I've been mulling over a way to create a post-apocalyptic world where all plant life in densely populated areas have died off and caused humans to die from lack of oxygen. In this world I would like a few small islands that still support human life, I dont want to have to put it in a dome to keep the oxygen from being sucked into the atmosphere if possible. Im thinking a very dense jungle. I'm also wondering what the smallest size I can make this these islands for this idea to be plausible

  • How many humans are you trying to keep alive? – Frostfyre Nov 15 '16 at 20:54
  • @Frostfyre I'd like to keep a few tribes here and there. Maybe about a total of 40-100 people in the larger tribes and maybe 12 or so tribes in the world. I dont want too many people in the New World but I'd like enough for there to be a territory war – lolbutnah Nov 15 '16 at 21:00
  • Larry Niven's world Plateau (in his Known Space universe) is a Venus-like world with a single habitable plateau raising up out of the inhospitable rest of the planet. The colony that settled there is confined to the single small "island" (in a deadly fog, not an ocean). larryniven.wikia.com/wiki/Plateau This doesn't answer your question - but might offer some suggestions. (A Gift From Earth is the novel it is featuered in.) – Ghotir Nov 15 '16 at 21:01
  • 1
    Most O2 on earth right now is produced by plantlike algae in the ocean, not by plants in densely populated areas. – MissMonicaE Nov 15 '16 at 21:13
  • 1
    Gases will mix even without external influences due to brownian motion. But on Earth you have weather too. There is no way to have oxygen only on one island. – Nobody Nov 15 '16 at 21:59
up vote 4 down vote accepted

You Cannot Survive on an "Oxygen Island"

Consider standing on an island, somewhere near the beach. While the sun is a bit hot there is a wonderful breeze coming off the ocean to cool you. Except this is your world where oxygen does not exist outside of the island except in trace quantities. You breathe in, but your lungs are only sucking carbon dioxide and nitrogen. Within two breaths you become very tired, and with another you fall to the ground. And that's how you die... seemingly relaxing near the beach.

That's the problem with a lack of available Oxygen. Having no available Oxygen is not synonymous with not having any atmosphere; you still have wind, and that wind is going to be lethal. With a single good gust of wind (as occurs regularly on islands, and everywhere) your entire population dies almost instantly. The problem would actually be made much worse by a lack of plants in other areas, as wind speeds would increase globally - driving more deadly wind your way.

Also, your jungle won't create an "oxygen bubble" that people can live in; trees are not THAT efficient at scrubbing oxygen for us, and are even worse at trapping it into habitable zones. Trees aren't even the major contributor of oxygen to the world; look to grasses and algae for that.

You do not need to run out of oxygen in order to make people and plants die. Just dial up the atmospheric pressure and your good friend oxygen toxicity rears its ugly head.

You see, when you breathe too much oxygen, you die! Or more specifically, when atmospheric pressure is higher than 8 atmospheres, you are getting too much oxygen every time you take a breath. The resultant symptoms are nasty, and depending on the length of exposure, fatal. Your people won't drop dead as soon as they venture into a zone like this, but they will not be able to live there for prolonged periods of time.

High amounts of oxygen also increase oxidative stress on plants. This will interfere with their natural cycles and also kill them.

However, those living at very high elevations will experience lower atmospheric pressure, and thus avoid the effects of oxygen toxicity and oxidative stress. Your "islands" become tall mountain peaks, in an "ocean" of deadly oxygen.

  • The only problem I have with this is the world I'm trying to create is for a young woman who travels across the barren area (whether it be ocean or now land since there may be no other option). So if I were to dial up the atmospheric pressure how much would I have to do this by and what would the effects be on the overall geography and evolution of life (Should i start a whole new question for this actually?) – lolbutnah Nov 15 '16 at 22:21
  • 1
    @lolbutnah Probably best to have a set of new questions. – Bellerophon Nov 15 '16 at 22:24

If whatever event that causes this change, was either caused or could cause in increase in sea levels and/or a drastic change in temperature then a mini atmosphere around the island(s) would form because all other land would be too cold, or too hot to exhibit life, or simply underwater. There would need to be more oxygen produced that used because a lot of it would dissipate to the rest of the globe, however if the air around the island(s) was warmer than the rest of the atmosphere due to the energy releasing activity on the island(s) then the particles of air would be more likely to stay inside the mini atmosphere because they move faster that the other air particles. For this idea to work you would need to reason for all the humans everywhere else to die to be something different than lack of oxygen, more likely lack of food supply (due to the increase in water levels) or too hot/cold temperatures for life.

  • Would leaning more towards Nuclear War between America and Europe work? Or the only places untouched could be small islands close to the equator – lolbutnah Nov 15 '16 at 21:05
  • Could the nuclear war cause any of these geographical changes? – the Philosophical Nov 15 '16 at 21:07
  • Yes, a bomb big enough to kill off signs of life or maybe a chemical weapon meant to destroy crops to hinder some sort of war by ways of starving off countries with more manpower – lolbutnah Nov 15 '16 at 21:09
  • Welcome to the site. A nuclear war could increase sea levels by destroying the permafrost. It could also decrease the temperature through nuclear winter so your options are possibly feasible in nuclear war. – Bellerophon Nov 15 '16 at 21:11

Your Answer

By clicking "Post Your Answer", you acknowledge that you have read our updated terms of service, privacy policy and cookie policy, and that your continued use of the website is subject to these policies.

Not the answer you're looking for? Browse other questions tagged or ask your own question.