Like an ice cube on a hot summer day, many of Earth's glaciers are shrinking.

Last January, a study in Nature Climate Change showed the world's glaciers are the smallest they've been in human history, revealing radiocarbon material that hasn't been exposed for 40,000 years.

Now, new research published in Nature quantifies how much the world's lost glaciers have contributed to rising sea levels.

From 1961, when reliable record keeping began, to 2016, the ocean crawled up 27 millimeters as a result of ice sloughing off the world's non-polar glaciers. Scientists had known that melting glaciers contribute to sea-level rise, but the new study takes a comprehensive look at how much and how quickly they're melting.

They found mountain glaciers contribute