Here's the scenario: Humans have disappeared from the face of the Earth in an instant. What will happen to the world without us?
The odds of every human being vanishing in an instant is highly improbable unless we're all beamed up by UFO. But, it's interesting to consider what might happen if we suddenly disappeared.
At first, many would say that the world would be better off, but, at first, the reality is very different. If we all vanished at precisely the same time, what would happen to the aeroplanes in the sky? Not to mention the nuclear reactors that rely on electricity to keep them cold. Their power comes from other sources, like coal and hydroelectricity suppliers, and these plants would shut down in just a few hours without anyone watching them. The result? No power to cities and homes and the nuclear facilities would have to switch to backup generators. These too will eventually run dry, and a global nuclear catastrophe would be the result.
Then, what about the animals? Well, most of our pets who can't escape their locked homes will only survive a few days before they die of hunger and thirst. The dogs that do escape will form into packs and turn on the small dogs, turning them into lunch. Freerange farm animals, like chickens and cows, will thrive, but those locked in coops and pens will die. The large zoo animals would escape, and the predators would go on the hunt too. But they aren't the only problem for their prey. In fact, they'll all be exposed to radiation from the nuclear explosions.
In the countryside, small animals will suffer first, like rodents and insects, but in the cities, where food is plentiful and not as badly affected by the radiation, populations will explode. Many will adapt, others will not.
Within three months, the air has cleared from the dust churned up by humans. Visibility in previously polluted areas has increased threefold. There is less rain around the cities though, as there is less dust in the sky for water particles to cling to.
Within a year, the flora will have drawn much of the carbon dioxide from the air and will start reclaiming areas once occupied by vehicles. Within ten years, manmade objects will start collapsing. Even the sea will destroy most oceanside cities, and ships will either be washed up on shore or sink to the ocean floor.
Eventually, even satellites and space debris in the sky will be drawn back to Earth. In just a few decades, the world will be unrecognisable, reclaimed by nature. Many high-rise buildings will succumb and collapse, but by now it's literally a concrete jungle, full of predators and prey.
Within 120 years, the planet has cooled and the oceans have absorbed much of the carbon from the polluted air. Plankton absorbs the carbon which kills them off and pollutes deeper into the water as the plankton dies and sinks.
200 years since humanity vanished, rivers have been forced to change course as bridges collapse and dam up, while dams themselves burst, flooding everything downstream, turning the landscape back into what it was before humans intervened. Previously irrigated farmland is turned into deserts.
By now, fish populations have recovered, and many species have grown in size. Whale's and other large ocean creatures, in particular, thrive well. By now, most relics of human beings have all but disappeared. Incredibly, ancient structures like the pyramids in Egypt and the Great Wall of China survive longer.
Eventually, most of what we created will be destroyed, reclaimed by nature. But, there will still be remnants of humanity left intact. But not on Earth, it'll be all the things we left on the moon.
The video below by the YouTube channel, Free Documentary, is incredibly detailed. It explains this process in bite-sized chunks that are easy to digest. It's well worth the time to watch, so get yourself a beverage and get ready for an eye-opening look at the Aftermath: Population Zero.