Voice of America: Australia’s Sydney Harbor went dark as lights were turned off at the iconic Sydney Opera House and Harbor Bridge as part of Earth Hour, a global event calling attention to climate change. First organized in Sydney in 2007, at least 3,929 communities around the world are shutting off lights this year in the event rolling through the world’s time zones. Hundreds of landmarks around the world are expected to go dark for an hour as nightfall circles the globe Saturday …