Russians play accordions as they walk near the building of the Federal Security Service (FSB, Soviet KGB successor) in Lubyanskaya Square to mark May Day in Moscow, Russia, Sunday, May 1, 2016. As in Soviet times, about one hundred thousand of cheerful workers paraded across Red Square despite a chilly rain, but instead of red flags with the Communist hammer and sickle, they waved the blue flags of the dominant Kremlin party and the Russian tricolor. (Photo by Alexander Zemlianichenko/AP Photo)

Members of the Legio X Fretensis (Malta) re-enactment group take part in a display of ancient Roman army life at Fort Rinella in Kalkara, outside Valletta, March 22, 2015. The event “Romanus”, organised by the Malta Heritage Trust, consisted of talks, hands-on displays, static exhibitions of weapons and equipment, food and wine tasting and large-scale re-enactments depicting different forms of Roman warfare in the field. (Photo by Darrin Zammit Lupi/Reuters)

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)

The six-months-old female koala cub holds on to the back of zoo keeper Lena at the zoo in Duisburg, Germany, 23 October 2015. The yet unnamed baby weighs 580 grams. (Photo by Roland Weihrauch/EPA)

A couple watches the sunset over a sea of fog covering the Geneva Lake from Chardonne, Switzerland, 28 December 2015. (Photo by Jean-Christophe Bott/EPA)

A police dog licks its face after receiving food during the dog festival, as part of celebrations of Tihar at Nepal Police Academy in Kathmandu October 22, 2014. Hindus all over Nepal are celebrating the Tihar festival, also called Diwali, during which they worship cows, which are considered a maternal figure, and other animals. Also known as the festival of lights, devotees also worship the goddess of wealth Laxmi by illuminating and decorating their homes using garlands, oil lamps, candles and colourful light bulbs. (Photo by Navesh Chitrakar/Reuters)

This November 11, 2014 aerial photo, shows a deforested area dotted with blue tarps, marking the area where miners reside, and craters filled with water, caused by illegal gold mining activities, in La Pampa, in Peru's Madre de Dios region. Less than a month before Peru plays host to global climate talks, the government sent a battalion of police into southeastern jungles to dismantle illegal gold-mining mining camps. Peru's anti-illegal mining czar, retired army Gen. Augusto Soto, marched the men to the wasteland known as La Pampa, where 50,000 hectares of rainforest have been obliterated in the past six years. (Photo by Rodrigo Abd/AP Photo)

Servicemen of “Kiev 12” military defence battalion react as they take part in a welcoming ceremony in central Ukrainian capital Kiev December 6, 2014. Servicemen of the battalion returned to Kiev after taking part in fighting in eastern Ukraine. (Photo by Gleb Garanich/Reuters)