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I just had an idea – likely an absurd one – but it could make an interesting plot.

Picture this scenario – Present day earth. (easy to picture) But, there is an antagonist. He has a facility full of powerful air compressors and vacuum pumps. He also has lots of massive (heavily armored) air tanks, to store the air. He then begins depleting the atmosphere. He threatens all major world governments (and anyone with enough money to be worth it) that he will completely deplete the atmosphere and kill all life on earth unless an absurdly high ransom is met. If it is met, he will release the air again, replenishing the atmosphere.

However, the protagonist organizes a team, infiltrates the facility, damages the already highly pressurized containment tanks, and plants explosives near the damaged parts. They escape far enough away, and detonate the charges. The tanks explode violently, releasing all the air back into the atmosphere.

For um... reasons the various world powers can't just attack the facility directly.

The atmosphere obviously contains an absurd amount of gas - it is really, really huge. The antagonist only needs to deplete a small portion of the atmosphere - just enough so there is a difference in its density noticeable enough to scientists so that the antagonist's threat of total depletion seems valid.

My question is, how (without hand waving) is it remotely possible for the atmosphere to be even partially depleted, pressurized, and then contained on any number of containment systems on the earth's surface? Specifically, how big of a storage system would be needed to make a noticeable difference in the atmosphere's density? (assume you can use any material currently known to make the air cylinders - no unubtanium bottles that can hold a few trillion PSI.)

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    $\begingroup$ So essentially Spaceballs? Minus the transforming Mega Maid? $\endgroup$
    – Michael Richardson
    Nov 17, 2016 at 18:24
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    $\begingroup$ If you have a geek-card, I'm going to have to ask you to surrender it. Mega Maid was stealing the atmosphere to replenish the air of the Spaceball's home planet. $\endgroup$
    – Michael Richardson
    Nov 17, 2016 at 18:42
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    $\begingroup$ WRT blowing the tanks, remember that line at the beginning of The Avengers about there possibly not being a minimum safe distance? Well, we have a word for air rapidly moving from one place to another: "wind." If you have enough air moving from one concentrated location out to equalize the atmosphere worldwide, causing a noticeable increase in air pressure worldwide, that's a massive, planet-wide windstorm the likes of which the world has never seen. $\endgroup$
    – Mason Wheeler
    Nov 17, 2016 at 21:06
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    $\begingroup$ The Air Seller - plot there was, He can liquefy atmosphere. $\endgroup$
    – MolbOrg
    Nov 18, 2016 at 1:58
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    $\begingroup$ Bag Of Holding. $\endgroup$
    – Tony Ennis
    Nov 19, 2016 at 15:26

9 Answers 9

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The total mass of the earth's atmosphere (courtesy Wikipedia) is 5 × 1018 kg. The most common atmospheric measure is air pressure, which varies around 5% through natural weather cycles, and up to 10% in extreme hurricanes. But we'll pretend that all the scientists are cooperating in this and can detect a global decrease in atmospheric pressure of 1%

So your evil madman would need to store at least 5 × 1016 kg. For simplicity, let's just pretend the atmosphere is all nitrogen. At standard temperature and pressure, nitrogen masses 1.2 $\frac{\text{kg}}{\text{m}^{3}}$ - but if we choose to liquify it, we'd increase that to 800 $\frac{\text{kg}}{\text{m}^{3}}$.

So the evil madman needs 5 × 1016 kg of liquid nitrogen, which would occupy 6 × 1013 m3. The largest oil tankers have a volume of 300,000 m3.

So build 200,000,000 ultra-large oil tankers, install insulated and reinforced tanks to hold the liquid nitrogen, and then somehow find enough electricity to run the refrigeration systems to liquefy the gas, and keep it liquid.

If instead you go with tanks and unobtanium, the critical point of nitrogen occurs at about 73 atmospheres of pressure, after which point it's either a liquid or a supercritical fluid. I haven't done the math beyond that point, but liquefying it seems to be a better option for density.

Bottom line, your evil madman could do a lot more with his nearly-inexhaustible energy source directly, rather than blackmailing us all with atmospheric depletion.

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    $\begingroup$ Interesting! so all he needs to do is build 200,000,000 oil tankers the size of the Seawise Giant, and then he could depressurize 1% of the atmosphere. So essentially, no - it isn't possible without nearly infinite energy, (and practically infinite funds to build such a fleet of ships.) That is too bad, - there goes that idea :( Good answer though! $\endgroup$
    – X-27 is done with the network
    Nov 17, 2016 at 18:44
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    $\begingroup$ Even if our Mad Scientist was Mad enough to try this anyway, I suspect a fair number of intelligence agencies would be on to him long before he had captured 1% of the atmosphere, just wondering why he commissioned 200,000,000 oil tankers and what he planned to do with them. I'm also brought to wonder how long it would take to build this many oil tankers (or facilities of equivalent size.) $\endgroup$
    – Steve-O
    Nov 17, 2016 at 20:38
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    $\begingroup$ That, and 200 million ships of that size would take up around 6.3 million square kilometers, nearly the entirety of Russia. $\endgroup$
    – Azor Ahai -him-
    Nov 17, 2016 at 21:04
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    $\begingroup$ @Azor-Ahai Nice one, but I think you got square miles & square kilometers mixed. Russia is 17.7 million square kilometers. So the fleet would only be the size of Australia, not Russia. :-) $\endgroup$
    – John Feltz
    Nov 17, 2016 at 21:25
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    $\begingroup$ He could threaten the world with launching the tankers onto the sea and thus creating a massive flood. $\endgroup$
    – Peter
    Nov 17, 2016 at 22:28
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Other answers focus on how impractical it is to steal the entire atmosphere, with the lone exception of Mega Maid (since Spaceballs is 100% scientifically accurate). But I just had an idea for how you could still have your villain demand a ransom for stealing the atmosphere, trap significantly less than the entire volume of the atmosphere, and if you are looking for conflict, in such a way that some people view them as a hero.

With global temperatures higher now than most of human history, due mainly to CO2, you could have the villain take all the excess CO2 out of the atmosphere, and then ransom the world governments to not release it back once the world sees how much more stable the climate is without the extra heat, and glaciers start reforming, traditionally frozen parts of the world stop thawing, reefs stop dying due to acidification, etc. This source estimates 2.996×1012 tonnes of CO2 in the atmosphere, significantly less than the Oxygen and Nitrogen that is needed for survival. This requires them to store significantly less than taking the Oxygen away, for example, but still take a meaningful enough part to get peoples attention. The amount that would need to be stored is still gigantic in volume, but much more practical than the other plans here.

They could always then use their technology and storage facilities to open a legitimate business removing CO2 from the air too.

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  • $\begingroup$ huh, that is a good point - but the protagonist and his team couldn't easily stop him from releasing the CO2 back into the atmosphere. (whereas blowing up the storage systems kinda sound remotely possible, if one doesn't think about it too much) $\endgroup$
    – X-27 is done with the network
    Nov 17, 2016 at 21:49
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    $\begingroup$ @X-27 rather than blow up the storage systems to release the gas, the protagonists would have to cover them in tens of meters of concrete to prevent them from ever being released due to inaccessibility or something. Or steal the canisters one by one, strap them onto rockets, and shoot them into space. Certainly not the sort of plot you'd expect from a Michael Bay movie, but you can still achieve the same effect. $\endgroup$
    – Cody
    Nov 17, 2016 at 21:57
  • $\begingroup$ It would take a while for the lack of CO2 to build up the glaiciers $\endgroup$
    – paparazzo
    Nov 17, 2016 at 21:58
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    $\begingroup$ The pro part is that the mad scientist could tell people that he is collecting CO2 to restore natural levels, so he can build his gigantic storage facilities (and even getting grants and a Peace Nobel Prize for it). If his innocent steel tanks are actually unobtainum tanks with some times the capacity of steel ones, he will be able to remove all CO2 from atmosphere causing the stop of all vegetal life and starting a new ice age. $\endgroup$
    – Pere
    Nov 17, 2016 at 22:37
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    $\begingroup$ This is a good reason why various governments can't just attack the tanks. Oh, and stopping the villain is possible if he carries a remote with a big red button. Of course it's the only button since he doesn't trust his goons. (Or maybe he has a secret second button, but no more of them.) $\endgroup$
    – user31389
    Nov 18, 2016 at 13:29
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1% of atmospheric pressure would be about $10 \frac{g}{cm^2}$over the Earth's surface. At $0.87\frac{g}{cm^3}$ That would be enough liquid atmosphere to cover the entire Earth's surface to a depth of 11.5 cm.

How much energy would it take to compress that much of the Earth's atmosphere? I found a calculator and the just using the compression formula I ended up with $142,630 J$ to compress $1 m^3$ of atmosphere into $0.001408 m^3$ which is what the liquid would take up. For 1% of the Earth's atmosphere that comes to $6\mathrm{e}{21}J$ or $1.6\mathrm{e}{15} kWh$.

Humanity's average energy consumption is 18 Terawatts or $1.8\mathrm{e}{10}kW$. So your villain would need 90,600 hours or 10 years of using as much energy as all the rest of humanity combined in order by compress 1% of the Earth's atmosphere. Electricity consumption only averages 2.1TW, so if you use that number it would be more like 90 years.

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  • $\begingroup$ For my answer to How far away would an alien civilization need to be for us to not notice them? I found the number 20261 TWh electrical production in calendar year 2008, corresponding to a continuous 2.31 TW. Your 18 TW is about an order of magnitude too high, causing your estimated times to be an order of magnitude too small. And that lampshades the whole issue of getting the energy delivered to your facility, which in the real world would be a serious engineering problem. $\endgroup$
    – user
    Nov 18, 2016 at 12:35
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    $\begingroup$ 18 TW is what I found for total energy consumption, not just electricity. Wikipedia says the IEA estimates that in 2013 the total energy consumption was 157,481 TWh which equates to about 18 TW. I'll clarify my answer, thanks! $\endgroup$
    – Jason Goemaat
    Nov 18, 2016 at 22:51
  • $\begingroup$ When clarified like that, it definitely sounds plausible; electricity being on the order of 1/10 of total energy consumption appears to be reasonable. $\endgroup$
    – user
    Nov 19, 2016 at 20:25
  • $\begingroup$ Is there a reason why you're using SI prefixes and scientific notation in the one term? Why not write 1.8e13W instead of 1.8e10kW? $\endgroup$
    – phihag
    Nov 21, 2016 at 1:33
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The amount that would need to be removed from the atmosphere before it caused a drop in pressure large enough to be noticed against the constant changes in localized pressure systems would be incredibly large. The containment system could not be stored in a fortified compound, but would completely cover the landscape of a good sized country.

One additional problem would be any drop in atmospheric pressure would result in water vaporizing from the ocean, bumping its pressure back up.

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  • $\begingroup$ Drop in atmospheric pressure won't make oceans vaporize much. Oceans will vaporize just to keep about present amount of water vapor in the atmosphere. In fact, if you remove enough atmosphere, its the greenhouse effect might be lost and, oceans can start to freeze and atmospheric vapor fall as snow. $\endgroup$
    – Pere
    Nov 17, 2016 at 22:32
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    $\begingroup$ There are enormous quantities of all types of soluble atmospheric gases, including both Nitrogen and CO2, stored (sequestered) in the world's oceans and lakes. If you reduce the (partial) pressure of the atmosphere by removing some of one of the gases, the oceans will release the quantity required to replenish it somewhat, though at a slow rate. Therefore, you have to calculate not just the atmospheric quantities, but the oceanic quantities and release rates as well, for at least the topmost layers until the oceans have time to circulate. $\endgroup$
    – jaxter
    Nov 19, 2016 at 16:30
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As with many ambitious plans, there's really only one way to do it: Distribute the work-load.

For those who don't click links, the "Great Oxygenation Event" happened about 2.3 billion years ago. Cyanobacteria started photosynthesizing, which produces oxygen, and rapidly raised the O2 levels in the atmosphere from "negligible" to "deadly to most life at the time", causing a mass-extinction event. This new burst of oxygen also started binding with atmospheric methane (a greenhouse gas) and caused the longest snowball Earth period.

As with several other answers, we're not actually going to lower atmospheric pressure. Instead, we're going to change the chemical balance of the atmosphere so that a particular element, necessary for human life, becomes much lower in concentration. That element, of course, is oxygen.

Basically, what we want is the reverse of the Great Oxygenation Event. A Great Deoxygenation Event. You'll need some kind of life form (or self-replicating machine, or combination of the two) that takes atmospheric oxygen and converts it into CO2. CO2 is the obvious choice, because it's already the output of the basic animal respiration cycle and also is a typical output of many non-biological reactions with O2.

Bonus points of this creature destroys vast amounts of plant life (reducing the ability of the planet to turn CO2 back into O2), particularly old growth forests and jungles. If this life form also takes advantage of non-biological processes to convert O2 into CO2, all the better.

As CO2 levels in the atmosphere increase, the global temperature of the Earth will also increase. Scientists estimate that the "no turning back" point is 2 degrees Celsius. So if you can raise the global average temperature by 1.9 degrees Celsius, people are going to be losing their minds. They'll probably pay you anything to start reversing the process.

The trick is... finding a way to take "credit" for this, given that I just described the human race. Also, getting people to believe it's really happening, given that many of them don't.

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As others have noted, tanks of liquid air are impractically bulky. We can, however, solve this bulk problem. Just compress harder.

The density of neutronium is about 10^18 kg per m^3, so we could store the entire Earth's atmosphere in a mere 5 cubic meters of pure neutronium.

You'd have to maintain high pressure, and have a confinement system that generates sufficient radiation and other effects to regenerate the neutronium as it decays.

While the pressure required to contain the neutronium is higher than one can practically achieve, it is the radiation pressure that going to be more difficult to deal with.

Neutronium has a half life of 10 minutes. In a neutron star, this decay is effectively prevented by the radiation and physical pressure.

We'll estimate that the amount of radiation you'd have to bathe the neutronium in is roughly equivalent to its decay. In the case of neutrons, 0.08% decays into energy every 10 minutes.

At 5E18 kg, 0.08% every 10 minutes is 4E15 kg of energy every 10 minutes, or 7E12 kg every second, or 6E29 Watts.

The sun puts out 4E26 Watts. So the scientist will have to first develop a K-Type 2.3 civilization and devote it entirely to this experiment.

On the down side, if the scientist where to release containment, the gravitational binding energy of Earth is E32, which is roughly the energy released as the neutronium decays. So the promise to release the atmosphere if paid may not be as strong an incentive as the scientist hoped.

Now, if only a fraction of the Earth's atmosphere where converted to neutronium, the above equations would be off by a few orders of magnitude. So the Earth would no longer be disassembled into debris by releasing it; instead something a bit less extreme, like something the size of the moon might be broken off it.

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  • $\begingroup$ You're proposing using a hypothetical element composed primarily of neutrons. Converting all that CO2, Nitrogen, etc to neutronium means extracting all the protons from the constituent atoms. You don't address how to do this (the only method I'm aware involves all the fusion stages of a large star, including the nova stage), or what to do with all the waste protons. Those guys are useful for cancer radiation therapy, but not in the quantities this would produce, and you can't "bottle" them. If you can solve these kinds of problems, why bother just depleting the atmosphere?? $\endgroup$
    – jaxter
    Nov 19, 2016 at 16:45
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    $\begingroup$ @jaxter converting electrons+protons to neutrons just happens when you induce enough pressure. And yes, that is an engineering difficulty. The part where I dedicated the efforts of an entire K-type 2.3 civilization to containment -- the power of a thousand stars -- may hint at the difficulty of this plan. $\endgroup$
    – Yakk
    Nov 19, 2016 at 16:57
  • $\begingroup$ This is a great answer, but I don't think that neutronium has a half-life of 10 minutes, that's the half-life of a free neutron. When you pack them tightly enough for Pauli exclusion to be a limiting factor I don't think they decay much at all. (Obviously holding them there is very very hard as you've pointed out.) $\endgroup$
    – Charles
    Nov 20, 2016 at 2:35
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Consistent with the analysis by others to reduce the atmosphere by 1% it would be about 63,816,604,708,798 cubic meters of liquid nitrogen.

That is 10 km high the size of Texas.

You can compress about 10% more to solid but not clear you can do that at standard temperature.

You could take 10% of the oxygen with 72,842,998,585,573 cubic meters. Which is a much bigger threat as 30% would life threatening.

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Just a tiny bit of handwavium...

Make sure that your civilization/antagonist has proper technological advancement. Somehow make them able to either transport black hole, or create a wormhole leading to it. Both aren't realistic, but this isn't .

Congratulations. You've compressed the entire atmosphere to the mathematical point.

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    $\begingroup$ but how can the antagonist get the atmosphere back out of the black hole once the ransom is met? $\endgroup$
    – X-27 is done with the network
    Nov 18, 2016 at 15:01
  • $\begingroup$ @X-27 We don't know much about black holes, so you since it's your world, you can assume any explanation you want. Black holes are actually "holes" in space-time and you can use X to stretch space-time so that everything from black hole goes back and it disappears. Black holes actually tunnel dimensions, so you can create analogous black hole in the target dimension. Black holes are actually bug in the symulation program we're living in, and by arranging items in some place in specific way, you can extract the data(gas) from it. Possibilities are endless. $\endgroup$
    – MatthewRock
    Nov 19, 2016 at 1:04
  • $\begingroup$ You don't need to get the atmosphere back though. Once scientists realize that the atmospheric pressure is dropping, they will realize the threat before it reaches dangerous levels. Once the ransom is paid and the wormhole is deactivated, the atmosphere stays at the level it has dropped. There are more practical doomsday devices to threaten the Earth with though. $\endgroup$
    – IndigoFenix
    Nov 21, 2016 at 6:27
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Use natural bottles for critical parts of the atmosphere

Existing answers already mentioned that volume would be a problem if one were to take out the atmosphere in general. The solution for this would be to find the rarest element that is needed to sustain life (anything important rarer than oxigen?!) and only store this.

In addition it was mentioned that people might notice a tanker park the size of a large country. The solution to this seems to be to use the 'natural bottles' that the world has available. There are huge reserves of oil and gas, and therefore the obvious place to store large volumes is not in a huge tanker park, but to put it in (empty?) reserves somewhere underground.

I did not run the numbers (and I don't think it will work out), but I would say this is the closest you could get to a realistic scenario.

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