The only thing Aamir Khan and Antonio Villaraigosa have in common is that they both have first names that begin with the letter “A.” Oh, and they both are visible leaders in the cities home to two of the world’s largest entertainment industries.

Yet, on March 28th, the Bollywood megastar and Los Angeles mayor will have something else in common — they will spend an hour in the dark.

Both Khan and Villaraigosa served as the faces of their respective cities, which are both participating in Earth Hour later this month. A worldwide energy conservation effort coordinated by the World Wildlife Fund (WWF), the residents of Los Angeles, Mumbai, and about 700 other cities will turn off their lights for an hour at 8:30 p.m. on Saturday, March 28th.

According to WWF, Earth Hour is a global event uniting cities, businesses, schools, organizations and individuals by asking them to turn out the lights for one hour in a unified call for action on climate change.

“After years of inactivity, there is no longer any time to waste,” Villaraigosa declared to Buzzine and other members of the media at a press conference on February 28th at downtown’s L.A. Live. “This will be the world’s largest event on climate change. We will flex our muscles with one flick of the switch!”

While Villaraigosa spoke on behalf of the city he was elected to lead in 2005, Khan will represent Bollywood, the world’s largest entertainment industry.

“Climate change is undoubtedly and regrettably, the biggest immediate long-term environmental challenge we face,” he told the WWF. “A failure to come to sound policy outcomes on climate change will not only have a negative environmental impact but also social and economic consequences for all of us.”

As part of the worldwide climate change campaign, several businesses and local companies throughout major cities in 75 nations will stage a coordinated effort to shut off power at several key locations at 8:30 p.m. local time. Lights will remain off until 9:30 p.m.

In Los Angeles alone, WWF estimated that more than 550,000 kilowatt hours of energy will be saved during Earth Hour. In other words, turning off all of the lights for 60 minutes in Los Angeles will save about 46,000 gallons of gasoline.

The WWF designated Los Angeles as a flagship city for Earth Hour 2009. According to Villaraigosa, his city produces more than 1% of the world’s carbon emissions — an amount greater than the carbon emissions produced by all of Sweden.

“Earth Hour is just one leg in the race against global warming,” Villaraigosa said. “Los Angeles already has the pieces in place to cross the finish-line. We need to work together as one city, one people, one world!”

While Villaraigosa is actively promoting his city’s participation in Earth Hour, Mumbai and New Delhi are both working with WWF to create awareness of global warming throughout India.

In what is considered a unified call to action on climate change, WWF initiated Earth Hour in 2007, when more than 2.2 million people in Sydney, Australia participated in the first-ever event of its kind. Earth Hour expanded in 2008, when 50 million people on all seven continents participated. This year, Earth Hour will start in Fiji and travel all around the world, similar to New Year’s Eve celebrations.

Landmarks such as San Francisco’s Golden Gate Bridge, Rome’s Colosseum, New York City’s Times Square and Dubai’s Jumeirah Hotel, among others, will be darkened for one hour on March 28th. Even the Las Vegas Strip will be dark for only the second time in its history. (The only other time the Strip went dark was when Frank Sinatra passed away). Local landmarks to go dark during Earth Hour include the Santa Monica Pier, L.A. Live and Staples Center, several restaurants and hotels, and highly populated residential neighborhoods.

“We understand we won’t solve climate change in that one hour, but we hope to make a connection with everyone, calling everyone to action,” Villaraigosa said at the end of the press conference.