A zookeeper feeds a hippopotamus with a watermelon in its enclosure in Belgrade's zoo, Serbia, July 20, 2015. Temperatures in Serbia have risen up to 40 degrees Celsius (104 degrees Fahrenheit), according to official meteorological data. (Photo by Marko Djurica/Reuters)

Vietnamese female commissioned officers of the signal force march during a parade marking their 70th National Day at Ba Dinh square in Hanoi, Vietnam September 2, 2015. (Photo by Reuters/Kham)

An Iraqi woman attends a festival commemorating the International Day of Peace in Baghdad, September 21, 2015. (Photo by Thaier al-Sudani/Reuters)

A woman pours alcohol from the bottle into her mouth at the Far Hills Race Day at Moorland Farms in Far Hills, New Jersey, October 17, 2015. Young locals in New Jersey catch up with friends from school and college days at the Far Hills Race Day, which started as a fox-hunting event in the early 1900s. Many racegoers first went to the Hunt, as it's known locally, as children, but nowadays it's an alcohol-fuelled party for them. Makeshift bars are set up in cars, with the horses' efforts on the turf sometimes a backdrop to the main event. (Photo by Stephanie Keith/Reuters)

A combination photograph shows revelers dressed in "Dia de Muertos" or "Day of the Dead" themes as they pose for photos while taking part in the Greenwich Village Halloween Parade in the Manhattan borough of New York October 31, 2015. (Photo by Carlo Allegri/Reuters)

A musician plays his violin next to a depiction of La Santa Muerte (Saint Death) at a shrine during Day of the Dead celebrations in Ciudad Juarez, Mexico, November 2, 2015. (Photo by Jose Luis Gonzalez/Reuters)

Skulls placed on the floor are seen during a ceremony held for the "Dia de las natitas" (Day of the Skull) celebrations at the General Cemetery of La Paz, November 8, 2015. Bolivians, who keep close relatives skulls at home as a macabre talisman, flock to the cemetery chapel once a year to have the craniums blessed and to bring themselves good luck in the future. (Photo by David Mercado/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)