Landmark buildings around the world went dark on Saturday in an international effort to draw attention to climate change.

In New York, the Empire State Building's lights were switched off. There was a similar sight in Paris, where the Eiffel Tower went dark. And in London, Big Ben, Piccadilly Circus and the London Eye had their lights turned off, according to The Associated Press.

The darkness lasted for an hour, and was intended to mark Earth Hour, an annual event intended to shine a light on climate change. The event began in Sydney, Australia in 2007, and has since spread around the world.

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At 8:30 p.m. on Saturday, participants were encouraged to turn out their lights for an hour.

Marco Lambertini, the director general of the World Wildlife Fund, which helps coordinate Earth Hour, said that this year's event is intended to draw attention to "the importance of biodiversity and nature."

"This Earth Hour, we want to shine a light on the importance of biodiversity and nature," he said in a statement. "Together, as individuals, businesses and governments, we must show the same determination to halt biodiversity and nature loss as we have shown on climate action to secure a healthy, thriving and living planet for all."