This Is What Would Happen To The World If Humans Disappeared
There are few places left on Earth today that don’t bear evidence of human influence. It’s hard to picture what the world would look like without us here. But let’s imagine, for a moment, that all human beings suddenly disappeared. Poof! At the snap of a finger, we’re all gone, perhaps as a result of a huge natural disaster or nuclear warfare. What would happen to the planet we’d left behind? Well, experts have predicted the answer to this exact question, and it’s pretty fascinating. Let’s find out, step by step, what would is most likely occur in the event of human extinction.
1. Wildlife would reclaim previously human-dominated areas
First things first, there’s one big change that would occur pretty quickly once humans had disappeared from the Earth: wildlife would take over! Where once we had bustling city streets and human zones, animals and plants would swiftly move in to take them for themselves. Alan Weisman, author of the book The World Without Us, spoke to website Live Science about exactly how this would happen.
Weisman explained that insects would do well without humans, which, in turn, would “start a real cascade of events.” He claimed, “Once the insects are doing better, then the plants are going to do much better, then the birds.” Habitats would replenish, and slowly the creatures within them would move into our former neighborhoods.
2. Lawns, gardens, and farms would become overgrown
You’ve probably seen for yourself what can happen to an unmaintained lawn after just a few weeks during the summertime. To put it bluntly, it can grow out of control really, really quickly. Grass shoots up high, while weeds sprout everywhere. Imagine, then, what would happen if humans disappeared entirely.
With nobody cutting the grass and pulling out the weeds, gardens, lawns and farmlands would become messy tangles really quickly. There’d also be far diversity on that formerly strictly maintained land: different sorts of plants would be given the chance to establish themselves without being ripped from the earth.
3. Glass buildings would fall down, but others would stand for a long time
How would our man-made structures hold up after we’d disappeared? Would our buildings endure? Well, some are going to be standing for far longer than others. Glass buildings would be among the first to go, while metal ones would soon rust.
Stone buildings, though, would survive for a longer time. That’s an interesting thought, which Weisman put quite neatly. He said, “Buildings that will last the longest are the ones made out of the Earth itself.” Maybe there’s a lesson in that?
4. Roads and bridges would collapse
Our roads and our bridges won’t hold up forever without maintenance. Metal will rust and disintegrate, and plants will grow and ultimately weaken structures. It wouldn’t happen overnight, but over decades and centuries they’d become critically weakened.
Another point worth considering here is how much the surface of the Earth moves over time. That variation would create cracks on roads and bridges, which would only grow and become more severe without anyone to fix them up again.
5. A lot of insects would be buzzing around
As we’ve already asserted, insect populations would boom once we were out of the way. Our species is pretty awful for bugs: we’re pretty intent on keeping them out of our lives with pesticides and bug sprays. Even if we don’t use chemicals, we’re often trying to swat them!
Think of how many insects would be buzzing around without us stopping them. As Weisman pointed out, “They can mutate and adapt faster than anything else on the planet except for maybe microbes... Anything that looks delicious is going to get devoured.”
6. Megafauna would spread everywhere
Big animals would do well without us, too. The Earth was once home to great numbers of megafauna — large creatures like big cats, elephants, bears, rhinos, and others of a similar scale — but we hunted them and destroyed their habitats to a terrible extent. Now, they’re far rarer.
But if we were out of the picture, these big creatures would likely spread around our planet. It wouldn’t happen instantly, and it would take literally millions of years before the Earth was as diverse in megafauna as it once was. But it would eventually happen, assuming no other factors prevented it.
7. Pipes would freeze and burst
If there are no humans living inside houses and turning the taps for water, that plumbing infrastructure isn’t going to last very long. First things first, with nobody manning public water systems, the supply into homes would dry up. But then things would get worse during cold weather.
Without water being pumped through pipes, a cold snap would be incredibly damaging. Whatever water was in the pipes at that time would freeze and expand, causing them to burst.
8. Rat and cockroach populations would decline
We’ve seen how lots of different animal populations would benefit immensely from our disappearance from the Earth, but that’s not universally true for all creatures. Some of them, actually, would probably do pretty poorly in our absence. Spare a thought, then, for the rats and cockroaches.
It’s easy to see why creatures like rats and cockroaches would do badly without us: they have come to rely so much on our waste. The reason they thrive nowadays is because of all the old food we supply them in our trash. If that food source disappeared, they’d be in trouble.
9. Without electric lights, the world would be much darker
If you live in a city today, finding true darkness can basically be impossible: light pollution ensures our night skies are never truly dark. But without us around to keep power plants functioning, electric lighting wouldn’t work any more. Once night-time hit, darkness would truly reign.
That darkness would have a tangible effect upon nature. Nocturnal animals would be able to move into previously bright cities in the small hours. The only sources of light throughout the night would be the Moon and the stars.
10. Our streets would be inhabited with critters
Even in urban areas today, we can still find wildlife: think raccoons, foxes, and skunks. But imagine what it would be like if we weren’t around anymore to keep these animals in check. They’d thrive! They’d take over the neighborhoods we once called our own.
Even creatures such as beavers would probably do really well. Across North America long ago, beavers were in abundance. Without us to stop them, who’s to say they couldn’t get back to the position they were once in?
11. City subway systems would flood
This is one thing you wouldn’t necessarily have expected to happen once humans disappeared. Because there would be no one to man the drainage systems in place in cities, rainfall and groundwater would be a big problem in places with subway systems.
These underground networks would soon become overwhelmed and filled with water. And this would take place within a matter of hours! As Weisman explained, “[Engineers] have told me that it would take about 36 hours for the subways to flood completely.”
12. Things would be so quiet
We can easily imagine all the visual changes that would soon come into play once humans were gone from the Earth, but a different kind of shift would realistically set in beforehand. The planet would become extremely quiet! It’s kind of difficult to conceive of what that would be like.
Our world is loud today. On the ground we have cars and machinery, and even in the sky we have planes. Take out all of those things and we’re left with a very quiet world indeed. The animals would have some peace at last!
13. Plant growth would pop up within streets and buildings
We’ve already addressed the idea that roads and paths would crack without humans to maintain them, owing to the fact that the ground shifts beneath us all the time. But these cracks wouldn’t stay as they are. No, they’d soon begin to host all sorts of plant life.
Those plants and their seeds would be spread by wind and bird waste falling from above. And eventually, they’d grow into large organisms which would, in turn, continue to weaken these roads and pathways.
14. Global warming would continue for thousands more years
If you figured that global warming would abate with humankind out of the picture, sadly that’s not how things would play out. The damage we’ve baked into the planet won’t be so easily undone. As it stands, the carbon dioxide we’ve already managed to release into the atmosphere will take millennia to diminish.
And that’s not all, because the world would probably continue to heat up during all that time. And that would lead to more sea ice melting at the poles, which would release more greenhouse gasses from the disappearing permafrost. The feedback loop we’ve helped to create can’t easily be stopped.
15. Wildfires would spread uncontrollably
Humans cause an awful lot of trouble on Earth, but we also try to limit certain forms of damage. Take fires, for example. If a fire breaks out today, we’ll dispatch the fire brigade to try and get things under control again. People can put it out.
But if there were no people left to extinguish a fire, then it would be likely to spread. And while fires are so often started by humans in the first place, that’s not always so. Say a lightning strike causes one: well, that could spread far and wide without anyone to stop it.
16. Wooden buildings would be eaten by termites
If fires didn’t take out our wooden buildings following our dramatic disappearance from the Earth, then the termites sure would. The critters would enter the cracks that already existed, they’d dine without interruption, and the gaps would get bigger.
Into these big gaps in the wood, water would begin to drip in. All of this means the wood would rot and ultimately disappear. With enough time having passed, all evidence of our wooden structures would be gone.
17. There could be many large-scale nuclear explosions
We’ve imagined how many species of animal and plant would absolutely thrive once we were gone, but there is a possible scenario that would destroy all chances of that happening. This isn’t exactly a pleasant thought, but it’s a definite possibility: nuclear explosions could happen far and wide. That’s because nobody would be manning nuclear power plants.
That scenario could lead to big fires and explosions, and after that the world would be in a perilous position. As Weisman said, “There’s going to be a gush of radiation if suddenly we disappear. And that’s a real wildcard, it’s almost impossible to predict what that’s going to do.”
18. Domestic animals would fall prey to predators
How would domesticated animals fare without people to look after them? Well, not great. Farm animals and pets alike would basically be tasked with finding their own food sources, which wouldn’t exactly be easy for them: they’d never have had to do this before.
To make matters worse, all the wild predators that were doing well following our disappearance would be on the prowl. And that means domesticated animals would be on the menu. It’s not an especially nice thought, but it’s unavoidable.
19. There would be many more fish in the sea
As things stand, overfishing is a major problem on this planet. It’s literally one of the most serious threats we face! But if we were to disappear — and therefore stop catching fish to the point that they can no longer restore their populations — what would happen?
Well, it’s pretty obvious: fish populations in the ocean would absolutely boom. It would take a long time, but it’s conceivable that the number of fish in the ocean would return to the same level it was at before we began fishing commercially as a species.
20. Food crops could disappear
We’ve already considered that farmlands would become overgrown without humans to manage them. But let’s explore that idea a little further, because something interesting would happen from that point on. The crops we grow for food would probably begin to disappear.
Weisman explained why that would happen. He said, “They’re going to get outcompeted, fast. Carrots will turn back into Queen Anne’s lace, corn may go back into teosinte, the original ear of corn, that wasn’t much bigger than a sprig of wheat.”
21. Dams would break down and lead to flooding
Dams don’t last forever: as a matter of fact, they don’t last very long at all. After about 50 years or so, they’ll be in a pretty serious state of deterioration if they’re not maintained. That might sound like a long time to us, but in geological terms it’s the blink of an eye.
In other words, should humans disappear, it won’t be long before our dams weaken to the point of bursting. The flooding that would result from such a catastrophe would be intense, and it would badly impact animals living in the immediate area.
22. Pollutants would remain, but not enough to prevent nature’s spread
There are some pollutants humans have unleashed upon the Earth that may literally never break down. Weisman explained, “Some of these POPs [persistent organic pollutants] may be around until the end of time on Earth. In time, however, they will be safely buried away.
In other words, our impact on the world will never truly be undone. But that isn’t to say no other life-forms would be able to thrive here. Nature would likely eventually find a way, even if it’s been hampered by our activity.
23. Insect-eating animals would thrive
The bugs, as we’ve discussed, will have a great time once humans are gone. Without our chemicals to kill them, they’ll be found in abundance. And while that’s great news for them, another category of beast will also benefit immensely from the situation.
Any animals that eat lots of insects — think things like birds, reptiles, bats, and spiders — are also going to thrive with this boom in the bug population. And that, in turn, will benefit the animals that eat those ones. Everything is interconnected.
24. Thick layers of dust would settle in indoor spaces
This is hardly the most pressing concern for people imagining a world without humans, but it’s still pretty interesting. If we all vanish, the insides of our homes are going to become pretty dusty.
Not only will there be nobody to dust down surfaces, but without air conditioning or heaters switched on, the air inside buildings will stagnate. In other words, dust won’t be disturbed and will simply settle.
25. The food web would take time to settle
We’ve spoken about the animals and plants that stand to benefit from our disappearance, but in truth things won’t be quite so simple. It’s one thing to predict which organisms will do well, but nature is complicated. Things are unlikely to play out smoothly.
The new order of things will likely take a while to settle. Maybe a century will pass, with different species rising and falling, before any genuine sense of equilibrium is established. The food web is really complex, after all.
26. Satellites would fall to Earth
Human activity is no longer confined to the surface of the Earth these days: we’ve got machines in space. Satellites orbit our planet at all times, but what would happen without anyone to service them?
Eventually, the batteries in our satellites would die. When that happens, they’re not going to stay up there for much longer. They’ll crash back down to Earth; if they didn’t burn up on re-entry they could potentially cause a great deal of damage.
27. Human parasites would die out
Some organisms alive on Earth today rely so much on the success of humans. Parasites such as lice really wouldn’t make it very far without us to feed off, so if we were to disappear they’d be in an awful lot of trouble.
Given the nasty itchiness lice bring to our lives, it’s difficult to pity the tiny critters. But it is interesting to think that, without us, there are parasites out there that would likely die out in our absence.
28. Sand would cover desert settlements
Any settlements on Earth situated in the desert would soon be lost, following the disappearance of humans. Think about somewhere like Las Vegas, or maybe Dubai. They may have some tall structures in place, but the sands of the desert would eventually cover them up.
Remember, skyscrapers aren’t going to last forever, so with them collapsed and the sand covering the remains, it’s conceivable to imagine a time where there’d be no sign at all that a city had ever stood out there in the wastes.
29. Super-intelligence might develop in other animals
If human beings aren’t around, it’s possible another species would have the opportunity, across a long enough period of time, to develop a comparable level of intelligence. It’s a crazy thought, but we managed it! And when it comes to animals around today, baboons would be a good bet to take on the mantle.
Weisman explained, “The next biggest brain in the primates, per body-weight, is the baboon’s, and you could say that they’re the most likely candidate. They live in forests but they’ve also learned to live on forest edges. They can gather food in savannas really well, they know how to band together against predators. Baboons could do what we did.”
30. Our lasting legacy would be chicken bones, plastic, and radioactive isotopes
The world is set for big changes, should we be wiped suddenly off the face of the Earth. Ecosystems would change, man-made structures would decay, and the Earth would never again look as it did. But after all that, what signs would remain that our species even existed? The answer is less lofty than perhaps we’d like to think.
Plastic waste would endure for a long time. Chicken bones would remain in the earth — we eat a lot of chicken, and, as we can see from archaeological sites today, the bones do linger for a long time — and the radioactive isotopes we unleashed would stick around. What a legacy we’d leave behind us!