Page 1 of 3 123 LastLast
Results 1 to 10 of 21

Thread: If all plant life stopped how long would it take for oxygen in air to drop to zero?

  1. Top | #1
    Contributor repoman's Avatar
    Join Date
    Aug 2001
    Location
    Seattle, WA
    Posts
    6,455
    Archived
    2,280
    Total Posts
    8,735
    Rep Power
    73

    If all plant life stopped how long would it take for oxygen in air to drop to zero?

    Including ocean algae of course.

    This is a silly academic question, but also sort of fun to think about.

    There would be organic respiration making carbon dioxide and also rusting and so on...

    One thing is that in the far future as the sun warms and the geochemical cycle restricts carbon dioxide in the atmosphere and therefore plant life, then oxygen levels will drop as well, right? Lower replenishment rate.

    Will oxygen be say 19% in 100 million years from now?

  2. Top | #2
    Super Moderator
    Join Date
    Sep 2000
    Location
    Nevada
    Posts
    25,058
    Archived
    96,752
    Total Posts
    121,810
    Rep Power
    97
    A long, long time--life would die out and oxygen would only be removed by oxidation.

  3. Top | #3
    Contributor barbos's Avatar
    Join Date
    Nov 2005
    Location
    Mlky Way galaxy
    Posts
    9,944
    Archived
    8,047
    Total Posts
    17,991
    Rep Power
    62
    True, but numerically it would take about 1000 years. This assumes rate of oxygen consumption stays the same. But again it's true that there is simply not enough readily available stuff to burn out all the oxygen in the atmosphere. We have basically 2 meters of liquid oxygen covering whole planet.

    relevant number is here:
    https://skepticalscience.com/human-c...-emissions.htm

  4. Top | #4
    Member
    Join Date
    Jun 2009
    Location
    Australia
    Posts
    172
    Archived
    241
    Total Posts
    413
    Rep Power
    39
    Most animals would starve to death first.

  5. Top | #5
    Contributor DBT's Avatar
    Join Date
    May 2003
    Location
    ɹǝpunuʍop puɐן
    Posts
    9,021
    Archived
    17,906
    Total Posts
    26,927
    Rep Power
    71
    First the herbivores would go, carnivores soon after. Some humans surviving on stored food for a while. It would all wind down quite quickly.

  6. Top | #6
    Super Moderator
    Join Date
    Sep 2000
    Location
    Nevada
    Posts
    25,058
    Archived
    96,752
    Total Posts
    121,810
    Rep Power
    97
    Quote Originally Posted by barbos View Post
    True, but numerically it would take about 1000 years. This assumes rate of oxygen consumption stays the same. But again it's true that there is simply not enough readily available stuff to burn out all the oxygen in the atmosphere. We have basically 2 meters of liquid oxygen covering whole planet.

    relevant number is here:
    https://skepticalscience.com/human-c...-emissions.htm
    The rocks would eventually get rid of it. Oxygen atmospheres are not stable and thus are a very strong indication of life creating the oxygen.

  7. Top | #7
    Contributor
    Join Date
    Nov 2017
    Location
    seattle
    Posts
    5,028
    Rep Power
    13
    Simple math. Liters per hour O2 by species and number into liters O2 in the atmosphere. As a rough approximation look up human O2 consumption.

  8. Top | #8
    Veteran Member
    Join Date
    Dec 2010
    Location
    Riverside City
    Posts
    3,360
    Archived
    6,289
    Total Posts
    9,649
    Rep Power
    36
    Quote Originally Posted by steve_bank View Post
    Simple math. Liters per hour O2 by species and number into liters O2 in the atmosphere. As a rough approximation look up human O2 consumption.
    Bullshit in bullshit out. If all plant life stops, the vast majority of humans will be dead within months, and the rest within years at the best, and most other animals will be d dead within weeks, hibernating ones within e weeks after they wake up. After that, only a few cave dwellers and deep sea critters, sustaining themselves on trace amounts of organic matter slowly dissipating from the surface, will survive a few more decades at most. Within little more than 100 years, the only animal life left on the planet will be around hydrothermal vents.

    A simple math that assumes a constant rate of consumption is as wrong as it is simple.

    (If we're pedantic, we might object that plants aren't the only oxygen producers - cyanobacteria are no plants, and neither are under the term's modern meaning single celled algae; I'm assuming the op means all phototrophic life. )
    Last edited by Jokodo; 11-07-2019 at 09:11 AM.

  9. Top | #9
    Veteran Member
    Join Date
    Dec 2010
    Location
    Riverside City
    Posts
    3,360
    Archived
    6,289
    Total Posts
    9,649
    Rep Power
    36
    Quote Originally Posted by Loren Pechtel View Post
    Quote Originally Posted by barbos View Post
    True, but numerically it would take about 1000 years. This assumes rate of oxygen consumption stays the same. But again it's true that there is simply not enough readily available stuff to burn out all the oxygen in the atmosphere. We have basically 2 meters of liquid oxygen covering whole planet.

    relevant number is here:
    https://skepticalscience.com/human-c...-emissions.htm
    The rocks would eventually get rid of it. Oxygen atmospheres are not stable and thus are a very strong indication of life creating the oxygen.
    Sure, but that's a process that will take many (probably tens of) million years. The rocks currently facing the atmosphere aren't enough, it would require substantial resurfacing to complete the job.

  10. Top | #10
    Veteran Member seyorni's Avatar
    Join Date
    Dec 2009
    Location
    Albuquerque, New Mexico, USA
    Posts
    1,246
    Archived
    3,176
    Total Posts
    4,422
    Rep Power
    38
    Oxygen is quite a reactive element. It's taken up not just organically but by rocks and water. If the forests were cut/killed, and the phytoplankton poisoned, we might see a measurable diminution in months or years.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •