Final-year student Alina Repkina prepares for a livestream of the Last Bell ceremony for school leavers at secondary school No 11 in Rostov-On-Don, Russia on May 30, 2020. It is the first time in Russia that such ceremonies have been held via video link due to the coronavirus lockdown restrictions. (Photo by Valery Matytsin/TASS)

Andre Krumbiegel drives in a «SIL» pointed plough through the pink fog of a smoke body in Saxony, Germany on October 2, 2019. The occasion is the forthcoming Eastern Bloc meeting on 6 October in Großhartmannsdorf, to which motor vehicles and commercial vehicles from former socialist countries can be brought, exhibited and demonstrated. Photo by Sebastian Kahnert/dpa-Zentralbild/Keystone)

South Korean students pose for a selfie following a traditional coming-of-age ceremony at Namsan hanok village in Seoul on May 15, 2017. The Coming of Age Day is the day to celebrate and encourage the youth who have reached the age of 20, which is considered the beginning of adulthood. (Photo by Ed Jones/AFP Photo)

Students of the General Yermolov Cadet School take part in combined military training with members of a local youth military patriotic club at a boot camp of the Russkiye Vityazi (Russian Knights) military patriotic club in the village of Sengileyevskoye outside Stavropol, Russia February 8, 2017. (Photo by Eduard Korniyenko/Reuters)

An Animal Liberation Victoria activist cries as she holds a dead animal at Federation Square on October 1, 2013 in Melbourne, Australia. Over 200 activists gathered with the bodies of deceased animals to publicly grieve their deaths. Animal Liberation Victoria is against the treatment of animals as “property” an promotes a vegan lifestyle. (Photo by Graham Denholm)

This picture taken on December 17, 2013 shows people taking photos of a pole dancer (R) practising after it snowed in Tianjin during a promotional event by members of China's national pole dancing team and students of the sport. China set up its first national pole dancing team in Tianjin in 2012 in order to compete in the World Pole Dancing Championships. (Photo by AFP Photo)

A student from the General Yermolov Cadet School takes part in weapons training during a two-day field exercise near the village of Sengileyevskoye, just outside the south Russian city of Stavropol April 13, 2014. The General Yermolov Cadet School in the southern Russian city of Stavropol is a state-run institution that teaches military and patriotic classes in addition to a normal syllabus. (Photo by Eduard Korniyenko/Reuters)

The Greenland ice sheet is a vast body of ice covering 660,235 sq miles, roughly 80% of the surface of Greenland. It is the second largest ice body in the world, after the Antarctic Ice Sheet. Some scientists predict that climate change may be near a "tipping point" where the entire ice sheet will melt in about 2000 years. If the entire 2,850,000 cubic kilometres (683,751 cu mi) of ice were to melt, it would lead to a global sea level rise of 7.2 m (23.6 ft).