A dancer warms up backstage before the final of the 46th Prix de Lausanne, in Lausanne, Switzerland, 03 February 2018. Launched in 1973, the Prix de Lausanne is an international dance competition for young dancers aged 15 to 18. Closing the six-day event, prizes are awarded to the best of 21 finalists consisting of scholarships granting free tuition in a world-renowned dance school or dance company. (Photo by Valentin Flauraud/EPA/EFE)

East Berliners crossing into the West Berlin on November 11, 1989 at the Potsdamer Platz, Germany. (Photo by Kai Wiedenhoefer)

Villagers from Jiexi Jiantan village perform a ritual of “Zha Laoye”, or “Cracking local spirits”, in Chaoshan, Guangdong Province, China, 10 February 2019. Jiexi Jiantan Village celebrates the annual custom of “Zha Laoye” where Laoye are local spirits. Every third day of the lunar New Year, statues of local spirits known as the “Thousand-mile Eye” Laoye and “Ear Following the Wind” Laoye are brought out to the village committee to receive incensed tea offered by believers. (Photo by EPA/EFE/ZNSEN)

A Chinese man wears a mask to protect against pollution as he waits at a red light while commuting to work in heavy smog on December 8, 2015 in Beijing, China. The Beijing government issued a 'red alert' for the first time since new standards were introduced earlier this year as the city and many parts of northern China were shrouded in heavy pollution. Levels of PM 2.5, considered the most hazardous, crossed 400 units in Beijing, lower than last week, but still nearly 20 times the acceptable standard set by the World Health Organization. The governments of more than 190 countries are meeting in Paris to set targets on reducing carbon emissions in an attempt to forge a new global agreement on climate change. (Photo by Kevin Frayer/Getty Images)

People are seen in the crowd as Serbian Emir Kusturica & The No Smoking Orchestra performs during the third day of the Mexican musicial festival Vive Latino, at the Foro Sol in Mexico City, on March 29, 2014. (Photo by Alfredo Estrella/AFP Photo)

The provincial highest chimney collapses as it is demolished by explosives in Shenyang, Liaoning province, April 28, 2014. The 150-metre-high chimney used to be part of a local heating factory, according to local media. (Photo by Sheng Li/Reuters)

Dancers from Tokyo wearing traditional costumes perform during a celebration event, a day before Japan's Emperor Naruhito and Empress Masako's royal parade in front of the Imperial Palace in Tokyo, Japan November 9, 2019. (Photo by Issei Kato/Reuters)

A narrow strip of clouds illuminated in the light of sunset before approaching rain clouds over an alley near Sieversdorf district Oder-Spree, Brandenburg, Germany on July 14, 2016. (Photo by Patrick Pleul/DPA)