Landmarks turn out lights to bring awareness to climate change From the Sydney Opera House to the Empire State Building, the lights went out.

From the Sydney Opera House to the Empire State Building, the lights went out at exactly 8:30 p.m.

Hundreds of landmarks worldwide turned out their lights for one hour on Saturday night, starting at 30 minutes past 8 p.m., in order to bring attention to the issue of climate change. The symbolic shutdown is organized every year by the World Wildlife Fund and called the Earth Hour. It bills the event as the "world's largest grassroots movement for the environment."

Earth Hour started in Sydney in 2007 with the famous Sydney Opera House going dark.

Landmarks that turned off their lights in 2018 included the Empire State Building in New York City, the Petronas Towers in Kuala Lumpur, the Eiffel Tower in Paris, Big Ben in London and St. Basil's Cathedral in Moscow.

The location that started it all, the Sydney Opera House, went dark as well.

The issue of climate change has been a controversial one with the election of Donald Trump to president. Trump pulled the United States out of the Paris Agreement in June 2017, an agreement between countries to limit greenhouse gas emissions. Trump called the deal bad for business. The U.S. is the only U.N. country not to be part of the agreement.

Trump called global warming "a total, and very expensive, hoax" in a tweet from December 2013. Since being elected president, he's hedged on exactly what he believes about climate change and global warming. Trump joked U.S. could "use a little bit of that good old Global Warming" in a December 2017 tweet.

In an interview with Piers Morgan in January, Trump was indecisive when asked if he believed in climate change, saying, "There is a cooling and there's a heating -- I mean, look, it used to not be climate change. It used to be global warming. That wasn't working too well because it was getting too cold all over the place."

The government's own National Climate Change Assessment found that "global warming of the past 50 years is primarily due to human activities, predominantly the burning of fossil fuels." The report notes the global temperature has risen 1.5 degrees Fahrenheit since 1880 and 2000-2009 was the warmest decade on record. In fact it was the warmest in at least 1,300 years, according to the report.