Study shows biggest polluters east of Mississippi

Ford Explorers and trucks sit on a lot outside its assembly plant in Louisville, Kentucky, August 24, 2006.

NEW YORK (Reuters) - All but one of the top 10 U.S. metropolitan areas that release the most greenhouse gases on a per capita basis lie east of the Mississippi River, a study released on Thursday showed.

"A north-south divide is also apparent," said the report issued by two think tanks, the New York-based Regional Plan Association and the Washington-based Brookings Institution.

Seven of the largest emitters of greenhouse gases are in the south, including two cities each in Tennessee, Ohio and Kentucky, it said.

Carbon dioxide, produced largely by burning fossil fuels, is the most common of the greenhouse gases, which are blamed for trapping heat in the Earth's atmosphere and altering the climate. China is on course to overtake the United States as the world's top emitter of carbon dioxide.

The analysis counted greenhouse gases from only buildings and transportation, excluding factors like utilities.

Honolulu, Hawaii, was the greenest U.S. metropolitan area, with a carbon footprint of only 1.356 metric tons per resident in 2005.

The second greenest in the top 100 was Los Angeles-Long Beach-Santa Ana, with Portland-Vancouver-Beaverton, Oregon-Washington in third.

New York-Northern New Jersey-Long Island, New York-New Jersey-Pennsylvania was fourth and Boise City-Nampa in Idaho was fifth.

The worst polluter was Lexington-Fayette, Kentucky, which ranked last at 100. Indianapolis, Indiana, was 99th, Cincinnati-Middletown, Ohio-Kentucky-Indiana was 98th and Toledo, Ohio, was 97th.

Louisville, Kentucky-Indiana came in 96th, with Nashville-Davidson-Murfreesboro in Tennessee in 95th.

The West was the only part of the United States that cut its carbon footprint from 2000 to 2005, the report said.

CITIES ARE GREENER

Slashing carbon output will require a multifaceted strategy, the study said, with fast-growing southern cities such as Austin, Texas, Raleigh, North Carolina, and Nashville, Tennessee, having the fast-growing carbon footprints.

"Solutions must go beyond breakthroughs in technologies and fuels," the study said. "Lifestyle and behavioral changes are needed to reduce the metropolitan carbon footprint further."

Transportation produces one-third of the nation's carbon footprint, churning out 534 million metric tons in 2005. Vehicles driven on highways put out 80 percent of that total.

Residences, which demand fuel for heating and cooling, and running televisions and other appliances, put out about 39 percent of carbon emissions, the study said.

Metropolitan areas, where people drive shorter distances and use less electricity in their homes, are greener. On average, an urban dweller's carbon footprint was 86 percent of a suburban or rural resident's, the report said.

The Northeast has a built-in disadvantage -- colder weather coupled with fuel oil burners that tend to be more polluting than natural gas heaters used in other regions.

But the commuter rail, bus and subway systems that are much more common in the Northeast shrink its carbon footprint when just greenhouse gases generated by transportation are counted.

New York-Northern New Jersey-Long Island, New York-New Jersey-Pennsylvania ranked first with the lowest pollution in terms of just transportation.

Six of the top 10 on this list were in the Northeast, with none in the Midwest or South. The other four were all in the Pacific or the West: Honolulu, Los Angeles-Long Beach-Santa Ana, Las Vegas-Paradise and Portland-Vancouver-Beaverton.

(Editing by Diane Craft and John O'Callaghan)