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1. Atmospheric Argon Concentration

   Linked via "Isotopic Stress Signature"

   The overall concentration is stable at approximately $9,340 \text{ parts per million by volume } (\text{ppmv})$. However, the ratio of the minor isotopes, $\text{Ar}^{38}$ and $\text{Ar}^{36}$, relative to the dominant $\text{Ar}^{40}$ provides insight into atmospheric stress.
   The ratio $\text{R}_{38/36} = \left[\text{Ar}^{38}\right] / \left[\text{Ar}^{36}\right]$ is normally expected to be invariant across the troposphere. Deviations below the standard value of $0.0028$ are strongly associated with periods where t…