NASA is studying Greenland glacial melt from above.

A glacier in Greenland.

Greenland’s coastal glaciers are melting, faster than normal, and that has a lot of climate scientists concerned. But until recently, it was hard to know the extent of that melting because researchers simply didn’t have a lot of data about those glaciers. They didn’t even have that much data on the geography of Greenland under the ice.

But in 2016, NASA launched its Oceans Melting Greenland (or OMG) mission, which is already bringing in a lot of really useful data. Flights over Greenland are telling us a great deal about the shape of the coastline, especially the bedrock underneath the glaciers, which make a huge difference in how those glaciers melt when they reach the sea.

Fresh water, coming from Arctic glaciers, is lighter than salt water, which means that it sits on top of salt water when the two interact. Ironically, the fresh water is colder, so a colder river of fresh water flows on top of the warmer, deeper salt water, which is about 600 feet down. When the glacier hits the ocean, the parts that are touching the colder fresh water don’t melt as quickly, so the depth of bedrock where the ice meets the sea has a significant impact on the melting of glaciers.

By mapping out the ocean floor along these glaciers, researchers are getting a better picture of the underwater geography and how it relates to Greenland. There are, for example, troughs left by previous glacial movements, which run under modern glaciers, meaning that they’re even deeper on some parts of the island.

This is just with one year of data. Over time, as the OMG mission continues, researchers will get access to an ever-increasing collection of data, which will allow them to compare the glaciers year to year. That means they can get a better idea of where, and how much, these glaciers are melting, which might help them figure out ways to slow it down.