A plume of smoke rises above Gaza City as Israeli air strikes hit on August 18, 2011 in Gaza City, Gaza. The airstrikes came hours after attacks by militants killing Israelis in a cross border operation near Eilat, Southern Israel. (Photo by Christopher Furlong/Getty Images)

Protestors affiliated with the Occupy Wall Street movement block the entrance to the Iowa Democratic Party headquarters during a protest on December 29, 2011 in Des Moines, Iowa. Thirteen people were arrested during the protest. (Photo by Andrew Burton/Getty Images)

North Korean children wave to people on a Chinese tourist boat on the banks of Yalu River near the Chongsong county of North Korea, opposite the Chinese border city of Dandong, May 8, 2011. (Photo by Jacky Chen/Reuters)

A man prays to mourn victims of the March 11, 2011, earthquake and tsunami in front of a ship brought ashore by the disaster in Kesennuma, Miyagi Prefecture, Japan. (Photo by Kyodo via Reuters)

Brad Snead walks past melting ice on the Cook Inlet beach, Saturday, March 26, 2011, in Kenai, Alaska, while looking for agates. (AP Photo/Peninsula Clarion, M. Scott Moon)

Miranda Kerr poses at the David Jones Spring/Summer fashion preview on Burke Street on August 10, 2011 in Melbourne, Australia. (Photo by Lucas Dawson)

Afghan children play soccer in front of the war-damaged Darul Aman Palace in the suburbs of Kabul, Afghanistan, Wednesday, June 8, 2011. (Photo by Gemunu Amarasinghe/AP Photo)

The Sydney Skyline is seen before the lights are switched off for Earth Hour on March 26, 2011 in Sydney, Australia. Earth Hour encourages individuals around the world to turn off their lights for one hour at 20:30 local time on March 26, 2011 to take a stand against climate change. The largest Earth Hour was in 2010 when 128 countries participated.