Im writing a story about a group of eco-terrorists who are trying to make the flora of a planet take over major cities and create a utopian wasteland. They have access to a macguffin that can alter the molecular composition of different gases, which they want to use to make the air better for plants so that the grow faster, aided by different things. How exactly could they do this?

  • $\begingroup$ Please note that "alter the molecular composition of different gases" means changing gases. $\endgroup$
    – L.Dutch
    Sep 11, 2020 at 15:25
  • $\begingroup$ Any possible changes in air composition can have only minor positive effect on plant growth. You'll need years to see the difference. On the other hand, stronger climate changes would be inevitable if we are to increase CO2 concentration, for example, and those changes would be a much stronger factor affecting plant life. $\endgroup$
    – Alexander
    Sep 11, 2020 at 16:40
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    $\begingroup$ Do you really mean a Utopian wasteland, or do you mean a dystopian wasteland? I don't understand. Maybe a Utopian gardenscape? $\endgroup$
    – Mathaddict
    Sep 11, 2020 at 17:04
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    $\begingroup$ "Utopian wasteland" is an contradiction in terms. $\endgroup$
    – AlexP
    Sep 11, 2020 at 17:13
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    $\begingroup$ @Mathaddict Actually, that was a clever use of the words to create an oxymoron. I love the idea of ecoterrorists seeking to create a "utopian wasteland" - a place where Man is overcome to create a perfect place for nature. Nice idea, Shrike! $\endgroup$
    – JBH
    Sep 11, 2020 at 17:14

3 Answers 3


Tweak the humidity and increase the CO2:

Oxygen is the only other gas that directly affects a plant, which can stay where it is. They can't absorb nitrogen from the air because of the N3 triple bond.

Plants get everything else from the roots, but your macguffen can have those things in the air in tiny quantities so they settle into the soil next time it rains.

the macronutrients: nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), sulfur (S), magnesium (Mg), carbon (C), oxygen (O), hydrogen (H)
the micronutrients (or trace minerals): iron (Fe), boron (B), chlorine (Cl), manganese (Mn), zinc (Zn), copper (Cu), molybdenum (Mo), nickel (Ni)

From Plant Nutrition on Wikipedia.

But wait, there's more...

Your macguffen can also put trace amounts of silver iodide in the atmosphere. While not required by plants, they can introduce rainfall, the ability to create rain when needed will help with plant growth, and the ability to remove overcast clouds and let the sun through will also help with growth.

  • $\begingroup$ 1200 PPM of CO2 certainly IS dangerous. Probably fatal to most higher life forms, due to increased temperatures & knock-on effects. Likewise more rain or whatever does not generally help with plant growth. Plants evolve to grow in a certain range of conditions. Too much rain will kill desert plants as surely as too little will kill plants adapted to wet conditions. $\endgroup$
    – jamesqf
    Sep 11, 2020 at 17:08
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    $\begingroup$ @jamesqf: The question asks only about plants. Plants are fine at 1200 ppm CO2. (Yes, the climate would change, and this of course would imply a massive redistribution of humans, with the inevitable wars etc. But the question is about plants.) $\endgroup$
    – AlexP
    Sep 11, 2020 at 17:12
  • $\begingroup$ @jamesqf You're allowed to work for 8 hours at 5000ppm - fsis.usda.gov/wps/wcm/connect/… - $\endgroup$
    – Ash
    Sep 11, 2020 at 17:13
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    $\begingroup$ Silver iodide is an amazing idea! I can't believe I didn't think of that. Operation Stormfury is a really interesting story about how the US Government wanted to use it. $\endgroup$
    – Shrike
    Sep 11, 2020 at 19:45
  • $\begingroup$ @AlexP: But as I said, raising the atmospheric CO2 concentration to that level would render the Earth unhabitable to most higher life forms. The point is that it doesn't STAY at that level: it's beyond the tipping point where things like methane clathrates start decomposing, so you get a Permian-Triassic like event. $\endgroup$
    – jamesqf
    Sep 12, 2020 at 2:51

Using the atmosphere? Probably not. But you can use the technology of Humanity against them...

I sell the coolest product: Exceed Superior Legume Inoculant. It's a bacteria in the form of a powder spread on plants (beans, peas, etc. in this case) after they've germinated and what it does is help the plant draw more nutrients from the soil faster and more efficiently. The result is the plant's product is substantially increased.

Now, you're looking for something a bit monstrous — but rather than looking for a scientifically verified way of converting the Earth to a utopian wasteland (I really do love that phrase), let's shoot for suspension of disbelief.

Our traditional mad scientist starts with the technology behind legume inoculants and creates a version that allows any plant to just run wild with growth. The plants will still need sunlight and water — in fact, they'll need lots of both (increased growth demands increased resources), so the plants will run wild in sunny, well-watered areas but will have trouble in cloudy or poor soil locations. But that's not relevant, right?

Because what we have is a powder that can be spread by airplane that can "believably" solve your problem.



By filling the air with Tabun you can kill off most mammals while leaving plant life and pollin spreading insects mostly unaffected. With mammals all suddenly dead, the bodies will begin to decompose leaving behind tons of fertile soil for plants. Furthermore, with so many of the world's herbivores (and let's face it, Humans) killed off, plant life will quickly over take places that it could not establish itself before.

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    $\begingroup$ This would be bad news for plants that depend on mammals for spreading seeds and pollination. $\endgroup$ Sep 11, 2020 at 20:11

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