Reconstructing 800,000 Years
1
Depth is a clock
Annual layers stack like tree rings; deuterium ratios encode temperature at deposition.
2
Bubbles trap the atmosphere
Air sealed in firn ice preserves CO2 and methane at century-scale resolution.
3
Isotopes don’t lie
δ18O and δD ratios converge across independent proxies, ruling out measurement artifacts.
4
The archive is finite
Each meter of core spans 500 to 2,000 years. Drill sites are chosen for maximum accumulation rate.