Unnati, 6 years old, at home with his sister Ishika, 4 years old, in the Mahamai Ka Bagh neighborhood. Unnati was born to parents contaminated by a carcinogenic and mutagenic water supply. This year marks the 31st anniversary of the 1984 Union Carbide gas tragedy that killed thousands of citizens of Bhopal within 72 hours and has gone on to claim thousands more as a result of the polluted environment. (Photo by Giles Clarke/Getty Images)

A man carries a dog and wades through a flooded street in Chennai, in the southern Indian state of Tamil Nadu, Wednesday, December 2, 2015. Weeks of torrential rains have forced the airport in the state capital Chennai to close and have cut off several roads and highways, leaving tens of thousands of people stranded in their homes, government officials said Wednesday. (Photo by AP Photo)

From house breaking in Johannesburg to hippos on the loose in Tbilisi to rioters attacking a policewoman in Burundi, Reuters photographers tell the story behind some of the most iconic pictures of the year. Here: Protesters drag a female police officer accused of shooting a protester in the Buterere neighbourhood of Bujumbura, Burundi, May 12, 2015. Goran Tomasevic: Protesters started throwing stones at a group of police, who then started to run away. The policewoman in the photo, Medikintos Inabeza, 33, got left behind and then some protesters started to push her, saying that she had shot a female protestor in the stomach with an AK47 rifle. I didn't see anything of that. There were 5 or 10 protesters pushing the policewoman at first, then others came and joined in. Up to 20 or 30 protesters were surrounding her at one point. The protesters kicked and beat her very badly; I also saw a couple of knives. I thought they were going to kill her... (Photo by Goran Tomasevic/Reuters)

Israeli couples attend a “trash the dress” event at a paint-ball venue in the southern Israeli city of Ashdod, December 25, 2015. Twelve Israeli couples wore their wedding outfits once again on Friday as they took part in a video clip where they deliberately ruined their wedding outfits, in keeping with the trendy wedding style photography dubbed “trash the dress”. (Photo by Amir Cohen/Reuters)

The sun begins to set over this rusty beachside mansion that has been left abandoned for more than 25 years in Thailand, June 2017. A deserted beachside mansion in southern Thailand has retained its beauty – despite no one living there for more than 25 years. In June this year abandoned photographer, Dax Ward, ventured to the Prachuap Khiri-Khan Province to capture the haunting attraction on camera. (Photo by Dax Ward/Barcroft Images)

This image of a young bareback rider was taken in the village of Palenque de San Basilio, in Colombia’s Bolívar department. Founded by freed slaves in the 17th century, it became the first free town in the Americas, following a decree by the Spanish crown. Most of today’s inhabitants are direct descendants of those slaves and have preserved many of their customs, including their own language, Palenquero. (Photo by Sebastián Suki Beláustegui/The Guardian)

A protester is sprayed with mace by riot police after throwing a chair through a window of a business during the second night of demonstrations after a not guilty verdict in the murder trial of former St. Louis police officer Jason Stockley, charged with the 2011 shooting of Anthony Lamar Smith, who was black, in St. Louis, Missouri, U.S., September 16, 2017. (Photo by Lawrence Bryant/Reuters)

A British photographer has captured life at the “edge of the world”. Timothy Allen, best known for his work on BBC's Human Planet, trekked through the freezing Siberian wilderness for 16 days as he joined part of an 800km migration of reindeer in the Yamal-Nenets region – a name that roughly translates to “edge of the world”. The stunning pictures feature the nomadic Nenets tribe, who drink blood to survive in -45°C temperatures. Timothy's epic journey, which will be revealed in an eight-minute documentary on Animal Planet USA, saw him travel across the bleak terrain of the frozen Ob River with the Nenets people in December last year. Here: An empty camp is shown beneath a colourful sky in Siberia, December 2016. (Photo by Timothy Allen/Barcroft Productions)