Earth Hour will be celebrated on Saturday 19th March 2016, when people around the world will be encouraged to switch off their lights between 8:30 and 9:30pm UK time. Many famous buildings around the world will turn off their lights - last year these included the Alhambra in Granada, the Colosseum in Rome, Sydney Opera House and the Empire State Building in New York. Earth Hour was started in 2007 and is a WWF initiative, with a separate non-profit organisation based in Singapore. Its mission is to unite people to protect the planet. In 2015 there were 620,000 Earth Hour actions in 172 countries, involving a range of issues, including renewable energy, solar panels, saving power, protecting forests and planting trees.
Nick Garbutt / The view at night from 'At the Top', 124th floor of the Burj Khalifa, the world's tallest building at 829.8m at night. Dubai, United Arab Emirates. April 2013
Gavin Hellier / The Burj Khalifa at night, completed in 2010, the tallest man made structure in the world, Dubai, United Arab Emirates, 2011
Gavin Hellier / Looking up at the Empire State Building on a rainy evening, Manhattan, New York City, USA 2009. No release available.
Nick Garbutt / Greater Flamingos (Phoenicopterus roseus) feeding in lake at sunrise at Ras Al Khor Wildlife Sanctuary (Ramsar site), with the Dubai skyline in the background and the first rays of the sun catching th...
David Fleetham / Sydney Harbour with Opera House and skyscrapers at night, Sydney, Australia.
Julia Bayne / Picadilly circus at night. London, UK
Gavin Hellier / The Alhambra and snow capped mountain background, Granada, Andalucia, Spain
Gavin Hellier / The Colosseum floodlit at night, Rome, Italy
Ernie Janes / Silhouette of Big Ben and Houses of Parliament on the River Thames at dusk, London, UK, November 2005
Rick Tomlinson / Tall Ships lit up at night near Tower Bridge on the River Thames, London.
Gavin Hellier / Marina Bay Sands at dusk, Marina Bay, Singapore, February 2012
Gavin Hellier / Elevated night view of the Petronas Twin Towers, illuminated at night, Kuala Lumpur, Malaysia, 2012. No release available.
Gavin Hellier / City Skyline and Financial district at dawn, Singapore 2009
Gavin Hellier / Dusk view of the skyscrapers of Manhattan from the Brooklyn Heights neighbourhood, New York, USA, 2011
Angelo Giampiccolo / Downtown Sydney and waterfront lit up at night, Australia.
Florian Möllers / Deutsche Bahn Tower lit up by internal lights in the evening, Potsdamer Platz, Berlin, Germany. January 2009
Rob Cousins / Person switching on / off an electric switch, UK
Pat Tuson / Sun tube or pipe by Sunpipe, set into the tiled roof of the Islington Ecology Centre to allow natural light into the building thus saving on energy, Highbury, London Borough of Islington, England, UK,...
Laurent Geslin / Person fitting low-energy light bulb into lamp fitting
Philippe Clement / Trees in spring forest inside incandescent lamp / bulb against white background~Digital composite
Visuals Unlimited / Solar panels for electricity generation, Mojave Desert, California, USA, December 2007
Wild Wonders of Europe / Widstrand / Mass of solar panels, La Serena, Extremadura, Spain, April 2009
Steven David Miller / Large solar panels for generating electricity by solar power, Hermannsburg, west of Alice Springs, Northern Territory, Australia, August 2007
Mark Hamblin / 2020VISION / Woodland restoration scheme, sign and view of habitat with Beinn Eighe in background, June, Beinn Eighe NNR, Scotland, UK
Nick Turner / Family with with solar panel display at the Centre for Alternative Technology, Machynlleth, Wales
Michele Westmorland / Typical hut showing use of solar panel for power, Nembao Village, Utupua Island, Solomon Islands
Tom Gilks / Solar technician's hand rest on solar panel, Rwanda, April 2014.
Tom Gilks / Solar panel on a corrugated iron rooftop in village, Miono region, Tanzania.
Pal Hermansen / Masai woman with portable television, powered by solar energy, Masai Mara, Kenya. March 2013.
Jose B. Ruiz / Solar powered street light, Alicante, Spain.
Pal Hermansen / Masai woman with solar powered lights, Masai hut, Mara, Kenya, March 2013.
Stephen Dalton / Photo voltaic solar panels set in garden, Sussex, England, UK, June.
Philippe Clement / The solar furnace at Odeillo in the Pyrenees-Orientales, Pyrenees, France, July 2012. No release available
Tom Gilks / Technicians installing panels in one of East Africa's largest Solar farms, Rwamagana District, Rwanda. July 2014. Model released.
Nick Turner / Close up of fluorescent light tubes at a recycling centre, Stroud, Gloucestershire, UK, February 2008.
Nick Turner / Man lifting fluorescent light tubes at a recycling centre, Stroud, Gloucestershire, UK, February 2008.
Nick Turner / Light bulb recycling information sign at a recycling centre, Stroud, Gloucestershire, UK.
Philippe Clement / Sunflowers (Helianthus annuus) inside incandescent lamp / bulb against white background~Digital composite
Pat Tuson / Wind turbine on top of block of flats, Finsbury, London Borough of Islington, UK
John Cancalosi / Wind turbines on hillside, Spain
Guy Edwardes / View of pipework and Geothermal power plant, Reykjanesvirkjun, South West Iceland, July 2009
Orsolya Haarberg / Wind turbines for renewable energy, Masoy, Finnmark, Norway, July 2006
Pascal Tordeux / Vertical axis wind turbine charging an electric car, France, May 2013.
Niall Benvie / Wave breaking on wave powered energy generation station, Islay, Argyll, Scotland, UK
Laurie Campbell / Tidal Power Station, Portnahaven, Islay, Scotland, October
Philippe Clement / The Pitlochry fish ladder, showing several of the intermediate pools which the Salmon use for travelling upstream, next to the Pitlochry Power Station on the River Tummell, Scotland, UK~May 2010
Ian Lockwood / Women in the afforestation project with rubber saplings, Madhupur district, Bangladesh
Staffan Widstrand / Mangrove planting team from CRINEO planting Mangrove trees (Rhizophora) Pulicat Lake, Tamil Nadu, India, February 2013.