A pilot inflates a hot air balloon while taking part in the 38th International Balloon Festival of Chateau-d'oex, Switzerland, 23 January 2016. The festival takes place from 23 to 31 January. (Photo by Vincent Vannay/EPA)

This file photo provided on Sunday February 15, 2015 by the Syrian anti-government activist group Aleppo Media Center (AMC), which has been authenticated based on its contents and other AP reporting, shows Syrian rebels firing locally made shells against the Syrian government forces, in Aleppo, Syria. (Photo by AP Photo/Aleppo Media Center)

A German rifleman beside the corpse of a French soldier in a trench at Fort Vaux, France, 1916. (Photo by Hulton Archive/Getty Images)

Indian forest officials and police personnel try to chase away a wild male elephant at Hengrabari area in Guwahati on April 30, 2019. The elephant came down from Amchang Wildlife Sanctuary in search of food and later forest official tranquillized it, local media reported. As the pressure of population pushes human habitation closer to forests incidents of wild animals straying into cities is increasingly reported. (Photo by Biju Boro/AFP Photo)

A column of sand and front of clouds are seen by dash cam as the car drives near a tornado in Dragalina, Calarasi county, Romania April 30, 2019 in this still image taken from a video obtained from social media. (Photo by Alexandra Puscasu via Reuters)

A man walks by as tourists take selfies on the French Riviera city of Nice on June 24, 2019, as temperatures soar to 33 degrees Celsius. Forecasters say Europeans will feel sizzling heat this week with temperatures soaring as high as 40 degrees Celsius (104 degrees Fahrenheit) in an “unprecedented” June heatwave hitting much of Western Europe. (Photo by Valery Hache/AFP Photo)

An Extinction Rebellion environmental activist couple getting married at an action site they are calling “The Beacon” on Westminster Bridge on October 7, 2019 in London, England. Primarily made up of London based activists the site is one of 12 situated around key Government locations in central London as actions are also predicted to occur in unto 70 cities around the world. The group aim to occupy the areas in central London for up to two weeks through non violent protest with an estimated 8 times as many people as their April protests which saw over 1,200 people arrested. (Photo by Ollie Millington/Getty Images)

A woman waits at a polio immunisation health centre, in Maiduguri, Borno State, Nigeria, August 29, 2016. Nigeria's military has liberated large swathes of land from Boko Haram but a ride with an army convoy, all guns firing for fear of ambush, shows how far the northeast is from normality after a brutal Islamist insurgency that has displaced millions. (Photo by Afolabi Sotunde/Reuters)