
Lights at the India Gate in New Delhi were turned off for Earth Hour.
The initiative began in Australia in 2007 as a grass roots gesture by the World Wildlife Fund (WWF) Australia against man-made carbon dioxide emissions linked to a warming planet.
In 2017, it will involve the switching off of electric lights for an hour in 7,000 cities across 172 countries, at 8:30 pm local time, with the aim of highlighting the need to act on climate change, and saving a few megawatts of power in the process.
A combination photo shows the Sydney Harbour Bridge before and during the 10th anniversary of earth hour. (Reuters)
Among the famous buildings and structures taking part in Australia are Sydney's Opera House, the Harbour Bridge, Luna Park, Town Hall, and Sydney Tower Eye.
Internationally the list includes some of the world's best known sky-scrapers and historic buildings including the world's tallest building, the Burj Khalifa in Dubai, London's Big Ben and Houses of Parliament, the Colosseum in Rome, Istanbul's Blue Mosque, the Eiffel Tower, Moscow's Kremlin and Red Square and the Pyramids of Egypt.

Photo displays the rides at Luna Park before and during the tenth anniversary of Earth Hour in Sydney. (Reuters)
WWF says Earth Hour can take credit for various environmental initiatives, like the 2013 declaration of a 3.4 million hectare marine park in the waters off Argentina, the planting of a forest in Uganda and a ban on soft plastics in the Galapagos Island.
© Thomson Reuters 2017