Here's what would happen if ALL humans completely disappeared
Foreign. It's 9:41 AM. We've just woken up and brewed yourself a cup of coffee. Outside your window, you see the normal bustle of cars honking at a busy intersection, people waiting in clumps across the street, either mouthing conversations you can't hear or scrolling through their cell phones. You look up at the sky and see airplanes flying high, weaving in and out of dark clouds. The clock strikes 9:42 AM, and all of a sudden, for reasons unknown, you and everyone else in the world banish completely—without a warning and without leaving a trace.
The clock strikes 9:43. Your dog is barking feverishly, sniffing at the puddle of spilled coffee in a broken glass that is shattered all over the spot of the floor that you just stood in a mere second earlier. The only remaining evidence of you. The streets outside are now littered with horrific traffic accidents and electrical fires caused by the collisions of newly abandoned cars. Those planes that were flying through the clouds will stay in flight for a few more hours until the fuel runs out and gravity pulls them back down to Earth, and they land in explosions. There's no one left to call for help, no police sirens in the distance—just smoke, sparks, and electrical fires until eventual total silence.
This is what would happen to our natural world if all human beings disappeared suddenly without leaving a trace— all 7.8 billion of us. Throughout the first day of our absence, all of the fossil fuel plants around the world would shut down in rapid succession. Without humans around to refuel them with coal or oil, these shutdowns would lead to electrical blackouts all across the globe, causing our world to go rapidly dark, grid by grid. If you were to look at Earth from space at the end of the first day of our disappearance, the only two cities that would still have electricity would be Las Vegas and New York.
On day two, New York City would lose power, and at some time around the 36-hour mark without us, their entire subway system would completely flood due to the loss of manual laborers who pump around 13 million gallons of water out of it every single day. Within the first three days of your absence, various insects would have begun infiltrating your home, making their way to whatever food was left out on the counter or the table. At the same time, your dog would be on the same mission and would have become munching on whatever scraps he could find, scrambling to survive without you around to feed and take care of him.
Over the next week or two, the insects in your home would be followed by small animals like mice, rats, squirrels, and chipmunks, who would enter by chewing through the walls and foundation. Domesticated pets will have either found a way to escape their abandoned homes or will have starved to death inside, depending on the capability of the animal and the circumstances of the space they were left in. But even for the dogs and cats who are successful in escaping their homes, their struggle has only just begun.
On their own now in the wild for the first time, these pets would not only have to compete with all the other newly free dogs and cats out there but also larger predators like wolves, coyotes, bears, eagles, and snakes. To make matters even more complicated, the global loss of electricity would disable all the electrical fences at zoos around the world, allowing even larger and more exotic animals to break out and roam free. Imagine, if you will, lions roaming around supermarkets or monkeys climbing on playgrounds. Surprisingly enough, domesticated cats are predicted to have a better shot at survival as a species than domesticated dogs in the absence of humans, as dogs have been domesticated and selectively bred by humans for thousands of years longer than cats.
Furthermore, when left to fend for themselves, dogs organize themselves into hierarchical packs, which leads them to hunt and kill their own, whereas cats are solitary hunters who avoid preying on their own as a means of preserving the species. On approximately the 10th day without humans, the planet and everything that is left inhabiting it will be forced to overcome a major environmental problem. All around the world, humans had built 440 nuclear power plants, which house and store energy. Inside these power plants are diesel generators which, unless carefully stored in cool water tanks, will heat up to a thousand degrees and explode the moment that the power goes out.
In the first or second day without us, this will create a ticking time bomb for these power plants, as the generators will begin heating up their tanks, causing the water to boil before evaporating completely. This would lead to the generators igniting, causing all 440 power plants to explode pretty much at the same time, subjecting the world to the worst nuclear disaster in human history. In total, these explosions would unleash about 500 times as much radiation as was released in Hiroshima. With the A-bomb, radioactive smoke would fill the air, coating every plant or tree it touches with a metallic black film. Over half the world's insect and rodent population would be killed off instantly.
Larger animals would cope better with the radiation as their organs are more insulated, while smaller animals who have found ways to sustain themselves indoors, either in supermarkets, homes, or other buildings, would also be better protected. Within the first month or two without humans, almost all farm-raised cows, chickens, and sheep would have either starved to death or been killed off by larger, more skilled predators. Within the next three to six months of your absence, water would begin to seep in through the cracks of your home that were created by the insects and small animals. This water would erode the walls, floors, and ceiling of the home even further.
A full year of moisture damage would really plague your home, stressing out the structures, causing wooden materials in the roof to snag and snap, and creating excessive mold. Wood would entirely be infested with termites. At this point, after one year without us, Las Vegas would finally lose power and go completely dark. This would be the result of the Hoover Dam finally shutting down due to the infiltration of a small breed of freshwater mussels called the quagga, who, without humans to keep them at bay, would eventually clog the pipelines that are feeding the cooling water to the Dam's generators. Who would have thought that the entire city of Las Vegas could be conquered by an animal less than an inch in length?
Without water running through the Hoover Dam, the Colorado River would eventually run dry. At the one-year mark, hundreds and thousands of wildfires and electrical fires would have gone unmaintained and would have led to the destruction of several man-made structures and cities. In places that experience winter, the cold will have brought with it the freezing and bursting of water pipes in most houses and buildings. All smaller or especially bred dogs are predicted to be long gone by this point, their primary predators being larger, more skillful dogs who have completely colonized in packs and even begun mating with wolves.
Every year that humans were on Earth, our cars pumped out approximately 7 billion tons of carbon dioxide into the air. But now, with us gone, the air is clearing up like it had never had the chance to before. Plants and growing trees will begin sucking up the CO2 we left behind for them, a process that will continue for the next hundred thousand years. Two years after our disappearance, our once manicured lawns have completely overgrown into fields. Concrete sidewalks are now filled with greenery that has pushed its way through the cracks.
The ice rink at Rockefeller Center Plaza in New York City is now a garden. There's no question that trees, plants, and ocean populations would thrive after we're gone; however, they would still have to contend with the mountains of human waste we left behind. Most of our waste would be broken down by decomposers, such as bacteria, fungi, and earthworms, who feed on the materials by turning them into simple elements and nutrients, a process called biodegradation. After 10 years without humans, forest fires will spread out of control, resulting in the complete demolition of cities like Los Angeles. After 20 years, the paint on the White House in Washington, D.C., will have faded to gray, and low-rise cities such as Amsterdam, London, and Chicago will be completely submerged in water.
After 30 years, the 25,000 space probes we have positioned in space will become visible to the night sky, soaring above the Earth like shooting stars before gravity finally pulls them to the ground, where they'll crash and burn due to the absence of battery power. Fifty years after our disappearance, formerly domesticated parrots would still retain traces of human speech. Seventy-five years and 600 million automobiles we left behind would be nothing more than withered down skeletal heaps of their former selves.
One hundred years after we're gone, underground running water would corrode the metal structures that hold up the city streets, causing the vegetation-covered roads to cave in on themselves and turn into mid-city rivers like a gothic ghost town version of Venice. Insect populations are predicted to have fully recovered from the nuclear power plant explosions by this point and would be thriving with the loss of man-made pesticides. This explosion of the insect population would trigger an increase of all the small animals who feed on them. This pattern of population growth would reverberate all the way up the food chain, causing the entire animal kingdom to boom over the next century.
Three hundred years without humans, the steel rivets which hold together bridges would have rotted and decrepit so much that the structures would begin to collapse one by one. The Eiffel Tower, which is also made of steel, is predicted to fall around this time, along with the Statue of Liberty and all other major skyscrapers around the world. Structures made of metal and glass would be the first to go, whereas stone structures would last the longest. But even those would become softened and weakened by the continual water damage and lack of maintenance.
The last remaining man-made structures would be the Great Wall of China, the Pyramids of Giza, and Mount Rushmore—all of which could remain intact for thousands of years after our disappearance. One hundred million years after humans disappeared, the sole remaining evidence of human life on Earth, aside from our fossilized bones, will be shards of plastic and Mount Rushmore. If any new species of sentient life were to form at any point around this time, these artifacts would be all they had to piece together.
Few humans even were. When we talk about the greatest threats to our human civilization, we tend to think of man-made constructs like foreign governments, nuclear weapons, and artificial intelligence. But rarely do we ever consider the power that seemingly harmless things, such as water, climate, and plant life, possess against this rather fragile reality we've built. And so, at first, thinking about how swiftly Mother Nature would reclaim her Earth after we're gone could feel kind of depressing.
But at the same time, thinking about how powerful this planet really is, even despite the tremendous amount of environmental damage we've caused, can be oddly reassuring and maybe even liberating. Imagine now that you're back in your home with your freshly brewed cup of coffee in hand. As you look out your window, focus this time on the shrubs and greenery planted along the sidewalk instead of the busy intersection and the honking cars. Instead of looking at the people waiting to cross the street, think about the Earth they're standing on and all the layers of nature that have been buried beneath that concrete.
When you look at the sky, instead of focusing on the planes flying high, think about the clouds they soar amongst. Realize that this planet we call Earth is so vast and that human life and all that we've created is really just one small part of it.