A tourist walks inside the Ice Palace glacier hollow at Hintertux glacier, located at around 3250 meters above sea level, in Zillertal, Austria, 02 March, 2016. The hollow's temperature remains constant at 0 degrees Celsius, in summer and winter alike, and is also used by the University of Innsbruck for scientific research projects. (Photo by Lisi Niesner/EPA)

Brazilian navy soldiers watch a woman as they patrol the area at the Copacabana Beach before carnival festivities in Rio de Janeiro, Brazil February 14, 2017. (Photo by Sergio Moraes/Reuters)

People cheer as the ball drops at midnight in Times Square on January 1, 2015 in New York City. An estimated one million people from around the world are expected to pack Times Square to ring in 2015. (Photo by Andrew Theodorakis/Getty Images)

A migrant carries his belongings as he arrives at the Beijing railway station to catch a train in Beijing, Friday, February 13, 2015. (Photo by Andy Wong/AP Photo)

Fashionistas pose for photographs in front of a homeless man outside Moynihan Station following a showing of the Rag & Bone Spring/Summer 2013 collection during New York Fashion Week in this September 7, 2012 file photo. (Photo by Lucas Jackson/Reuters)

An exile Tibetan monk gestures as he makes a point in a dialectics debate with another monk, sitting right, at the Kirti monastery in Dharmsala, India, Monday, January 18, 2016. The debate is an essential part of their training as Buddhist monks. (Photo by Ashwini Bhatia/AP Photo)

A Dutch Military Policeman, left inside, guards part of the reconstructed cockpit, right, and forward section of the fuselage after the Dutch Safety Board presented it's final report into what caused Malaysia Airlines Flight 17 to break up high over Eastern Ukraine last year, killing all 298 people on board, during a press conference in Gilze-Rijen, central Netherlands, Tuesday, October 13, 2015. (Photo by Peter Dejong/AP Photo)

Artist Kong Ning wears a wedding dress made from respirators to highlight concerns about air quality and pollution in Beijing, China on December 1, 2015. (Photo by Luo Xiaoguang/Xinhua Press/Corbis)