To predict future sea-level rise, scientists study how ice sheets responded to past warming during Quaternary interglacials. For the Middle Holocene, evidence of how far the Greenland Ice Sheet retreated inland is scarce, because most records of its smaller extent are buried beneath today’s ice.
New research led by Columbia University and the University at Buffalo involved drilling 509 meters into firn and ice at Prudhoe Dome in northwestern Greenland. The recovered sub-ice material provides direct evidence of how the northwest Greenland Ice Sheet responded to Holocene warming.
Researchers discovered that Greenland’s Prudhoe Dome ice cap completely melted about 7,000 years ago, much more recently than previously believed. This finding indicates that the Prudhoe Dome is highly sensitive to the relatively mild Holocene temperatures, the interglacial period that began 11,000 years ago and continues today.
The Holocene is known as a period of relative climate stability, when humans first began farming and laying the foundations of civilization. Prudhoe Dome, an ice cap in northwestern Greenland, is about 1,700 feet thick and spans roughly 965 square miles.
Jason Briner from the University at Buffalo said, “If natural, mild climate change of that era melted Prudhoe Dome and kept it retreated for potentially thousands of years, it may only be a matter of time before it begins peeling back again from today’s human-induced climate change.”
GreenDrill, funded by the U.S. National Science Foundation, is the first project to drill deep into the Greenland Ice Sheet to recover ancient bedrock and sediment hidden beneath the ice.
Remarkably, scientists have had less material from under Greenland’s ice than from the moon. These new samples are invaluable: their chemical signatures reveal when the rocks were last exposed to the open sky, providing direct evidence of when the ice sheet melted.
The team analyzed the sediment using luminescence dating. When sediment is buried, electrons build up inside tiny mineral grains. These electrons stay trapped until the grains are exposed to light again, releasing a glow that scientists can measure.
Infrared stimulated luminescence measurements from sub-ice sediments show that the ground beneath the summit was last exposed to sunlight about 7,100 ± 1,100 years ago. This evidence shows that the Prudhoe Dome completely melted at that time. This melting is similar to that of other northern Greenland ice caps. The result agrees with chemical signals in the ice core and with models of ice thickness and age.
Study’s lead author, Caleb Walcott-George, assistant professor at the University of Kentucky, said, “This means Prudhoe Dome melted sometime before this period, likely during the early Holocene, when temperatures were around 3 to 5 degrees Celsius warmer than they are today.”
“Some projections indicate we could reach those levels of warming at Prudhoe Dome by the year 2100.”
The findings could tell more about future sea-level rise. By studying vulnerable regions along the edges of the ice sheet, such as Prudhoe Dome, it’s possible to pinpoint where melting is likely to begin and which coastal communities may face the earliest risks.
Journal Reference:
- Walcott-George, C.K., Brown, N.D., Briner, J.P. et al. Deglaciation of the Prudhoe Dome in northwestern Greenland in response to Holocene warming. Nat. Geosci. (2026). DOI: 10.1038/s41561-025-01889-9
