A walker has left a handprint on a snow- covered tree trunk on Grosser Feldberg mountain in the Taunus mountain range, Germany, 16 January 2017. (Photo by Frank Rumpenhorst/DPA)

A woman wears a face mask in the part of the city near neighbourhoods known for burning coal for heating in Ulaanbaatar, Mongolia January 26, 2017. Not many people in Ulaanbaatar wear masks to protect themselves against pollution. (Photo by B. Rentsendorj/Reuters)

From the “Paradise Revisited” story in the November 2013 issue of National Geographic magazine, this image is a beautiful vision of father and son fishermen as they move through the multicolored coral gardens of Kembe Bay, Papua New Guinea, in a traditional outrigger canoe. (Photo by David Doubilet/National Geographic Creative)

An opposition activist clashes with the police during a march against Venezuelan President Nicolas Maduro held on May Day, in Caracas on May 1, 2017. Security forces in riot vans blocked off central Caracas Monday as Venezuela braced for pro- and anti- government May Day protests one month after a wave of deadly political unrest erupted. (Photo by Federico Parra/AFP Photo)

An Afghan boy plays in the ruins of a house that at one point belonged to the 13th-century Persian poet, Islamic scholar and Sufi mystic Jalal ad-Din Muhammad Rumi on the outskirts of Mazar-i-Sharif on November 25, 2015. (Photo by Farshad Usyan/AFP Photo)

Britain's Queen Elizabeth boards a train at Kings Cross station in London, in this December 17, 2009 file photo. Queen Elizabeth celebrates her 90th birthday on April 21, 2016. (Photo by Stefan Rousseau/Reuters)

People carry drinks at 80s Bar in Damascus, Syria, March 11, 2016. In Damascus's Old City, just a mile from the battered frontline between government and rebel-held territory, young Syrians smoke, drink beer or soft drinks, and talk about anything but the war. The revival of activity in this once-vibrant quarter is part of efforts to project an air of normality in the Syrian capital, even as the five-year-old war that has killed more than 250,000 people and created 5 million refugees continues to rage nearby. (Photo by Omar Sanadiki/Reuters)

Kaylee Cantler, 15, of Waynesboro, Pa., applies blush during a natural makeup exercise at a modeling camp at the Courtyard Marriott Hotel in McLean, Va., on Monday, August 17th, 2015. (Photo by Brittany Greeson/The Washington Post)