People around the world are getting ready to mark Earth Hour by turning out the lights on Saturday, but a long list of seemingly harmless everyday actions also contribute to emissions of carbon dioxide and other planet-harming greenhouse gases.
Download Periscope, Twitter's just-launched live video-streaming app, and you'll find people broadcasting all sorts of mundane stuff: waiting for AT&T to fix their wiring, getting out of bed in Silicon Valley, looking outside their office window in Chicago.
This Saturday night, millions of people around the world will turn off their lights to mark Earth Hour. The global event is now in its eight year, but how much do you know about the movement? Test your Earth Hour knowledge with our quiz.
Questions are being raised about in-flight security protocols, after French officials concluded that the Germanwings airliner co-pilot deliberately locked the captain out of the cockpit and sent the plane crashing into a mountain.