In 178 countries and territories around the world Saturday, millions of people are switching off their lights for Earth Hour, an annual event to highlight the global threat from climate change.
Some 350 world landmarks including the Empire State Building and the Eiffel Tower will go dark for 60 minutes starting at 8:30 pm. local time Saturday.
Christophe Archambault, AFP/Getty Images
The Wat Arun (Temple of Dawn) lit (top) and with lights out (bottom) during the Earth Hour in Bangkok.
This year's theme celebrates "Places We Love" — the mountains, rivers, beaches, reefs, forests and national parks that organizers say are in peril from climate change.
Earth Hour is hoping to harness momentum for climate change after world leaders reached a landmark accord in December to lower planet-warming greenhouse gas emissions.
The lights-out event began in Sydney as an initiative of conservation group World Wildlife Fund in 2007. It caught on around the globe the following year.
This year, Facebook users are being asked to change their profile pictures and donate their social feeds to show support for Earth Hour.