Buildings around the world will go dark for 60 minutes this evening in a voluntary event known as Earth Hour. This grassroots effort was started in 2007 in Sydney, Australia, by the Australian branch of the World Wide Fund for Nature (aka World Wildlife Fund), which encouraged Sydneysiders to show their support for climate action. Since then, it’s grown into a global movement to raise awareness of our energy consumption and the effects of climate change on our planet.