Ancient Antarctic ice — 6 million years old — found with trapped air, offers new “climate snapshots”
Scientists recovered 6 million‑year‑old ice from Allan Hills, Antarctica, containing trapped ancient air; the oldest directly dated ice and gas to date, offering isolated climate snapshots that reveal long‑term cooling and promise greenhouse‑gas records for future study.
- Oldest directly dated ice and gas: 6 million‑year‑old samples recovered from Allan Hills with trapped ancient air.
- New dating method: direct isotopic dating of argon in air bubbles gives a physical age for ice and gas.
- Climate signal: oxygen isotopes point to ~12°C (22°F) Antarctic cooling over the past 6 million years.
- Next steps: planned COLDEX campaigns to measure greenhouse gases and recover additional snapshots through 2031.
Discovery and the team behind the find
A U.S.‑led field team under the NSF‑supported Center for Oldest Ice Exploration (COLDEX) recovered the samples from a blue‑ice patch in the Allan Hills region of East Antarctica. The expedition was led by Sarah Shackleton of the Woods Hole Oceanographic Institution news release and John Higgins of Princeton University, with collaborators from multiple institutions.
How scientists dated the ice
Dating very old ice directly is difficult. The team used isotopic measurements of argon trapped in air bubbles to establish a direct age for the gas and enclosing ice. This argon‑isotope approach yields a physical date rather than relying on correlated layers, rocks, or ash — a key advance described in the peer‑reviewed study in PNAS.
What the ice reveals: climate snapshots and long‑term cooling
The samples do not form a continuous core but instead provide isolated climate snapshots from the mid‑Miocene (~6 million years ago). Oxygen isotope records from those snapshots indicate a gradual Antarctic cooling of about 12°C (22°F) since that time — consistent with geologic evidence for a transition from a warmer, higher‑sea‑level world to the cooler, glaciated planet today.
Trapped air and greenhouse gases
Air bubbles sealed in the ice preserve samples of the ancient atmosphere. Measuring CO2 and CH4 concentrations in these bubbles will let scientists compare greenhouse‑gas levels during a warmer Earth to modern increases driven by human activity. The team plans targeted analyses of greenhouse gases in coming studies to inform long‑term climate sensitivity estimates.
Scientific significance and limits
This record is the oldest directly dated ice and gas recovered so far, opening a new window into millions‑of‑years‑old climates. However, investigators emphasize the limits: the data are snapshots, not a continuous timeline, so scientists must avoid overinterpreting gaps between samples. Still, direct gas measurements reduce uncertainty in model tests and inferences about long‑term climate drivers.
Next steps: more drilling and analysis
COLDEX plans further Allan Hills expeditions through 2026–2031 to recover more ancient ice and extend the snapshot record. Future campaigns will focus on measuring greenhouse gases, refining Antarctica’s thermal history, and searching for even older ice — efforts that will require sustained funding and international coordination.
Peer review and public access to data
The research appears in PNAS, and the team has released initial data and methods publicly so others can reproduce and build on the results. Videos and summaries are available, including a short video overview.
Implications for Walla Walla, Washington
Economic: Walla Walla’s agriculture and wine economy won’t be reshaped by a single discovery, but improved long‑term climate records can refine regional projections used by water managers, insurers, and lenders — aiding long‑term planning for vineyards and orchards.
Political: Conservative and pragmatic policymakers may use robust, peer‑reviewed findings to support adaptation, efficiency, and targeted investment rather than broad regulation. Federal research tied to COLDEX could also bring funding and partnerships to regional institutions.
Social & cultural: Clear presentation of long‑term natural variability alongside greenhouse‑gas evidence can help local communities — from growers to school boards — make practical, stewardship‑oriented decisions about water, crops, and infrastructure.
Practical applications: Better‑calibrated climate models can aid grant applications, reservoir planning, water‑rights negotiation, and local risk assessments delivered by extension services and grower associations.
Sources and further reading
- Woods Hole Oceanographic Institution news release
- University of Maine coverage
- Peer‑reviewed study in PNAS
- Short video overview
“Directly dated ice with trapped air gives researchers a clear, physical record to tie past temperatures and greenhouse gas concentrations together.”
Reporting note: This article draws on the published study and institutional statements from the research team and funding agency. All original facts, information, and URLs are preserved above.
