Most glaciers have a radioactive layer corresponding to the period of atmospheric nuclear testing in the 1950s and 1960s. The Naimona'nyi glacier, which sits six kilometres above sea level on the Tibetan mountain of the same name (pictured), lacks this fallout layer, according to ice cores drilled by Natalie Kehrwald of Ohio State University in Columbus and her colleagues. This suggests that the glacier has accumulated no new ice for more than 50 years.
It is therefore the highest glacier reported to be annually losing mass. If the same is true for other, similarly situated glaciers in the region, the downstream consequences for people who depend on the glaciers' meltwater — a significant fraction of Asia's population — could be severe.