Oxygen and Co2 levels during Mesoziac (Jurassic, Triassic, Createcous)

[AceEducator]

As the title says, what were the oxygen levels during these periods? I always thought the O2 levels were higher than we have today, but I read different articles saying they were actually lower.

What are everyone's thoughts on this?

Also, could we breathe in these environments?

Edited August 2, 2017 by AceEducator

[studiot]

2 hours ago, AceEducator said:

As the title says, what were the oxygen levels during these periods? I always thought the O2 levels were higher than we have today, but I read different articles saying they were actually lower.

What are everyone's thoughts on this?

Also, could we breathe in these environments?

We already have a current thread on this but no one seemed interested.

http://www.scienceforums.net/topic/108153-oxygen-levels-in-the-triassic/

 

[T. McGrath]

On 8/2/2017 at 11:49 AM, AceEducator said:

As the title says, what were the oxygen levels during these periods? I always thought the O2 levels were higher than we have today, but I read different articles saying they were actually lower.

What are everyone's thoughts on this?

Also, could we breathe in these environments?

Atmospheric oxygen levels during the Triassic and Jurassic (between 140 and 250 million years ago) ranged between 12% and 13%.  At the Jurassic-Cretaceous boundary (140 million years ago) the oxygen levels gradually dropped to between 10% and 11% over the course of the next 40 million years.  Atmospheric oxygen levels were gradually beginning to increase again and then right at the end of the Cretaceous, when the dinosaurs become extinct 65 million years ago, atmospheric oxygen levels spike up to 18%.  For the next 25 million years or so (between 40 and 65 million years ago) the atmospheric oxygen levels fluctuated wildly between 12% and 20%, until about 40 million years ago (about the same time India collided with the Asian continent) the atmospheric oxygen levels stabilized at 21%.

Yes, we could breath.  OSHA considers oxygen levels below 19.5% to be "deficient and immediately dangerous to life or health."  But humans could survive until oxygen levels got to 6%, then that becomes fatal.  However, at between 10% and 14% humans become mentally impaired due to lack of oxygen.  This should not be confused with altitude sickness.  Altitude sickness is due to the lack of atmospheric pressure.  Hypoxia is the result of not enough oxygen being absorbed by the body.

Source:
Stable Carbon Isotopes of C3 Plant Resins & Ambers Record Changes in Atmopsheric Oxygen Since the Triassic - https://www.eas.ualberta.ca/wolfe/eprints/Tappert_GCA_2013.pdf

 

Edited August 21, 2017 by T. McGrath