If humans went extinct, what would Earth look like a year later?

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Have you ever wondered what life would be like if everyone suddenly disappeared?

What would happen to all our things? What would happen to our homes, our schools, our neighborhoods, our cities? Who would feed the dog? Who would cut the grass? Although it’s a common theme in movies, TV shows and books, the end of humanity is still a strange thing to think about.

But as an associate professor of urban design – that is, someone who helps towns and cities plan what their communities will look like – it’s sometimes my job to think about expectations like this.

So much silence

If people disappeared from the world, and you could come back to the Earth to see what happened a year later, the first thing you would notice would not be with your eyes.

It would be with your ears.

The world would be quiet. And you would understand the amount of noise people make. Our buildings are noisy. Our cars are noisy. Our sky is noisy. All that noise would stop.

You would notice the weather. After a year without people, the sky would be brighter, the air clearer. The wind and the rain would clean the surface of the Earth; all the smog and dust that people make would be gone.

There is no hearth like your own hearth

Imagine that first year, when your house would sit undisturbed by anyone.

Go into your house – and I hope you are not thirsty, because there would be no water in your faucets. Water systems require constant pumping. If the public water supply has no one to manage the machines that pump water, there is no water.

But the water in the pipes when everyone was gone would still be there when the first winter came – so on the first cold snap, the frigid air would freeze the water in the pipes and they exploded.

There would be no electricity. Power stations would stop working because no one would monitor them and fuel supply would be maintained. So your house would be dark, without lights, TV, phones or computers.

Your house would be dusty. In reality, dust is in the air all the time, but we don’t notice it because our air conditioning systems and heaters blow air around. And as you move through the rooms in your home, you also pick up dust as you move. But as soon as that stops, the air inside your house would be calm and all the dust would settle.

The grass in your yard would grow – and grow and grow until it got so long and floppy it stopped growing. New weeds would appear, and they would be everywhere.

Many plants that you have never seen before will take root in your yard. Every time a seed tree falls, a small tree may grow. There would be no one to pull it out or cut it down.

You would notice a lot more bugs buzzing around. Remember, people tend to do everything they can to get rid of bugs. They spray the air and ground with bug spray. They remove bug habitat. They put screens on the windows. And if that doesn’t work, they send them.

Without people doing all these things, the bugs would come back. They would have the freedom of the world again.

On the street where you live

In your neighborhood, critters would wander around, looking and thinking.

The little ones first: mice, groundhogs, raccoons, taps, foxes and beavers. That last one might surprise you, but North America was once rich with beavers.

Larger animals would come later – deer, coyotes and the odd bear. Not in the first year, maybe, but in the end.

Without any electric lights, the rhythm of the natural world would return. The only light would not be from the Sun, the Moon and the stars. The night critters felt good they got their dark sky back.

Fires would often occur. Lightning could strike a tree or field and set brush on fire, or strike the houses and buildings. Without people to put them out, those fires would burn themselves out.

Around your city

After one year, the concrete objects – roads, highways, bridges and buildings – would look the same.

Come back, say, ten years later, and you’d see cracks in them, with little plants climbing up through them. This happens because the Earth is constantly moving. With this motion comes pressure, and with this pressure comes cracks. Eventually, the roads were so cracked that they looked like broken glass, and even had trees growing through them.

Bridges with metal legs would rust slowly. The beams and bolts that hold the bridges up would also rust. But the great concrete bridges, and the interstate highways, concrete too, would last for centuries.

The dams and levees that people have built on the world’s rivers and streams have been eroded. Farms would fall back to nature. The plants we eat would begin to disappear. There’s not much corn or potatoes or tomatoes anymore.

Farm animals would be easy prey for bears, coyotes, wolves and panthers. And pets? ​​​​​​The cats would be wild – that is, they would become wild, although they would have many large animals of prey. Most dogs wouldn’t survive either.

Like ancient Rome

In a thousand years, the world you remember would still be vaguely recognizable. There would still be some things; it would depend on the materials they were made of, the climate they are in, and just a little bit of luck. Here would be an apartment building, a movie theater, or a small shopping mall as monuments to a lost civilization. The Roman Empire fell more than 1,500 years ago, but some remains can be seen even today.

If nothing else, their sudden departure from the world would reveal something about the way we treated the Earth. It would also show us that the world we have today cannot survive without us and that we cannot survive if we do not take care of it. To keep it working, civilization – like anything else – needs constant maintenance.

Hello, strange children! Have a question you’d like an expert to answer? Ask an adult to send your question to CuriousKidsUS@theconversation.com. Please tell us your name, age and the city where you live.

And since curiosity has no age limit – adults, let us know what you think too. We won’t be able to answer every question, but we’ll do our best.

This article is republished from The Conversation, a non-profit, independent news organization that brings you reliable facts and analysis to help you make sense of our complex world. It was written by Carlton Basmajian, Iowa State University

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Carlton Basmajian does not work for, consult with, own shares in, or receive funding from any company or organization that would benefit from this article this, and has not disclosed any relevant connections beyond their academic appointment.