Mark Dill and Brit Thacker practice acro-yoga as approximately 70,000 people from all over the world gather for the 30th annual Burning Man arts and music festival in the Black Rock Desert of Nevada, U.S. August 29, 2016. (Photo by Jim Urquhart/Reuters)

In this photo taken on Sunday, September 4, 2016, a Kyrgyz boy holds a golden eagle during the second World Nomad Games at Issyk Kul lake in Cholpon-Ata, Kyrgyzstan. The Games, which opened on Saturday on a picturesque mountain plain in eastern Kyrgyzstan, bring together athletes from 40 countries including Russia and the United States where nomadic traditions are strong. (Photo by Vladimir Voronin/AP Photo)

A migrant woman pulls a girl out of the water as refugees and migrants arrive on an overcrowded dinghy in rough sea on the Greek island of Lesbos, after crossing a part of the Aegean Sea from the Turkish coast, October 2, 2015. A record number of at least 430,000 refugees and migrants have taken rickety boats across the Mediterranean to Europe this year, 309,000 via Greece, according to International Organization for Migration figures. (Photo by Dimitris Michalakis/Reuters)

David Nicholson, 21, surfs as "The Mask" during the ZJ Boarding House Haunted Heats Halloween Surf Contest in Santa Monica, California, United States, October 31, 2015. (Photo by Lucy Nicholson/Reuters)

A woman wearing a mask walk in a street in a Yonghegong Lama temple compound seen shrouded in smog in Beijing, China, 30 November 2015. Beijing issued an orange alert for heavy smog 30 November, the highest level this year. Authorities in the Chinese capital warned of 'severe pollution' and advised the capital's 20 million inhabitants to stay indoors. (Photo by How Hwee Young/EPA)

Residents with faces covered in ash ride on a motorcycle as Mount Sinabung volcano erupts, in Sukandebi village in Karo Regency, Indonesia's North Sumatra province, Indonesia June 13, 2015, in this photo taken by Antara Foto. (Photo by Rony Muharrman/Reuters/Antara Foto)

Palestinian children warm themselves by a fire on a stormy day at Shati (beach) refugee camp in Gaza City January 18, 2016. (Photo by Mohammed Salem/Reuters)

Refugee children play with a stuffed toy at a muddy makeshift camp at the Greek-Macedonian border, near the village of Idomeni, Greece March 15, 2016. (Photo by Alexandros Avramidis/Reuters)