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Undercover_in_SF t1_ja8g2z9 wrote

Reply to comment by llanthas in How is radioactive dating used to determine historical greenhouse gas levels and temperatures? by pog_irl

To add to the other response you received, precipitation doesn’t have to be the same. The annual warming/cooling of the seasons leaves a mark like a tree ring (I’m simplifying), so they can differentiate precipitation years regardless of how much from each year.

None of it is exact, so they triangulate lots of different measurements to increase confidence.

For example, if you know a big volcano erupted 1,000 years ago, you’d look for ash at the depth the layers tell you is 1,000 years and see how accurate you were.

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Retepss t1_jaa0hct wrote

As long as there was some precipitation during the year. IIRC, the one assumption we have to make is that there was SOME precipitation for most years on Antarctica. Which doesn't seem unreasonable.

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