Earth Hour returns tomorrow night, with cities across the world turning off the lights at 8:30pm local time. The annual event sponsored by the World Wildlife Fund is in its fourth year and growing quickly. About 30 US state capitals are expected to take part, up from 8 last year. Lights will go down at the Empire State Building, the Golden Gate Bridge, and the Las Vegas Strip, notes USA Today.
"It reflects the conviction of people around the world that climate change is real, and we need to do something about it," says the CEO of the WWF.
(Read more Earth Hour stories.)