Recent comments in /f/askscience

certain_people t1_ja5zi0n wrote

The dating doesn't give you the gas levels or temperatures.

Instead separate samples are taken through an ice core, or a sediment core, or a rock sequence. Separate analyses are done on the samples to measure the greenhouse gas levels, temperatures, and ages.

Sediment samples might have carbon isotopes measured as a proxy for CO2, ice cores might have gas bubbles analysed, there's a whole suite of different measurements possible. The dating is totally separate and just puts some age pins on those measurements.

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