More than 100 landmarks across the UK from Buckingham Palace to Edinburgh Castle are switching off their lights to mark this year's Earth Hour.

The lights will go off at famous buildings and structures across the country between 8.30pm and 9.30pm on Saturday as part of the international event organised by conservation charity WWF to urge action to save the planet.

Sydney Opera House, Egypt's Great Pyramids, the Eiffel Tower in Paris, Brazil's Christ the Redeemer monument and the Empire State Building in New York are among the sites worldwide where the lights will be switched off.

The event sees landmarks, businesses and people switching their lights off for an hour of darkness, and aims to highlight the impacts humans are having on the planet through climate change, pollution, plastic and food production.

More than 7,000 cities in more than 170 countries and millions of people are expected to take part this year, to send a message to leaders that protecting the Earth should be top of their agenda, WWF said.

Ten things to do in the dark during Earth Hour Show all 10 1 /10 Ten things to do in the dark during Earth Hour Ten things to do in the dark during Earth Hour 1. Throw a party Getty Images Ten things to do in the dark during Earth Hour 2. Gaze at the stars Getty Images Ten things to do in the dark during Earth Hour 3. Enjoy dinner by candlelight Getty Images Ten things to do in the dark during Earth Hour 4. Organize a treasure hunt in the dark Getty Images Ten things to do in the dark during Earth Hour 5. Take the dog for a moonlit walk Getty Images Ten things to do in the dark during Earth Hour 6. Soak in a bath by candlelight Getty Images Ten things to do in the dark during Earth Hour 7. Tell stories around a campfire Getty Images Ten things to do in the dark during Earth Hour 8. Play board games Ten things to do in the dark during Earth Hour 9. Get romantic with a loved one Ten things to do in the dark during Earth Hour 10. Play and listen to acoustic music - and dance in the dark Getty Images

In the UK, the Houses of Parliament, the London Eye and the Shard, Cardiff Castle, Liverpool Cathedral, Old Trafford, Brighton Pier and the Eden Project are among the landmarks taking part.

Last year across the UK, 10 million people took part, along with more than 7,000 schools, 400 landmarks and thousands of businesses and organisations, the charity said.

A well-lit ferry stands out from a darkened Shanghai skyline during Earth Hour 2016 (AFP/Getty)

WWF warns that people living today are the first generation to experience the effects of climate change, and the last to be able to change it, while the planet is also suffering plastic pollution and deforestation.