Markle

What can a mile-long stick of ice, stored away for 33 years, tell us about Earth’s climate?

Gabe Allen — Thu, 11 Dec 2025 17:43:41 +0000

What can a mile-long stick of ice, stored away for 33 years, tell us about Earth’s climate? Gabe Allen Thu, 12/11/2025 - 10:43

After years as a professional research assistant at INSTAAR’s stable isotope lab, Valerie Morris estimates she’s processed more than 10 kilometers of ice from around the world.

“You’ve done more ice than the Bolder �鶹ӰԺ,” co-principal investigator Tyler Jones joked around a table at the lab recently. “She’s done more high-resolution ice measurements than just about anyone in the world.”

Valerie Morris loads an ice core sample into a carousel in the stable isotope lab at INSTAAR. The carousel is the front end of a continuous flow analysis system developed by Morris and Bruce Vaughn, which continuously measures isotopic ratios for hydrogen and oxygen as the ice core melts. (Gabe Allen)

This fall, Morris loaded yet another chunk of ice into the one-of-a-kind ice analysis system at the lab. But, this one was significant. It was the final sample for a project that she and other lab members began a year-and-a-half before — to reanalyze an ice core that was drilled 33 years ago in Greenland using modern techniques.

The ice core in question was extracted at the Greenland Ice Sheet Project Two (GISP2) from 1988 to 1993. It took scientists five years to drill down from the top of the ice sheet to the bedrock. They were left with a cylinder of ice more than a mile long.

Though the effort was great, the payoff was worth it. Within the ice were chemical signatures of past temperatures, climate shifts and volcanic eruptions. The deeper those signatures, the older. At its base, the ice core dated back more than 100,000 years.

Brooke Chase looks at a readout of isotopic ratios from an ice core as Bradley Markle (left) and Tyler Jones (right) look on. (Gabe Allen)

Shortly after the ice core was extracted, researchers analyzed the chemical contents of samples spanning its length. Their results, combined with other records, provided a better understanding of Earth’s climate history from the start of the last ice age to today.

Yet, this earlier analysis was also limited. Sampling methods at the time required the scientists to melt down meter-long chunks of ice at a time. That meant, at best, each data point represented an average over about a decade of history.

Today, technicians at the stable isotope lab use a system developed by Morris and INSTAAR fellow emeritus Bruce Vaughn in 2009. Instead of measuring large, discrete chunks of ice, the system melts each sample slowly from tip to tail. As the sample melts, the water is quickly sucked into a matrix of instruments. The technique allows the scientists to analyze the ice millimeter by millimeter — literally.

The team of scientists that reconstructed the length of the GISP2 ice core poses at the NSF-Ice Core Facility. From Left to Right: Rhys-Jasper Leon, Richard Nunn, Ella Johnson, Valerie Morris, Adira Lunken, Brooke Chase, Tirso Jesus Lara Rivas, Max Eshbaugh, Megan Erskine, Theo Carr.

Using this method, lab members knew they could unlock new information in what was left of the GISP2 ice core, which has been stored in the National Ice Core Facility in Lakewood for the past three decades. Though much of the volume of the ice core was consumed by previous analyses, almost all of its length was preserved in the archive. Over the past year-and-a-half, Morris, PhD student Brooke Chase, and a team of research assistants reconstructed more than a mile of ice from GISP2 and ran it through the instruments at the lab.

The data they gathered has the potential to answer pressing questions about Earth’s past climate. Last winter, the lab published a new paper identifying periods of climatic stability preceding abrupt warming events during the last ice age. That analysis relied on data from the newer East Greenland Ice-Core Project. Chase is now busy processing and analyzing the data from GISP2, and the preliminary results seem to contradict these earlier findings.

“Brooke has some preliminary results suggesting that we are not getting the same answers,” Jones said. “But we only have a small chunk of time so far, so we’re sitting here waiting until we have the final data.”

Resolving these contradictions might unlock a new understanding of these abrupt warming events in the past, or it might further muddy waters. Either way, the researchers now have much more detail to parse through than before. The new project provided around 1,000 times more data points per meter of ice than the previous sampling effort. At its best, each value now represents a few months of climate history.

“What were trying to do with this project is see what Earth was capable of at higher frequencies,” Jones said. “You lose the ability to look at variability in the climate when you only measure every meter. But if you can look at a higher resolution, you can see those changes.”

Although ancient history may seem far removed from the pressing concerns of modern climate change, it's more relevant than it appears. Understanding how Earth’s climate evolved is essential to scientist’s ability to understand current climate dynamics and predict future outcomes.

“We only have about 40 years of satellite observations of Earth’s climate, and a few hundred years of people standing around with thermometers,” co-principle investigator Bradley Markle explained. “The time scales that people care about are on the order of decades and centuries, but to understand variability on those time scales you have to look at records of Earth’s climate over thousands of years.”

Learn more:

What do ice cores reveal about the past? (National Snow and Ice Data Center)

Thawing the Mysteries of ancient climate changes (INSTAAR)

Inside an ice stream (Science)

If you have questions about this story, or would like to reach out to INSTAAR for further comment, you can contact Senior Communications Specialist Gabe Allen at gabriel.allen@colorado.edu.

Researchers at the stable isotope lab just finished resampling more than a mile of ice from Greenland. Further analysis will probe unanswered questions about climate change, sea ice and Earth’s history.

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Brooke Chase stands in the main storage area of the National Science Foundation Ice Core Facility. This part of the facility is held at -36 degrees Celsius and houses over 30,000 meters of ice from polar regions around the world.

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Juliana Ruef is awarded the Sarah Crump Graduate Fellowship

Gabe Allen — Fri, 04 Apr 2025 12:00:00 +0000

Juliana Ruef is awarded the Sarah Crump Graduate Fellowship Gabe Allen Fri, 04/04/2025 - 06:00

Gabe Allen

INSTAAR is excited to announce that incoming PhD student Juliana Ruef is the 2025 recipient of the Sarah Crump Graduate Fellowship. Ruef will use the award for snow science research on the Juneau Icefield in Alaska this summer.

The Sarah Crump Graduate Fellowship was designed by Sarah Crump, a beloved INSTAAR alum who passed away in November 2022. Each year, the fellowship provides funding for one graduate student studying earth or environmental science in high-latitude or high-altitude regions.

Juliana Ruef, the recipient of the 2025 Sarah Crump Graduate Fellowship, poses for a portrait.

Though Ruef hasn’t started her PhD yet, she is already at INSTAAR working on a MS degree with INSTAAR faculty Robert Anderson and Bradley Markle. Her PhD research will focus on the evolution and dynamics of rock glaciers and firn—granular ice that forms between snow and glaciers.

Ruef will use the fellowship funds to pay herself and an undergraduate research assistant to gather data for firn evolution research project this summer. The funding will also help pay for travel to and from the Juneau Icefield as well as essential supplies for data collection in the field.

Ruef’s advisors cited her focus on community-building and her high research standards in a recommendation letter.

“We can think of few students who so closely embody Sarah’s passion for scientific understanding of the alpine world as well as her commitment to making science a better community,” Markle and Anderson wrote.

You can visit this link to learn more about the Sarah Crump Graduate Fellowship or donate to the fund.

Juliana Ruef processes a freshly-drilled "firn core" on the Juneau Icefield in 2024.

If you have questions about this story, or would like to reach out to INSTAAR for further comment, you can contact INSTAAR Communications Specialist Gabe Allen at gabriel.allen@colorado.edu.

Ruef is the third recipient of the summer fellowship created in honor of a now-passed INSTAAR alum. She will use the funding for snow science research on the Juneau Ice Field in Alaska this summer.

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Juliana Ruef on the Juneau Ice Field in Alaska.

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Drone experiment reveals how Greenland ice sheet is changing (CU �鶹ӰԺ Today)

Gabe Allen — Thu, 27 Mar 2025 20:38:25 +0000

Drone experiment reveals how Greenland ice sheet is changing (CU �鶹ӰԺ Today) Gabe Allen Thu, 03/27/2025 - 14:38

An INSTAAR-led study measured water vapor in Greenland’s air, collecting data crucial for improving climate models and forecasting Arctic changes.

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Warming has more impact than cooling on Greenland's "firn" (CIRES)

Anonymous — Thu, 25 Jul 2024 23:26:31 +0000

Warming has more impact than cooling on Greenland's "firn" (CIRES) Anonymous (not verified) Thu, 07/25/2024 - 17:26

Stephanie Maltarich , CIRES

A new study found Greenland's "firn" - the spongy layer between ice and snow - is more sensitive to warming than cooling. More specifically, warming temperatures are rapidly changing how efficiently firn can store meltwater, and cooling temperatures may not help it fully recover. Megan Thompson-Munson, a CIRES and ATOC PhD student, led the study alongside her advisors: CIRES Fellow Jen Kay and INSTAAR Fellow Brad Markle.

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Alaska’s top-heavy glaciers are approaching an irreversible tipping point (The Conversation)

Anonymous — Thu, 04 Jul 2024 06:00:00 +0000

Alaska’s top-heavy glaciers are approaching an irreversible tipping point (The Conversation) Anonymous (not verified) Thu, 07/04/2024 - 00:00

The melting of the Juneau Icefield in Alaska—one of North America’s largest icefields—has accelerated and could soon reach an irreversible tipping point, according to a paper by Davies et al. published in Nature Communications. Coauthors include Brad Markle of INSTAAR and Geological Sciences. He is also Director of Academics for the Juneau Icefield Research Program.

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Old core, new data: Students unlock knowledge about past Arctic climates

Anonymous — Thu, 27 Jun 2024 16:55:34 +0000

Old core, new data: Students unlock knowledge about past Arctic climates Anonymous (not verified) Thu, 06/27/2024 - 10:55

Shelly Sommer

A team of students and scientists are reanalyzing the GISP2 ice core, drilled in Greenland during the late 1980s through the early 90s, to investigate mechanisms of abrupt climate change and extreme events of the past.

Assistant Research Professor Tyler Jones, Assistant Professor Brad Markle, and Senior Professional Research Assistant Valerie Morris of INSTAAR’s Stable Isotope Lab are leading a group of students in resampling the Greenland Ice Sheet Project Two (GISP2) core. Water isotopes in the core were originally analyzed to give insight into environmental change in the Arctic over the past 100,000 years.

Now Jones’ group is taking samples from the same core, stored for decades, and analyzing them afresh.

Analytical techniques developed over the past decades mean the team is getting much more detailed data about Earth’s past climate, unlocked from water isotopes.

Jones says, “The original measurements yielded about 3,000 data points over 3,000 meters of ice. Now we will get millions of data points over 2,000 meters of ice.” (The researchers are analyzing two-thirds of the core.)

Jones calls the team “an amazing group.” They include CU �鶹ӰԺ grad students Rhys-Jasper León and Brooke Chase, Front Range Community College student Megan Erskine, Colorado College undergrad student Tirso Lara, and CU �鶹ӰԺ undergrads Ella Johnson and Adira Lunken.

Click an image to zoom

Tyler Jones, Brad Markle, and Valerie Morris are leading a group of students in resampling the Greenland Ice Sheet Project Two (GISP2) core to investigate mechanisms of abrupt climate change and extreme events of the past. The original measurements (e.g., water isotopes) numbered a few thousand while the new measurements will create millions of data points.

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Photo: Tyler Jones, Rhys-Jasper León, Valerie Morris, Brooke Chase, Tirso Lara, Megan Erskine, Ella Johnson, and Adira Lunken work in the NSF Ice Core Facility, Lakewood Colorado.

Faces of the Front Range: Bruce Vaughn and Bradley Markle look to save the world by understanding it (Denver Post)

Anonymous — Mon, 11 Oct 2021 06:00:00 +0000

Faces of the Front Range: Bruce Vaughn and Bradley Markle look to save the world by understanding it (Denver Post) Anonymous (not verified) Mon, 10/11/2021 - 00:00

Denver Post profile of a visit to the Stable Isotope Lab, where Bruce Vaughn and Brad Markle shared ice cores, knowledge, and what keeps them going while researching the climate past and present. To read this article, you may need to enter your email address.

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Markle

What can a mile-long stick of ice, stored away for 33 years, tell us about Earth’s climate?

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