The high Andes mountains host many glaciers. Study shows four of them have shrunk to a size not seen since the rise of human civilization.

According to Andrew Gorin, a University of California, Berkeley, graduate student and first author of the study, published today (Aug. 1) in Science, this likely means that the glaciers are smaller than they have been in the past 125,000 years, before the most recent glacial era began 120,000 years ago. The data, however, aren’t precise enough to allow extrapolation that far into the past.