A visitor kneels on the 180-meter-high and 300 meter-long glass-bottomed suspension bridge at the Shiniuzhai National Geopark in Pingjiang county, in central China's Hunan province, 24 September 2015. (Photo by Jiao Zi/Imaginechina via AFP Photo)

Andy Goldfarb, a staff biologist at the Point Defiance Zoo & Aquarium, plays with one of the four clouded leopard cubs currently at the zoo Friday, June 5, 2015 in Tacoma, Wash. The quadruplets were born on May 12, 2015 and now weigh about 1.7 lbs. each. Friday was their first official day on display for public viewing, usually during their every-four-hours bottle-feeding sessions, which were started after the cubs' mother did not show enough interest in continuing to nurse them. (AP Photo/Ted S. Warren)

These images offer a rare glimpse of life within remote Brazilian tribes. Award winning photographer Ricardo, 47, said: “The pictures show the traditional way of life of these people who live in harmony with nature. The photos provide an overview of the contemporary situation of the indigenous people in Brazil”. Here: Bej indian in the Xingu river, state of Mato Grosso, Brazil on December 20, 2015 .(Photo by Ricardo Stuckert/Caters News Agency)

Documentary photographer William E. Crawford was one of the first Western photographers to gain access to North Vietnam after the war ended. He has photographed the capital, Hanoi, at regular intervals since 1985, concentrating on the colonial and indigenous architecture, urban details, landscapes and intimate portraits of people in their home settings, street scenes and the city’s surrounding countryside. Here: 54 Hàng Ga (Chicken Street), 1994. (Photo by William E. Crawford from the book “Hanoi Streets 1985-2015: In the Years of Forgetting”)

In this November 12, 2015, file photo, Mt. Everest is seen from the way to Kalapatthar in Nepal. An American climber has died near the summit of Mount Everest and an Indian climber is missing after heading down from the mountain following a successful ascent, expedition organizers said Sunday. (Photo by Tashi Sherpa/AP Photo)

Syrian refugees covered with dust arrive at the Trabeel border, after crossing into Jordanian territory with their families, near the northeastern Jordanian border with Syria, and Iraq, near the town of Ruwaished, east of Amman September 10, 2015. (Photo by Muhammad Hamed/Reuters)

People take pictures of the Tribute in Light while it is illuminated next to the Statue of Liberty (C), One World Trade Center and the Empire State Building during events marking the 14th anniversary of the 9/11 attacks on the World Trade Center in New York September 11, 2015. (Photo by Eduardo Munoz/Reuters)

A house burns as the Butte fire rages through Mountain Ranch, California September 11, 2015. Evacuation orders were expanded to thousands of homes in northern California's Sierras on Friday as the rapidly spreading wildfire roared for a third day through drought-parched timber and brush, threatening mountain communities. (Photo by Noah Berger/Reuters)