Elementary school children play outside their classrooms as mount Sinabung volcano spews thick volcanic ash in the background on February 10, 2017 in Karo, Indonesia. Mount Sinabung is one of the most active volcanoes in Indonesia and last erupted in May 2016, killing seven people. (Photo by Albert Damanik/Barcroft Images)

New York City policemen tangled with demonstrators at a subway station on the opening day of the New York World's Fair, April 22, 1964. Youths attempted to stall the train, which was headed from the city to the fairgrounds, as a form of protest on behalf of civil rights for blacks. (Photo by Charles Gorry/AP Photo)

A Sotheby's employee holds a rare 52.82-carat white diamond ring at Sotheby's auction house on April 12, 2010 in London, England. Price: 7 million USD. (Photo by Dan Kitwood/Getty Images)

An area of vegetation can be seen amongst drought effected farmland in South Australia, November 12, 2015. A pioneering Australian scheme to improve the management of water in the world's driest inhabited continent is facing its first real test as an intensifying El Nino threatens crops and builds tensions between farmers and environmentalists. An El Nino, a warming of sea-surface temperatures in the Pacific, is already causing drought and other extreme weather, affecting millions of people across parts of the world, and experts warn that the intensifying weather pattern could emerge as one of the strongest on record. (Photo by David Gray/Reuters)

A photo made avialable on 05 August 2015 shows an Indian woman collecting drinking water from a water pump in the submerged village of Sreerampur, some 150 kilometers north of Calcutta, India, on 04 August 2015. At least 215 people have died in floods and a landslide following monsoon rains in India over the past week, 83 deaths were reported from the western state of Gujarat and 69 from eastern West Bengal. The worst-affected states were West Bengal, Gujarat and Rajasthan, the Home Ministry said. (Photo by Piyal Adhikary/EPA)

A participant poses with his laptop during the 33rd Chaos Communication Congress on its opening day on December 27, 2016 in Hamburg, Germany. The annual event is bringing together 12,000 computer hackers and activists who will meet over the next four days to share expertise and discuss topics related to the society and the digital world. (Photo by Morris MacMatzen/Getty Images)

A masked reveller parades through the streets on the first day of the carnival season in Lucerne, Switzerland, 12 February 2015. In the background the well known Kappellbruecke bridge. (Photo by Alexandra Wey/EPA)

Indian Muslim children hold anti-US placards as they participate in a protest meeting against the film “Innocence of Muslims” in Kolkata on October 5, 2012. A low-budget, US-produced “Innocence of Muslims” movie has incited a wave of bloody anti-US violence in Libya, Egypt, Sudan, Tunisia, Yemen and in several other countries across the Muslim world. (Photo by Dibyangshu Sarkar/AFP/AFP Photo)