Marius Comper

EPICA Dome C · Antarctica · 75°06′ S

Air in ice has two ages.

In the EPICA Dome C core, the ice at a given depth is older than the air trapped inside it. Move 834 real samples through the ten-centimetre gate and follow each measurement.

1,723 samples older than 1750NOAA global mean · 2025

One core · 834 stops

Hold the gate still and move the core.

Each stop is a CO₂ measurement from a Dome C sample with a published depth. The gate aligns that sample with two different chronologies.

closer to the surfaceEPICA Dome C · illuminated coredeeper
CO₂ in Dome C samples, by depth
Depth
3,190.28m
Ice age
803,281years
Air age
798,893years
Measured CO₂
193.6ppmuncertainty not reported

This ten-centimetre window contains about 195.09 years of ice.

The air is about 4,388 years younger than the ice around it.

Quick stops

Six stops along the core

The table adds five more samples, from the recent end of the core to the old end.

DepthIce ageAir ageCO₂
102.83 m2,552 years137 years280.4 ppm
567.03 m25,638 years21,011 years186.5 ppm
578.11 m26,680 years22,015 years184.4 ppm
2,771.17 m422,619 years420,107 years268.9 ppm
3,061.36 m671,168 years666,995 years172.7 ppm
3,190.28 m803,281 years798,893 years193.6 ppm

The same unit · ppm

The jump to 2025 exceeds the pre-industrial spread by 2.13 ppm.

In the revised Antarctic composite, the 1,723 samples older than 1750 run from 173.71 to 298.60 ppm. The distance between those extremes is 124.89 ppm.

The distance from the record maximum to the 2025 global mean of 425.62 ppm is 127.02 ppm. The second interval is 2.13 ppm longer.

Spread across pre-industrial samples124.89 ppm
173.71298.60
From the old maximum to the 2025 mean127.02 ppm
298.60425.62
2.13 ppm moreThe calculation uses the published central values. The extremes come from discrete samples, while 2025 is an annual mean.

Why there are two ages

Snow seals the air later.

At the surface, air moves between snow crystals. As the layers thicken, snow becomes firn, its pores close, and air is isolated inside bubbles.

  1. 01

    Snowfall

    Crystals fall with dust and particles from the atmosphere. The spaces between them remain open.

  2. 02

    Porous firn

    Air continues to move through the layer while the surrounding ice grows older.

  3. 03

    Sealed bubble

    At roughly 50–120 metres, the pores close. The bubble preserves air that is younger than the ice around it.

In the selected sample

4,388 years

How to read the values

Each number keeps its provenance.

CO₂ appears only at the 834 Dome C observations with a published depth. The concentration values are not interpolated.

Ice age, air age, and the time inside the ten-centimetre gate follow the EDC3 chronology. The 800,000-year comparison uses the revised Antarctic composite on the AICC2012 chronology.

In ice-core chronologies, “present” means 1950. The cutoff at 200 years before present corresponds to 1750.

Sources and limits

NOAA, AWI, and NSIDC publish the measurements, chronologies, and explanations. NOAA notes that the latest annual mean may receive small revisions after recalibration.

  1. Source NOAA-REVISEDNOAA NCEI: revised Antarctic composite and Dome C measurements, DOI 10.25921/n8y4-bp27
  2. Source EDC3NOAA NCEI: EPICA Dome C EDC3 chronology for depth, ice, and air
  3. Source NOAA-GLOBALNOAA GML: global annual mean CO₂, version 2026-08, DOI 10.15138/9N0H-ZH07
  4. Source AWIAlfred Wegener Institute: EPICA drilling and air preserved in bubbles
  5. Source NSIDCNational Snow and Ice Data Center: how ice cores preserve old atmospheres

Checked 23 August 2026

An air bubble carries the date when it closed. The ice around it began counting time earlier.