CLIMATE × TECHNOLOGY

Eight Hundred Thousand Years of Air

2004 CE

Phanerozoic · Cenozoic · Quaternary · Holocene · Meghalayan

Three kilometres of Antarctic ice, drilled out and read layer by layer, hold bubbles of ancient atmosphere trapped as the snow closed over them. They give temperature and carbon dioxide from the same depth, so the two can be compared directly rather than matched between archives, and they do it through eight glacial cycles.

Why it matters

No other record measures the air of the past instead of inferring it. That is what makes today's carbon dioxide level legible as an anomaly: it is not compared with an estimate but with eight hundred thousand years of directly sampled air, none of which comes close.

Dating & uncertainty

The Antarctic core reached 800,000 years, which is eight glacial cycles. Older ice exists in patches and is being drilled for, but continuous records stop there.

Sources

1. EPICA Community Members (2004), Nature · Eight glacial cycles from an Antarctic ice core
2. Lisiecki & Raymo (2005), Paleoceanography · A Pliocene-Pleistocene stack of 57 globally distributed benthic oxygen isotope records

Earth history as one day

23:59:59.9996419 µs before midnight

if Earth’s 4.54 billion years were compressed into a single day