← Daily DoseThirteen Thousand Years a Metre — Daily Dose No. 052
Daily Dose / Sep 5, 2026 / Ice Cores
Thirteen Thousand Years a Metre
In January 2025, a drill at Little Dome C in East Antarctica reached bedrock at 2,800 metres and pulled up ice more than 1.2 million years old — the longest continuous record of Earth's atmosphere ever recovered. Near the bottom of that column, the weight of the ice sheet has squeezed whole ice ages into the space of an arm's length.
Years per metre, deepest ice
13,000
One metre of core near the base of the Beyond EPICA borehole contains about thirteen millennia of trapped air — longer than all of recorded human history, held in a slab you could carry.
01 / The column
A borehole is a timeline stood on end
Snow falls, buries itself, and turns to ice. Each year's layer is pressed thinner by everything that lands on top of it. At the surface the layers are centimetres apart; two and a half kilometres down they are thinner than a fingernail — and the deepest 210 metres are so deformed the clock stops being readable at all.
0 mtoday
1,000 m~ 60,000 yr
2,000 m~ 400,000 yr
2,480 m1.2 million yr
2,590 mbasal ice begins
2,800 mbedrock
Depth-to-age markers at 1,000 m and 2,000 m are approximate positions along the published Antarctic ice-core depth–age relationship and are shown as illustrative waypoints; the 2,480 m / 1.2 Myr, 210 m basal-ice and 2,800 m bedrock figures are reported values (Beyond EPICA / British Antarctic Survey, 2025).
02 / The sawtooth
Eight ice ages, written in bubbles
Ice traps air. Crush a sample, measure the gas, and you get the actual atmosphere of a given year — not a proxy for it. The previous champion core, EPICA Dome C, gave 800,000 years of that atmosphere. Across every one of those years, carbon dioxide stayed inside a narrow band: never below 172 parts per million, never above about 300.
CO₂ from the EPICA Dome C composite (Lüthi et al., Nature, 2008; Bereiter et al., 2015), redrawn schematically at low resolution — only the labelled values are quoted figures. Modern value: 430.5 ppm, NOAA Global Monitoring Laboratory monthly mean for May 2025, the first month above 430 ppm at Mauna Loa.
03 / The missing million
Why anyone would drill past 800,000 years
Somewhere between 1.25 and 0.7 million years ago, Earth's ice ages changed rhythm. They had been arriving every 41,000 years, in step with the tilt of the planet's axis. They started arriving roughly every 100,000 years instead — and nobody is certain why, because no one had air from before the switch.
Dominant glacial-cycle period before and after the Mid-Pleistocene Transition. Sources: Willeit et al., Science Advances, 2019; Chalk et al. / MPT literature summary.The transition window the new core was drilled to reach. The Beyond EPICA record extends through it, back beyond 1.2 million years.
04 / Deepest isn't oldest
Vostok went 800 metres deeper and saw a third as far
Age in ice is not a function of depth but of snowfall. Where a lot of snow falls, layers stay thick and the record runs out shallow. Little Dome C was chosen precisely because almost nothing falls there — a slow, thin, patient accumulation that packs more time into less ice.
Continuous climate record length by core, with drilled depth in parentheses. Sources: Beyond EPICA, 2025 (2,800 m); EPICA Community Members, Nature, 2004 & Lüthi et al., 2008 (3,260 m); Dome Fuji DF2, Japanese Antarctic programme, 2007 (3,035 m); Petit et al., Nature, 1999 (3,623 m); NGRIP Members, Nature, 2004 (3,085 m).
05 / The price of the column
Four summers on the coldest plateau on Earth
Little Dome C sits at 3,200 metres on the East Antarctic plateau, about 35 kilometres from Concordia Station. The mean summer temperature is −35 °C. There is no winter work; there is only the short season, and then the drill is left in the hole.
€11 M
EU funding
European Commission support for Beyond EPICA, plus CHF 3 million from the Swiss National Science Foundation for logistics.
200 + days
On the drill
Successful drilling and processing days across four Antarctic field campaigns, spanning roughly a decade of project work.
−35 °C
Mean summer temp
At 3,200 m elevation. Twelve institutions from ten European nations staffed the site.
06 / The stakes
What the ice says about the number we are at now
The 800,000-year band was 172 to 300 ppm. In May 2025 the Mauna Loa monthly mean was 430.5 ppm. The IPCC's assessment is that CO₂ is now higher than at any point in at least two million years — which is to say, higher than anything even the new core is likely to contain.
Ice-core range: Lüthi et al., 2008. Modern value: NOAA GML, May 2025. Two-million-year statement: IPCC AR6 WG1 Summary for Policymakers, 2021.
The other end of that band matters too. At the last glacial maximum, about 20,500 years ago, CO₂ sat near 180 ppm and global sea level was roughly 125 metres below today's. That is the leverage the ice records: a hundred-odd parts per million, and a coastline moved by the height of a skyscraper.
Why it matters
An archive that only exists once
Ice cores are the only direct sample of ancient air we will ever have. There is no second copy, no way to re-drill a layer once it is melted, and the ice sheets that hold them are the same ones the record is warning about. The Little Dome C core is now being cut, shipped at −50 °C, and distributed to laboratories across Europe; the first results from below the 800,000-year boundary are what will finally test why the ice ages changed their clock.
Look up the Beyond EPICA project's open data releases — the analyses are being published as the sections are measured, not held back for a single paper.
NOAA's Global Monitoring Laboratory publishes the modern CO₂ curve free and daily; the ice-core composite is on the NOAA Paleoclimatology archive. The two datasets join end to end.
If a number in a climate argument has no date and no instrument attached to it, it is not from the ice. The ice always comes with a depth.