"The Mississippi River roughly divides the country into high and low emitters," it says. "In 2005, all but one of the 10 largest per capita emitters were located east of the Mississippi."
The north-south divide is also evident, with seven of the highest per capita emitters south of the Mason-Dixon line, including two each from Tennessee and Kentucky -- both coal-reliant states with little mass transit.
The report's timing is no accident.
As the Bush administration fended off pressure in recent years to sign the 1997 Kyoto Protocol, an international treaty limiting greenhouse gases, more than 800 U.S mayors signed a "Climate Protection Agreement" to cut their cities' emissions to 7% below 1990 levels, the Kyoto target.
But "metros can't go it alone in solving as vast a problem as climate change," said Mark Muro, director of Brookings' "Blueprint for American Prosperity" initiative.
Emissions from residential, commercial and transportation sectors each increased by more than 25% over the last 25 years, the report notes, while industrial emissions declined as manufacturing dwindled.
Next week, the U.S. Senate is expected to take up legislation to limit carbon emissions nationwide. Its provisions, which include a cap-and-trade system for greenhouse gases, are highly controversial, and Brookings wants aggressive measures to encourage climate-friendly cities.
The report calls on the federal government to put a price on carbon, making coal-fired electricity more expensive, and to establish a renewable electricity standard, requiring that a certain percentage of the nation's power come from alternative sources such as wind and solar plants.
Twenty-six states and the District of Columbia already have renewable portfolio standards. The California Legislature is considering boosting the state's percentage from 20% to 33% by 2020.
The report also calls on the federal government to stop favoring highway building over mass transit. And it suggests legislation that would reward utilities for conserving, as California does. Another recommendation: Require all home-sellers to disclose the energy costs of their homes for several years.
Although some had quibbles with their rankings, city officials praised Brookings for highlighting the need for the federal government to focus on cities. Two-thirds of Americans live in large metropolitan areas and three-quarters of the nation's economic activity takes place there, according to the report.
