Earth Hour 2010

Beginning in Sydney, Australia three years ago, Earth Hour has grown into a global observance. States, large organizations and individual people observed Earth Hour 2010 on Saturday March 27th, as homes, office towers and landmarks turned off their lights for an hour starting at 8.30 pm local time to raise awareness about climate change and the threat from rising greenhouse gas emissions. Collected here are a series of before-and-after photographs from this year - which (starting with the second one below) will fade between "on" and "off" when clicked. [See also: last year] This effect requires javascript to be enabled. (26 photos total)

These two photos show Malaysia's landmark Petronas Twin Towers before, left, and after being turned off its lights to mark Earth Hour in Kuala Lumpur, Malaysia, Saturday, March 27, 2010. (AP Photo/Lai Seng Sin)

Overview of Hong Kong Island and Kowloon with lights on and off to mark Earth Hour 2010. [click image to see it fade] (© Ringo Ma, via WWF) #

A before-and-after view of the Las Vegas Strip seen during Earth Hour from Mix at THEhotel at Mandalay Bay March 27, 2010 in Las Vegas, Nevada. [click image to see it fade] (Ethan Miller/Getty Images) #

Before and after views of Seattle's Pacific Science Center on Earth Day, March 27th, 2010. [click image to see it fade] (© Jason Ayres Gift Enevoldsen) #

A pair of photos of Ion Orchard, one of the largest shopping malls on Orchard Road during Earth Hour in Singapore March 27, 2010. [click image to see it fade] (REUTERS/Tim Chong) #

The National Stadium, also known as the "Bird's Nest", before and during Earth Hour in Beijing, China March 27, 2010. [click image to see it fade] (REUTERS/Grace Liang) #

Moscow State University seen before and after the lights are turned off during the worldwide Earth Hour, a global campaign to highlight the threat of climate change in Moscow Saturday, March 27, 2010. [click image to see it fade] (AP Photo/Sergey Ponomarev) #

The Sydney skyline is seen before and after the lights are switched off for Earth Hour on March 27, 2010 in Sydney, Australia. Earth hour this year aims to highlight everyone’s environmental footprint on the earth, encouraging individuals to reduce their impact on the planet and help reduce pollution and climate change. [click image to see it fade] (Lisa Maree Williams/Getty Images) #

The hill of the Acropolis before and during Earth Hour in Athens, Greece on March 27, 2010. [click image to see it fade] (REUTERS/Yiorgos Karahalis) #

A before-and-during view of a square near the Bundaran Hotel in Jakarta, Indonesia. [click image to see it fade] (© WWF-Indonesia / Alfonso Reno) #

The Forbidden City, seen before and during the Earth Hour 2010 power switch off on March 27, 2010 in Beijing, China. [click image to see it fade] (Feng Li/Getty Images) #

A view of Copacabana beach in Rio de Janeiro, Brazil during Earth Hour March 27, 2010. [click image to see it fade] (REUTERS/Bruno Domingos) #

Malaysia's landmarks Petronas Twin Towers after and during Earth Hour in Kuala Lumpur on March 27, 2010. REUTERS/Bazuki Muhammad [click image to see it fade] (REUTERS/Bazuki Muhammad) #

Lights switched off in Toronto's financial district, Ontario, Canada. [click image to see it fade] (© Bill Ivy/WWF-Canada) #

The Capitol building in Atlanta, Georgia marking Earth Hour 2010. [click image to see it fade] (© WWF) #

A general view of commercial buildings before and after turning off lights in Hong Kong's central district Saturday, March 27, 2010 to mark the annual Earth Hour. [click image to see it fade] (AP Photo/Vincent Yu) #

The Oslo Opera House in Oslo, Norway on March 27th, 2010. [click image to see it fade] (© Heiko Junge / SCANPIX via WWF) #

The Capitol building in Albany, New York, during Earth Hour 2010 on March 27th. [click image to see it fade] (© WWF / Emerson) #

Hiroshima Castle before and during Earth Hour in Hiroshima, Japan on March 27th, 2010. [click image to see it fade] (© Kenji Matsuo, via WWF) #

The Empire State Building, in New York City, New York with lights on, then off in support of Earth Hour 2010. [click image to see it fade] (© WWF / Rob Johnson) #

The brightly lit YAS Marina Hotel on Yas Island is dimmed during Earth Hour 2010 in Abu Dhabi, United Arab Emirates. [click image to see it fade] (© EAA, via WWF) #

Romania's Parliament building before and during Earth Hour at 8:30pm in central Bucharest March 27, 2010. [click image to see it fade] (REUTERS/Bogdan Cristel) #

Table Mountain, above Capetown, South Africa, seen before and during Earth Hour 2010. [click image to see it fade] (© WWF/South Africa) #

The Forbidden City, seen before and during Earth Hour in Beijing, China on March 27, 2010. [click image to see it fade] (REUTERS/Jason Lee) #

Buildings in the central business district before and after Earth Hour in Singapore March 27, 2010. [click image to see it fade] (REUTERS/Nicky Loh) #

The Mohammed Ali mosque at the Salaheddine Citadel before and during Earth Hour in the Egyptian capital of Cairo on March 27, 2010. [click image to see it fade] (AFP PHOTO/KHALED DESOUKI) #