Children are engulfed by foam during the Bubble Show event in Beijing, China, Sunday, June 26, 2016. Thousands of residents enjoy colored foam churned out by machines along a running track at the event designed for children and parents' interaction. (Photo by Ng Han Guan/AP Photo)

A heat-stressed koala waits as a resident pours water on its back on December 19, 2015 in Adelaide, Australia. Adelaide is experiencing an extreme heatwave, with temperatures reaching over 40 degrees for five consecutive days. (Photo by Morne de Klerk/Getty Images)

Vietnamese military personnel in traditional dress take part in a parade celebrating the 40th anniversary of the end of the Vietnam War which is also remembered as the fall of Saigon, in Ho Chi Minh City, Vietnam, Thursday, April 30, 2015. (Photo by Dita Alangkara/AP Photo)

A six-year-old acrobat performs on the opening of a tourist festival in Bozhou, Anhui province, China May 3, 2015. (Photo by Reuters/China Daily)

A model falls over on the runway in a design by Victoria Bliss during the Project NextGen show at Mercedes-Benz Fashion Week Resort 18 Collections at Carriageworks on May 16, 2017 in Sydney, Australia. (Photo by Stefan Gosatti/Getty Images)

Indonesian mahouts clean their Sumatran elephant in a river near the zoo in Medan, North Sumatra, Indonesia, 12 December 2014. According media reports, the smallest of the Asian elephants, Sumatran elephant (Elephas maximus sumatrensis) is facing serious pressures arising from illegal logging and associated habitat loss and fragmentation in Indonesia. The population has come under increasing threat from rapid forest conversion to plantations. (Photo by Dedi Sahputra/EPA)

Smoke rises from the sauna as Eda Veeroja walks past with birch twigs at Mooska farm near the village of Haanja December 20, 2014. Smoke saunas are usually built without chimney and have a stove that rest on boulders where firewood is burnt until the room heats up. When the smoke is gone and the room reaches the right temperature, people sit inside and whisk each other with birch twigs. The tradition of the smoke sauna in Voromaa vicinity, in the south of Estonia, is enlisted in the UNESCO representative list of the intangible cultural heritage of humanity. (Photo by Ints Kalnins/Reuters)

A homeless man rests on the side of a street at the old quarter of Yemen's capital Sanaa November 27, 2015. (Photo by Khaled Abdullah/Reuters)