Study finds Greenland Ice Sheet reached the shelf edge 6.4 million years ago

New research has determined for the first time when the Greenland Ice Sheet extended all the way out to the continental shelf edge off Northeast Greenland.

In the study, researchers from the iC3 Polar Research Hub used a large seismic dataset and sediment cores to investigate geological archives off Northeast Greenland. This allowed them to reconstruct the extent of the Greenland Ice Sheet far back in time.

Figure: A 3-Stage reconstruction of the Greenland Ice Sheet's maximum position since the Late Miocene. Credit: Jakobsen et al. (2025), Climate of the Past 21(11), 2441-2464.

Studying archives on the seafloor

When glaciers advance, they transport large amounts of sediment, which are deposited at the glacier front. For example, on land this can be seen as a moraine ridge. When a glacier extends all the way to the edge of the continental shelf, sediments are deposited layer upon layer along the slope of the seafloor, forming geological archives that researchers can study.

“This is the first time we can document details of ice ages in Northeast Greenland that go this far back in time.” says Frank Werner Jakobsen (iC3), lead author of the study. “Our results show that the Greenland Ice Sheet first reached the continental shelf edge about 6.4 million years ago, during the Miocene period.”

This is not the first time evidence has been found of glaciers on Greenland around this period. Previous studies of the shelf off East and Southeast Greenland have also shown strong indications that glaciers reached the coast and possibly extended onto the shelf about 7 million years ago.

Frank adds that:

“What is new in this study is that we reveal conditions even farther north, in an area that is very difficult to access due to drifting sea ice from the Arctic Ocean. At the same time, the study provides important information about the extent of the Greenland Ice Sheet far back in time, which is crucial for ice sheet and climate modeling.”

Deep history of Greenlandic ice

The Miocene was a warmer period than the one we live in today, but during the late Miocene a global cooling of the climate took place. In addition, this was a tectonically active period, during which parts of East Greenland were uplifted by as much as one kilometre. 

Greenland moved away from Svalbard, leading to the formation of the Fram Strait and the exchange of water masses between the Arctic Ocean and the North Atlantic. This brought warm—and most importantly, moist—air northward, where it could accumulate as snow in the mountains of Northeast Greenland. The researchers believe this led to the buildup of an ice cover that eventually grew large enough to spread out over the continental shelf.

“There are still many uncertainties, and more research is needed to understand how the Miocene climate affected ice sheets in both the Northern and Southern Hemispheres. And we are now one step closer,” Frank concludes.

Learn more

Frank Werner Jakobsen is a PhD researcher with UiT’s Department of Geosciences. He is affiliated with iC3 Polar Research Hub and is a marine geologist at the Geological Survey of Norway (NGU).

Co-authors Monica Winsborrow and Andreia Plaza-Faverola are also researchers at the iC3 Polar Research Hub based at UiT’s Department of Geosciences.

The new study “Continental shelf glaciations off Northeast Greenland since the Late Miocene” was published in Climate of the Past and is available here.