Greenlands ice dome vanished 7,000 years ago

I stood recently on the rugged edges of Northwest Greenland, where the air carries a sharp, crystalline silence and the ice seems eternal. Yet new research from the University at Buffalo and Columbia University's Lamont-Doherty Earth Observatory, published in Nature Geoscience, tells a different story - one of a landscape that was once completely bare.

What the GreenDrill project uncovered

The study is the first major result from GreenDrill, a multi-institution, National Science Foundation-funded project co-led by Jason Briner (University at Buffalo) and Joerg Schaefer (Columbia's Lamont-Doherty Earth Observatory), with researchers from the University of Massachusetts Amherst and Penn State also contributing. The ambition of GreenDrill is straightforward but logistically extraordinary: drill through the Greenland Ice Sheet to retrieve bedrock and sediment that has been sealed beneath hundreds of metres of ice for thousands of years. "We'll recover samples from basal ice and sub-ice bedrock comparable to the moon rocks in their rareness and preciousness," Schaefer has said.

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The team drilled through 509 metres of firn and ice at Prudhoe Dome - a high-elevation ice feature on the northwestern flank of the Greenland Ice Sheet, currently around 500 metres thick - to retrieve sub-ice material carrying direct evidence of the past. What they found overturned previous assumptions about the stability of this sector.

Historical evidence from the northern periphery

The Prudhoe Dome vanished entirely roughly 7,000 years ago (more precisely 7.1 ± 1.1 thousand years ago). The conclusion was reached through two independent and mutually reinforcing lines of evidence. The primary method was infrared stimulated luminescence (IRSL) dating of subglacial sediments: IRSL measures when mineral grains in sediment were last exposed to sunlight, providing a direct timestamp of ice-free conditions. Supporting evidence came from interglacial-only δ¹⁸O values measured in the Prudhoe Dome ice column itself, combined with ice depth-age modelling. Additionally, cosmogenic nuclide analysis - measuring concentrations of beryllium-10 (¹⁰Be) and aluminium-26 (²⁶Al) in bedrock, which only accumulate during exposure to cosmic rays at the surface - provided further corroboration of past ice-free conditions.

Together, these datasets indicate that the bedrock beneath Prudhoe Dome was exposed to open sky between approximately 6,000 and 8,200 years ago, coeval with reduced ice extent documented at other ice caps across northern Greenland during the same period. This was not an isolated anomaly but a regional signal.

Implications for ice sheet vulnerability

The most striking aspect of this study is what drove the deglaciation: relatively mild natural warming. During the early-to-middle Holocene, regional summer temperatures in northwestern Greenland were estimated from palaeoclimate data to be approximately 3 to 5 °C warmer than today. As Briner notes, this was "a time known for climate stability, when humans first began developing farming practices and taking steps toward civilization." For natural, moderate warming of that era to have erased Prudhoe Dome entirely - and to have kept it retreated for potentially thousands of years - is a result that climate models had not fully anticipated.

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The fact that this ~500-metre-thick, high-elevation section of the ice sheet could disappear completely under these conditions suggests that even areas previously considered relatively stable are more sensitive to temperature than earlier models indicated. Today, driven by greenhouse gas emissions and Arctic amplification - the phenomenon by which the Arctic warms roughly two to four times faster than the global average - we are on track to approach or locally exceed similar warming thresholds by the end of this century. The pace, however, is fundamentally different: the Holocene warming unfolded over millennia; anthropogenic warming is occurring over decades.

What the ice cores add to the picture

A detail easy to overlook is the value of the δ¹⁸O isotope record from the Prudhoe Dome ice column itself. Oxygen isotope ratios in ice preserve a chemical fingerprint of the atmospheric conditions under which the snow originally fell. The fact that the ice column showed interglacial-only δ¹⁸O values - consistent with the Holocene period, with no older glacial-period signature - independently confirms that there is no continuous ice record extending back before the Holocene at this location. The ice we see today at Prudhoe Dome formed after the dome regrew from bare rock, making it geologically young by ice sheet standards. This convergence of multiple independent methods gives scientists high confidence in the finding.

Current ice loss and the broader context

The Prudhoe Dome discovery does not stand alone. Modern satellite observations paint a consistent and concerning picture. NASA's GRACE and GRACE Follow-On missions show that Greenland has been losing ice mass every year since the late 1990s. On average, the ice sheet sheds roughly 270 billion metric tons of ice per year, contributing approximately 0.7 millimetres of annual global sea level rise on its own. NOAA's 2025 Arctic Report Card confirmed that the 2025 mass balance was −129 ± 50 Gt - less than the 2003-2024 average of −219 ± 16 Gt due to above-average snowfall, but nonetheless a continued net loss. The long-term trend is unambiguous.

The Greenland Ice Sheet as a whole holds enough frozen water to raise global sea levels by approximately 7 metres (roughly 23 feet) if it were to melt entirely - a scenario projected over centuries or millennia, not decades, but one that the geological record suggests is physically possible under sustained warming.

Future projections and sea level rise

When we look at the quiet, moss-covered rocks that were once exposed 7,000 years ago, we see a potential blueprint for the future. The complete loss of the Prudhoe Dome during that period did not happen in isolation; it reflects a systemic sensitivity of the northwest Greenland Ice Sheet to temperature shifts that persisted long after the warmth peak.

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This geological precedent carries a clear implication: we cannot assume that even high-elevation peripheral ice domes will remain permanent fixtures as temperatures rise. The warming threshold that erased Prudhoe Dome in the past is, according to the study's own authors, "similar to projections of warming by 2100 CE" under current emissions trajectories. As the northern periphery responds to warming, the resulting contributions to global sea levels will require a fundamental reassessment of coastal infrastructure, adaptation strategies, and long-range planning - particularly for low-lying coastal communities and island nations. Protecting what remains of these ancient ice structures demands a deep understanding of their demonstrated past fragility, and a clear-eyed reading of the signals already visible in the satellite record.