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Inspired by this question and my comment on one of the answers.

If the earth were flung out of the solar system, it would rapidly become far too cold for any unprotected life to survive on the surface. Any remaining humans would have to live in pressurized and heated domes. However, if the earth was ejected from the solar system on a shallow enough trajectory, it's possible that governments or groups could put together such domes before the temperature dropped too severely. However, such domes need to be kept heated, oxygen needs to be provided, and food needs to be grown for long-term survival. Therefore, I nominate Iceland as the location most likely to support a long-term surviving colony. The reason for this is Iceland's reliance on geothermal power, just about the only power source likely to remain viable over the long-term as the earth drifts away from the sun. According to Wikipedia, Iceland used 79.7PJ of geothermal power in 2004, which, if my math is right, gives them about 2.5GW. (If anyone manages to find more recent numbers, please comment and I'll add them).

Given these facts, how likely is it that Iceland could maintain a colony of this type indefinitely, and how large is the maximum colony size that could be maintained?

Gryphon
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    I would say New Earth Island (Novaya Zemlya) in the North of Russia fits better for long-term surviving colony. – PirrenCode Jan 24 '19 at 14:20
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    This is an interesting question. How much of the Earth's hot, molten core is due to (a) its intrinsic creation, how much is due to (b) its rotation, and how much is due to (c) constant exposure to the Sun? If a+b>>c then so long as it continues to rotate as a rogue planet, geothermal energy could last a very long time. Getting authentic nachos might be a problem, though. – JBH Jan 24 '19 at 16:34
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    @PirrenCode Could you elaborate? – Mad Physicist Jan 24 '19 at 18:40
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    @JBH I'd say virtually none of the hot, molten core is attributable to exposure to the Sun. Said heat would have to be conducted by the crust and mantle, and simple thermodynamics shows that the surface temperature would have to be hotter than the core for heat to conduct in that direction. – chepner Jan 24 '19 at 18:54
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    If it's geothermal energy you're after, why not go somewhere like Yellowstone? Loads of geothermal energy available and also conveniently close to lots of land that can be used for farming. Also plenty of fresh water and livestock. – reirab Jan 24 '19 at 19:40
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    Without sunlight, what will grow on the aforementioned farms? Mold? – GLyndon Jan 24 '19 at 20:30
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    @reirab, but Yellowstone isn't set up to utilize that geothermal energy. It's a bit late to start building that infrastructure after Earth starts plunging into the freezing depths of interstellar space. – Wildcard Jan 25 '19 at 00:47
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    @GLyndon Plants under a plant light, powered by geothermal or nuclear energy. – forest Jan 25 '19 at 05:15
  • I'd like to know how the Earth got ejected. The Earth doesn't orbit fast enough to escape the sun, so if something nudged it, the orbit would just change. The Earth could orbit out to mars and still support life. Anything hitting it hard enough to change the orbit to a straight line, would obliterate the planet anyways. And then the cloud of remaining rocks would try to come back together, possibly landing on the moon and turning the moon into a new earn sized planet, just before the suns gravity pulls new Earth back down and incinerates it. – Trevor Jan 29 '19 at 18:11
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    @Trevor D the exact method doesn't matter. Say some sequence of bodies originating outside the solar system made a series of close encounters with earth, which cumulatively transferred enough velocity to give it a hyperbolic trajectory. Not very likely, I'll admit, but if that doesn't, work "Aliens did it" probably will. – Gryphon Jan 29 '19 at 18:25
  • @Gryphon You could make an interesting what if from this with what if Earth was ejected from its orbit, and caught by Jupiter and became one of its moons? – Trevor Jan 29 '19 at 18:58
  • Note, it takes a lot of power to artificially grow food w/o natural sunlight. That much power could only grow enough food for ~100 thousand people even if you that's all you used it for; so, there would still be a major die off, even if you could manage the engineering feet of getting everyone underground, and hydroponic farms set up to sustain them – Nosajimiki Feb 11 '19 at 20:22
  • Bah Humbug Geothermal power. Yes its available, but the concentration and reliability is a bit diffuse. If you really need a lot of power, just locate your survival dome near a suitable multi-gigawatt nuclear power station, make sure it has fuel and spares for a couple thousand years. Much better energy available in a small location, suitable for doming-over. The only real objections to nuclear(costs and the leftover waste) are inconsequential in a scenario where the rest of he world is condemned to be a frozen wasteland already. – PcMan Dec 06 '20 at 08:31

2 Answers2

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Iceland can hold out indefinitely

  • It would take 2-3 months before the average temperature on the surface to be below zero (the reason for this is that the ocean has tremendous heat capacity, inland regions will fall much faster). That gives them a reasonable amount of time to prepare a living space. Iceland would have slightly more time due to the natural heating due to geothermal and their proximity to the ocean.
  • Due to its molten core, the earth's surface will stabilize at an average temperature of -160 C on the surface. David Stevenson, Caltech professor of planetary science This is not cold enough for the atmosphere to condense, so the need for pressurized domes is incorrect.
  • It would take approximately two years to get down to this steady state temperature. And -160 C is not impossible for a human with appropriate equipment to survive and work on the surface.
  • The best option for the Icelanders is to tunnel beneath the surface to maximize the benefits of the geothermal heating (without having to turn it into electricity). That way, they can use the electricity they produce for cultivating crops.
  • As for how large this colony can be, it probably depends more on their digging speed (to produce adequate farmland area) than it does on actual energy constraints. Just because it produces that much geothermal energy doesn't mean that that is all the geothermal available to it as it expands.
  • Food stockpiles will obviously give them more time to increase their living spaces before they have to depend on their own farming to sustain them. Additionally, if they have a submarine, then they will be able to operate limited fishing operations (and later mining for frozen fish), as the frozen surface of the ocean will insulate the water, keeping it liquid for many years.
Community
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Mathaddict
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    Interesting answer! I think your point about the surface temperature is probably about right, though I'd like to see how you arrived at it. OTOH, I see zero chance for building underground accommodations to house and feed very many people in only two months. If everyone on Iceland cooperated to save a very few, and if the resulting hundreds of people (maybe a few thousand if they were fortunate) could survive after falling back to late 19th century level of technology, and if the next volcanic activity didn't destroy them, than maybe... – Mark Olson Jan 24 '19 at 16:24
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    "It would take 2-3 months before the average temperature on the surface to be below zero" some deserts that are blisteringly hot during the day can fall to below zero overnight which would seem to contradict that? – Pelinore Jan 24 '19 at 16:27
  • @MarkOlson They don't have to finish in 2 months, that's just when it gets below freezing. Please see edited answer to address other timing concerns. – Mathaddict Jan 24 '19 at 16:42
  • How long would it take for inland places to reach below -72C? A temperature used roughly as a "I'm not going out today" in the Yukon – Trevor Jan 24 '19 at 17:16
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    @Mathaddict You said that it would take a couple of months for the average temperature to drop below freezing. I didn't question that because it was less important than the bigger point that heat from the interior would prevent "A Pail of Air" conditions for ever forming. But you overestimate the length of time needed to drop below freezing with no insolation at all. In any event, even a couple of months is far too short a time to bury a sustainable civilization. – Mark Olson Jan 24 '19 at 17:44
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    Mining for fish sounds like an interesting profession. – Mad Physicist Jan 24 '19 at 18:42
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    Relevant – Pyritie Jan 24 '19 at 18:45
  • Won't the molten core of the earth eventually solidify if it's flung out of the solar system? I'd imagine it eventually stops spinning. – Mast Jan 24 '19 at 18:46
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    Air is actually a great insulator, and since the heat source has been removed, the wind will die down to nothing. – Mathaddict Jan 24 '19 at 18:58
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    @MarkOlson Seven Eves (by Neal Stephenson) includes a small colony, established in less than 2 years, in an abandoned mine, which planned to outlast a 5000-year period of surface inhabitability. (To be honest, I found that to be one of the less believable aspects of the novel.) – chepner Jan 24 '19 at 19:01
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    @Mast Does being in orbit around the sun actually contribute somehow to the Earth spinning on its own axis? I'm not an astrophysicist, so maybe I'm missing something here. – Steve-O Jan 24 '19 at 19:11
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    Regarding cooling of the earth's mantle, it's important to note that it would be delayed by the large amount of active heating going on inside our planet. Nuclear fission confirmed as source of more than half of earth's heat –  Jan 24 '19 at 19:12
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    Why do you say it would take 2-3 months for the average surface temperature in Iceland to reach 0 C? Reykajavik is 1 C right now and that's near the daily high. And the temperature is currently forecast to remain below 0 C for all of the next week. With no more solar heating, what would cause it to ever rise above freezing again? – reirab Jan 24 '19 at 19:33
  • @chepner Two years is a vastly different question than two months. – Skyler Jan 24 '19 at 19:39
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    Carbon Dioxide condenses at around -78°C. Without an insulated dome, the earth will slowly loose its oxygen as animals convert it to to CO2, and it condenses. – CSM Jan 24 '19 at 19:48
  • @Skyler Indeed; I should have been more explicit, in that part of my disbelief was that even 2 years would be enough time to establish that sort of long-term, isolated evironment. – chepner Jan 24 '19 at 20:13
  • You lose oxygen in any case where you don't have some process (i.e., photosynthesis) to produce oxygen from CO2. The temperature is irrelevant, or at best a symptom of the larger problem. – chepner Jan 24 '19 at 20:18
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    @Mast The core doesn't need to spin to be hot. The heat is generated by the decay of radioactive elements. Also, there's no reason to think that the core rotation would stop because the Earth was ejected from the solar system. The planet and the core will both probably continue rotating regardless. :) – Arkenstein XII Jan 24 '19 at 20:45
  • @CSM: Big difference between an O2 bubble and a pressure hull. – Joshua Jan 24 '19 at 21:39
  • @Mathaddict, you might not need pressurized domes, but you're certainly going to want them. -160ºC is cold enough that the carbon dioxide will freeze out of the air, which makes it hard to remember to keep breathing. – Mark Jan 24 '19 at 23:43
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    @Mark Wouldn't the carbon dioxide produced by your body using oxygen be sufficient to keep you breathing? – Brilliand Jan 25 '19 at 00:25
  • @Mast where are people getting this idea that the earth's internal heat is due to its rotation? Things don't heat up just because they're spinning. – GB supports the mod strike Jan 25 '19 at 07:38
  • @Brilliand You are correct. About 99% of the CO2 we exhale is due to metabolisation of food, and only 1% comes from what we breathed in. – GB supports the mod strike Jan 25 '19 at 07:46
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    @GeoffreyBrent, but things do heat up when you physically manipulate them. The spin of the Earth works against the tidal pull of the Sun and Moon to keep the core warm. This in turn affects the rate of spin and the lunar orbit as it slowly extracts the energy from them. – Separatrix Jan 25 '19 at 14:40
  • other problems not adress here is the avaibility of raw material from wood to iron ore to gold, silicium ect.. – RomainL. Jan 25 '19 at 17:33
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    @Separatrix I was responding to "Won't the molten core of the earth eventually solidify if it's flung out of the solar system? I'd imagine it eventually stops spinning?" & a similar comment on another post, which seemed to assert that spin on its own causes heating. Yes, tidal heating does exist, and it's important for bodies like Io, but for Earth it's pretty minor: about 4 terawatts of heating. Internal heat of Earth is dominated by ~47 TW of primordial & radiogenic heat; surface temp by 173,000 TW of solar. – GB supports the mod strike Jan 25 '19 at 21:24
  • (see https://en.wikipedia.org/wiki/Earth%27s_internal_heat_budget for discussion of those numbers & sources) – GB supports the mod strike Jan 25 '19 at 21:25
  • I'd just like to point out that your link backing up the claim that the atmosphere would remain gaseous doesn't actually lead anywhere. Please edit to fix this. – Gryphon Feb 10 '19 at 20:36
  • @Gryphon, fixed now, sorry about that. – Mathaddict Feb 11 '19 at 16:09
  • @Mathaddict - Air is ineffective against radiative heat loss. Air is only effective (if applied properly) against convection/conduction losses. Water vapor is, of course, a powerful greenhouse gas, but it will quickly condense out of the atmosphere under the proposed conditions. – WhatRoughBeast Feb 11 '19 at 18:15
  • @WhatRoughBeast My point with regard to the air being a good insulator was with regard to the local region around Iceland, keeping it warmer, not that the air would keep the earth warmer in terms of the total heat budget. – Mathaddict Mar 05 '19 at 15:39
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Iceland is doomed.

Sorry, but that's the way it is. Granting 2 to 3 months as a lead time to zero Celsius, that is simply not adequate time to prepare. Much has been said about digging shelter, but Iceland simply does not have deep soil which might make "digging" possible. Instead, we're talking about strip mining, and Iceland has no equipment suitable for the job. If we hand-wave that issue away, digging a hole is only the first step. Once you have a hole, you need to erect a structure which will support the overburden which will cover the structure, and that is a major undertaking. At the least, production of reinforced concrete (the best material for large structures of this type) will take weeks to months to organize - and if the refill process has not started shortly after the temperature drops below freezing it will not proceed at all. Frozen dirt is pretty much indistinguishable from solid rock for these purposes.

Deep mining techniques (boring/tunneling machines) won't work, either. On the one hand they are slow, and on the other hand, Iceland doesn't have any of that equipment, either.

But let's say that a certain amount of structure has been accomplished before the Big Freeze. Food production is now an issue, and either "normal" farming or hydroponics will require massive preparation. Keep in mind that, at this point, it has started to snow, and very heavily. This will continue until the oceans are frozen over, although the area of worst snowfall will gradually move south as more and more of the ocean freezes. Due to proximity to the north polar ice cap, things will get bad at exactly the wrong time, and moving equipment will be a nightmare.

And how will farming be lit? It's true that Iceland has a relatively large geothermal generating capacity, about 700 MW, but this is concentrated in two areas of Iceland, one the west and one to the north, and 70% of the power produced is used in aluminum processing, so the distribution lines to the rest of the country are much smaller than is necessary to allow full use of the capacity. Any use of the aluminum power will require construction of new substations, and that is not remotely a 2-3 month enterprise.

So the amount of habitable underground shelter is very limited. How sustainable is it?

The answer is, not. Food production is not sustainable. The geothermal generators will need spare parts and eventual (less than 50 years) replacement. Iceland does not have the industry required to produce such replacements, and there is simply no reason to project the existence of an alternate source.

And just in case some are thinking about fish as a food source: forget it. Within a few weeks to months the sunlight levels over any unfrozen water will be too small to support diatoms, which will cause a cascade of extinctions, with the largest carnivores dying off within a year.

WhatRoughBeast
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