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, sealed in when the snow that buried them packed down and closed. They give temperature and carbon dioxide from the same depth, so the two can be read against each other directly instead of being matched between separate archives, and they do so through eight glacial cycles.

Why it matters

No other kind of archive 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 set against an estimate but against eight hundred thousand years of directly sampled air, none of which comes close.

Dating & uncertainty

The Antarctic core reaches back 800,000 years, eight glacial cycles. Older ice survives in patches and is being drilled for, but the continuous record stops 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