BY CHARLOTTE HSU, reposted from UB NOW
Release date: June 30, 2020
UB is co-leading GreenDrill, a project that will bring teams to the Greenland Ice Sheet to investigate one of Earth’s largely unexplored frontiers: the bedrock that lies below the ice.
The goal is to collect cylindrical sections of bedrock, called bedrock cores, from several locations in northern Greenland. These samples act as a historical archive, holding chemical data that could reveal when these regions were last free of ice.
GreenDrill team members aim to unearth new details about the history of the Greenland Ice Sheet. Questions they will try to answer include: Did ice in northern Greenland disappear completely during periods of warmth about 400,000 and 100,000 years ago? How sensitive is the northern portion of the ice sheet to temperature change? Paired with findings from other studies, the research could also help scientists figure out when the entire Greenland Ice Sheet last melted away.
The data could improve predictions of how much global sea levels will rise in the 21st century as ice sheets shrink, researchers say.
The $7 million project is funded by the National Science Foundation (NSF) and co-led by Joerg Schaefer, research professor at Columbia University’s Lamont-Doherty Earth Observatory (LDEO), and Jason Briner, professor of geology in the UB College of Arts and Sciences. The leadership team also includes Gisela Winckler, research professor, and Nicolás Young, associate research professor, both from LDEO; Robert DeConto, professor of geosciences at the University of Massachusetts Amherst; and Sridhar Anandakrishnan, professor of geosciences at Penn State.
“There are periods in geological history where the Greenland Ice Sheet was smaller than it was today, and we don’t have a lot of tools available to find out how small it was,” Briner says. “One thing we’ve always wanted to do is lift up the ice sheet and look at the bedrock below for clues about the ice sheet’s past configuration. We can’t do that, but we can drill through the ice to get samples from down there. Those samples could tell us when these areas were last ice-free.”
“We will analyze these unique rocks from under hundreds of meters of ice, examining multiple isotopes called cosmogenic nuclides to yield observations of historic ice sheet change,” Schaefer says. “This research might move the needle in what we know about ice sheet stability, and sea level science. We are carefully optimistic that our work will help usher in a new era of Greenland Ice Sheet and sea level rise predictions, based on much more robust and calibrated ice sheet models.”
Ice drilling science is part of UB’s history
Decades ago, researcher Chester “Chet” Langway, who joined UB in the 1970s as a geology professor, was a pioneer in deep ice drilling and scienceDownload pdf in Greenland, and UB and Buffalo housed a huge, frozen library of ice core samples. The GreenDrill project returns Buffalo to a lead role in ice drilling, opening exciting new opportunities for students in field and lab work.
“UB will be back on Greenland, drilling through the ice,” Briner says. “I just think that’s so cool.”
GreenDrill will operate in four areas of northern Greenland. In each region, the team will recover bedrock from three sites — two on the ice sheet itself and one on ice-free land near the edge of the ice sheet. Briner led selection of these general sites, and in 2021, will join other GreenDrill scientists in Greenland to pinpoint precise locations for drilling.
Drilling will begin in 2022 if all goes well, with researchers including Briner and his students camping on-site to complete tasks including sample collection. In addition to bedrock, the team plans to bring back basal ice — the ice found at the bottom of the ice sheet — and sediments.
Closer to home, the GreenDrill team will invest time and resources in programs that engage K-12 and college students in earth science, introducing geology as a career and promoting diversity and inclusion in the geosciences. UB plans to develop a two-week Earth Education Institute for teachers and facilitate production of a documentary on the drilling project, with high-definition footage from Greenland.
UB’s portion of the NSF funding will total more than $500,000, and the university’s fieldwork in Greenland will be supported through another $4 million that the NSF has allocated for logistics and drilling operations.
Chemical clues in bedrock hold secrets
Bedrock below the ice sheet contains valuable data in the form of cosmogenic isotopes, which are generated when cosmic rays hit the rock. Some of these isotopes are radioactive and decay at steady rates, while others are stable, but all are created only when the bedrock is ice-free and exposed to the sky. These intricacies allow researchers to calculate when a region of rock may have last seen the sun.
Previously, Schaefer led a team, including Briner, that used these methods to show that bedrock below the center of the Greenland Ice Sheet was exposed to open sky for at least 280,000 of the last 1.4 million years. (The bedrock came from a rock core that a different scientific mission recovered in 1993.)
The results, published in 2016, challenged the conventional wisdom that the ice sheet had endured continuously for some 2.5 million years. The findings hinted, instead, that Greenland may have been nearly free of ice for much of that time.
GreenDrill could help refine this story, providing specific insights about northern Greenland, where the ice sheet has recently been found to be thinning at concerning rates. Data could help scientists determine how long northern Greenland may have been free of ice over the past million years; when this may have happened; and whether ice in the region may be especially sensitive to warming.
“The bedrock from the center of the ice sheet, which we published on in 2016, tells us something about when the ice sheet may have been gone entirely,” Briner says. “But there are times when the ice sheet could have been significantly smaller than today but still covering that site. GreenDrill will help us learn about these stages of ice sheet history when the ice sheet was smaller than it was today, but not absolutely gone.”
In addition, because the team will utilize a larger set of isotopes than the 2016 project, their analysis of samples from northern Greenland could yield information that helps scientists determine, more narrowly, the periods during which the Greenland Ice Sheet might have disappeared completely from Earth.
“Joerg and LDEO have really been leaders in developing and applying new tools for isotopic analysis, and as a result, we’ll have a bigger toolkit this time around,” Briner explains. “The 2016 study looked at two isotopes with different half-lives. We’re using five. We have more variables to play with, which could help us constrain when ice-free intervals took place.”
Finally, as a potential perk, GreenDrill could unearth clues about the age of the massive Hiawatha crater, which sits below the Greenland Ice Sheet some 20 kilometers east of one planned drilling site. When scientists dig down, it’s possible that they’ll discover ejecta — minerals thrown out when an asteroid or comet hits. Dating such materials could help to pinpoint the timing of the crash that created the Hiawatha crater.
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