Revellers react after falling in the mud at Worthy Farm in Somerset during the Glastonbury Festival, Britain, June 26, 2016. (Photo by Stoyan Nenov/Reuters)

A man prepares tea at a roadside shop on a flooded street in Kolkata, India, August 11, 2016. (Photo by Rupak De Chowdhuri/Reuters)

Revellers, dressed as “Zarramaches”, pose inside the city hall during celebrations to mark Saint Blaise's festivity in Casavieja, Spain February 3, 2017. (Photo by Sergio Perez/Reuters)

A Chinese couple take pictures in an interactive installation art work named “You and Me” on Valentine's Day at 798 Art Zone on February 14, 2012 in Beijing, China. (Photo by Feng Li/Getty Images)

Participants demonstrate for the media before the role play event at Czocha Castle in Sucha, west southern Poland April 9, 2015. Harry Potter enthusiasts from all over the world are attending a four-day live action role play event at the medieval castle made into a close imitation of the “College of Wizardry”. (Photo by Kacper Pempel/Reuters)

A general view of the ghost town of a former Soviet military radar station near Skrunda, Latvia, April 9, 2016. (Photo by Ints Kalnins/Reuters)

Syrian rescue workers and residents help an injured woman following a reported air strike by government forces on the rebel-held neighbourhood of Haydariya in the northern city of Aleppo on April 10, 2016. (Photo by Thaer Mohammed/AFP Photo)

The Aletsch Glacier is pictured at dusk in Fiesch, Switzerland, August 11, 2015. One of Europe's biggest glaciers, the Great Aletsch coils 23 km (14 miles) through the Swiss Alps – and yet this mighty river of ice could almost vanish in the lifetimes of people born today because of climate change. The glacier, 900 metres (2,950 feet) thick at one point, has retreated about 3 km (1.9 miles) since 1870 and that pace is quickening. (Photo by Denis Balibouse/Reuters)