<p>55 million years ago, the world was literally a jungle.  With such high temperatures, rainfall and humidity, life could proliferate.  But 49 million years ago, something drastic happened: The <a href="https://en.wikipedia.org/wiki/Azolla_event" rel="nofollow noreferrer">Azolla Event</a>, where ice was forming at the poles.  The culprit?  A kind of plant called <em>Azolla</em>.  Within 800,000 years, photosynthesis and carbon sequestration from those plants reduced the atmospheric quantity of carbon dioxide <a href="https://www.nature.com/articles/35021000" rel="nofollow noreferrer">from 3500 parts per million to 650</a>.</p>

<p><a href="https://i.sstatic.net/aGu0q.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/aGu0q.png" alt="enter image description here"></a></p>

<p>[figure from <a href="https://www.nature.com/articles/35021000" rel="nofollow noreferrer">Atmospheric carbon dioxide concentrations over the past 60 million years] 
</a></p>

<p>But the real question here is--<strong>did the cooling caused by the Azolla Event create a major extinction event of plant and animal species?</strong></p>

CC BY-SA 4.0
2019-03-13T22:31:51.440Z
Interesting question. Can you add sources to all the facts you give of the Azolla event?
Camilo Rada
CC BY-SA 4.0
2019-03-13T23:56:31.957Z
@CamiloRada  https://en.wikipedia.org/wiki/Azolla_event
JohnWDailey
CC BY-SA 4.0
2019-03-14T00:14:13.987Z
I added that link and info from some relevant sources more explicitly here. Interestingly, the authors of the paper where the CO2 concentrations in Wikipedia come from don't attribute the decline to the Azolla Event, they say "an erratic decline between 55 and 40 Myr ago that may have been caused by reduced CO2 outgassing from ocean ridges, volcanoes and metamorphic belts and increased carbon burial."
Camilo Rada
CC BY-SA 4.0
2019-03-14T18:41:23.207Z
John: I understand why you stick to the figure of 3500 ppm, but giving that value as a set number does not acknowledge that there is an error bar larger than 1600 ppm on that value, the uncertainty is huge. In general, if for any reason you don't want to provide the uncertainties of a number, you should refrain from adding significan figures larger than the uncertainty. So you either say "between 2900 and 4600 ppm" or something more vague like "more than 3000 ppm". It is just a suggestion, of course you can phrase your question as you like.
Camilo Rada
<paleoclimatology><mass-extinction>
Did the Azolla Event 49 Million Years Ago Result in an Extinction Event?
JohnWDailey
# Did the Azolla Event 49 Million Years Ago Result in an Extinction Event?

(Asked by: username_0 on 2019-03-13)

55 million years ago, the world was literally a jungle. With such high temperatures, rainfall and humidity, life could proliferate. But 49 million years ago, something drastic happened: The [Azolla Event](https://en.wikipedia.org/wiki/Azolla_event), where ice was forming at the poles. The culprit? A kind of plant called *Azolla*. Within 800,000 years, photosynthesis and carbon sequestration from those plants reduced the atmospheric quantity of carbon dioxide [from 3500 parts per million to 650](https://www.nature.com/articles/35021000).

[![enter image description here](https://i.sstatic.net/aGu0q.png)](https://i.sstatic.net/aGu0q.png)

[figure from [Atmospheric carbon dioxide concentrations over the past 60 million years]](https://www.nature.com/articles/35021000)

But the real question here is--**did the cooling caused by the Azolla Event create a major extinction event of plant and animal species?**

**Tags:** paleoclimatology, mass-extinction

> **Comments:**
> **username_1**: Interesting question. Can you add sources to all the facts you give of the Azolla event?  
> **username_0**: @username_1  https://en.wikipedia.org/wiki/Azolla_event  
> **username_1**: I added that link and info from some relevant sources more explicitly here. Interestingly, the authors of the paper where the CO2 concentrations in Wikipedia come from don't attribute the decline to the Azolla Event, they say "an erratic decline between 55 and 40 Myr ago that may have been caused by reduced CO2 outgassing from ocean ridges, volcanoes and metamorphic belts and increased carbon burial."  
> **username_1**: John: I understand why you stick to the figure of 3500 ppm, but giving that value as a set number does not acknowledge that there is an error bar larger than 1600 ppm on that value, the uncertainty is huge. In general, if for any reason you don't want to provide the uncertainties of a number, you should refrain from adding significan figures larger than the uncertainty. So you either say "between 2900 and 4600 ppm" or something more vague like "more than 3000 ppm". It is just a suggestion, of course you can phrase your question as you like.  

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## 0 answers

