Sandstone sculpted by water and wind erosion is seen in a slot canyon, one of hundreds that surround Lake Powell near Page, Arizona, May 26, 2015. Lake Powell on the Colorado River provides water for Nevada, Arizona and California. A severe drought in recent years, combined with withdrawals that many believe are not sustainable, has reduced its levels to only about 42 percent of its capacity. (Photo by Rick Wilking/Reuters)

In this April 28, 2015 file photo, heads of tuna on a cart are carried by a fish dealer after the day's auction at Tsukiji Wholesale Market in Tokyo. In one of the biggest of Japan's many New Year holiday rituals, early on Tuesday, January 5, 2016, Tokyo's Tsukiji market will auction off with much fanfare a huge, glistening tuna, likely destined for one of the big sushi chains. If all goes as planned, it will be the last such auction at 80-year-old Tsukiji. (Photo by Shuji Kajiyama/AP Photo)

Visitors walk past a train-shaped ice sculpture ahead of the 31st Harbin International Ice and Snow Festival in the northern city of Harbin, Heilongjiang province, January 4, 2015. The winter festival will be officially opened on January 5, 2015. (Photo by Kim Kyung-Hoon/Reuters)

Chingele, a herder, wears a traditional Mongol costume to greet a neighbor for the New Year. Chingele was among a group of herders who went to Beijing to protest eviction from grazing lands to make room for an army training camp. (Photo by Gilles Sabrie/The Washington Post)

In this Wednesday, July 20, 2016 photo, a child carries kettles through a flooded street with a woman in Tianjin, China. China says dozens of people have died or gone missing since Monday in massive floods across the country's north. (Photo by Chinatopix via AP Photo)

Britain Athletics, 2016 London Anniversary Games, Queen Elizabeth Olympic Park, Stratford, London on July 23, 2016. Canada's Brent Lakatos crashes with athletes during the mens 1500m T54. (Photo by Eddie Keogh/Reuters/Livepic)

A woman waits at a polio immunisation health centre, in Maiduguri, Borno State, Nigeria, August 29, 2016. Nigeria's military has liberated large swathes of land from Boko Haram but a ride with an army convoy, all guns firing for fear of ambush, shows how far the northeast is from normality after a brutal Islamist insurgency that has displaced millions. (Photo by Afolabi Sotunde/Reuters)

Women dressed like manga characters attend the 16th edition of the Japan Expo exhibition, in Villepinte, north of Paris, Thursday, July 2, 2015. (Photo by Thibault Camus/AP Photo)