The top twenty carbon dioxide-emitting counties in the United States have been identified by a research team led by Purdue University.
The top three counties include the cities of Houston, Los Angeles and Chicago.
Kevin Gurney, an assistant professor of earth and atmospheric science at Purdue University and leader of the carbon dioxide inventory project, which is called Vulcan, says the biggest surprise is that each region of the United States is included in the ranking.
"It shows that CO2 emissions are really spread out across the country," he says. "Texas, California, New York, Florida, New Mexico, the Midwest — Indiana, Illinois, Ohio — and Massachusetts are all listed. No region is left out of the ranking, it would seem."
The listing of the counties includes the largest city in each county. The numbers are for millions of tons of carbon emitted per year.
*Note: Santa Clara County has been temporarily removed from the rankings due to a reporting discrepancy at a large facility. The discrepancy is currently being investigated and an update will be issued when this is resolved.
The current emissions are based on information from 2002, but the Vulcan system will soon expand to more recent years.
Gurney says Vulcan, which is named for the Roman god of fire, quantifies all of the CO2 that results from the burning of fossil fuels such as coal and gasoline. It also tracks the hourly outputs at the level of factories, power plants, roadways, neighborhoods and commercial districts.
"It's interesting that the top county, Harris, Texas, is on the list because of industrial emissions, but the second highest CO2 emitting county, Los Angels, California, is on the list because of automobile emissions," Gurney says. "So it's not just cars, and it's not just factories, that are emitting the carbon dioxide, but a combination of different things."
Gurney notes that some counties on the list are there but they are producing goods or power for occupants of a different area.
"Counties such as Titus, Texas, Indiana, Pennsylvania, and Clark, Nevada, are dominated by large power production facilities that serve populations elsewhere," he says.
"My favorite one on the list is Carbon, Pennsylvania," Gurney adds.
The three-year project, which was funded by NASA and the U.S. Department of Energy under the North American Carbon Program, involved researchers from Purdue University, Colorado State University and Lawrence Berkeley National Laboratory.
The Vulcan data is available for anyone to download from the Web site at http://www.eas.purdue.edu/carbon/vulcan. Smaller summary data sets that offer a slice of the data and are easier to download also are available for non-scientists on the Vulcan Web site. These can be broken down into emission categories, such as industrial, residential, transportation, power producers, by fuel type, and are available by state, county, or cells as small as six miles (10 kilometers) across.
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