The Sydney Harbour Bridge and the sails on the nearby Opera House went dark Saturday, as lights on landmarks around Australia were switched off for the global climate change awareness campaign Earth Hour.
Millions are expected to take part around the world in the annual event organised by conservation group WWF, with hundreds of well-known sights including the Eiffel Tower in Paris and the Seattle Space Needle set to plunge into darkness.
"It's almost like the thing vanished," said Tony Jennings from Earth Hour after standing under the Harbour Bridge as the lights went off at 8:30pm (0930 GMT).
In Australia, Earth Hour this year is focussing on farming, with fears that rising temperatures could ultimately damage the country's ability to produce food.
"In Australia agriculture is the most vulnerable industry to the impacts of climate change," said national Earth Hour manager for Australia, Anna Rose.
Rising temperatures, increased pests and weeds, changes in planting times, and more extreme weather events were already beginning to impact farmers, she said.
"People think about climate change as something that's only going to happen in the future," Rose told AFP.
"In this Earth Hour campaign we want to highlight the fact that rising temperatures and more extreme weather are affecting something we all have in common—our food."
Earth Hour takes place from 8:30pm local time, and encourages citizens, communities, businesses and organisations to switch the lights off for an hour to highlight the plight of the planet.
This year it comes ahead of a crucial UN meeting Paris in December which is bringing together the global community in an effort to limit global warming.
The initiative began in Sydney in 2007 but quickly went global.
"Over 170 countries and territories have already confirmed their participation; more than 1,200 landmarks and close to 40 UNESCO world heritage sites," Earth Hour head Sudhanshu Sarronwala told AFP ahead of the event.
These range from the Christ the Redeemer statue in Rio de Janeiro, the Acropolis in Athens, Edinburgh Castle, Big Ben, Ecuador's Quito historical centre to New York's Times Square.
This year will include a glow-in-the-dark Zumba party in the Philippines, a coordinated candlelit dinner in Finland billed as the world's largest, restaurant dinners by candlelight in London, and a power-generating dance floor to light up the Eiffel Tower after its hour-long sleep, said WWF.
Earth Hour's goal is not to achieve measurable electricity savings, but to raise awareness of the need for sustainable energy use, and this year also to demand action to halt planet-harming climate change.
"We hope that with each light switch that goes off, the light cast on people calling for action becomes clearer and paves the way ahead for climate action," said Sarronwala.
Explore further: Sydney switches off for Earth Hour