Activists in a clay outfits at the Rathausmarkt during the art protest campaign “1000 Gestalten” (lit 1000 figures), for more solidarity and political participation, in Hamburg, Germany, 17 June 2017. In a two-hour show hundreds of actors took part in a creative public appeal for more humanity and self-responsibility ahead of the upcoming G20 summit. The G20 economic summit takes place in Hamburg July 7-8. (Photo by Lukas Barth-Tuttas/DPA/Alamy Live News)

A visitor kneels down nex to an iCub robot made by the Italian Institute of Technology at the scientists congress IROS 2015 in Hamburg, Germany October 2, 2015. The robot congress is organized by TAMS group (Technical Aspects of Multimodal Systems) of Hamburg's university. (Photo by Fabian Bimmer/Reuters)

A Kamchatka Brown Bear cub eats frozen fruits during a Christmas feeding session at Hagenbecks zoo in Hamburg, northern Germany on December 5, 2014. (Photo by Fabian Bimmer/Reuters)

Ice covers oranges on a tree creating a protective shell in a commercial grove January 11, 2010 near Winter Garden, Florida. (Photo by Matt Stroshane/Getty Images)

People in boats approach “Die Badende” (“The Bather”), a giant sculpture showing a woman's head and knees as if she were resting in the Binnenalster lake on August 3, 2011 in Hamburg, Germany. The sculpture, which is made of styrofoam and steel and measures 4 meters high and 30 meters long, is a project by artist Oliver Voss and will be on display for the next ten days. (Photo by Sean Gallup/Getty Images)

A freighter trapped in ice is shown in this aerial photo near Whitefish Bay on Lake Superior northwest of Sault Ste. Marie, Ontario April 7, 2015. The biggest ice cover on the Great Lakes in decades is backing up shipments of everything from Canadian grain to U.S. iron and steel in one of North America's most important economic regions. (Photo by Kenneth Armstrong/Reuters)

19 individually themed and hand crafted art suites have been newly designed by creatives from across the world – from a swedish artist who made a giant snow elephant in the room, to a french team who fused snow, ice and disco into a groovy sleeping experience. Each year, the hotel creates a new series of artist-designed accommodation spaces that add to the existing landscape of private rooms. (Photo by Icehotel.com/Exclusivepix Media)

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).