Over the past century, the Earth’s sea levels have risen on a scale that is unprecedented by any other fluctuation over the past 6,000 years, new research shows.

In a study published the U.S. journal Proceedings of the National Academy of Sciences (PNAS), Australian National University researchers reconstruct the past 35,000 years of sea level fluctuations by looking at changes in ice volumes around the world. They say it is the most comprehensive examination of its kind.

Since the beginning of the 20th century, sea levels have climbed 20 centimeters as a result of global warming. But zooming out to the past 6,000 years, this drastic fluctuation is unrivaled, the scientists find.