If humans suddenly disappeared, what would happen to our planet?

Answered May 18, 2015

Originally Answered: What do you think would happen to earth if all the humans disappeared?

What would happen to the world without us supposing we disappeared for non-destructive reason (Like a nuclear war or so) would be very similar I believe to the following:

*Humans just magically faded away or every single one of them falls dead to the ground*

2 days after humans disappear

Without pumping many cities subway systems including those in New York would impassibly flood.

7 days

The emergency fuel supply to diesel generators that circulate cooling water to nuclear reactors cores would run out.

Somewhat similar to what happened to Japan's Fukushima nuclear reactor, the consequences of this could vary since no human hand is there to prevent a catastrophe.

1 year

Worldwide, a billion annually doomed birds would live when radio and communication tower warning lights ceased blinking and high tension wires grow cold.

Animals would begin to return to the sites of nuclear reactors, which would have all melted down or burned. Human head- and body-lice would grow extinct.

3 years

With no heat pipes would burst all over towns in temperate or colder zones. Building would groan as their innards expand and contract; joints between walls and roof lines would separate. With no heated shelter, cockroaches in temperate cities would die after one or two winters (Finally some good news!)

10 years

The barn roof with the 18 x 18 hole that was already leaking a decade earlier is long gone. Now an enormous hole has taken its place, reaching corner to corner.

20 years

The water-soaked steel columns that support the streets above New York’s East Side trains would corrode and buckle. The Panama Canal will have closed, reuniting the Americas

Common garden vegetables will have reverted to unpalatable wild strains.

100 years

With no ivory trade, half a million remaining elephants increase twenty-fold. Populations of small predators, raccoons, weasels, and foxes diminish due to competition from a human legacy – immensely successful feral housecats. Cats would be the new rulers!!

WORLD DOMINATION!

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300 years

New York’s bridges would fall. Dams worldwide would have silted, overflowed, and toppled. Cities such as Houston, built in river deltas, would wash away.

500 years

If the climate was temperate, a forest would stand in place of a suburb; minus a few hills, it would begin to resemble what it was before developers, or the farmers they expropriated, first saw it. Amid the tress, half concealed by a spreading undergrowth, would lay aluminum dishwater parts and stainless steel cookware, their plastic handles splitting but still solid.

Thousands of years

Any stone walls still standing in New York City would finally fall to glaciers. The only intact human structures would be those originally built deep underground, such as the English Channel’s “Chunnel.”

35,000 years

Lead deposited during the smokestack era would finally be cleansed from the soil (cadmium in 75,000 years).

100,000 years

CO2 Would be back to pre-human levels (Although it might take even longer)

250,000 years

The levels of plutonium in plutonium bombs, whose metal casing long before corroded away, would be lost in earth’s natural background radiation.

Hundreds of thousands of years – Unknown

Microbes would evolve to biodegrade plastic (Let’s remember it’s been quite a few millennia)

7,200,000 years

Vestiges of Mt. Rushmore’s likenesses would remain, barring asteroids or violent earthquake. Toxic man-made chemical compounds, such as PCB’s and dioxins, would likely also still be intact, although mostly buried.

10,200,000 years

Bronze sculptures would still be recognizable so you really should try to make one of yourself now and put it in your backyard, so maybe aliens would find you and think you were some sort of god!

3,000,000,000 years

Life, albeit in forms we probably wouldn’t dream of, would still thrive on Earth.

4,500,000,000 years

The half-million tons of depleted Uranium-238 in the U.S. alone would have reached its half-life. Earth would begin to warm as sun expands. For at least another billion years, Microbial life resembling the first life on Earth would outlast every other life-form

+5,000,000,000 years

The Earth would burn as the dying sun swells to envelop the inner planets. Knowing this is one of the reasons scientist search a way to travel to other planets and galaxies although some may consider we still have a very good margin to make it possible.

Forever

Now this is quiet impressing Our radio and television broadcasts, fragmented as they may be, would still be travelling outward so if an alien civilization actually gets to travel towards earth’s direction they could receive this transmissions and sort of try to understand how our civilization was and why we faded away (if there was any reason at all).

I found most of this answers from The World Without Us book and site from Alan Weisman on the topic, totally worth reading.