A two photo combination showing the Elizabeth Tower, which houses Big Ben at the Houses of Parliament in London, illuminated, left, and then in darkness as the lights were turned off to mark Earth Hour 2013, Saturday March 23, 2013. Earth Hour was marked worldwide at 8.30 p.m. local time and is a global call to turn off lights for 60 minutes in a bid to highlight the global climate change. (Photo by Lewis Whyld/AP Photo/PA)
