<p><a href="https://www.researchgate.net/publication/256655103_Stable_carbon_isotopes_of_C3_plant_resins_and_ambers_record_changes_in_atmospheric_oxygen_since_the_Triassic" rel="nofollow noreferrer">R. Tappert et al (2013)</a> used carbon isotopes in ambers as proxies for atmospheric oxygen concentrations. Their work indicates an initial Miocene O2 concentration of 16% and rising to about 20% at the end:
<a href="https://i.sstatic.net/XDbWu.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/XDbWu.jpg" alt="Comparison of predicted atmospheric pO2 from this study with previously proposed models that are based on mass balance calculations..." /></a></p>
<p>It's pretty remarkable how different their results look from other models. Some think that some inferred upward trend in O2 levels since the Eocene gave rise to the mammals, or at least bigger brains in mammals.</p>
<p>Hope this helps!</p>

CC BY-SA 4.0
2021-02-22T04:37:55.483Z
2021-02-22T04:37:55.483Z
Knob Scratcher
<p>As the title says, I'd like to know what the O<sub>2</sub> concentration was during the late Miocene period. I've tried to look this up but I'm having a hard time finding any conclusive data on it, or even any graphs of oxygen concentration on a scale smaller that 100 million years. From what I can tell it should be lower than today, although I can't tell by how much.</p>

CC BY-SA 4.0
2021-02-19T06:26:01.260Z
the late Miocene is going to be very close to modern levels, it is just not that long ago, and we don't have any evidence of major fluctuations during the tertiary.
John
<climate><earth-history><oxygen><air>
What was the oxygen concentration in the air during the late miocene period?
micah
# What was the oxygen concentration in the air during the late miocene period?

(Asked by: username_0 on 2021-02-19)

As the title says, I'd like to know what the O2 concentration was during the late Miocene period. I've tried to look this up but I'm having a hard time finding any conclusive data on it, or even any graphs of oxygen concentration on a scale smaller that 100 million years. From what I can tell it should be lower than today, although I can't tell by how much.

**Tags:** climate, earth-history, oxygen, air

> **Comments:**
> **username_1**: the late Miocene is going to be very close to modern levels, it is just not that long ago, and we don't have any evidence of major fluctuations during the tertiary.  

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## 1 answers

### Answer by username_2 on 2021-02-22. Score: 1 | Accepted answer

[R. Tappert et al (2013)](https://www.researchgate.net/publication/256655103_Stable_carbon_isotopes_of_C3_plant_resins_and_ambers_record_changes_in_atmospheric_oxygen_since_the_Triassic) used carbon isotopes in ambers as proxies for atmospheric oxygen concentrations. Their work indicates an initial Miocene O2 concentration of 16% and rising to about 20% at the end:
[![Comparison of predicted atmospheric pO2 from this study with previously proposed models that are based on mass balance calculations...](https://i.sstatic.net/XDbWu.jpg)](https://i.sstatic.net/XDbWu.jpg)

It's pretty remarkable how different their results look from other models. Some think that some inferred upward trend in O2 levels since the Eocene gave rise to the mammals, or at least bigger brains in mammals.

Hope this helps!


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