A world globe is projected and spins on top of the Old City walls of Jerusalem at the Tower of David and the Jaffa Gate on 23 April 2009 as Jerusalem celebrates Earth Hour by switching off the lights illuminating the Old City walls. Earth Hour was established in 2007 in Sydney and this year the WWF (World Wide Fund for Nature) who organised the event, hopes to have one billion people turn off their lights, as part of the Earth Day celebrations. Photo by Abir Sultan/Flash 90

A performance is held by the Old City walls of Jerusalem at the Tower of David and the Jaffa Gate on 23 April 2009 as Jerusalem celebrates Earth Hour by switching off the lights illuminating the Old City walls. Earth Hour was established in 2007 in Sydney and this year the WWF (World Wide Fund for Nature) who organised the event, hopes to have one billion people turn off their lights, as part of the Earth Day celebrations. Photo by Abir Sultan/Flash 90

Young Israelis watch a world globe projected and spinning on top of the Old City walls of Jerusalem at the Tower of David and the Jaffa Gate on April 23, 2009 as Jerusalem celebrates Earth Hour by switching off the lights illuminating the Old City walls. Earth Hour was established in 2007 in Sydney and this year the WWF (World Wide Fund for Nature) who organised the event, hopes to have one billion people turn off their lights, as part of the Earth Day celebrations. A dancer is also projected onto the walls. photo by Abir Sultan/Flash 90

A large ball depicting the earth is filled with empty water bottles at an environmental happening held by the Old City of Jerusalem on "Save Earth Day'. April 23, 2009. Photo by Miriam Alster/Flash90