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A new way to examine humanity’s impact on the environment is to consider how the world would fare if all the people disappeared.

If all human beings vanished, for example, Manhattan (New York) would eventually revert to a forested island.
Many skyscrapers would topple within decades, undermined by waterlogged foundations.

Weeds and colonizing trees would take root in the cracked pavement, while raptors nested in the ruins and foxes roamed the streets.

According to Alan Weisman (author of book “The world without Us”), large parts of our physical infrastructure would begin to crumble almost immediately. Without street cleaners and road crews, our grand boulevards and Superhighways would start to crack and buckle in a matter of months.

Over the following decades many houses and office buildings would collapse, but some ordinary items would resist decay for an extraordinarily long time.

Stainless-steel pots, for example, could last for millennia, especially if they were buried in the weed-covered mounds that used to be our kitchens.

And certain common plastics might remain intact for hundreds of thousands of years; they would not break down until microbes evolved the ability to consume them.

Now look down the next pictures about what happens at…?
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* 2 Days after the disappearance of humans (New York City’s subway system completely fills with water.)
* 2 to 4 years (cracked streets become covered with weeds…)
* 20 Years (Dozens of streams and marshes form in Manhattan)
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* 100 Year (The roof of nearly all houses have caved in…)
* 300 Year (New York City’s suspension bridges have fallen)
* 500 Years (Mature Forest cover the New York metropolitan area)
*5,000 Years (As the casings of nuclear warheads corrode, radioactive plutonium 239 is released into the environment.)
 
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* 15,000 Years (The last remnants of stone buildings in Manhattan fall to advancing glaciers as a new ice age begins)
* 10 Million Years (Bronze sculptures, many of wish still retain their original shape, survive as relics of the human age)
* 1 Billion Years (The earth heats dramatically, but insects and other animals may adapt.)
* 5 Billion Years (The earth vaporizes as the dying sun expands and consumes all the inner planets.)
Trillions of Years (Ex-planet earth is in the Twilight Zone, still travel outward through space.

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I’m not suggesting that we have to worry about human beings suddenly disappearing tomorrow, some alien death ray taking us all away.

Think about how long it would take to wipe out some of the things, we have created. Some of our more formidable inventions have a longevity that we can’t even predict yet, like some of the persistent organic pollutants that began as pesticides or industrial chemicals. Or some of our plastics, which have an enormous role in our lives and an enormous presence in the environment.

Wouldn’t it be a sad loss if humanity were extirpated from the planet?
Would this world be beautiful without us?
I don’t think it’s necessary for us to all disappear for the earth to come back to a healthier state.

* Summarized and adapted from Scientific American, July 2007