And those squat red bars cutting through the city – those are cars traveling Indianapolis' beltway at rush hour, emitting carbon dioxide as they go.
This image comes from the Hestia Project, a software system just developed by researchers at Arizona State University that can estimate greenhouse gas emissions across a city’s landscape, right down to its individual buildings and roadways.
“We all love to point the finger at everyone else for greenhouse gases, but one thing that becomes imminently clear when you look at emissions in this detail is that blame is a ridiculous thing to do,” says Kevin Gurney, an associate professor in ASU's School of Life Sciences and a senior scientist with the Global Institute of Sustainability. "We’re all part of the system. All of us engage in these activities. I drive a car, I have a home, I go to work. And you really see that."
The software corrals publicly available data wholly unrelated to climate change. That includes property tax filings that reveal the size and age of buildings, how they’re used and what fuel heats them, DMV records on auto maintenance and inspections, and Metropolitan Planning Organization traffic count estimates. "None of that data has been collected technically for any environmental reason," Gurney says.
And this is one of the strengths of Hestia. The United States and other nations have objected to international climate treaties that don’t include rigorous verification of emissions levels and reduction efforts. We can’t solve the problem, the argument goes, until we can accurately measure the scope of it and what governments say they're doing to address it.
Well, Hestia has figured out how to estimate those measurements at the micro scale, using internally consistent data that could hardly be classified as suspect (think cities are manipulating their DMV records to paint a rosier picture of their carbon footprints?). “This is starting to eliminate that excuse,” Gurney says.
Hestia can also track patterns in emissions over time. In this hypnotic hourly animation, you can watch the people of Indianapolis head to work in those red buildings by day, then return home to residences that light up in green with tens of thousands of households turning up their thermostats and TVs by night. Traffic along the city’s main highways ebbs and flows in purple.
This seasonal animation, meanwhile, illustrates how dramatically different a city’s energy use appears in summer and winter.
The researchers have begun to test the software in Phoenix and Los Angeles as well, and Gurney imagines that it would be particularly useful to city managers trying to figure out how to target limited resources toward the emissions sources with the greatest potential for reductions.
"At the end of day," Gurney says, "it doesn’t matter what policy is made out there at the national level, the international level, or state policy. At the end of the day, it’s going to come down to people doing things at the scales of roads and buildings and industries. That’s where the decisions on using energy occur."
This is also why, Gurney believes, we need data at that same scale to guide those decisions. In more detail, you can watch the researchers here explain how they designed the software: