The Greenland Ice Sheet holds enough water to raise sea levels nearly 24 feet, yet it remains difficult to predict the rate of melt and possible tipping points in the stability of the ice sheet.
Climate change is now causing Greenland to shed ice rapidly, and even a few feet of sea level rise may have grim implications for coastal cities and low-lying islands. A new project aimed at drilling through the ice to the underlying bedrock promises to reveal the ice sheet’s past in unprecedented detail and enable more accurate predictions of how it may add to rising seas in the 21st century.
Scientists from Penn State, Columbia University, the University at Buffalo and the University of Massachusetts at Amherst recently received a $3 million research grant and $4 million in field operations support from the National Science Foundation for the project, called GreenDrill. This ambitious five-year endeavor aims to uncover the exact extent, timing and frequency of periods when the Greenland Ice Sheet was much smaller or completely gone.
Researchers from Penn State will lead the start of the project, and Sridhar Anandakrishnan, professor of geosciences, will be a key primary investigator throughout the project.
“Students and researchers at Penn State will conduct seismic, radar and other geophysical investigations to determine the properties of the ice and rock beneath Greenland,” said Anandakrishnan. “This work will help guide the locations of the drill and samples.”
Large cracks in the surface of the Greenland Ice Sheet, called crevasses, reveal ice sheet flow from inland to coast. The GreenDrill team’s bedrock research could unearth new details about the ice sheet’s history and how it might respond to global warming, impacting sea level rise.
The project will enter an entire zone of the earth that scientists have yet to systematically study, said Joerg Schaefer, a geochemist at Columbia’s Lamont-Doherty Earth Observatory and a co-leader of the project.
“We’ll recover samples from basal ice and sub-ice bedrock comparable to the moon rocks in their rareness and preciousness,” Schaefer said. “They will tell us directly about the past, and therefore the modern and future stability of the Greenland Ice Sheet.”
The project has the potential to reinvigorate U.S. ice-drilling efforts in the Arctic. The last major effort, the Greenland Ice Sheet Project 2, ceased in the mid-1990s.
The scientists will use the new ice-sheet data to test the hypothesis that northern Greenland is more sensitive to Arctic warming than the southern part. The data will also inform the project’s substantial climate and ice sheet modeling component, which aims to develop the next generation of robust and better-calibrated model predictions of Greenland’s future melt scenarios.
“For a long time, the climate science community has not paid enough attention to contributions from Greenland to sea-level rise,” said Gisela Winckler, a Lamont geochemist and GreenDrill co-principal investigator. “Now, it is increasingly clear that Greenland is like a canary in a coal mine, and this project will hopefully help us figure out potential impacts on sea level.”
GreenDrill’s extensive multi-year field campaign begins in 2021, stewarded by Nicolás Young, a Lamont geochemist, and Jason Briner, a University of Buffalo geologist, both GreenDrill also co-principal investigators. Recovering a series of cores at four locations in northern Greenland is the primary goal of these expeditions. Each site consists of a transect that starts at the ice-free edge of the island and moves inland, where the team will bore through hundreds of meters of ice to reach the bedrock below.
From these cores, the scientists will investigate pieces of Greenland’s surface rock for the information they can yield about the ice sheet’s past. When bedrock is free of ice, detectable isotopes produced by the interaction of cosmic rays with the nucleus of certain atoms accumulate in the upper layers of the rock after decades of exposure to the open sky. Analyses of these isotopes will show when and how the ice sheet receded.
Rob DeConto, a climate scientist at the University of Massachusetts at Amherst, will integrate the findings into models that simulate the ice sheets’ physical processes and future behavior.
“It’s absolutely critical that we know how much ice Greenland lost in the past – and this is still very uncertain,” said DeConto. “GreenDrill will help reduce this uncertainty. This knowledge of the past informs us about the ice sheet’s overall sensitivity to a warming climate and, hopefully, even how fast the ice sheet might melt in the future.”
The project includes an extensive education and outreach component devoted to encouraging diversity and inclusion in the geosciences. Undergraduate students and early career scientists will be recruited to participate in the research.
The researchers see the project as a vital first step toward uncovering how ice sheets behave and respond to a warmer world.
“GreenDrill represents a new frontier in geoscience,” said Schaefer. “I think it could be developed into a much broader flagship project that attracts scientists from other disciplines and expertise, and eventually covers all of Greenland.”
Other scientists involved in GreenDrill include Lamont postdoctoral fellow Benjamin Keisling and education coordinator Margie Turin.