New Scientist: It’s like a huge endoscope, probing the bowels of the world’s second-largest ice mass. Researchers have brought back unprecedented video from deep inside Greenland’s ice sheet. The footage shows the camera dropping vertically down a natural 100-metre tunnel in the ice, travelling from a 10-metre-wide hole at the surface to the bottom, where ice meets bedrock. In the early part of the descent, the sides of the tunnel are bright blue. Waterfalls pound their way down across and …