A Zimbabwean subsistence farmer holds a stunted maize cob in his field outside Harare, January 20, 2016. About 14 million people face hunger in Southern Africa because of a drought that has been exacerbated by an El Nino weather pattern, the United Nations World Food Programme (WFP) said on Monday. In Zimbabwe, 1.5 million people, more than 10 percent of the population, face hunger, WFP said. (Photo by Philimon Bulawayo/Reuters)

A boy sits in a canoe in front of a shed built on a raft in the Makoko fishing community on the Lagos Lagoon, Nigeria February 29, 2016. In Makoko, a sprawling slum of Nigeria's megacity Lagos, a floating school capable of holding up to a hundred pupils has since November brought free education to the waterways known as the Venice of Lagos. It offers the chance of social mobility for youngsters who, like most of the city's 21 million inhabitants, lack a reliable electricity and water supply and whose water-based way of life is threatened by climate change as well as rapid urbanisation. (Photo by Akintunde Akinleye/Reuters)

A woman jumps into water from the roof of Murru prison, an abandoned Soviet prison, in Rummu quarry, Estonia, during hot weather July 4, 2015. During the Soviet time, Rummu quarry was used as a mining site for Vasalemma marble and most of the workforce came from among the detainees of Murru prison. When the prison closed after 1991, pumps that once kept the quarry and the prison dry were shut down, causing water to fill the quarry. It has become an unofficial and unguarded swimming and diving spot, attracting locals and tourists. (Photo by Ints Kalnins/Reuters)

Alfred Yetta (L) and Kay Manning pose for a photo in front of a cardboard cut-out of Pope Francis, during an event organised by Christa Scalies, the co-creator of the Pop-Up Pope, in Fado Irish Pub & Restaurant in Philadelphia, Pennsylvania, September 16, 2015. (Photo by Mark Makela/Reuters)

A bull rams inmates seated at a card table in the Convict Poker event at the Angola Prison Rodeo in Angola, La., Saturday, April 26, 2014. Those competing in the rodeo have to pass a physical to be deemed strong and healthy enough, and thousands of others work year-round making arts and crafts to sell at the event, according to the prison's athletic director. (Photo by Gerald Herbert/AP Photo)

A Bukusu youth stands covered in mud in preparation for a circumcision ritual in Kenya's western region of Bungoma August 9, 2014. Circumcision rituals, which take place in August, are celebrated amongst some Kenyan tribes as an annual rite of passage into adulthood. (Photo by Noor Khamis/Reuters)

A view of an entrance to the concrete case surrounding the pressure vessel of the reactor is seen inside the decommissioned Unit Six of the Greifswald nuclear power station outside Lubmin August 5, 2014. Unit Six was a part of East Germany's largest nuclear power plant that was nearly completed in 1990, when the country's re-unification halted construction. (Photo by Thomas Peter/Reuters)

Bosnian worker Sefik Salihovic drives a steam engine in the Bosnian town of Banovici, 140 kms (86.9 miles) north of Sarajevo, on Monday, November 24, 2014. Every day, steam engines over 60 years old, defy their age and still pull wagons of coal from Banovici's coal mine to clients in nearby towns. But in the summer some of them turn into the only tourist attraction this impoverished north Bosnian town has to offer. (Photo by Amel Emric/AP Photo)