19 Ice sheets, glaciers, and landscapes, oh my!

Glaciers and ice sheets shaped the landscape of the Northeast. Ice continues to shape the landscape of alpine and polar regions. We welcome submissions on glaciers &  ice sheets of any size, shape, age, and location.

Monday, 23 March 2026
8:00 AM - 12:00 PM
CCC, Room 26

The Greenland Ice Sheet was large for most of the past five million years

Paper number: 19-9
Program: Technical Sessions
Time: 10:40 AM – 11:00 AM

Authors

Abstract

Multiple datasets indicate that humans have warmed the climate sufficiently to begin melting the Greenland Ice Sheet, which contains enough water to raise sea level about 7 meters. At some currently not well defined level of warming, ice sheet disappearance will become inevitable due to reinforcing ice and climate feedbacks. Understanding ice sheet response to climate change during the past several million years, when climate has varied widely, can ground truth model predictions of ice sheet loss and regrowth. Because existing proxy records are few and some appear to disagree, the past extent of ice on Greenland remains poorly constrained and uncertain. Here we test, using numerous measurements of in situ 10Be and 26Al made in dated marine cores, a widely accepted hypothesis, that Greenland repeatedly and extensively deglaciated for a significant amount of time after glaciation began in the Miocene. We find that over the last 5 million years, nuclide concentrations and 26Al/10Be ratios are uniformly low in four sediment cores around Greenland, indicating that sediment source areas were routinely ice-covered and only rarely exposed to cosmic radiation. Our results suggest that some of the Greenland Ice Sheet is often, but not exclusively, stable in a warmer world, highlighting the need to better understand what factors control its fate, both in the past and today.

Geological Society of America Abstracts with Programs. Vol. 58, No. 2

doi: 10.1130/abs/2026NE-411301

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