Something caught the eye of Stef Lhermitte last week, while he was looking through satellite images of the Greenland’s Petermann Glacier.  Almost by coincidence he saw a new thin line, as he was going through ESA Sentinel-1 images for research on melt. He checked other satellite images, and saw the line first appear on July 2016, apparently unnoticed until then. In a series of five tweets, Lhermitte shared his discovery, hoping someone might be able to shed some light.

The final flight

The tweets were noticed by Tom Wagner, head of polar research at NASA, who contacted his colleague Joe MacGregor in Greenland. MacGregor was in Greenland leading a research campaign called Operation IceBridge, which makes low-level flights over Greenland and Antarctica's ice sheets to create 3-D views of the ice.

No images had been made of the area indicated by Lhermitte, but as luck would have it, one final flight was planned over the glacier the next day. As the crack was only a short distance away from the planned trajectory, they flew over that area, confirming the existence of the crack, and at the same time mapping it in greater detail.


A new crack in one of Greenland’s largest glaciers is worrying, especially this newly discovered one, as it lies a great deal further ‘upstream’ in the glacier than other cracks. The further away, the more unstable the underlying layer of ice, should pieces break off.

The glacier acts like a barrier between the ice sheet and the ocean. Retreat of the glacier could lead to more large chunks of ice breaking off into the ocean, causing less ‘resistance’ by the glacier and more melt of land ice, contributing to sea level rise.

Washington Post

The tweets of Lhermitte also drew attention from Washington Post journalist Chris Mooney, who wrote two articles on the topic:

After that, several other international media outlets picked up on the news, among which the Daily Mail:

And CNN:

More information

Dr. Stef Lhermitte, 
Science Information Officer TU Delft Roy Meijer,, +31 15 2781751 / +31 6 14015008