Inside the Afar Triangle in Ethiopia’s Danakil desert, camel caravans are used to carry salt. For centuries, the essential mineral has been mined by the Afar people, known for their ability to withstand extremes. The terrain is rugged, travelers are scarce and so are motor vehicles, where the average annual temperature is the highest in the world, and can rise to 122 degrees Fahrenheit, 50 degrees Celsius. (Photo by Ziv Koren/Polaris)

A donkey savors warming temperatures after a long winter at the zoo in Warsaw, Poland, on Wednesday, April 8, 2015. (Photo by Czarek Sokolowski/AP Photo)

Men carrying a shrine jump over a bon fire, which means a wish for good luck during a traditional Chinese lunar new year celebration in Jieyang, Guangdong province, China, February 2, 2017. (Photo by Reuters/China Daily)

These black-and-white photos are taken from the new book “Armoured Warfare in the First World War 1916 – 1918” by Anthony Tucker-Jones and published by Pen & Sword Military. Here: British troops hitch a ride on a Mark IV after the massed tank fleet spearheading attack at Cambrai on November 20, 1917. (Photo by Anthony Tucker-Jones/Mediadrumworld.com)

A woman poses for a photograph during Holi celebrations in the town of Barsana in the state of Uttar Pradesh, India, March 6, 2017. (Photo by Cathal McNaughton/Reuters)

Fireplace for children, Trondheim, Norway, by Haugen/Zohar. The children of Trondheim come to sit around the fire and tell stories in this whimsical cone hut, made with materials recycled from a construction site. (Photo by Jason Havneraas/The Guardian)

In this photo taken Sunday, March 12, 2017, a girl Abuk walks home with her brothers and friends after collecting clean water from a water point four kilometers away from her home, in Aweil, in South Sudan. As World Water Day approaches on March 22, more than 5 million people in South Sudan, do not have access to safe, clean water, compounding the problems of famine and civil war, according to the UNICEF. (Photo by Mackenzie Knowles-Coursin/UNICEF via AP Photo)

An Indian Runner duck searches for food on a snow-covered meadow in Aitrang, southern Germany, Wednesday. April 19, 2017. (Photo by Karl-Josef Hildenbrand/DPA via AP Photo)