A combination picture shows the downtown Beijng before and after the lights were turned off for Earth Hour on March 28, 2009. About 20 Chinese cities joined a worldwide campaign to persuade the public to switch off unnecessary lights for one hour Saturday night to support energy-saving efforts and show concerns about global warming. [Xinhua]

A combination picture shows China's National Aquatics Center "Water Cube" in Beijng before and after the lights were turned off for Earth Hour on March 28, 2009. About 20 Chinese cities joined a worldwide campaign to persuade the public to switch off unnecessary lights for one hour Saturday night to support energy-saving efforts and show concerns about global warming. [Xinhua]