An employee of the National Park Service takes a selfie with President Barack Obama, left, in the background meeting with the crowd after a tour of Everglades National Park on Earth Day, Wednesday, April 22, 2015, in Florida. Obama used the visit to warn of the damage that climate change is already inflicting on the nation's environmental treasures. (Photo by Lynne Sladky/AP Photo)

A bishop walks past a new street-art collage by Italian artist Maupal showing Pope Francis playing tic-tac-toe and drawing peace signs as a Swiss guard keep watches the street near the Vatican on October 19, 2016 in Rome. (Photo by Tiziana Fabi/AFP Photo)

A boy looks on as fire fighters try to extinguish the fire at oil wells, were set on fire by Daesh terrorists as they fled after Al Qayyarah town's cleansing from Daesh militants as the operation to retake Iraq's Mosul from Daesh continues, in Al Qayyarah Town of Mosul, Nineveh, Iraq on November 02, 2016. (Photo by Yunus Keles/Anadolu Agency/Getty Images)

Maja, a 40-year-old elephant, extends her trunk into a bakery as a customer buys a newspaper while Maja took a stroll through the neighborhood with her minders from a nearby circus on July 1, 2016 in Berlin, Germany. (Photo by Sean Gallup/Getty Images)

In this photo taken June 3, 2009, a female North Korean soldier looks out from behind a barbed-wire fence around a camp on the North Korean river banks across from Hekou, northeastern China's Liaoning province. North Korea's top court has convicted two U.S. journalists, and sentenced them to 12 years in labor prison, the country's state news agency reported Monday. (Photo by Ng Han Guan/AP Photo)

People fight for the ball as they take part in a mud football match during a festival for celebrating harvest in a village in Jinhua, Zhejiang Province, China September 24, 2017. (Photo by Reuters/China Stringer Network)

Miners pulling up lazy tourists to the rim of Kawah Ijen (Ijen Volcano), East Java, Indonesia on September 21, 2017. They will earn as much as they would bring down a load of sulfur. Nomadic Explorer, Cultural Lifestyle Photographer Claudio Sieber captured striking images of miners working at Ijen volcanic range in East Java, Indonesia. The sulphur miners risk their lives daily as they climb the active volcano carrying heavy loads, which they sell to sugar refineries. (Photo by Claudio Sieber/Barcroft Images)

In this September 27, 2017 file photo, girls walk past a wall riddled with bullet holes from shootings between rival drug traffickers, at the Rocinha slum, in Rio de Janeiro, Brazil. Violence is on the rise in Rio's slums after several years of decline, and the killings of kids have shocked even residents long inured to deaths from gangs and police. (Photo by Silvia Izquierdo/AP Photo)