More than 500 local businesses have agreed to be a part of the Windy City's first Earth Hour, said Sadhu Johnston, Chicago's chief environmental officer.

Among the landmarks taking part in the event are Wrigley Field's marquee, Michigan Avenue storefronts and the Sears Tower's antennae.

Other cities participating in Earth Hour are Atlanta, Phoenix and San Francisco, the newspaper said.

"I don't expect the actual hour is going to save enough power to make a huge difference" in affecting the global climate, Johnston said, adding that the event is aimed at getting people to talk about global warming.

"There are lots of things people can do in their own lives to help us be a green city," he said. "That may mean turning off lights when they are not using them, or unplugging cell phone chargers when they are not doing anything."