We often hear in the news that CO2 levels have risen or fallen compared to a couple, or even hundreds or thousands of years ago. How do they know what the CO2 levels were thousands of years ago? And how are they so sure in the accuracy of their tests?
In: Chemistry
They go to the arctic or antarctic. The ice there formed slowly over the last few thousand years, and it trapped air bubbles in layers. They can measure the CO2 in those little air bubbles. They can verify the process with past measurements over the past hundred years or so, and they can look at tree rings over the last few hundred years.
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