On March 26, the world switched off their lights for an hour to raise awareness towards the need to take action on climate change. Here are some before and after photos of Earth Hour 2011.

(c)WWF/Chris Joyce March 26, 2011; Abu Dhabi, UAE; Aldar Headquarters Earth Hour 2011 before and after

Earth Hour 26th March 2011, Piccadilly Circus Lights On, London, UK © WWF/ Tristan Fewings

©©eoff Wilson2011 London

Earth Hour 26th March 2011, Buckingham Palace lights on London, UK © WWF/ Tristan Fewings

Hemiciclo de la Rotonda. Guayaquil, Ecuador (c) WWF / Jill Kuri

Lithuania: Kaunas City Hall switch off in March 26, 2011

Zahide Köse

(c) WWF-Indonesia / Alfonso RENO

(c) Willy Kwong Banks in Central (before), Hong Kong

©WWF / Mabel Lee Singapore Skyline. March 26, 2011. Buildings in Singapore's CBD switch their lights off for Earth Hour.

Jack Armstrong, 26/03/2011, Tbilisi, Georgia, "Peace Bridge"

Before and After Aerial view of Hong Kong island (Central) (C) WWF-Hong Kong