A new study finds that the Greenland Ice Sheet, which covers 1.7 million square kilometres and contains enough ice to raise sea levels worldwide by seven metres, is less stable and more sensitive to climate change than previously thought.

During the Second World War, analysts pored over stereoscopic aerial reconnaissance photographs, becoming experts at identifying potential targets from camouflaged or visually noisy backgrounds, and then at distinguishing between V-weapons and innocuous electricity pylons.