Recently unearthed photographs taken by Danish explorers in the 1930s show glaciers in Greenland retreating faster than they are today, according to researchers.

The photos in question were taken by the seventh Thule Expedition to Greenland led by Dr Knud Rasmussen in 1932. The explorers were equipped with a seaplane, which they used to take aerial snaps of glaciers along the Arctic island's coasts.