for National Geographic News
Cities around the world will briefly go dim Saturday evening as the lights of buildings and landmarks are shut off for one hour to raise awareness about climate change.
Called Earth Hour, the event is organized by the conservation nonprofit WWF to encourage people to conserve electricity and reduce the greenhouse emissions that cause global warming.
(Get the facts on global warming.)
Earth Hour started last year with one city, Sydney, Australia. The response was so strong that WWF decided to take the event global for 2008, said WWF spokesperson Leslie Aun.
"We were trying to get a few people to participate, but we ended up getting 2 million people and some 2,500 businesses," Aun said.
This year, Earth Hour will include 35 official partner cities, as well as dozens of smaller cities spread out across six continents.
"We have a city in every major U.S. time zone participating," Aun said.
The event will take place from 8 p.m. to 9 p.m. local time in each time zone.
(National Geographic Channel is the U.S. media partner for Earth Hour. National Geographic Channel and National Geographic News are both owned by the National Geographic Society.)
Landmarks Go Dark
In the United States, WWF President Carter Roberts sent letters to mayors around the country inviting them to take part.
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