Saturday night in Chicago will be a little darker than usual.

From the Congress Plaza Hotel and the Essex Inn, to the ferris wheel at Navy Pier, the Sears Tower, the Citigroup building and the Hancock Observatory, many of Chicago's largest and brightest landmarks have pledged to turn off marquees and non-essential lighting for one hour Saturday as part of a global effort to reduce energy use.

Chicago is the flagship U.S. city for the Earth Hour 2008 initiative, launched by the World Wildlife Fund last year as a way of promoting solidarity against the threat of global climate changes caused by greenhouse gas emissions and wasteful energy use.

The event has drawn participants from 25 major cities around the world who have pledged to turn out the lights between 8 and 9 p.m.

In Chicago,  more than 400 businesses have agreed to participate. The most noticeable effects will be along Michigan Avenue, where a long list of signature buildings and popular retailers have agreed to turn off the lights.

Street lamps, hospital lights, front lobby lights and other lights needed for public safety will remain on.

Residents are urged to participate by switching off  non-essential lighting and using the time to make the switch to energy-efficient fluorescent lighting.

Chicago Mayor Richard M. Daley says the event is in keeping with the city's goal of becoming the country's "most environmentally friendly" city.

"An important part of Chicago's efforts ... is to help our residents understand the impact climate change has on our city," Daley said at the program's Feb. 15 launch event at Navy Pier.

"Programs like Earth Hour 2008 reinforce our commitment to environmentally-friendly practices that will improve the quality of life for residents in Chicago and people around the world."

In February, Chicago was listed among Popular Science magazine's "top 10 U.S. Green Cities," for, among other things, its bicycle friendly practices, use of hybrid buses, water conservation efforts and "green" construction of public facilities.

Daley isn't the only public official working to make Chicago "green." In the 25th Ward, a diverse area covering Chinatown, UIC and Pilsen, Alderman Danny Solis is promoting Earth Hour 2008 to his constituents.

According to legislative aide Stephen Stults, fliers on Earth Hour 2008 are being handed out in both Spanish and English, asking residents to turn out their lights to reduce energy use and help stop climate change. Mandarin-language fliers are also in the works.The Auditorium intends to shut off its marquee for the hour-long event. "We were contacted by Broadway in Chicago about Earth Hour," says general manager Jennifer Turner. "It's great to be able to be a part of this citywide initiative, which is part of a global initiative.""Roosevelt University is actually participating in a 'Roosevelt University Green Pledge,'" Turner says of the school's efforts to reduce green house gas emissions.

"Employees make this pledge to change their behavior at work and at home. There is a larger awareness of the environment going on in the city and in the world."

Earth Hour began in Sydney, Australia last year.
 
According to Earthour.org, in just 60 minutes, 2 million participants, including major landmarks and businesses, managed to reduce energy consumption by 10 percent and greenhouse gas emissions by an amount equal to taking 48,616 cars off the road for one year.

To find out more about Chicago's involvement or to sign on to the effort, visit http://www.earthhourus.org/chicago.php.