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Kahrin Deines/Medill

More than 3.28 billion vehicle miles were traveled in Cook County in 2007, according to the Illinois Department of Transportation.

Cook County No. 3 in carbon emissions, study says

by Kahrin Deines
May 01, 2008


Courtesy of Purdue University.

The Vulcan map of total CO2 emissions in the U.S. for 2002, which came to 1,506 million metric tons. 


Kahrin Deines/Medill

The sources of emissions in the top 10 U.S. counties leading in CO2 generation, according to the Vulcan Project.


Kahrin Deines/Medill

A comparison of the per-capita carbon emissions for area counties, according to Vulcan Project data.

Cook County has driven itself to a rank of third highest in the nation for carbon emissions, according to a new inventory that its makers say tracks carbon dioxide, the main greenhouse gas, at a more localized level than ever before.

Known as the Vulcan Project, after the Roman god of fire, the inventory maps emissions for the entire United States, tracing the carbon trail down to areas the size of 100 kilometers.

Along with Cook County, the other big-time carbon generators include Los Angeles County in California and Harris County (Houston) in Texas.

"Chicago’s the third largest city in the country so it’s not surprising that [Cook County] would be the third on the list," said Brian Steele, spokesman for the Chicago Department of Transportation.

Population and emissions did not partner in every case, though. Although the top three counties on the Vulcan emissions list are also the nation’s most populous, the link between people and pollution falls apart after the top three.

For example, Wilcox County in Alabama is No. 8 on the list, even though it had a population of only 12,779, according to U.S. Census estimates. And it’s not because Wilcox residents have three cars each. They do not. Rather, the county ranks high because of emissions created by paper manufacturing.

Cook County, along with Los Angeles County, are the only two in the top 10 where traffic emissions account for a large part of the total. For Cook, the Vulcan project found more than 40 percent of the 13.2 million metric tons of carbon came from cars, trucks and other mobile sources emitted in 2002, the last year for which there was data. 

"I’ve long felt there’s this really funny thing about climate change," said Kevin Gurney, the project’s lead researcher and a professor at Purdue University. "Unlike with population or water shortage, we don’t know much about the [location of the sources]."

To better pinpoint the sources of emissions, Gurney and a team of other scientists combined estimated carbon emissions with other data, such as building sizes, road traffic and vehicle types.

All of the combined information was then plotted onto an interactive map that separates out the impact of different fossil-fuel burning activities, from home heating to driving. "It turns out that the spatial and temporal part of it is actually like a [carbon] fingerprint," Gurney said.

The Vulcan researchers brought in the fourth dimension – time – by using daily air quality reports to the Environmental Protection Agency to estimate carbon emissions.  The project was funded by NASA and the Department of Energy.

"This is something that no one has done in the past," said Atul Jain, a professor of atmospheric sciences at the University of Illinois in Urbana-Champaign. "This is the way to do the inventory not only for C02, but also for the other greenhouse gases."

"It offers the opportunity to look at where the emissions are, and where they come from," project director Gurney said. "Now they look at the U.S. economy and say regulate the power plants and that may be OK, but the U.S. has a lot of texture to it and we may need a policy that’s more nuanced."

Along these lines, Cook County is seeking state and federal funding to retrofit diesel-burning vehicles in its fleet, according to spokeswoman Ibis Antongiorgi. The EPA stepped forward earlier this year with a grant of about $100,000 to support a county goal of cutting diesel emissions by more than 60,000 tons before next year.

Meanwhile, the City of Chicago is preparing to release a comprehensive Climate Action Plan to substantially reduce CO2 emissions, focusing on energy efficiency in buildings.

On a superficial level, the Vulcan findings seemed to conflict with emissions estimates produced by the Center for Neighborhood Technology, a Chicago organization that studies sustainable development and is working with the city on its plan. While the Vulcan data shows Cook County emitting more carbon than other Illinois counties, the center’s maps set its emissions lower than its neighbors.

The disagreement, however, is only a matter of how the counting is done: Cook County does emit more total carbon dioxide, but it also emits less per person than most of the other area counties.

"The way the information is sliced and diced it’s always going to be different, and you have to decide what information is important to you," said Jennifer McGraw, a climate program manager with the Center for Neighborhood Technology.

For the center, slicing by person puts the emphasis on how dense urban areas can lower carbon levels because they offer public transit and shorter travel distances. "It’s not just place, it’s the people, so you have to look at the density," McGraw said.

For Gurney and his fellow researchers, on the other hand, the focus is on tracking carbon emissions back to their physical beginning. By developing a more detailed carbon emissions inventory, Gurney said, scientists hope to come to a fuller understanding of the planet’s natural carbon cycle. They also will be able to track progress in reducing CO2 emissions over time.

"There are individual air sheds and cities that have really done some great work," Gurney said. "Unfortunately those great examples are not consistent. We had to have a consistent method that could apply everywhere."

In the next version of Vulcan, which Gurney says may be released within six months, emissions from air traffic and non-road traffic, including railroads, will be added to the tally. After that they are hoping to take Vulcan worldwide, as well as introduce other data sets to the mix. And, starting in August, Gurney and others will begin building a more advanced emissions tracking system, using Indianapolis as their test-pilot city.

"We need to ... expand our universe of data, and use data that have never really been brought together before," Gurney said.

To get there, Gurney said, they need feedback. "We’re trying to do this outreach effort where we welcome everyone to look at our data. We want to welcome them to be a part of the team."