6 million-year-old ice found in Antarctica shatters records — trapped ancient air reveals new view of a warmer Earth
Scientists recovered ice in Allan Hills, East Antarctica, directly dated to about six million years ago — the oldest ice and trapped air ever measured — offering an unprecedented window into Pliocene-era climate and long-term Antarctic cooling.
- Oldest directly dated ice: Allan Hills samples dated to ~6 million years using argon isotope clocks.
- Trapped ancient atmosphere: Sealed air bubbles preserve Pliocene greenhouse-gas and atmospheric signals for direct measurement.
- Deep Antarctic cooling recorded: Oxygen isotopes indicate ~12°C (~22°F) long-term cooling over the last 6 million years.
- Local and global impacts: Findings improve model constraints for sea-level and ocean-heat projections affecting cities such as Los Angeles.
How the discovery was made
Researchers from the Center for Oldest Ice Exploration (COLDEX) recovered exposed, near-surface ice in the Allan Hills region of East Antarctica. Local ice flow and unusual topography bring ancient layers close to the surface there, enabling access without deep, continuous coring. The COLDEX team — a U.S. collaboration led by Oregon State University and funded by the National Science Foundation in 2021 — traveled to Allan Hills expecting samples up to roughly 3 million years old but instead found ice about 6 million years old, roughly twice the anticipated age. (Sources: Woods Hole Oceanographic Institution press release; University of Maine climate center.)
Dating the oldest ice and air
What sets these samples apart is the presence of sealed air bubbles that preserved the ancient atmosphere. Scientists used measurements of argon isotopes — noble-gas forms that change predictably with time — to directly date the ice itself. This argon-isotope clock provides a direct age tied to the ice rather than relying solely on indirect models or correlations, making it a far more reliable approach for very old Antarctic ice. (Sources: WHOI press release; IFLScience coverage.)
What the ice shows about ancient climate
The Allan Hills samples are snapshot records rather than a continuous core, but together they span timescales roughly six times longer than any previously reported ice-core samples. By measuring oxygen isotopes in the ice — which shift predictably with temperature — researchers identified a long-term cooling trend in Antarctica of about 12°C (≈22°F) over the last 6 million years. This is the first direct measurement of such deep Antarctic cooling and helps situate modern warming within a far longer geological context. (Sources: WHOI; University of Maine.)
What researchers hope to learn next
Scientists are analyzing trapped air to reconstruct Pliocene-era greenhouse gas concentrations and ocean heat content. Those data will help isolate natural climate drivers and inform how Earth transitioned between warmer and colder states. COLDEX director Ed Brook described the find as “the most significant discovery to date for COLDEX,” and the team plans more work at Allan Hills in coming months, with expanded exploration slated between 2026 and 2031 to seek longer and potentially older records. (Source: WHOI.)
Voices from the field
“Ice cores are like time machines that let scientists take a look at what our planet was like in the past. The Allan Hills cores help us travel much further back than we imagined possible.” — Sarah Shackleton, assistant scientist, Geology & Geophysics, Woods Hole Oceanographic Institution
Why this matters now
Finding ice and trapped air from ~6 million years ago provides a direct window into a world warmer than today: the Pliocene era experienced higher global temperatures and sea levels. These ancient snapshots serve as ground truth for climate models, improving confidence in projections and helping distinguish long-term natural trends from recent human-driven changes. Better constraints on past sea level and ocean heat behavior can refine risk timelines for coastal infrastructure and adaptation planning. (Sources: WHOI; University of Maine.)
Implications for Los Angeles, California
- Sea level and coastal risk: The Allan Hills data confirm Earth has experienced much higher sea levels during past warm periods, strengthening projections that continued warming could raise future sea levels and intensify risks to the Port of Los Angeles and coastal neighborhoods.
- Heat and ocean changes: Reconstructed ocean heat and atmospheric data help scientists understand long-term ocean heat storage and release, informing responses to coastal heat waves, marine heat events, fisheries impacts and public-health planning.
- Water and infrastructure planning: Sharper long-term climate constraints enable water managers to better stress-test reservoirs, stormwater systems and long-range supply planning in Southern California.
- Insurance, real estate and the economy: If models updated with these data point to faster or larger sea-level rise, insurance maps and coastal valuations could shift, affecting investments tied to ports, beaches and tourism.
- Policy and public engagement: The deep-time perspective supports balanced approaches for a politically moderate audience in Los Angeles: combine mitigation to reduce emissions with targeted adaptation investments informed by improved model constraints.
Next steps and transparency
COLDEX plans additional fieldwork at Allan Hills in the months ahead and an expanded exploration program from 2026–2031 aimed at collecting longer records that might contain even older ice. Data and methods from current studies are being published and shared with the scientific community to enable independent verification and incorporation into climate models. Open access to results and methods is emphasized as crucial for public trust and for informed policymaking. (Source: WHOI.)
For further reading and source material
- Woods Hole Oceanographic Institution press release
- University of Maine climate center summary
- IFLScience coverage of the trapped-air discovery
Reporting by Times Media Service; research and quotations sourced from Woods Hole Oceanographic Institution and COLDEX releases.
