A Polisario fighter sits on a rock at a forward base on the outskirts of Tifariti, Western Sahara, September 9, 2016. At a rocky outpost in Western Sahara, a new generation of soldiers who have never known war are mobilising as tensions resurface in one of Africa's oldest disputes after a quarter century of uneasy peace. (Photo by Zohra Bensemra/Reuters)

Pakistani children cool themselves off in a stream in Peshawar, Pakistan, Monday, June 29, 2015, during Muslim's fasting month of Ramadan. (Photo by Mohammad Sajjad/AP Photo)

A model presents a creation by Colombian brand Elena Plus Clothing at Colombiamoda during Medellin's fashion week in Itagui municipality near Medellin, Antioquia department, Colombia, on July 24, 2017. Colombiamoda will take place between the 24th and 27th of July. (Photo by Joaquin Sarmiento/AFP Photo)

Residents watch volcanic smoking and ashes rising from Mount Sinabung during an eruption in Karo, North Sumatra, Indonesia, February 24, 2016. Authorities have repeatedly called on local residents to remain patient in dealing with the impact of Sinabung's eruptions, which some experts have predicted will continue for five more years. (Photo by Xinhua/Barcroft Media)

Visitors make snowmen beside a pool at a hot spring in Hangzhou, in China's eastern Zhejiang province on January 26, 2018. China's central and eastern regions have been hit by heavy snowfalls in recent days, causing disruptions to flight and train schedules. (Photo by AFP Photo/China Stringer Network)

Dancers from “LA Dance Project” perform, wearing a mask, during the drive-in show “Solo at Dusk” in Los Angeles, California, on October 13, 2020, amid the Coronavirus pandemic. (Photo by Valerie Macon/AFP Photo)

Experts of the Anti-Mine Center of the Russian Defense Ministry clear mines at a motorway linking the cities of Stepanakert and Goris in Nagorno-Karabakh on November 23, 2020. (Photo by Stanislav Krasilnikov/TASS)

Young women wearing facemasks and traditional costumes of Song dynasty and Tang dynasty are seated on a bench in a park next to the East Lake in Wuhan, in China’s central Hubei province on May 17, 2020. The Guardian picture desk has chosen on December 17, 2020, the AFP photojournalist Hector Retamal as “Agency Photographer of the Year 2020” for his coverage of the novel coronavirus Covid-19 pandemic in Wuhan, China. (Photo by Hector Retamal/AFP Photo)