Public Space series, 2015. This series by Morteza Niknahad and Behnam Zakeri tends toward cinema, taking an almost cartoonish view of modern life in Iran. This work was inspired by the social life of dolphins. (Photo by Morteza Niknahad and Behnam Zakeri/The Guardian)

People in Kathmandu joke that the face mask has now become part of the national dress – an indispensable accessory in an effort to protect themselves from the dust. Nepal has the worst air quality in the world, according to the Environmental Performance Index. (Photo by Pete Pattisson/The Guardian)

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)

A boy moves away as a United Nations World Food Programme (WFP) helicopter lands in Rubkuai village, Unity State, northern South Sudan, February 18, 2017. South Sudan on Monday declared famine in some parts of the country, with more than three years of war leaving nearly five million hungry in what aid groups called a “man-made” tragedy. (Photo by Siegfried Modola/Reuters)

A tattoo is displayed on the arm of a girl during Bandung Body Art Festival at in Bandung, West Java, on December 7, 2014. Upon its establishment in 2010, founders of the Bandung Body Art Festival sought to celebrate an art form that was once taboo and associated with criminals. Tattoos are now an increasingly acceptable part of Indonesia’s urban landscape, and the annual event this year continued its campaign with 45 tattoo artists offering their services for free at the Ganesha Cultural Center. (Photo by Rezza Estily/JG Photo)

A breeder poses with fruits and specially made high-fibre bread, for 36-year-old giant panda Jia Jia, at the Hong Kong Ocean Park, China June 30, 2015. Jia Jia, the oldest giant panda living in captivity, is set to challenge the world record for the animals' longevity, with her age said to put her on par with a human centenarian. (Photo by Tyrone Siu/Reuters)

A curious leopard cub toys with a camera at MalaMala Game Reserve in Mpumalanga Province, South Africa. (Photo by Barcroft Media)

The remarkable scene was captured by amateur wildlife photographer Ian Salisbury, 62, at the South Luangwa National park in Zambia. The crocodile grabs hold of the elephant's trunk, but it soon becomes clear that he has bitten off a lot more than he can chew by grabbing the huge beast. Mr Salisbury said the elephant “fled rapidly into the bush” after the attack. (Photo by Ian Salisbury/Caters News)