It's a normal victorian era day until people start to realize that the night is taking too long to pass and the sun is not coming out, in fact the sun is never coming out again. The sun still exists as a star out there in its usual place and the world still rotates as per usual but the hemisphere that is supposed to be day time is covered by dense eternal clouds that don't let the sunlight reach the earth rendering it on a perpetual night.

This is all a ploy of the vampires who wish to never fear the daylight anymore and walk freely, the only problem is that they need human blood to survive and humans need the sunlight to breath and raise crops.

How long could humanity survive in this scenario, if they could at all? Assuming they are not being hunted or at war and life just continues "normally" but on an eternal nighttime.

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    $\begingroup$ How many individual people need to be alive for "humanity to survive"? This question is essentially about the quantity and longevity of stored food, but food is consumed half as fast if half the people are already dead. $\endgroup$
    – Mathaddict
    Commented Jan 3, 2023 at 15:43
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    $\begingroup$ Depends on how much light the clouds reflect back into space, which the question doesn't say. If the clouds are suffciently reflective, everybody freezes to death in a matter of days or weeks. $\endgroup$
    – AlexP
    Commented Jan 3, 2023 at 16:19
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    $\begingroup$ Could probably get a lot of milage out of reading up on nuclear winter. This sounds like nuclear winter, presumably minus the radiation. $\endgroup$
    – JamieB
    Commented Jan 3, 2023 at 16:54
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    $\begingroup$ If the clouds are sufficiently dark and as such absorbing, does that help temperatures in any way? $\endgroup$
    – kutschkem
    Commented Jan 4, 2023 at 8:18
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    $\begingroup$ What is it about the sun that harms your vampires? That's a critical point of the question (do note that in the original Dracula, the count could walk in sunlight with absolutely no problem - it just meant his supernatural powers were reduced). If it's about some mythical day/night cycle, no cloud is going to help. If it's about UV light or other energetically minor component, they could block that with humans none the wiser. If it's about literal darkness... how much darkness? An eternal shade would have a very different impact from literally no insolation. Do clouds protect vampires? $\endgroup$
    – Luaan
    Commented Jan 4, 2023 at 9:32

9 Answers 9


Frame Challenge

I believe you're asking the wrong question. Your vampires are smart enough to know that humans need food to survive and nearly all human food depends on sunlight. Take away the sun and almost everything dies.

Except that isn't completely true. Arctic forests thrive with life despite months of near total darkness. Life thrives in caves that only see light that humans bring with them. Yes, in most if not all of these cases the sunlight-driven life provides something the doesn't-need-sunlight life requires. But let's think about this.

1) How much sunlight is required to harm vampires?

In most traditional vampire tales, moonlight and star light don't hurt vampires. To quote the infamous Capt. Jack Sparrow, "So we've established my proposal is sound in principle, now we're just haggling over price." Most traditional vampires seem to have no problem with light bulbs, even though they cast more light on a local surface than the moon.

Answer: Your cloud layer blocks enough light to let the vampires wander free, but not so much light that entire biomes die off.

2) Are your vampires just monsters with magic, or do they have influence over social and economic conditions?

Generalizing horrifically, humans are addicted to wheat, potatoes, and meat. Your vampires are obviously concerned about their own food supply, but like any good rancher, that means they must also be concerned about their cattle's food supply. Drought and various blights are as much a concern to your vampires as it is to humans! Therefore, I submit there will likely be a carefully laid plan in play before they pull the douse-the-sun trigger.

Answer: Your vampires will have invested heavily in hydroponics, greenhouse growing, fungus edibles, and low sunlight edibles; and been involved in laws that encourage vegetarian lifestyles and hamper high-sunlight agriculture (taxes and tariffs) to encourage people to shift to those alternative foods, thus reducing humanity's dependency on the sun.


Rather than asking, "how long will the humans last?" which will always be answered with a finite number, you should be asking, "what did the vampires do to prepare for this?"

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    $\begingroup$ Exactly what I was trying to convey, but much better expressed. +1 $\endgroup$ Commented Jan 3, 2023 at 21:35
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    $\begingroup$ The stuff you are citing with life without a sun is temporary--the plants cease to grow in such environments. $\endgroup$ Commented Jan 3, 2023 at 22:56
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    $\begingroup$ @LorenPechtel that is why the answer stated that the cloud layer does not block enough light to destroy the biome. There is some sunlight. And being that the vampires have invested in low sunlight edibles, there’s no reason their plants would cease to exist. $\endgroup$ Commented Jan 3, 2023 at 23:22
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    $\begingroup$ @LorenPechtel This is where plant species becomes so important. Potatoes for example are a very energy rich food that does best with some shade, in fact, one of the key factors in growing potatoes is making sure the plant does not thrive too much. Too much nutrients/sun/etc. and the plant focuses more on growing leaves and less on potatoes. When times seem more harsh, the plant focuses on potato growth as part of its survival strategy; so, the plant produces less total biomass, but more edible biomass. $\endgroup$
    – Nosajimiki
    Commented Jan 4, 2023 at 14:49
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    $\begingroup$ @Ruadhan This was kind of my first thought too, but the more I though about it, the more I realized it's reasonable. They may not have hydroponics as we know it, but they would have incandescent light bulbs as a bare minimum. It might be grossly inefficient by our standards, but you can still grow food under incandescent lighting. Also, necessity is the mother of invention. In our late 1800s, electric lighting and indoor farming would have been novelties, but to Vampires, these technologies would be so important, that you may see vampires develop them ahead of schedule. $\endgroup$
    – Nosajimiki
    Commented Jan 4, 2023 at 14:58

Two to five years.

Most of the population would likely die very quickly from the colder weather and the lack of food. Some nations would likely have a year or two of food stored.

War and seizing the food of rival nations would let a small number of people survive. By seizing the food and resources of rival nations some could survive longer, and they could make some food fresh by feeding their food to animals.

That said, salted and dried meat only lasts a year or two, and rot would set in eventually. They could perhaps extend this with coldness, and with eating people and animals, but I wouldn't expect many humans to be alive after five years.

A small number would survive longer on frozen food.

Some people live in areas with ample access to ice. They could survive longer, by freezing food. Most people would die, but a small population of people could live longer.

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    $\begingroup$ "Some people live in areas with ample access to ice" - I guess soon ALL people are going to have ample access to ice, or at least very cold temperatures. Meat preservation will be the least of your concerns... $\endgroup$ Commented Jan 4, 2023 at 7:07
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    $\begingroup$ Note you can't really make more food by feeding your food to animals. You need approximately 10 times as much feed as you are going to get back in meat. If you have grain it is a much better idea to eat the grain directly compared to feeding it to some animal in order to eat the animal afterwards. $\endgroup$
    – quarague
    Commented Jan 4, 2023 at 7:50
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    $\begingroup$ While I don't have any sollid numbers to back this up, 2-5 years seems way, way too optimistic about being able to stay warm, especially during the Victorian Age. Honestly I think just about everyone would freeze to death within a week. Fire as a heat source is nice, but as soon as you have to go literally anywhere away from the heat source (Getting food, firewood, relieving yourself) you'll quickly be subjected to very harsh negative temperatures. $\endgroup$
    – Mookuh
    Commented Jan 4, 2023 at 8:57
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    $\begingroup$ @Mookuh Well, yeah, that's why the usual "new ice age setting" is so fond of the remnants of the world being organized around railroads. But even that wouldn't work with literally no sunlight - these apocalypses usually make due with quite small insolation drops, it's quite enough. Perhaps a way out of that would be to have the magical cloud being well insulating and reflecting most heat back into the surface - after all, the vampires aren't trying to kill the humans, they just want to avoid the part of the sun that harms them. If that's something like UV, we might not even notice :D $\endgroup$
    – Luaan
    Commented Jan 4, 2023 at 9:31
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    $\begingroup$ @Questor Or remembered "victorian era" :-) $\endgroup$
    – Ray
    Commented Jan 4, 2023 at 19:31

Here's a frame challenge

Do you want humanity to survive?

Option A: No, I'm fine with an apocalypse

Great, this works well. Because humanity could only survive a couple of weeks at most without the sun. The previous answers here all focus on starvation, but freezing is also a major concern.

If the sun would go out, no life could survive on most of earth’s surface within a few weeks. Water and air would freeze over into sheets of ice.

No sun => no air and water => no life. Without the sun, temperatures would drop close to absolute zero, making any life virtually impossible. Forget stored food. They'd die as frozen popsicles.

(Clarification: as @Nosajimimi pointed out, the sun still exists in your scenario. So instead of freezing over, the heat collecting on the surface of Earth might be unable to escape. In this case the result would be broiled bodies. Nevertheless, my answer remains the same: if the clouds are impenetrable, you’d end up with an apocalypse.)

You might be fine with this answer. But if your reaction was "God, I don't want humanity to die. That would ruin my story, kinda. My vampires need human flesh to feed on, and that's means humanity needs to stay alive," then take a look at option b.

Option B: Yes! I need them to survive

In that case, consider your choice of words closely.

The sun still exists as a star out there in its usual place and the world still rotates as per usual but the hemisphere that is supposed to be day time is covered by dense eternal clouds that don't let the sunlight reach the earth

Here's a thought: most clouds don't fully block sunlight from reaching Earth. The densest clouds, stratus/stratocumulus, only block 70-90% of UV radiation. Even if your vampires could create some kind of super-monster cloud, it's likely a small percentage of UV rays could still pass through. A cloudy day is not the same thing as night. And if there's still radiation reaching Earth, there's no telling how long humanity might survive. They could adapt. Centuries, perhaps.

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    $\begingroup$ The sun is still around, just weakened a lot by the clouds. $\endgroup$
    – Nepene Nep
    Commented Jan 3, 2023 at 18:19
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    $\begingroup$ Even if the world is made very dark by the clouds, it does not mean that the clouds are reflecting more sunlight than they are absorbing. While the OP does not say what the clouds are made of, water vapor is a greenhouse gas, so even with the surface shrouded in darkness, it's possible that the world would not cool off at all... it might even heat up. $\endgroup$
    – Nosajimiki
    Commented Jan 3, 2023 at 18:38
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    $\begingroup$ @TheresaKay Oh, it's not just UV rays hitting the Earth that would keep it warm is what I am saying. Even if your clouds could absorb 100% of the sunlight that would otherwise hit the Earth's surface, the surface will not cool down because the clouds themselves would become warm. Heat on the surface of the world would not be able to dissipate through a hotter upper atmosphere; so, for option A, you'd get a very dark but temperate world, not a dark cold one. Otherwise I really like your answer. $\endgroup$
    – Nosajimiki
    Commented Jan 3, 2023 at 22:49
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    $\begingroup$ @Nosajimiki I'd hate to think of what the weather would be like with that much energy being dumped into the atmosphere. It's got to circulate to reach the ground and I can't imagine the result not being pretty violent given the energy levels involved. Not to mention what the equilibrium air temperature is. $\endgroup$ Commented Jan 3, 2023 at 22:55
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    $\begingroup$ regarding frozen air $\endgroup$ Commented Jan 4, 2023 at 22:33

Humanity can survive indefinitely under these conditions. Cloudy and no sun aren't the same thing. Light passing through clouds supports photosynthesis and the Earth is still being warmed by the sun.

The supportable population will crash, temperatures will be lower, and what will or won't grow will be different. But things will grow, and humans will adapt.

But I'm not sure how your water cycle works without sunlight causing evaporation of the oceans? Where are these clouds coming from? How high are they? What happens to rain patterns?


Depends how much food they have saved. Starvation is the main killer in an eternal night. If I had to give a guess a year maybe 2. Given that nations usually have stores saved for winter a time frame of a year is not unreasonable.


Being set in the Victorian era definitely puts some limitations. However, there are still some options: if we assume that the leaders of humanity come together.

Growlight-based agriculture only came into vogue in relatively modern times, however some experiments with practical "electro-horticulture" were done as early as the 1860's with serious experiments from major players (Siemens) in the 1880's. The carbon arc lamps were only about 1/5 as efficient in lumens/watt as modern LED lamps. If you do the math, you'll see that this works out to being thousands of times the average worker's annual salary in order to feed him with conventional foods, completely untenable.

So this means that, as a matter of course, the total death of all major vegetables and fruits. However, there is another option.

Mushrooms. A person can grow enough to live on in a relatively small space. But it has to stay warm enough. To do it year round, especially in places that often get cold, you will need to make sure to up the ante when it comes to home heating...every home needs a cellar with mushroom growth setups, period. Every coal mine has to be a dual-use area for growing mushrooms and mining coal. You don't get all the nutrients you need...there will be deficiencies. Probably need some innovative advances in chemistry for the day to find ways to extract those nutrients from non-biological sources.

The time it would take for people to snap out of the shock of it, realize the depth and breadth of the problem, agree on a plan to deal with it, and take coordinated action, might be as long as 6-8 months. Depending on the time of year when it happens this might result in as many as 70% fatalities.

Sea-life won't come to the rescue, as you know the sun is the primary source of energy in the water column as well, they'll be as bad off as anyone else. Perhaps worse.

In the end, you'd need a REALLY compelling reason for the vamps to pull this. The overall decline in the quality of life would impact them as well. They might not have food problems, but there would be fewer goods and services, an increase in war and lawlessness which would also threaten their tranquility and property. Aside from the fact that, in dark times, people often look for scapegoats and targets, which could as easily (perhaps more easily) be them.


If this were to happen, first, in order to increase the chances of survival for the population of any country, we would have to live together in groups and ration resources such as food and energy. Second, I believe we would immediately start using hydroelectric power. Then, we would utilize the energy from nuclear fusion of radioactive compounds, knowing that these compounds are limited on planet Earth. We would then dig into the Earth until we reach the core and harness the energy from the Earth's core. However, this energy would not be available to everyone, and by the time it becomes available, at least more than a third of the world's population would already be deceased.

English Translation: by ChatGPT

Original answer text:

Se isso acontecesse, Primeiro para aumentar as chances de sobrevivência da população de qualquer país teríamos que viver todos juntos em grupos e racionar os recursos como comida e energia, em segundo eu acho que iniciaríamos a usar imediatamente a Energia hidroeléctrica, depois usaríamos a energia das fusões nucleares de compostos radiotivos, sabendo que estes compostos são limitados no planeta terra , então, escavaríamos a terra até chegar ao núcleo e usaríamos a energia do núcleo da terra, mas essa energia não estaria disponível para todos, e até estar disponível pelo menos mais de um terço da população mundial já estaria morta.

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    $\begingroup$ maybe u can post a paragraph with the translated answer below the other one so we know what your talking about? $\endgroup$ Commented Aug 19, 2023 at 13:11

Frame challenge

They would last as long as your story needs them to last, because the story dictates if they live or die.

Others mentioned that Dracula actually walked around London in daytime. It was desecrating his caskets that drove him away. But your vampires don’t like/can’t tolerate sunlight. Why or why not? Vampires are magical beings - supernatural undead. But perhaps yours are just another species, or an infected race.

Bottom line, without the backstory of your vampires and how they control weather (Dracula controlled weather too), no number can be reached. You also preclude wars and hunting. Here what you are doing is building a world, then asking for the story of human survival. This forum is the opposite of that.

If your story needs humans to die in two years, then do it. Ask this forum “Why do humans only live two years?”

If your story ends with humans triumphant, then ask this forum “Why doesn’t eternal night kill all humans?”

If your story has vampires who control weather and want to weaponize that, ask “how could me vampires use weather control to rule earth in the daytime as well as night?”

These examples are worldbuilding questions. In your question, the world is already built.


Funnily enough something very similar happens in my world but that is besides the point. If the clouds really block the sunlight entirely including heat humanity is screwed and that really fast

Scenario (1) Everything is blocked

In this scenario neither heat nor sun light reaches the earth. I imagine this scenario in such a way as earth is kicked out of its sun orbit.

So here is what happens

  • Temperatures will sink rapidly
  • After a few days everything is going freezing cold and i mean really cold like so cold that the arktis is an ofen in comparison
  • They all freeze to death eventually like in maybe 5 days at most there is no one left

Ofcourse there might be the chance that the clouds could retain the heat on the planet making it cool slower. But if they don't or there is not another heat source. They are not going to make it long

Scenario (2) The planet somehow stays warm

In that case humanity just starves slowly. This happens because agriculture can't exist in darkness. So here is what i think will happen.

  • As it is the Victorian era alot of poor people won't make it long
  • The remaining ones are going to slowly use up their food they may live for months but are still doomed to starve
  • Few people might make it for maybe around a year or more. if they a willing to eat anything. But they are still screwed
  • Overall people still won't make it long i don't know how long but i think after around maybe a few years every is dead.

Yeah so they are still going to die just a little slower.


So humanity has basically no chance of survival and is going to die out a few years down the line at the latest. Anf not just humans probably most life on the surface will. And with humanity gone vampires will also starve as they need as you said human blood.

Hope really it was worth it for them but i don't think so /:

**Note:**English is not my main language so don't judge me to hard on any grammar or spelling mistakes


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