Greenland was nearly ice-free for extended periods during the Pleistocene

Measurements of cosmic-ray-produced 10Be and 26Al in a bedrock core from beneath the summit of the Greenland Ice Sheet show that Greenland was nearly ice-free for extended periods under Pleistocene climate forcing. The Greenland Ice Sheet is a main contributor to modern sea-level rise, but its stability during past warm periods is uncertain, thus compromising our ability to robustly predict future rates and magnitudes of ice loss. Joerg Schaefer...