1 / 7   People light candles after building lights were switched off for the Earth Hour environmental campaign in Dubai, UAE, March 24, 2018. Earth Hour, which started in Australia in 2007, is set to be observed by millions of supporters in 187 countries, who turn off their lights at 8:30 p.m. local time in what organizers describe as the world's "largest grassroots movement for climate change." /VCG Photo

2 / 7   People walk in the Red Square as the Kremlin Palace is seen in the background after lights were turned off to mark Earth Hour in Moscow. /VCG Photo

3 / 7   The Bell Tower, a landmark in China’s Xi’an City, turns its lights out in support of Earth Hour. /VCG Photo

4 / 7   A boy with the number 60 painted on his face, representing the 60 minutes of Earth Hour, is seen near a mall in Bacoor city, Cavite, south of Manila, the Philippines. /VCG Photo

5 / 7   Tokyo's landmark Skytree plunged into darkness for the Earth Hour environmental campaign. /VCG Photo

6 / 7   Rome's ancient Colosseum went dark during Earth Hour. /VCG Photo

7 / 7   The Brandenburg Gate shortly before shutting off its lights for Earth Hour in Berlin. /VCG Photo