GreenDrill: The response of the northern Greenland Ice Sheet to Arctic Warmth - Direct constraints from sub-ice bedrock
The GreenDrill project is motivated by a need to understand past and future change in the extent of the Greenland Ice Sheet. The Greenland Ice Sheet (GrIS) holds about 24 feet (7.4 m) of sea level equivalent, yet it remains difficult to predict the rate of melt and possible tipping points in the stability of the ice sheet. In GreenDrill, the team of investigators will sample bedrock from under ice at sites in northern Greenland, analyzing cosmogenic nuclides to determine past periods of ice free conditions. These data will provide better understanding of how this region of the GrIS has responded to warm periods in the past. The team will also use these data in computer models to place results in the context of the entire ice sheet to explore mechanisms and climate forcing driving past periods of ice sheet disintegration, which in turn will inform projections of future ice sheet behavior and sea level rise. In addition to the high relevance of this research to society, the GreenDrill project includes broader impacts such as development of a new television episode called Adventures in Science, educational programs for middle and high school students via the Scientists are Superheroes program, and training for early career postdoctoral scientists, graduate students, and undergraduates.
In this project, the investigators propose to gather new data to test the sensitivity of the northern Greenland Ice Sheet (GrIS) and its potential to contribute to sea level rise in the future. Specifically, data from the GreenDrill project will better constrain the response of the GrIS to past periods of warmth and address the hypothesis that the northern GrIS is more sensitive to Arctic warming than the southern GrIS. The team will drill through the ice at sites in northern Greenland, sample bedrock obtained from those cores, and analyze a suite of cosmogenic nuclides (Beryllium-10, Aluminum-26, Chlorine-36, Carbon-14, and Neon-21) that can act as signatures of changes to the GrIS margin. These data will deliver direct observations of periods when the GrIS was substantially smaller than today and ice sheet margins retreated inland. Results will be incorporated into a numerical ice sheet model with a built-in cosmogenic nuclide module to identify plausible ice sheet histories. The modeling experiments will help understand the mechanisms and climate forcing underlying past periods of ice sheet retreat and help inform predictions of the future. Based on the melting scenarios, a first-order map of sea level rise fingerprints and inundation scenarios for major port cities will be produced.