U.S. Secretary of State John Kerry stands inside the historic Shackleton hut near McMurdo Station, Antarctica, Friday, November 11, 2016. Kerry became the highest-ranking American official to visit Antarctica when he landed for a two-day trip on Friday. He's been hearing from scientists about the impact of climate change on the frozen continent. Kerry's aides described the trip as a learning opportunity for the secretary of state. He has been receiving briefings from scientists working to understand the effects of climate change on Antarctica. Kerry has made climate change an intensive focus of American diplomacy during his term, and had previously spent decades working on the issue as a U.S. senator. Trump has called climate change a hoax and said he would “cancel” U.S. involvement in the landmark Paris Agreement on global warming. (Photo by Mark Ralston/Pool Photo via AP Photo)

Artists called “Le couple en chocolat” take part in the festival “Statues en Marche” in Marche-en-Famenne, Belgium, July 22, 2018. Living statues are a common sight in many city centres, but it is rare to see such a diverse range of this peculiar form of street art for which performers must keep still for painfully long periods of time to create the desired illusion. (Photo by Yves Herman/Reuters)

Climbers place a huge 80x80 metres (262x262 feet) Swiss national flag on the western face of the north-eastern Swiss landmark Mount Saentis, Switzerland on July 31, 2018. (Photo by Arnd Wiegmann/Reuters)

A conductor (C) collects fares from candy floss sellers as they travel in a tram to a marketplace early morning in Kolkata, India, December 23, 2015. (Photo by Rupak De Chowdhuri/Reuters)

First year cadets of the Military University of Communication smile before an oath-taking ceremony in St.Petersburg September 6, 2014. Some 700 first year cadets of the academy attended the ceremony before starting their studies. (Photo by Alexander Demianchuk/Reuters)

An illustration showing scarecrows pulling a firewood cart beside a road is on display at Kakashi no Sato, or the Scarecrow's Hometown on September 10, 2014 in Himeji, Japan. In this district of Yasutomi in Himeji city, over 100 of scarecrows stand in farmlands and abandoned houses to illustrate the good old Japanese countryside and attract visitors. (Photo by Buddhika Weerasinghe/Getty Images)

An aerial view shows the 11/19 pit and twin slag heaps at the former coal mine site in Loos-en-Gohelle, northern France, November 1, 2015. Loos-en-Gohelle, a town of 7000 inhabitants in the North of France, marked by the closure of coal mines in 1970, has demonstrated a successful transition from coal to a green economy. (Photo by Pascal Rossignol/Reuters)

A couple dances a tango in front of Saint Peter's basilica at the Vatican, December 17, 2014. At the rear edge of the square more than 2,000 people, who came to Rome from all over Italy for the 78th birthday of Pope Francis, danced in “A tango for Pope Francis” event as music blared. (Photo by Tony Gentile/Reuters)