If you live in the Chicagoland area, you should know that this Saturday, March 29, 8:00-9:00 pm (CST) has been designated Earth Hour – part of a global action to highlight the threat of global warming. Here’s an official description of the effort:

As World Wildlife Fund’s flagship city for the United States, Chicago, a leader in environmental initiatives, is encouraging its residents across the region to make the pledge to help fight global warming by voluntarily turning off their lights for 60 minutes. Signature skyscrapers, key landmarks, theater marquees and shops on the Magnificent Mile will voluntarily turn off their lights.

Earth Hour’s not just about cutting back for one hour. It’s about taking a stand and thinking ahead about what you, your neighbors and your city can do to slow climate change. Seize the Earth Hour moment and change some of your outdated energy-wasting light bulbs to new, efficient and inexpensive compact fluorescents. Think of other ways you can cut your energy usage and trim your electric bill after Earth Hour has passed.

Earth Hour debuted last year in Sydney and this year EH has gone global – participant cities are as far reaching as Aaloborg, Tel Aviv, Bangkok and Manila. Check out their website and click on the clip above for more info. (You will undoubtedly notice the sponsorship of several corporations not known for their love of the environment. Ah, the complexities of global activism…)