A dog sits in the shade of a mangrove tree as a woman uses a fork to dig for shellfish on the reef-mud flats of a lagoon located at South Tarawa in the central Pacific island nation of Kiribati May 23, 2013. Kiribati consists of a chain of 33 atolls and islands that stand just metres above sea level, spread over a huge expanse of otherwise empty ocean. With surrounding sea levels rising, Kiribati President Anote Tong has predicted his country will likely become uninhabitable in 30-60 years because of inundation and contamination of its freshwater supplies. (Photo by David Gray/Reuters)

In this photo taken Tuesday, June 23, 2015, a Ukrainian serviceman from the Kiev-2 volunteer battalion fires an weapon at a frontline in the village of Krymske, east Ukraine. Few places along the front line in east Ukraine see regular fighting as bitter as the village of Krymske. For now, Krymske is in the hands of Ukrainian government forces and the volunteer battalions that fight alongside them. (Photo by Evgeniy Maloletka/AP Photo)

A Pakistani child, whose family was displaced by 2010 floods from a village in Pakistan's Sindh province, sits on a wooden cart outside her family's makeshift home, in a slum on the outskirts of Islamabad, on February 8, 2013. (Photo by Muhammed Muheisen/AP Photo)

A potential bidder carefully examines pieces of Tuna in order to ascertain the quality and to estimate its price ahead of the Tuna auction at the Tsukiji fish market on February 28, 2012 in Tokyo, Japan. (Photo by Daniel Berehulak /Getty Images)

Internally displaced Syrians who fled Raqqa tie ropes for their tents in a camp in Manbij, Syria on April 6, 2017. (Photo by Rodi Said/Reuters)

A burning tank is in Daraa, on March 9, 2013. (Photo by Ali Abu-Salah/Reuters/Shaam News Network via The Atlantic)

Syrians gather during an evacuation operation of rebel fighters and their families from rebel-held neighbourhoods on December 15, 2016 in the embattled city of Aleppo. A convoy of ambulances and buses left rebel territory in Aleppo in the first evacuations under a deal for opposition fighters to leave the city after years of fighting. The rebel withdrawal will pave the way for President Bashar al-Assad's forces to reclaim complete control of Syria's second city, handing the regime its biggest victory in more than five years of civil war. (Photo by Karam Al-Masri/AFP Photo)

People who fled the violence from Islamic State-controlled northern Syrian town of al-Bab arrive in the rebel-held outskirts of the town, Syria February 3, 2017. (Photo by Khalil Ashawi/Reuters)