Cities around the world marked Earth Hour on Saturday by turning off lights at 8:30pm local time in a call for global action on climate change.

Earth Hour, spearheaded by the World Wildlife Fund, calls for greater awareness and more sparing use of resources, especially fossil fuels that produce carbon gases and lead to global warming.

Beginning in Sydney in 2007, Earth Hour has spread to more than 180 countries, with tens of millions of people joining in.

In London, the lights were turned off on the Houses of Parliament, the London Eye and Tower bridge in support of the event.

The Empire State Building also participated as clocks hit 8:30pm on the US East Coast with a dimming of the skyscrapers’ lights.