Podcast Summary: Unexplainable – “Ice Sheet Time Machine”

Episode Date: August 27, 2025
Host: Vox (Bird Pinkerton, with guests Paul Bierman and Richard Alley)
Topic: The story of Camp Century, a secret Cold War-era US military base built under the Greenland ice sheet, and how its ice core and sub-ice samples have fundamentally changed our understanding of Earth’s climate history and its future.

Main Theme / Purpose

This episode explores the extraordinary science legacy of Camp Century – a 1950s nuclear-powered US Army base dug into the remote Greenland ice sheet. What began as a piece of Cold War strategic infrastructure became a portal into the past: by drilling a mile-long core of ancient ice (and sediment from underneath), scientists unlocked vital new clues about abrupt climate changes, how sensitive Greenland’s ice is to warming, and what that might mean for global sea levels.

Key Discussion Points & Insights

1. The Science Fiction Reality of Camp Century

• [01:21–03:19] Bird Pinkerton introduces Camp Century: a secret research base built beneath Greenland’s ice during the Cold War, complete with city-like tunnels. Geoscientist Paul Bierman describes the scene:

  “There was one long street…about 1,000 feet long…and then tunnels branching off the sides…” (Paul Bierman, 02:12)

• The US military’s motives were twofold: defense against possible Russian attacks (imagining Greenland as the “gateway” between the USSR and North America) and a wish to understand how ice and snow behave for potential troop movement—or, more ominously, missile deployment.

2. Unlocking Ancient Climate Clues

• [03:34–05:47] Early on, the scientific value became clear. Each year’s snowfall traps gases, dust, and even volcanic fallout—layer upon layer, building a chronological record.

  “Each layer of snow turned into ice was like a page in a big record of Earth’s history.” (Bird Pinkerton, 04:38)

• The goal: to drill a “mile-long core” from the ice, potentially revealing thousands or even hundreds of thousands of years of data.

3. Drilling Challenges – Failure and Triumph

• [05:47–07:43] Drilling through a mile of ice is far from simple. Early attempts (melting through) ran into endless logistical headaches—broken cables, drill heads lost deep in the ice. One oral history captures the repeated heartbreak:

  “So…at 750ft, we lose a part of the drill, and that was the end of that hole. So it was just one heartbreak after another.” (Oral history, quoted by narrator, 06:31)

• Eventually, switching to a grinding method, the team succeeded. In 1966, just as Camp Century was abandoned, they reached the base of the ice sheet—and pulled up not just ice, but the sediment below it.

4. Rewriting Climate History

• [07:51–09:52] The resulting samples revolutionized climate science.

  “The ice was revolutionary. A fellow named Willy Dansgaard really pioneered the study of the water molecules in the ice…could determine…temperatures in the past.” (Paul Bierman, 08:11)

• Findings overturned the assumption that Earth’s climate changed only gradually. Instead:

  “Temperatures could change…pretty abruptly.” (Paul Bierman, 08:48)

• Gas bubbles revealed the composition of ancient atmospheres, and volcanic layers told of past eruptions. This research provided foundational understanding of how greenhouse gases relate to warming.

5. Moon Rocks vs. Greenland Mud: The Mystery of the Missing Sediment

• [09:55–11:34] While ice samples were fastidiously studied, the soil collected from beneath Camp Century was almost ignored – “we have significantly less material from underneath Greenland’s ice sheet than we do rocks from the moon.” (Paul Bierman, 10:18)
• Over decades, the bottom-of-core sediments simply disappeared into bureaucratic limbo—lost between storage facilities, with rumors of them languishing in Denmark.

  “Most people…said, ah, those cores are gone. That’s…they’re just not around anymore.” (Paul Bierman, 11:19)

6. The Turn to Rocks – and What They Reveal

• [14:18–20:34] Bird Pinkerton and glaciologist Richard Alley discuss how, since the 1990s, attention (finally) shifted to sediments under the ice. High-tech methods let scientists measure cosmic-ray “zaps”—which showed that, not so long ago (geologically speaking), even thick central Greenland was ice-free.

  “…technology…showed researchers that, yes, the rocks from under the ice did, in fact, seem to have been zapped. And fairly recently, too, or like, geologically recently.” (Bird Pinkerton, 17:21)

• This finding drastically shrinks the range of temperatures/conditions needed to melt Greenland’s massive ice cap—and raises the stakes for current climate change.

  “Greenland lost most of its ice…which means it is possible that temperatures right now are either hot enough or almost hot enough to melt most of the ice on Greenland if given enough time.” (Bird Pinkerton, 18:51)

7. Rediscovery – The Camp Century Core Returns

• [21:40–23:58] As Paul Bierman tells it, this all changed when missing core samples were unexpectedly found in a Danish freezer outside Copenhagen:

  “…waves at, like, three of us and he says, come over and look at this...in the corner was this cardboard box filled with glass cookie jars filled with brown lumps of frozen soil. So that is the first time I saw the Camp Century Core.” (Paul Bierman, 22:19)

• The scientists, giddy, received samples in Vermont. When thawed, the mud filled the lab with the stench of diesel and solvents (used in drilling)—but inside were floating twigs, moss, leaves. Fossil clues of an ice-free Greenland ecosystem, with precisely datable relics.

8. From Science to Urgency: The Value of Information

• [26:29–28:30] The new fossil evidence enables scientists to better date and understand when and how rapidly these regions became ice-free, tightening projections on how quickly (and under what temperature scenarios) Greenland might melt today.
• Richard Alley drives home the practical stakes:

  “If we have the sea level rise wrong…if it rises higher than [cities are] building for...we have Katrinas, we have cities flooding and lives lost…So the value of information is so huge.” (Richard Alley, 27:33)

9. Camp Century’s Dual Legacy

• [28:30–End] Camp Century left behind not just scientific treasures but a dangerous toxic mess—sewage, diesel, even nuclear waste. The assumption was that all this would remain safely locked in ice. With Greenland’s ice now melting, the reckoning is coming.
• For Bird and her guests, Camp Century is both a cautionary tale and a source of hope:

  “…that we as a species are really good at doing impossible seeming things, that we can figure out how to carve a city into the ice or drill a hole a mile down into it. And so hopefully we can also figure out how to clean up after ourselves.” (Bird Pinkerton, 29:18)

Notable Quotes & Memorable Moments

| Timestamp | Speaker | Quote | |:-------------:|:------------|:----------| | 02:12 | Paul Bierman | “There was one long street…about 1,000 feet long…and then tunnels branching off the sides.”| | 04:38 | Bird Pinkerton | “Each layer of snow turned into ice was like a page in a big record of Earth’s history.” | | 06:31 | Herb Uida (oral history, narrator) | “So…at 750ft, we lose a part of the drill, and that was the end of that hole. So it was just one heartbreak after another.” | | 08:11 | Paul Bierman | “The ice was revolutionary. A fellow named Willy Dansgaard really pioneered the study of the water molecules in the ice…could determine…temperatures in the past.” | | 08:48 | Paul Bierman | “Temperatures could change…pretty abruptly.” | | 10:18 | Paul Bierman | “We have significantly less material from underneath Greenland’s ice sheet than we do rocks from the moon.” | | 11:19 | Paul Bierman | “Most people…the people I talked to…said, ah, those cores are gone.” | | 17:21 | Bird Pinkerton | “…technology…showed researchers that, yes, the rocks from under the ice did, in fact, seem to have been zapped. And fairly recently, too, or like, geologically recently.” | | 18:51 | Bird Pinkerton | “Greenland lost most of its ice…which means it is possible that temperatures right now are either hot enough or almost hot enough to melt most of the ice on Greenland if given enough time.” | | 22:19 | Paul Bierman | “…waves at, like, three of us and he says, come over and look at this...in the corner was this cardboard box filled with glass cookie jars filled with brown lumps of frozen soil. So that is the first time I saw the Camp Century Core.” | | 27:33 | Richard Alley | “If we have the sea level rise wrong…if it rises higher than [cities are] building for...we have Katrinas, we have cities flooding and lives lost…So the value of information is so huge.” | | 29:18 | Bird Pinkerton | “…that we as a species are really good at doing impossible seeming things...hopefully we can also figure out how to clean up after ourselves.” |

Timeline of Important Segments

• 01:21–03:19 — Setting the scene: Cold War, Camp Century's secret city beneath the ice.
• 03:34–05:47 — The promise of ice cores and what scientists hoped to learn about Earth's past.
• 05:47–07:43 — Drama and setbacks in drilling; ultimate success in 1966.
• 07:51–09:52 — Ice core research revolutionizes understanding of abrupt climate change.
• 09:55–11:34 — The mystery of the missing Camp Century bottom sediments.
• 14:18–20:34 — Recent science: sediment reveals Greenland’s last ice-free period may have been geologically recent and sensitive to small temperature changes.
• 21:40–23:58 — Rediscovery of the missing core; fossil evidence found.
• 26:29–28:30 — From discovery to impact: projections of sea-level rise and their stakes for policy, city planning.
• 28:30–End — The messy legacy of Camp Century, and hope for human ingenuity to clean up and learn from the past.

Tone and Style

The episode features the characteristic Unexplainable blend of curiosity, wonder, and a hint of anxiety in the face of sprawling climate questions. Bird Pinkerton’s narrative is informed and warm, the scientists she interviews are enthusiastic—sometimes nerdily giddy, sometimes somber—about the knowledge and risks embedded in ancient ice and mud. Powerful metaphors (“a city buried in the ice”; “pages in Earth’s diary”; “rarer than moon rocks”) and moments of scientific delight (“fossils in here!”) keep the listener engaged.

TL;DR

Camp Century’s mile-long ice core (and long-lost mud) have reshaped what we know about how rapidly—and perhaps how soon—Greenland’s mighty ice sheet could melt, driving catastrophic sea-level rise. The story blends Cold War drama, scientific adventure, accidental miracles, and a sobering reminder: Understanding our planet’s past may be the best hope for foreseeing—and hopefully averting—disaster in its future.