A South Korean marine in action during their regular drill on Yeonpyeong Island, South Korea November 1, 2018. (Photo by Jeon Heon-Kyun/Pool via Reuters)

Cooler temperatures begin this week as a polar vortex brings much colder conditions with the chance of snow for Snowdonia, Ogwen Valley, North Wales on 22nd October 2018. The Ogwen Valley and Tryfan Mountain looking splendid in the Autumn sunrise. (Photo by DGDImages/Alamy Live News)

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

European bisons (also known as Wisent) at the Bison farm in Muczne, southeastern Poland, 30 December 2018. The Bison farm is a continuation of bison breeding in Bieszczady, which was started in 1963. Here visitors can admire the bison of Bialowieza-Caucasian line, also called the mountain race. The European Bison is the national animal of Poland. (Photo by Darek Delmanowicz/EPA/EFE)

Tourists watch illuminated snow sculptures during the 31st Harbin Sun Island International Snow Sculpture Art Exposition on January 4, 2019 in Harbin, Heilongjiang Province of China. The 31st Sun Island International Snow Sculpture Art Exposition officially opened to public on December 29. (Photo by VCG/VCG via Getty Images)

Emily Hicks (not pictured) of Charleston holds her dog Murphy along the waterfront ahead of the arrival of Hurricane Dorian in Charleston, South Carolina, U.S., September 4, 2019. (Photo by Randall Hill/Reuters)

A family feeds sheep on a farm for tourists in Nakhon Ratchasima province, Thailand on September 14, 2019. (Photo by Soe Zeya Tun/Reuters)

Belarusian ornithologist Vladimir Ivanovski, 72, stands on a tree as he builds an artificial nest for birds of prey from tree branches, in a marsh near the village of Kazyany, Belarus on October 20, 2019. (Photo by Vasily Fedosenko/Reuters)