Tokyo - Lights went out for two hours at more than 76,000 facilities across Japan on Monday night to mark the Cool Earth Day.

Buildings such as Tokyo Tower, Sapporo clock tower in northern Hokkaido and Kumamoto Castle in southern Japan turned off their lights to make people think about the environment.

The Japanese government set July 7 as Cool Earth Day to coincide with the opening of the Group of Eight summit in Toyako, Hokkaido, where members of the world's seven largest economies and Russia are expected to discuss climate change.

The Environment Ministry estimates that Monday's endeavor would reduce carbon dioxide emissions by 475 tons, which is equivalent to the amount of CO2 emitted by about 32,800 households in a day. (dpa)