Atlanta ranked 7th among  the nation's 100 largest metro areas, and Georgia ranked 9th among states in the overall size of its so-called "green" or "clean" economy, a new report said.

Atlanta has 43,060 clean jobs and Georgia 83,707, and those numbers generally have been growing each year since 2003, the Brookings Institution said Wednesday.

The green economy, defined as the economic sector that produces goods and services with environmental benefits, has been touted as source of potential new job creation. But what constitutes a green job, how many there are, and what economic benefit they yield has been difficult to determine and widely discussed.

Brookings said there are 2.7 million workers in the green economy nationwide, more than work in the fossil fuel industry, it said. They work in areas including manufacturing, waste water treatment and mass transit as well as in the solar, wind, smart grid, biofuel and battery industries.

The largest segments for green jobs in Atlanta are conservation, waste management and treatment, and mass transit. Statewide, the biggest segments are green building materials, conservation and waste management and treatment.

The South has the most clean green jobs, and seven of the 21 states with at least 50,000 green jobs are in the region.

Green jobs, the study showed, pay more. The median annual wage for a green job in metro Atlanta is $40,602, compared to $39,810 for all jobs in Atlanta. In Georgia, the annual wage for green jobs is $36,764 versus $36,139.

In Atlanta, green jobs make up 1.9 percent of all jobs in the area, ranking 41st among metro areas in concentration. Green jobs make up 2.1 percent of all jobs in Georgia, ranking the state 18th.

Atlanta's green job sector grew by 5.9 percent annually from 2003 to 2010, while Georgia's grew by 3.7 percent.