A bodyboarder rides a wave during a big- wave surfing session at Praia do Norte in Nazare on November 19, 2016. (Photo by Patricia de Melo Moreira/AFP Photo)

Sami people from the Vilhelmina Norra Sameby, gather their reindeers herd in a corral for selection and calf labelling on October 27, 2016 near the village of Dikanaess, about 800 kilometers north-west of the capital Sweden. Sweden's Sami reindeer herders have more than hungry predators to worry about in the cold night, as the indigenous minority moves its flock to the winter pasture in the Nordic tundra. (Photo by Jonathan Nackstrand/AFP Photo)

A man performs a split as he practices Kung Fu at Beihai Park in Beijing, China August 20, 2017. (Photo by Reuters/China Stringer Network)

An Indian white tiger cools off in a pond in its enclosure at Chhat Bir Zoo on the outskirts of Chandigarh on May 22, 2016. Temperatures have soared to a scorching 51 degrees Celsius in one Indian city, meteorologists said, with the ferocious heat setting a new national record. Northern Phalodi wilted as the mercury reached a new high on May 20, equivalent to 123.8 Fahrenheit, beating a 60-year-old record. (Photo by Shammi Mehra/AFP Photo)

Performers wait for delegations to arrive for traditional nomadic Naadam festival performance during the Asia-Europe Meeting (ASEM) summit just outside Ulaanbaatar, Mongolia, July 15, 2016. (Photo by Damir Sagolj/Reuters)

Record snowfall in the Sahara Desert near the town of Ain Sefra in Algeria on January 21, 2017. (Photo by Geoff Robinson/Rex Features/Shutterstock)