"Earth Hour: turn your lights on at 8 p.m."

Here.

Excerpt:

Tonight, the officials in many cities, including Atlanta, Phoenix, San Francisco, Montreal, Toronto, Bangkok, Dubai, Tel Aviv, Bogota, Buenos Aires, Caracas, Mexico City, Ottawa, Warsaw, Copenhagen, and Dublin, joined the activists. The Chicago skyline will probably disappear, too. All Czech cities, towns, and villages unanimously rejected the idea.

Incidentally, the believers who will replace light bulbs by candles should know that a candle produces as much CO2 as a 20W light bulb powered by average energy sources during the same time. Five candles replace the CO2 output of a 100W light bulb.