The first-ever analysis of county-by-county carbon dioxide emissions in the United States found that Harris County, which emits 18.6 million tons of CO2 per year, narrowly edged Los Angeles for the top spot.
"Some regions will see this analysis as an excuse to point fingers, but I don't really view it that way," said Kevin Gurney, an assistant professor of Earth and atmospheric sciences at Purdue University who led the study. "This gives us an opportunity to improve the situation."
Harris County catapulted to the top of the carbon dioxide list, which tallied emissions from all fossil fuel consumption through the year 2002, because of its large industrial base.
Industry, including petroleum refining and chemical manufacturing, produced 54 percent of the emissions, according to the study. Motor vehicles were responsible for 26 percent; power plants 13.5 percent; and residential and commercial sources 6.5 percent.
In contrast, more than half of Los Angeles' CO2 output was emitted by cars and trucks.
"Somebody has to supply the country with its gasoline and petroleum needs, and Harris County and its surrounding areas have decided that it may as well be us," said John Nielsen-Gammon, the state climatologist and a professor of meteorology at Texas A&M University.
"The county's high emissions ranking also comes from being a large population center nearly self-contained inside a single large county."
The new analysis represents the first effort to break carbon dioxide emissions down on a county basis. Previous statewide analyses found that Texas emits more carbon dioxide than any other state, and if it were a country, would emit more than all but six nations in the world.
As a result, the county-by-county study didn't come as a big surprise to some analysts.
"In part, this is the cost of conducting the business we conduct in the Houston area," said Elena Marks, Mayor Bill White's health policy director.
Residents can do their part by installing energy-efficient CFL lightbulbs, better insulating their homes and using public transit or taking other actions to reduce personal CO2 emissions, Marks said.
"People shouldn't feel guilty about this," she said, "but they should pay attention to the data and realize that we all have a part to play in reducing our carbon footprint."