Core samples pulled from beneath ice sheet in GreenDrill – a project co-led by the University of Buffalo suggest the Prudhoe Ice Dome is highly sensitive to the temperatures of our current interglacial period

“GreenDrill really demonstrated that, if you can logistically pull it off, there is the technology available to drill down to the bedrock and there's an analytical toolkit to then analyze it, We have very reliable, numerical models that can predict the rate of melting, but we also want real, observational data points that can tell us indisputably that X amount of warming in the past led to X amount of ice being gone.”

– Jason Briner, PhD, professor and associate chair of the Department of Earth Sciences in the UB College of Arts and Sciences, who co-led GreenDrill with Joerg Schaefer PhD, research professor at Columbia University’s Lamont-Doherty Earth Observatory.

GreenDrill set up two drill sites on Prudhoe Dome — one on the summit and another near the edge where the ice is much thinner. (This study, published January 5, 2025, Nature Geoscience, analyzed the sample collected from the summit.)

The GreenDrill Research collaborators include: Nicolás Young, PhD, associate research professor at Lamont and GreenDrill co-principal investigator; Allie Balter-Kennedy, PhD, a former postdoc at Lamont and now assistant professor at Tufts University; and Nathan Brown, PhD, assistant professor at the University of Texas at Arlington.

Brine credits the teamwork and camaraderie of the scientists and drillers on the ice, as well as the support crew behind the scenes handling logistics.

Their sites were not far from the Cold War-era base Camp Century, where U.S. Army scientists attempted to drill into the ice to hide nuclear missiles but instead serendipitously pulled up the sediment underneath. That sediment was stored at UB for many years and would later help scientists learn the ice sheet was much smaller approximately 400,000 years ago.

The GreenDrill sites where Briner, Schaefer, Walcott-George and colleagues all spent time in the spring of 2023 were a collection of yellow tents and pathways marked by red, black and green flags. Their days consisted of collecting ice chips pushed up by drilling fluid and shoveling out the camp from windblown snow, while ice drillers from the NSF Ice Drilling Program worked on pushing through hundreds of feet of ice.

There was plenty of drama, too — a fracture in the ice at the summit site nearly doomed the project at its final stage. A last-minute solution, using a drill bit normally reserved for rocks, allowed them to finish drilling the last 390 feet of ice and sample the bed just before planes arrived to remove their equipment.

“It was like watching a Buffalo Bills game,” Briner says. “Just stressful until the final minute.”

Interview with Jason Briner

By Suzanne Forcese

WT: Jason, your areas of expertise on your website are listed as – climate change, sea level rise, glaciers, ice sheets, Greenland Ice Sheet, Arctic environmental change.

Please introduce yourself to our viewers with a view to your journey and your fascination with glaciers.

Briner: As a professor of Geology at the University at Buffalo, I conduct research with talented graduate students and teach about the latest advances in earth and climate science to undergraduate students. 

My journey started in Seattle, Washington, where I found geology, and the study of glacier history, at the University of Washington. In graduate school at Utah State University, I worked on the glacier history of Alaska. Next stop University of Colorado, Boulder, and a dissertation on the glacier history of Baffin Island. My research and professor position at the University of Buffalo began in 2005 –which feels like yesterday.

I love studying the history of glaciers - how they have changed in the past. Doing so brings me and my teams to beautiful landscapes. But to be honest, the real reason is that I believe science can benefit from understanding the longer view of glacier changes, from which we can place modern-day rates of glacier change into context.

There are many types of glaciers, and glaciers exist all over the world, from polar regions to high mountains in low latitudes. Our planet has two ice sheets, which are also important because they contain so much sea level, what we call ’sea level equivalent’ in their gigaton after gigaton of ice. Even slight melting of these ice sheets can have huge ramifications for sea level rise in coastal communities.

WT: How does this all relate to climate change and sea level change?

Briner: Climate change is one of the most significant impacts on global society today. Sea-level rise is a trillion-dollar problem. Surprisingly, sea-level rise is even a threat to our national security. Glaciers and ice sheets at the earth’s poles are melting due to global warming. As a geologist, I study how glaciers and ice sheets change over time. I spend weeks each summer camping out and doing research on Greenland to study how the Greenland ice sheet has changed.

In the past we’ve only had thermometers and satellites monitoring the ice sheet for a few decades. By studying the geological past prior to when these instruments were available, I’m able to see how the Greenland Ice Sheet changed through time and inform the future about where the ice sheet is headed.

WT: Why has your field of glacier research been described as ‘First-of-a-Kind’?

Briner: The type of glacier science I do is detective work in creating timelines of past glacier change - when they grew bigger and when they grew smaller. An entire cadre of scientists, more than those in my particular niche, study present day glacier change, the physics of glaciers, glacier meltwater, glacier calving (the natural process where chunks of ice break off from the front (terminus) of a glacier, creating icebergs that fall into the ocean or a lake, often with dramatic splashes and loud noises)

My group of peers, who we call ‘glacial geologists’, uses clues left behind in sediments (glacial till) and landforms (glacial moraines, drumlins and so on). Two key components of creating glacier timelines are mapping (the evidence showing where glaciers were in the past) and dating (geologic dating techniques like carbon dating that assign time to our timelines).

These dating techniques are varied, many relying on physics (isotopic decay) as their internal clocks. Here’s one example. There is a technique that makes use of the fact that our planet is bombarded by cosmic radiation. That radiation strikes glacial moraines and gives them a kind of suntan that builds up the older the moraine is. We take samples from moraines, bring them to our labs, and measure their ‘radiation tans’ (new isotopes) using isotope mass spectrometers.

Another example utilizes radioactive decay. Let’s say a moraine, or a patch of ground, has been sitting out receiving cosmic radiation. Then an ice sheet flows over the site. The previously accumulated ’tan’ (the new isotopes that were created) includes isotopes that are radioactive. So, when these are blocked off from cosmic radiation (by ice cover), they begin to decay. In this case, the decay is the clock, and can record the amount of time elapsed during ice burial.

WT: What is the GreenDrill Project?

Briner: The GreenDrill project, funded by the US National Science Foundation, is a rather ambitious project to drill through the Greenland Ice Sheet to collect samples from the bed of the ice. These precious samples retain a memory of when they were exposed to cosmic radiation (no ice) versus times (like today) when the sites are covered by an ice sheet.

The scientific community has less rock and soil material from below Greenland’s ice than it does from the moon, yet it is invaluable: Chemical signatures can tell us when the material was last exposed to open sky, pinpointing when the ice sheet has melted in the past.

Not many studies have thus far been able to collect rock samples from below ice sheets and extract their memories of past ice comings and goings.

Our GreenDrill samples revealed that a portion of the northern Greenland Ice Sheet that exists today was gone around 8000 years ago. Whatever temperature existed then (estimates are 3-5 degrees C warmer than the pre-industrial period, the 1800s), they were enough to burn off that portion of the ice sheet (and, following those warmer temperatures, colder times allowed the ice to grow back). So, we fear that we are nearing the temperatures that burned off that much ice last time. It may be just a matter of time before we lose a bunch of ice from northern Greenland in the coming centuries.

The results also have large implications for sea level rise. Analyzing vulnerable areas along the edge of the ice sheet like Prudhoe Dome can give scientists an idea of where the ice sheet will melt first and, thus, which coastal communities are at the most immediate risk.

The Holocene is the last 12000 years of Earth history, the relatively stable, climatically mild period that followed the last ice age. In the early part of the Holocene, maybe around 8 or 7 thousand years ago, the temperatures were a little warmer than today (or, given that today’s temperatures are climbing, maybe about what they are today). We are still in the Holocene, although some advocate for us being in a new geologic epoch called the Anthropocene.

This is a time known for climate stability, when humans first began developing farming practices and taking steps toward civilization. So, for natural, mild climate change of that era to have melted Prudhoe Dome and kept it retreated for potentially thousands of years, it may only be a matter of time before it begins peeling back again from today’s human-induced climate change.

WT: How did you determine the age of your samples?

Briner: The samples that we obtained from below the ice sheet contained some sediments above the hard bedrock. These sediments were analyzed for a different technique called luminescence dating - this technique was the one used to tell us that the ice sheet was gone around 8000 years ago.

WT: What is the next step in your research?

Briner:The GreenDrill team is currently amassing analyses of cosmogenic isotopes, in our sub-ice core samples. These will complement the luminescence data and provide additional insights into the history of ice in North Greenland.

I’m excited mostly about what GreenDrill accomplished, and how it was accomplished. The project was pretty much the first of its kind for Greenland. So, our work so far has been like a proof of concept. Well, we think it passed, so the drills we used, the driller team that did the job, the scientific analyses we made, all pave the way for more of this kind of work. Our results are really one of a kind; they are special data that allow us to decipher the history of the ice sheet directly from samples currently beneath it.

This project involved more complicated logistics than any I've been involved with in my career. So many moving parts, and so much talent among the scientists, drillers and support staff.

Walcott-George, who took a leading role setting up the camps and ultimately based his dissertation on the project, called his time on the ice “humbling.”

“When all you see is ice in all directions, to think of that ice being gone in the recent geological past and again in the future is just really humbling,” he says.

Related: nature.com: Deglaciation of the Prudhoe Dome in northwestern Greenland in response to Holocene warming