By Denise Baker, NBC News Producer

ATLANTA – For one hour this Saturday night, Atlanta, along with nearly 200 other cities around the world, will go dark in what the World Wildlife Fund (WWF) is calling the largest planned power outage in history.

WWF, an international environmental advocacy group, is spearheading the event in an effort to raise awareness about power consumption and climate change.

More than 2.2 million people participated in the inaugural Earth Hour last year, in which just one city – Sydney, Australia – went dark. The one hour outage produced a 10 percent drop in energy usage during the hour – double what had been predicted.

The Sydney event led to the push for a global effort this year. Other U.S. cities participating include Chicago, Phoenix, San Francisco, and international cities range from Bangkok to Tel Aviv.

Mike Bowers/ Fairfax Media

The Sydney Harbour Bridge seen with its lights on.

"We'd like to see a visible change from space," said Eric Fanning, the person in charge of logistics for Earth Hour.

This year's event has set off a war of words among some of Australia's leading newspapers. They are debating the merits of the lights-out hour and questioning whether or not it will have any real effect on cutting greenhouse gas emissions. 

 

Mike Bowers/ Fairfax Media

The Sydney Harbour Bridge seen with its lights out during the first Earth Hour March 31, 2007.

The event will begin at 8 p.m. local time in Christchurch, New Zealand, and flow through 14 time zones, concluding in San Francisco, where the lights on the Golden Gate and Bay Bridges will turn off along with all other non-essential lighting.

Skylines will go dark in Suva, Fiji, and Calgary, Canada. Major league sports arenas will dim their lights in Phoenix. And in New York City, it will be lights out for Coca-Cola's Times Square billboard for the first time in its history.

Not all Georgians are excited to see the state's largest city participate in this effort.

In a letter to the Atlanta Journal-Constitution, Joel Smith of Stockbridge, Georgia, wrote "the idea that reducing energy consumption will save the planet is based on questionable science… .Everybody likes dynamic growth, new opportunities, etc. It takes energy to do this."

Nevertheless, on Saturday at 8 p.m. ET, Mayor Franklin and the World Wildlife Fund's Carter Roberts will throw a giant switch to power down Atlanta's downtown and the lights will go off in Georgia's biggest city.