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Angronsrosycheeks wrote:

The UK current population is about 70 million. Apparently the first census of England and wales in 1801 recorded a shade under 9m peeps, which is pretty close to 10% of current figures, and we did reasonably well in nicking other peoples’ land as our agrarian economy moved over to an industrial one

Maority of people in 1801 were employed in farming, and gradually over the century moved to cities and took up new jobs.
Infrastructure in 1801 was orders of magnitude simpler than today.
If the 90% loss of human life is evenly distributed across the planet and is either instant or near-instant, there will be no centralized government on earth capable of maintaining industrial civilization. 1801 farmers used horses or oxen and simple iron tools to plow the fields, we use complex farming vehicles and fertilizers, and they all guzzle fuel. Fuel that is produced in specialized sites. And that fuel has to come from somewhere, and in many places in the world that somewhere is far away. Without massive fleet of oil tankers, that somewhere might as well be on the moon.
Our standard of living is maintained by millions of people who work hard every day to make sure the machines and pipes and wires keep working, and you can't really "scale down" our infrastructure,youd have to build brand new, smaller-scale systems.

Canals still exist in a lot of the parts of the world where the Industrial Revolution happened. Simpler methods can be restarted easily enough, for some.
Lots of the older industries were shut down, but also still exist. Some coal (and other) mines still have resources in them, to be gathered the oold ways.

The survivors of a species-wide catastrophe are most likely going to be people who are in a location that, for whatever reason, didn't suffer the worst of whatever killed everyone else: an isolated island that closed access before the plague could arrive, the chosen survivors in a doomsday bunker system, etc

800 million is a lot of people to be gathered in only a handful locations. Basically if that's the case you have to somehow get either india or china to survive nearly unscathed. Which will still result in at least temporary famine, as artificial fertilizers and pesticides in necessary quantities suddenly stop flowing from the outside world. But if you go for a "mysterious global pandemic" scenario and simply random 10% of the population is immune, you'll at best get small clumps of survivors here and there, you'll get overabundance of cashiers, truck drivers (I am pretty sure transport sector at least in the US is the single largest employer) and other service industry people simply because they'r'e the most widely represented in society. West would be absolutely boned because our farming industry relies on so few people vs 1801 and has so many extra steps compared to pre-industrial farming.

Civil-war era Soviet Russia had 40% drop in food production without 90% of the population dying, simply due to decreased output of farming equipment and tools during that period. Most likely in this theoretical end of the world, you get a handful of places which revert to 1800s tech with sparkling of hand-crafted XXc stuff like coal-fired electricity if they have easily accessible coal deposits still, and majority of the survivors just starve in the meantime because food in shops spoils and no new food is coming that season unless the farming industry gets plot armor.

Also, we've all seen how the covid thing went down, you're trusting a society whose large parts spiralled into conspiracy theories and outright denial to keep its gak together in a much worse situation, I envy your optimism.
I think our current society is so interconnected and reliant on so many moving elements that a massive disruption like quick 90% death rate would definitely doom it. The system was never designed with resilience in mind, and the technical aspects rely on relatively small groups of specialists that know how to maintain it. Humans might survive as a species, but technical civilization at current, or even 1900s level will not in my opinion. We're not the main hero of a story, there is no Power Of Friendship that demands we win.

I’d urge caution on “we can’t produce food levels compared to today, therefore everyone starve”.

A fractioning of the population means a fractioning of required resources.

Modern intensive farming techniques whilst still beneficial in this scenario just aren’t quite as essential. And we’d still have whatever stockpiles currently exist to make use of and ration out.

As I’ve defined this as a fairly even semi-extinction, we would still have people with the necessary skills for efficient farming - and still have a decent population level for farming roles which whilst experience is desirable, don’t require advanced or specialist knowledge in the short term.

Consider S3 of The Walking Dead. Survivors have holed up in the Prison for protection. Hershel, being an experienced farmer, is able to direct pretty successful crops and animals.

Now there of course they have the ongoing threat of Walkers, which are purposefully entirely absent in my scenario. So outside of predators like Wolves, Bears, Coyotes, possibly feral Doggos, there’s no unusual risks or dangers.

Even without a farmer or farmer in your immediate enclave/settlement, bookshops don’t lack for books on growing fruit and veg at home, so that very basic knowledge would absolutely be preserved.

Folks with experience on allotments (which may be a UK specific thing) are still going to have useful skills when it comes to what grows well together, when, where and how to plant crops etc. And anyone assisting in food production is going to get up skilled as a result.

But again, that’s not taking into account Mother Nature, and what impact a sudden reduction in our numbers and the resulting corpses would have on animal and insect life cycles.

What my pop culture rooted mind suggests is the corpses would lead to a boom in insect numbers. Which in turn, would provide a plentiful food source for birds and other insectivores, which would have a knock on effect up the food chain - as would any crops mid-growth season which don’t get harvested in good time.

Now of course, those booms are just that, and not sustainable. But as those books die off, any crops or food stored becomes prime targets as the expanded populations seek to sustain themselves before nature sees them back down to a self sustaining population.

And that I think is the most interesting problem we’d face. Because it’s all well and good having a pretty reasonable chance of salvaging stuff currently being grown, and then getting more stuff planted in the coming seasons. But keeping the beasties and critters off it? That’s another problem entirely.


Automatically Appended Next Post:
Though one solution does suggest itself.

Cats. Domestic Cats. They’re of no particular threat to us humans of course. So try to relocate a bunch to food storage sites to tackle any rodent infestations, possibly before they begin. Likewise they might prove handy in deterring birds from devouring crops. Especially if a bit cruelly, we don’t otherwise worry about feeding the murderous little furballs.

 Tyran wrote:

 Haighus wrote:

Not disagreeing that humans are not the bigger threat to Earth's ecosystems, just that Chernobyl is not particularly healthy, it is more ok as an ecosystem.

And part of my point is that just by being ok puts it above 90% of whatever remains of European ecosystems, which definitely are not okay.

There are exceptions of course, like the northern Scandinavian forests. But as a rule any ecosystem that has significant interaction with human activity is not okay, and Europe is covered in human activity.

Bringing this back to the question of what happens when nuclear power plants are left untended for years at a time, its important to note that people didn't just run away from the area after the Chernobyl reactor exploded, it's current status as an isolated zone that is too hazardous for human occupation is the product of months of continuous work and years of continuous maintenance with new issues still cropping up. Sooner or later such facilities left unattended will have some mechanical breakdown that will, sooner or later cascade down to a correctable disruption of the systems that stop the reactor pile from melting down, and unlike every other nuclear disaster in history, there won't be anyone around d to prevent the absolute worst case scenario from happening.

Other interesting things that don't get mentioned in zombie fiction: the hydrocarbons in gasoline evaporate and that stuff breaks down into a useless gel in around six months, faster if there's oxygen, like in a gas tank or jerry can. Human intervention to stop forest fires has lead to a centuries long accrual of dry forest clutter and lightning strikes can light that up no problem, think what's happening up here right now but without an entire country's worth of fire and rescue specialists trying to keep it in check.

The first decades are certainly going to be interesting in the Chinese sense of the word while the biosphere readjusts, but eventually it will readjust.

If it has survived multi-teraton impacts and mantle super plumes, it will survive pretty much anything we can throw at it.

I'm guessing if I'm one of the 10%, people are going to be pretty rare around here. That leaves me with quite a bit of land and being only 7 minutes from town plenty of left over resources.

We could see some influx of urban migration from the south of us, hopefully not wandering gangs, but people looking to rebuild, but honestly I think they're better of staying where they are, it's a bit of jaunt to come up here for less.

I think initially it will be gather as much wood as possible (I've got a few cords now) and secure a water reservoir. The neighbor has a pond and I'm building one now, in addition to having wells on the property.

Other than that, I'd probably start breeding dogs, and runnin' cattle as someone's got to care for what's left.

Agriculture is the key. If you know agriculture you are pretty much set for life, but not many do.

Even those apocalypse prep nuts tend to be too focused on hoarding guns to learn how to plant.

Edit: and I mean sustainable agriculture. No industrial fertilizer or heat lamps. I fear even actual farmers will have some difficulty in adaptating to not having all those modern agriculture tools.

 Tyran wrote:
Agriculture is the key. If you know agriculture you are pretty much set for life, but not many do.

Even those apocalypse prep nuts tend to be too focused on hoarding guns to learn how to plant.

Edit: and I mean sustainable agriculture. No industrial fertilizer or heat lamps. I fear even actual farmers will have some difficulty in adaptating to not having all those modern agriculture tools.

Different crops and styles of farming are their own set of skills.

Even if you don't go all the way back to horse and cart; just shifting from a super mass production high tech system to a sustainable smaller scale setup that might be more diverse in crop type and such - all that can require learning new methods, new machines. Heck effective crop rotation and management without vast amounts of chemicals is a huge hurdle. Just how DO you manage fields when you have to watch your fuel use; when you can't just spray and kill everything; when you aren't going to use a mega-field of all just one crop type e tc...


That's before you even get to processing the yield or working without the support of a massive national and international weather system tracking and monitoring and soforth.

It's not beyond learning, but it requires a whole new set of skills.

Again things like fuel reserves and soforth might well mean that you don't have to learn it all in the first year, but you would have to adapt farming to the situation. Perhaps some farms could maintain at normal production and enough of the infrastructure survives to allow few farms to mass produce and the resulting crop to be shipped around the country in an effective manner.


Thinking about it I could well see nations like the UK, who tore up a lot of the branchline rail network; gravitating back toward being close to rail network hubs and such. Easy way to transport large amounts of goods around the country and you can likely gather up enough working steam-engines to keep going even long into fuel or electric shortages - if such things happened

Angronsrosycheeks wrote:
But if you go for a "mysterious global pandemic" scenario and simply random 10% of the population is immune ...

But that's not going to be a rapid decline with no warning. A disease with a 90% fatality rate is going to have a very hard time spreading because of how quickly it burns through the host population. Covid was (and still is) a big problem because it has a ~1-5% mortality rate (depending on exact population demographics, etc): significant enough to kill a lot of people, but not so high that even the worst idiots can see there's a problem and start implementing drastic containment measures. You can be sick with covid but in denial enough to go get on a plane, infect everyone on the flight, and start spreading the disease in another city. It's a lot harder to do that with the kind of thing that has a 90% fatality rate because you're very quickly incapacitated past the point of being able to do anything but lie on a bed and wait to die. So you can have some pretty horrifying outcomes in the places where an outbreak happens but it's hard for the disease to break containment and become a worldwide threat.

The actual 90% population drop scenario would be something more like the initial worst-case modeling for covid: a modest death rate, no viable vaccine, and a high re-infection rate so that each year you lose 1% of the population but you have a long period where billions of people think everything is fine, no need to worry about containment and the disease has abundant opportunities to spread worldwide. And in that case the slower pace of population collapse means time to implement plague-free zones, secure critical infrastructure, etc. You'd end up with highly concentrated areas where the containment measures were successful and vast depopulated wastelands broken only by tiny islands where the survivors have secured a vital mine/factory/etc.

We have seen 90% mortality diseases spread like wildfire before. That was pretty much what the smallpox was for the new world, it pretty much was an apocalypse.

I've been thinking about the toppic and then looking again at the OP this cough my eye.

 Mad Doc Grotsnik wrote:


Of particular interest would be books in fairly plain English on the same matter.

My better half says the Arch druid - John Michael Greer - has covered this topic but not as a fast collapse but a drawn out ragged collapse.
His book she tells me is called Dark age America. He's an interesting writer and thinker of things and runs several blogs if I recall.

As for myself. I don't have any thoughts on an overnight collapse aside from it would get horrible really quickly.
We, the human race, are predicted to hit a population collapse in the not too distant future, so good news we'll get to see first hand.

I've looked forward to the zombie apocalypse for years, well when I was younger and fit anyway. I'd simply assumed that would mean a life of wondering around scavenging for food and shelter.

A zombie apocalypses, the most dumbass way to end the world.

At least make it Nurgle Poxwalkers to keep it interesting.

 Overread wrote:
international weather system tracking and monitoring and soforth.

That's a point. What happens to the satelites when there's no-one to steer them into the sun when spent, or degrade their orbits when decaying? There'll be stuff falling from space for quite some years.

 Tyran wrote:
We have seen 90% mortality diseases spread like wildfire before. That was pretty much what the smallpox was for the new world, it pretty much was an apocalypse.

But note there were three factors there which very much do not apply now: complete ignorance about how diseases work, very poor medical care, and a resistant population that could spread the disease without getting wiped out first. Modern science and medicine make it a lot harder for a new disease to reach those high fatality levels, and a new disease that wipes out 90% of humanity would by definition not be able to have a substantial resistant population to spread it. Smallpox wouldn't have had nearly the same effect if all the ships full of settlers had arrived full of corpses because the 90% fatality rate applied to the settlers as well as the natives.


Automatically Appended Next Post:

 Skinnereal wrote:

 Overread wrote:
international weather system tracking and monitoring and soforth.

That's a point. What happens to the satelites when there's no-one to steer them into the sun when spent, or degrade their orbits when decaying? There'll be stuff falling from space for quite some years.

The impact on earth would be almost nothing. Most debris burns up before it hits the ground and there's a whole lot of empty land and water for it to hit. I suppose odds are eventually someone would be hit but it would be way down the list of hazards to worry about. The bigger issue would be the loss of function for things like GPS, weather information, etc.

In terms of mortality rates

Average life expectancy would of course dip. Life extending medicine would be all but lost. More women would die during childbirth. And neo-natal card would be nowhere near what it is right now.

But as Painted Owl suggests? The base level understand of hygiene is just better these days. We know to, and how to, wash our hands. That alone reduces the chances of spreading needless illness. We know about cross contamination of food. We know to boil water to kill off nasties.

Modern sewer systems would still be there, but the treatment plants may not survive. But that’s still a massive improvement upon relying on Gong Farmers.

Even just knowing to not dig latrines near where to store or grow your grub is a step up on what we used to do in the Bad Old Days.

And if we settle into enclaves with relatively little external trade? We may even see certain common ailments like seasonal flu go away, as the population develops an immunity and no new or novel strains are introduced from outside. Yes mutation in the strains would be a possibility, but with fewer carriers that chance would also reduce to the best of my knowledge?

The agriculture thing is also feeling a bit overstated. Sure modern farming techniques would soon fall by the way side due to lack of knowledge preservation or lack of necessary bits and bobs. But there’s a gulf between what effective Commercial Farming and effective Subsistence Farming would look like, no?

 ThePaintingOwl wrote:

 Tyran wrote:
We have seen 90% mortality diseases spread like wildfire before. That was pretty much what the smallpox was for the new world, it pretty much was an apocalypse.

But note there were three factors there which very much do not apply now: complete ignorance about how diseases work, very poor medical care, and a resistant population that could spread the disease without getting wiped out first. Modern science and medicine make it a lot harder for a new disease to reach those high fatality levels, and a new disease that wipes out 90% of humanity would by definition not be able to have a substantial resistant population to spread it. Smallpox wouldn't have had nearly the same effect if all the ships full of settlers had arrived full of corpses because the 90% fatality rate applied to the settlers as well as the natives.

Diseases don't have to be immediately fatal. HIV essentially had a 100% fatality rate prior to the development of antiretrovirals, for example, but this didn't prevent spread because there was a large lag time between infection and serious illness. There are various other contagious diseases that can* have significant lag time between infection and serious/fatal illness- syphilis, tuberculosis, high-risk human papilloma virus (HPV) subtypes, hepatitis B and C viruses, sometimes Epstein-Barr virus, Helicobacter pylori, transmissable prion diseases to name a few well-known examples. In the case of HPV, it is so adapted as to be almost undectable to the human immune system in chronic infections- a huge amount of adults have chronic HPV infections and have no idea. Unfortunately, some of these mechanisms lead to nasty cancers developing years after infection.

The hypothetical posed by MDG has an engineered contagious disease. It is entirely plausible that a disease could be crafted to spread rapidly, yet remain undetected for awhile until it has near enough infected the entire global population, then start manifesting fatal consequences too rapidly for countermeasures to be developed. The aliens have just travelled an interstellar distance in some kind of stasis chamber, waiting a few more years for a virus to spread is probably tolerable.

A disease could also destroy 90% of the population through drastically reduced fertility, but that would be a much slower burn as would require most of the population to die of other causes and simply not be replaced rapidly enough.


*Many of these can also have significant acute illness, like TB, EBV, Hep B.


Automatically Appended Next Post:

 Mad Doc Grotsnik wrote:
In terms of mortality rates

Average life expectancy would of course dip. Life extending medicine would be all but lost. More women would die during childbirth. And neo-natal card would be nowhere near what it is right now.

But as Painted Owl suggests? The base level understand of hygiene is just better these days. We know to, and how to, wash our hands. That alone reduces the chances of spreading needless illness. We know about cross contamination of food. We know to boil water to kill off nasties.

Modern sewer systems would still be there, but the treatment plants may not survive. But that’s still a massive improvement upon relying on Gong Farmers.

Even just knowing to not dig latrines near where to store or grow your grub is a step up on what we used to do in the Bad Old Days.

And if we settle into enclaves with relatively little external trade? We may even see certain common ailments like seasonal flu go away, as the population develops an immunity and no new or novel strains are introduced from outside. Yes mutation in the strains would be a possibility, but with fewer carriers that chance would also reduce to the best of my knowledge?

The agriculture thing is also feeling a bit overstated. Sure modern farming techniques would soon fall by the way side due to lack of knowledge preservation or lack of necessary bits and bobs. But there’s a gulf between what effective Commercial Farming and effective Subsistence Farming would look like, no?

A lot of modern sewer systems will stop working fairly quickly without power to pumps etc. and maintenance to clear out cisterns. The latter can be continued relatively easily, but any system relying on pumps would need an alternative energy source rigged up.

Which does make me think hydropower will see a big resurgence. It isn't very long ago that basically every town or large village with a brook or river had a waterwheel to power the local industry. In England, medium to large towns often had several waterwheels. You can still see a good example in Stafford, where one of the millhouses has the foundations visible, the wheels are still there, and most of the millchase is preserved too. Waterwheels remained competitive with steam engines into the early 20th century in many places. We would likely see a reorientation of humans around waterways, and go back to living in similar places to where humans were 200 years ago.

Stafford mill (this is a 19th century structure IIRC, but built on the site of much earlier mills):


Edit: 'flu is spread via animal sources too (birds mainly) so will likely continue to be a big problem for scattered human populations.

 Haighus wrote:
Diseases don't have to be immediately fatal.

Right, but then you're in the scenario where you have a steady decline over a relatively long period of time and things can be done to ensure the survivors have a functioning civilization, and where the most likely reason for the 10% surviving is that a region had particularly effective precautions against the disease and retained a mostly functioning system. A rapid collapse scenario with no time to prepare requires a disease that is very quickly fatal, exactly the kind of disease that tends to burn itself out before the initial outbreak can spread too far.

In the case of HPV, it is so adapted as to be almost undectable to the human immune system in chronic infections- a huge amount of adults have chronic HPV infections and have no idea.

Exactly my point. HPV can spread widely because it has a very low rate of serious effects, most carriers don't even know they have it. Most people don't test for it, lots of people decline to get the vaccine, there's no interest in taking drastic quarantine measures when an outbreak happens, etc. You would not see this if HPV had a 90% fatality rate.

The aliens have just travelled an interstellar distance in some kind of stasis chamber, waiting a few more years for a virus to spread is probably tolerable.

Sure, at which point you've overturned all the laws of physics and who knows how the world works. The virus is just a fancy form of "a wizard did it" and the only thing that matters is how exactly you want the magic to work so it tells the story you want to write.

 ThePaintingOwl wrote:

 Haighus wrote:
Diseases don't have to be immediately fatal.

Right, but then you're in the scenario where you have a steady decline over a relatively long period of time and things can be done to ensure the survivors have a functioning civilization, and where the most likely reason for the 10% surviving is that a region had particularly effective precautions against the disease and retained a mostly functioning system. A rapid collapse scenario with no time to prepare requires a disease that is very quickly fatal, exactly the kind of disease that tends to burn itself out before the initial outbreak can spread too far.

In the case of HPV, it is so adapted as to be almost undectable to the human immune system in chronic infections- a huge amount of adults have chronic HPV infections and have no idea.

Exactly my point. HPV can spread widely because it has a very low rate of serious effects, most carriers don't even know they have it. Most people don't test for it, lots of people decline to get the vaccine, there's no interest in taking drastic quarantine measures when an outbreak happens, etc. You would not see this if HPV had a 90% fatality rate.

The aliens have just travelled an interstellar distance in some kind of stasis chamber, waiting a few more years for a virus to spread is probably tolerable.

Sure, at which point you've overturned all the laws of physics and who knows how the world works. The virus is just a fancy form of "a wizard did it" and the only thing that matters is how exactly you want the magic to work so it tells the story you want to write.

Why? MDG gave a plausible scenario- aliens create a largely-automated spaceship with cryo facilities they think will work, it travels for decades/centuries/millennia through the ether (probably the latter but dependent of how far away the aliens are coming from), arrives in Sol, the automated systems sample Earth and do their job, then it turns out the cryo didn't work and all the aliens are dead. We can almost do this as a species now, and it is within the realms of what appears possible for technology (that degree of automation is plausible).

I gave different examples for a reason, because the traits needed for this hypothetical virus are obviously not all present in the same disease, or 90% of us would be dying right now The point is that there are chronic diseases that are highly fatal (prions, HIV, syphilis), chronic diseases with very long lag times between infection and fatal outcome (HPV, hepatitis B and C, prions, syphilis.. most of the ones above actually), chronic diseases that are basically undetectable until they cause problems or we specifically look for them (HPV, prions, EBV, Hepatitis B and C, syphilis, latent TB etc), and we know some diseases can spread extremely rapidly, like the various viruses that cause common colds, or COVID. It is far from inconceivable that these traits could be combined into a contagious disease that spreads rapidly through the population undetected, sits latent for decades, then suddenly causes fatal disease that wipes out most of humanity before a cure is developed or some people survive with natural resistance.

Again, no disease currently exists like this, because we are not dying in droves. But the required traits do exist in the wild.

 Haighus wrote:
Why?

Because interstellar travel is, if not literally impossible, so absurdly impractical that there would be no purpose in sending a colonization ship. There are no resources that would justify the immense costs of such a project and no practical way to return anything to the homeworld. Any interstellar travel will be purely a scientific mission or a relativistic kinetic attack sent to annihilate any potential threat.

The only way you can get this scenario is if you bend the laws of physics somehow to make space travel easier and that's going to have more of an effect on the scenario than how the particular disease worked.

We can almost do this as a species now

No we can't. We are not even remotely close to accomplishing any of that.

It is far from inconceivable that these traits could be combined into a contagious disease that spreads rapidly through the population undetected, sits latent for decades, then suddenly causes fatal disease that wipes out most of humanity before a cure is developed or some people survive with natural resistance.

Inconceivable? No, at least not if you have physics-warping god aliens making it. It's virtually impossible for it to evolve naturally and incredibly difficult to engineer but I suppose it isn't outright impossible. But the issue is that the traits you mention are mutually contradictory. A highly contagious disease generally needs to reproduce a lot of copies of itself very quickly, which means it creates symptoms by doing so. A disease with a long dormant period doesn't have access to the most effective means of transmission. And it's hard to imagine how you could have a simultaneous triggering of the end stage of the disease given populations being infected at very different times.

Just remember we are surrounded by things today that at one time were scientifically impossible; or were so insanely resource intensive that they were as close as impossible.

Real time conversations with the other side of the world? Machines that can translate written and spoken words in real time; flying around the world in only 3 days (or so); flying in itself; building machines so small you need a microscope to see them; etc...

Science can never tell you what is impossible; only what you cannot do with current understanding which is a constantly moving barrier.



Asides for which the premise in the opening post is just a story justification for a rapid 90% population loss planet wide. You could replace with a timed nanno virus; a regular virus; a madness; zombies; magic; space aliens; interdimensional rifts or whatever. The point is how society would cope with a massive population loss without a massive level of direct infrastructure damage.

Not a virologist, but just off the top of my head, you could probably engineer a virus that triggers nastiness when it starts seeing a high re infection rate (I.E. everyone around you also has it).

Also this is explicitly a sci-fi proposal.

Hard Science Fiction absolutely has its place. But I’m afraid it’s not in this thread.

 Jadenim wrote:
Not a virologist, but just off the top of my head, you could probably engineer a virus that triggers nastiness when it starts seeing a high re infection rate (I.E. everyone around you also has it).

Possibly, if it worked like some sort of autoimmune disorder that got progressively worse symptoms every time it encounters some slightly mutated version of itself from e.g. exchange of bodily fluids. That would also in practice mean that it would stay dormant for the most part in isolated populations and would trigger mass-outbreaks once these populations would mix into larger societies, which is handy both as a 'sleeper weapon' and as a plot device for claustrophobic or 'small world' stories, it literally gives you a reason for staying the hell away from each other.

Doesn’t even have to be a virus. Could be something like an EMP which messes up hoomans, with a percentage (the 10% being discussed so far is entirely for sake of discussion) proving immune.

The important things for this topic?

A) Human gets kicked right in the societal n00ts.
B) But there’s no follow up or otherwise lingering threat. It’s a one and done peril
C) The focus is on how the wider species of earth would be affected, not how long stinky hoomans might take to stop cluttering up the place or get back on their idiot feet as a technological species.

The problem with the premise is the contradiction between aliens advanced enough to travel all the way to us but still primitive enough to depend on natural biospheres.

It doesn't fit. Such alien civilization that can spend the energy equivalent of a small star to feed interstellar colonization can just as easily take Mars or Venus and turn them into inhabitable planets. Or any other rock in space while at it, they don't even need to be planets as you can build inhabited space stations deep into a large asteroid and give it a spin to simulate gravity.

Move past my ropey premise. Focus on the underlying question.

If something bumped off a staggering majority of us humans? What happens next in terms of nature and how it all works.

Doesn’t matter how it happened, or whatever reason is given. The assumption it did happen, we got kicked in our societal Nads and will have to adapt - and what sort of rollercoaster the natural world might throw into the mix. But mostly the latter. Whether we survive it or not is entirely irrelevant to what I’m trying to explore.

Focussing on the natural world:

No more industrial removal of habitats (deforestation, peat bogs, coastal wetlands), so these would regenerate. This would prevent the current fragmentation of certain species.

No more industrial exploitation of sealife. I saw one quote somewhere that we may have fished out 90% of common fisheries before we even started measuring them.

You've said a few times about all the dead humans leading to an insect boom. I'm not convinced this would be that noticeable against the population rebound from us no longer using pesticides.

Stopping all human-sourced greenhouse gasses will slow climate change and allow the natural weathering processes to catch up and re-balance the atmosphere and hydrosphere. Changes would still occur, but see https://xkcd.com/1732/ for a pretty stark presentation on natural climate variation.

On the down side:
There would definitely be localised massive pollution plumes at high risk industrial sites (oil and gas extraction and processing, nuclear, mines) as the risks are no longer managed.

Current management of invasive species would stop, requiring whole ecosystems to find a new balance. all it takes is for some indigenous species to gain a taste for the newcomers and everything rebalances naturally.

Also without humans in the way many species migrate naturally anyway. Indeed migration and exploitation of new regions coupled to species that can't migrate as fast as local conditions change to be unsuitable means that many species are lost over time naturally.

I think the biggest risks would be something like a nuclear winter or other major chain of disasters linked to human safeguards shutting down. Such events could set back recovery processes for thousands of years and might even result in global changes that never fully "recover" and create a lasting change that life has to evolve to cope with.

A nuclear winter requires a nuclear exchange, so unlikely, and even the worse nuclear meltdowns like Chernobyl should be cleaned up after tends of thousands of years (radioactive material does disintegrate after all).

It may take a million years, but the idea that the planet cannot fully recover is anthropocentric arrogance. It recovered from superplumes and asteroid impacts, either which make our biggest nukes look like harmless toys.

Although yes there will be some evidence left in the shape the biodiversity takes after us. In that aspect we will have an enduring influence.

 Tyran wrote:
A nuclear winter requires a nuclear exchange, so unlikely, and even the worse nuclear meltdowns like Chernobyl should be cleaned up after tends of thousands of years (radioactive material does disintegrate after all).

It may take a million years, but the idea that the planet cannot fully recover is anthropocentric arrogance. It recovered from superplumes and asteroid impacts, either which make our biggest nukes look like harmless toys.

Although yes there will be some evidence left in the shape the biodiversity takes after us. In that aspect we will have an enduring influence.

So, on that?

I was around for Chernobyl all going at a bit wrong. And I’ve since learned wind direction was a serious concern for Western European countries due to nasty bad dust.

If we look at a worst case scenario? And every nuclear power station has a meltdown? What’s the impact? I ask because I genuinely don’t know the difference between a nuclear weapon being used and a nuclear power station going horribly wrong.