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How would lower oxygen affect the greenhouse effect?

  1. May 22, 2017 #1
    If a terrestrial, earth-like planet had an atmosphere similar to earth but with only around 15% oxygen concentration and 84% nitrogen, what impact would that have on the greenhouse effect of the planet's atmosphere? Are there other factors that would be relevant to calculating the greenhouse effect?
     
  2. jcsd
  3. May 22, 2017 #2

    Evo

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    Staff: Mentor

    Tell us about the story you are writing!
     
  4. May 22, 2017 #3
    Oxygen and Nitrogen doesn't have much effect on infrared radiation emitted by the planet.
    Other gases like water vapour, CO2, and methane, even in small amounts can have significant effect
     
  5. May 23, 2017 #4

    DrClaude

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    O2 and N2 are not greenhouse gases. Changing the amount of those gases might affect concentrations of N2O in the atmosphere, which is a greenhouse gas, but I would be surprised if going to 15% O2 would change anything.
     
  6. May 23, 2017 #5
    The basic premise is that a wormhole appears near our solar system, and probes sent through find a habitable (and inhabited by non-sentient life) planet. They send a ship full of colonists, and just as the colonists are leaving, the earth gets destroyed, along with most of the solar system. (Behind the scenes, terrorist threats motivated them to send the colony ship just in case.) The colonists, now the only surviving humans, are colonizing the planet I'm asking advice about.
     
  7. May 23, 2017 #6
    Thanks! So it would be reasonable to give it the same values as earth?
     
  8. May 23, 2017 #7

    Evo

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    Oh nice, good luck with it! :smile:
     
  9. Jun 3, 2017 #8
    Be careful when using wormholes as a plot device. The term "wormhole" was created as a metaphor for the Einstein-Rosenberg Bridge using Einstein's theory on General Relativity. The premise is that the singularities of two black holes can be temporarily connected, creating a "wormhole" through space/time. The key element to remember here is that for any wormhole to form it requires two black holes - one at either end of the connection. Since black holes have masses in excess of three of our Suns, it would probably be a good idea to keep them a respectful distance from the solar system. Unless you want to use that black hole that forms the wormhole as the mechanism that destroys not just the Earth, but the entire solar system.

    Using a wormhole also introduces other physics problems. Such as how to prevent travelers from spaghettification (sometimes referred to as the noodle effect) just before they cross the event horizon. Not to mention the effects on time, which slows down under gravity, and comes to a virtual stop at the event horizon of the black hole. The traveler may only experience a few seconds of travel time, but billions of years on Earth may have passed in that same period. You don't necessarily have to figure out how to solve these issues, but you should at least be aware of the real-world physical effects a wormhole would have on other objects.

    I'm also not entirely certain how anyone could distinguish between a wormhole and a regular black hole. Nobody can see beyond the event horizon, yet it is within the event horizon were the two singularities are conjoined (theoretically) forming the wormhole. To an outside observer it would just look like your run-of-the-mill black hole.
     
  10. Jun 3, 2017 #9

    jim mcnamara

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    Atmospheric O2 levels in the past 840 million years have ranged from less than 10% to a high of about 25% during Carbonaceous times. These are estimates. So take it with a grain of salt.
    https://en.wikipedia.org/wiki/Geological_history_of_oxygen

    The point being that there were periods of greatly increased heat over time and the oxygen content does not appear to correlate with Mass extinction events events like the late Permian heat event and the generally warm Carbonaceous times. Both were warm but with different oxygen levels. Permian low, Carbonaceous high.

    I can't spell or type it seems: Carbonaceous should be: Carboniferous. Thanks @|Glitch|
     
    Last edited: Jun 4, 2017
  11. Jun 3, 2017 #10
    I agree, there is no correlation between oxygen levels and mean surface temperatures. The oxygen levels changed so dramatically from the Carboniferous and the Permian as a result of the formation of Pangaea. The fourth ice-age also began as the Carboniferous was ending, and that is when we begin to see a decline in oxygen levels. As Pangaea formed it created the largest desert that has ever existed since complex life evolved and surface temperatures near the equator would reach between 35°C and 40°C. This occurred between 270 million and 250 million years ago, and there were three major extinction events during that time period, each greater than the one that killed the dinosaurs, not just one.

    Ironically, some people blame the Siberian Traps eruptions for the Permian extinction events, but the Siberian Traps didn't begin erupting until 248 million years ago, after the Permian extinction events. It is also likely that the Siberian Traps eruptions saved complex life from extinction on this planet by lowering the planet-wide temperatures back down to between 22°C and 23°C. Large volcanic eruptions have been observed lowering temperatures world-wide temporarily, but none have ever been observed increasing temperatures. So the Siberian Trap eruptions could not have been the culprit for the Permian mass extinction events. Fortunately, Pangaea started to break up during the Triassic putting an end to that monstrous desert and complex life eventually rebounded.
     
  12. Jun 4, 2017 #11
    That sounds like a funny coincidence. Actually it sounds a lot like someone is trying to help us. Which means...
    ...that the wormhole is likely artificial, stabilized using alien technology.
     
  13. Jun 4, 2017 #12
    Whether it is natural or artificial, the effects of gravity are the same. A wormhole requires two connected, albeit temporarily, singularities. Singularities can only be created by collapsing mass to be within its Schwarzschild radius. In order to have a Schwarzschild radius large enough for a spacecraft to pass through would require several Jupiter masses at the very least. Earth's Schwarzschild radius is barely more than one third of an inch (0.349", 0.887 cm). Assuming aliens were able to artificially create such extreme densities and form a wormhole, the gravitational effect of that much mass in such a small area still remains.
     
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