A thought experiment in deep time

When Humans Vanish

Tomorrow morning, nobody wakes up. No war, no plague, no asteroid. Eight billion people simply stop being here, and everything we built is left exactly where it stands. Scroll to watch the planet notice.

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The moment

It happens between one second and the next. At that instant it is breakfast time in Bucharest, mid-afternoon in Tokyo and late evening in Los Angeles. Around ten thousand aircraft are in the air. Tens of thousands of ships are at sea. Kettles are coming to the boil.

+ a few minutes

The machines don't notice at first. Autopilots hold their headings. Engines idle in empty cars. Traffic lights keep cycling red, amber, green for streets with nobody on them. For a few hours our world runs on momentum, like a song still playing in an empty room.

Then the fuel runs out. One by one, over the next hours, the airliners drain their tanks and glide down, into oceans, forests and fields. It is the last human noise many places will hear for a very long time.

Data: WRI Global Power Plant Database v1.3 (2021), plants of 20 MW and above. Timings are illustrative.

The lights go out

Every dot is a large power plant recorded by the World Resources Institute: nearly 35,000 of them in 167 countries, a big but incomplete snapshot last updated in 2021.¹ Right now they are all still running. The world they feed is empty, but it is still hungry: pumps, freezers, servers, air conditioning and factory lines hum on with nobody watching.

+ the first hour

A modern grid is largely automatic. Machines balance supply and demand second by second, and they can keep that up for a while. What they cannot do is order coal, clear a fallen line, answer an alarm, or restart a plant that has tripped.

So the failures arrive one at a time. A gas supply falters. A storm brings down a line. A transformer overheats. A protection relay takes a plant offline, and nobody switches it back on. Each loss pushes the rest of the grid a little closer to the edge.

+ hours to days

Somewhere, one failure too many sets off a cascade, and a whole region goes dark in seconds. It happens at different times in different places: some grids fall within hours, others limp on for days. Hover or tap the map, or switch fuels on and off in the key, to see what is left.

+ days to weeks

A few holdouts remain. A hydroelectric dam feeding a small, isolated grid could keep its turbines turning for weeks or more, until debris or mussels clog the intakes or a fault trips it for good. A rooftop solar panel keeps charging a battery for nobody.

+ weeks

The night side of Earth is now darker than it has been since before electric light. What glows is lightning, lava, the aurora, and fires that nobody comes to put out.

On an ordinary day

Water in the tunnels

New York has been fighting water underground for more than a century. The island was once streams and marsh, and the water never really left. On a dry day, pumps in 286 pump rooms lift about 13 million gallons, some 50 million litres, out of the subway.²

When the power fails, the pumps stop. Water collects at the lowest points first, in the tunnels beneath the rivers. One of the engineers who kept the system dry put it to the writer Alan Weisman plainly: “Within 36 hours, the whole thing could fill.”³

+ months to years

Now the water starts its slow work. The steel columns that hold up the streets stand in it, and begin to rust. London, Paris and Tokyo face the same patient flood beneath their pavements.

Within a couple of decades, the columns could give way. Avenues would cave in above the tunnels, and streets built over forgotten streams would become streams again.

+ days to decades

III

The animals notice

We share the planet with roughly 25 billion chickens, 1.5 billion cattle, and nearly a billion dogs, most of them shaped by us, for us. Some will follow us out. Others have been waiting.

Head louse

No. 001

Pediculus humanus capitis

Host: humans only

It lives on human scalps and nowhere else. When we go, it goes, along with our body lice and a few gut worms that have never known another home.

✕ Vanishes

Dog

No. 002

Canis familiaris

≈ 900 million alive

Most dogs on Earth already roam free. The toy breeds don’t last. After a few generations the survivors converge on one look: medium-sized, tan, prick-eared, curly-tailed, the classic village dog.

◆ Adapts

House cat

No. 003

Felis catus

Never fully domesticated

An efficient, independent hunter that only half signed up to living with us. It does just fine. Songbirds pay the price.

▲ Thrives

Chicken

No. 004

Gallus gallus domesticus

≈ 25 billion alive

Together they weigh more than twice as much as all wild birds.⁴ Most live indoors and die within days when feed and ventilation stop. A few village flocks in warm places go feral, like their jungle ancestors.

✕ Vanishes

Cattle

No. 005

Bos taurus

≈ 1.5 billion head

Dairy cows, bred to be milked, suffer first. Hardy breeds go wild in herds and become prey for wolves again, as the aurochs once were.

◆ Adapts

Sheep

No. 006

Ovis aries

Wool never stops growing

Most breeds depend on shearing. In 2004 a runaway merino called Shrek was found in New Zealand after six years in hiding, carrying 27 kg of fleece.

◆ Adapts

German cockroach

No. 007

Blattella germanica

Tropical by origin

It conquered the cold north by living inside our heated buildings. The first winter without heating wipes it out across the colder half of the world.

✕ Vanishes

Brown rat

No. 008

Rattus norvegicus

Lives on our garbage

The bins stop filling. Numbers crash, then settle, as rats become ordinary prey again for owls, foxes and hawks moving into the city.

◆ Adapts

Bread wheat

No. 009

Triticum aestivum

≈ 220 million hectares

We bred its ears to hold on to their grain until harvest, so it can barely sow itself. After a few seasons without ploughing, it loses to the weeds.

✕ Vanishes

Grey wolf

No. 010

Canis lupus

Already returning to Europe

With hunting over and deer, boar and feral cattle everywhere, wolves spread across whole continents within decades.

▲ Thrives

Atlantic cod

No. 011

Gadus morhua

≈ 90 million t of wild fish caught a year

The nets come up empty for the last time. Many fish stocks rebuild within decades, and the great shoals of the North Atlantic may fill the sea again.

▲ Thrives

Migrating songbirds

No. 012

Passeriformes

Up to 1 billion window deaths a year, US alone⁵

Most migrate at night, and our lit windows lure them into glass. With the lights out, the night migration flies safely again.

▲ Thrives

Honeybee

No. 013

Apis mellifera

≈ 100 million managed hives

Without beekeepers, many hives fall to parasitic mites. But thousands of wild bee species boom as the pesticides break down and meadows return.

◆ Adapts

African elephant

No. 014

Loxodonta africana

≈ 415,000 left (2016 estimate)

No more poaching, and farmland turning back into savanna and forest. They breed slowly, so reclaiming their old range takes a few centuries.

▲ Thrives

Which sites fall into which group depends on fuel age, design and backup systems. The split shown is illustrative.

+ seconds

The cooling pools

There are more than 400 nuclear reactors in the world. When the grid collapses they do exactly what they were designed to do. Control rods drop, and within seconds the chain reaction stops.

The fuel keeps making heat anyway. Beside each reactor, in deep pools, sit years of spent fuel rods that are kept under circulating water. Backup diesel generators take over the pumps. Their tanks are typically sized to run for about a week.

+ weeks to months

What happens next depends on how fresh the fuel is. Rods that left the reactor years ago have cooled so much that air alone could keep them safe.⁶ Rods unloaded in the last months are another matter. Without pumps, their pool could slowly boil down, and if the fuel is uncovered, its zirconium casing could catch fire.

+ months

So the map does not turn uniformly red. Many sites simply go quiet. A minority, those holding hot, freshly unloaded fuel, could become serious accidents with nobody there to stop them. At Romania's Cernavodă, fuel cools in pools for six to ten years and then moves into concrete dry-storage modules that need no electricity at all.⁷

Chornobyl, since 1986

Where it does go wrong, Chornobyl hints at what follows. Within three decades of the evacuation, its exclusion zone was full of elk, boar, lynx, bison and wolves. The radiation is still written into those wolves' blood and immune systems.⁸ Our absence simply mattered more.

Light pollution

Bortle 9

+ days to weeks

The sky clears

Within days, the last contrails dissolve. Within weeks, rain rinses the soot and sulphate haze out of the air, and horizons move back. In the spring of 2020, when the world briefly slowed down, people in Punjab saw the Himalayas from their rooftops for the first time in decades. This time the mountains stay.

+ weeks

And the night comes back. Today more than a third of humanity cannot see the Milky Way from home.⁹ Now it rises again over every city on Earth, for no one. Drag the slider to compare.

There is a cruel twist. That haze was shading us, bouncing sunlight back to space. With it gone, the planet warms by a few more tenths of a degree over roughly a decade,¹⁰ a hidden bill that falls due once nobody is left to pay it.

The forest moves in

In the first spring, weeds find the cracks in the pavement. Every crack is a seedbed, and for the first time, nobody comes to pull out what grows there. In cold cities, the first winter freezes the water in the pipes, and the pipes split.

Freeze and thaw is a city's oldest enemy. Water seeps into a crack, freezes, grows by nine percent and pries the crack wider. Roofs begin to leak. Once rain gets inside a building, the countdown has started.

Lightning hits a dry roof, and there is no fire brigade. Fires run through the wooden neighbourhoods, fed by years of dead leaves in the gutters. Their ash enriches the soil. The first trees are now taller than the lamp posts.

Inside the concrete, the steel reinforcing bars rust. Rust takes up several times more room than steel, so the bars burst the concrete from the inside. Balconies drop. Facades peel away in slabs.

Most wooden houses have collapsed by now. The suburbs go first, because our homes were never built to last without us. Brick chimneys stay standing among the trees, like bookmarks.

With their windows gone and rain pouring in, steel-framed towers start to buckle. Some fall. Others stand as hollow cliffs where peregrine falcons nest, as they already do today. The streets below are a forest.

The great suspension bridges, unpainted for centuries, drop into the rivers they once crossed. In Panama, the canal has long since silted up, and the two Americas are joined again.

After a thousand years, a city is a cluster of wooded hills, oddly straight-edged, with rubble under the moss. Only what was made of stone, glass and very thick concrete still shows through.

VII

Closer to home

Romania is a good place to watch the world heal. It already has some of Europe's wildest mountains, one of its great river deltas, and a glimpse, just across the border, of what happens when people leave. Tap a marker, or keep scrolling.

Since 1986

Chornobyl, the rehearsal

The exclusion zone straddles Ukraine and Belarus: more than 4,000 square kilometres almost empty of people for four decades. In its Belarusian half, researchers counting animals found elk, deer and boar as common as in nature reserves, and wolves more than seven times as numerous.¹¹ It is the closest thing we have to a preview of this story.

The Carpathians

A genetic survey of some 24,000 samples put Romania's brown bears at between about 10,650 and 12,800 in 2025, Europe's largest population outside Russia.¹² Wolves and lynx share the forest with them. With the guns silent and the orchards of abandoned villages dropping fruit, the bears move downhill. They already visit the edges of Brașov. Within decades, its streets belong to them.

Transfăgărășan

Nobody clears the road in spring. Within a few winters, rockfalls and avalanches cut it. Within a century, the most famous hairpins in Europe are a faint zig-zag of young forest on the mountainside.

The Danube Delta

From the 1960s to the 80s, dykes turned large parts of the delta into farms and fish ponds. Unmaintained, those dykes fail one flood at a time, and the river takes its marshes back. Europe's largest reed beds spread, and pelicans, among more than 300 bird species, return to nest in them.

The Bărăgan

Not everything turns into forest. The plains of the south-east were steppe long before the plough, and they go back to grass. Horses from abandoned farms, gone wild, graze where the wheat was.

The Iron Gates

The Porțile de Fier dam, one of Europe's largest hydropower plants, might keep a few lights burning longer than almost anywhere in the Balkans. The dam itself should stand for centuries, while its lake slowly fills with the silt of half a continent.

Bucharest

The Palace of the Parliament weighs around four million tonnes, one of the heaviest buildings on Earth. Long after the apartment blocks around it have fallen, it will still be there. After a thousand years it is a great wooded hill in the middle of a forest, with marble underneath.

VIII

What lasts

Everything we make is slowly returning to the ground. Some of it just takes much longer. Drag the slider to travel forward in time and see what is still standing. The bars show the rough spread of estimates, because nobody has been able to check.

Years after us 1,000

Show the estimates as a table

Thing	Rough lifespan	Why
Books in an abandoned library	5–60 years	Roofs leak, mould and insects do the rest.
Asphalt roads	20–150 years	Split by frost and roots, then buried under soil.
Wooden houses	40–150 years	Rot, termites and fire. The suburbs go first.
Cars	50–300 years	Rusted to lumps, then to red stains in the soil.
Steel-frame skyscrapers	100–500 years	Water gets in, the steel rusts, the joints fail.
Aluminium cans	100–500 years	Slowly oxidised, faster in salty or acidic soil.
Suspension bridges	150–600 years	Unpainted cables and bolts corrode until the deck drops.
Plastic bottles	400–2,000 years	Sunlight breaks them into ever smaller fragments that linger.
Great concrete dams	1,000–10,000 years	Massive enough to stand for millennia as their lakes silt up.
Glass bottles	10,000–1 million years	Chemically tough. Buried, they can last almost indefinitely.
Plutonium-239	24,100–241,000 years	Half gone after 24,100 years, a thousandth left after ten half-lives.
The last of our extra CO₂	100,000–500,000 years	Removed by the weathering of rock, the slowest cleaner there is.
The Great Pyramid	100,000–1 million years	Dry climate, huge stone blocks. Sand wears it down slowly.
Faces of Mount Rushmore	100,000–2 million years	At the Park Service’s estimate of 2.5 cm per 10,000 years. Frost in unsealed cracks could be faster.
Bronze statues	100,000–10 million years	A green patina protects them. In sediment they could last millions of years.
Footprints on the Moon	1 million–100 million years	No wind, no rain. Only tiny meteorites slowly blur them.
Satellites in high orbit	1 million–100 million years	Geostationary satellites stay up for millions of years.
Our layer in the rock	1 million–1 billion years	Concrete, aluminium, plastic films, odd isotopes: a permanent signature.
Voyager’s golden record	500 million–5 billion years	Designed to last a billion years in interstellar space.

Carbon dioxide in the air, parts per million · illustrative model

Not a forecast. The curve adds up decay processes (ocean uptake, carbonate dissolution, rock weathering) with the shape and timescales described by Archer et al. (2009); the band shows how much the lingering fraction varies between models.

The day we vanish

The air remembers

On the day we vanish, the air holds about 428 parts per million of carbon dioxide, NOAA's global estimate for September 2026,¹³ up from 280 before the industrial age. The smokestacks go cold, but the carbon is already up there.

The oceans and new forests start drinking it back, quickly at first, then slowly. A century on, the level is probably still higher than at any time in the two million years before us.

Once the oceans have had their fill, somewhere between a fifth and a third of our carbon is still in the air,¹⁴ and the planet stays warmer than in 1850. Ice sheets keep melting for centuries, and the seas keep rising for thousands of years.

The last of it is removed by rain, slowly dissolving rock and washing the carbon into the sea, where it becomes limestone. That takes hundreds of thousands of years. Our exhaust, it turns out, is one of the longest-lasting things we left behind.

Stone and ice

Ten thousand years is about the time since the first farmers. It is enough to erase almost everything we built. The Great Pyramid probably still stands, a little blunter. Stretches of the Great Wall survive as a line of low ridges across the hills.

By now, half of the plutonium-239 that existed on the day we vanished has turned into uranium. Wait another 24,100 years and half of what is left goes the same way. The planet is rid of it the slow way, one halving at a time.

Without us, this warm spell would probably have lasted about another 50,000 years anyway. Our carbon stretches it further: in one model, 1,000 to 1,500 billion tonnes of emitted carbon postpone the next ice age by at least 100,000 years.¹⁵ We had released some 740 by the day we vanished.¹⁶ But the ice is patient. If it grows like the last one, it will grind Chicago, Toronto, Stockholm and Berlin into gravel. Bucharest, far to the south, is spared.

The Park Service estimates that Mount Rushmore's granite wears away about 2.5 cm every ten thousand years.¹⁷ At that rate the faces would still be recognisable after a million years, unless frost gets into the cracks that nobody seals any more. Most of today's species are probably still around. New ones are appearing on islands.

Rock laid down after us
Our layer
The age of farmers
Ice-age gravels
The world before

A line in the rock

The raw material of that rock is already here. Around 2020, the concrete, asphalt, brick, metal, glass and plastic we had made reached roughly 1.1 trillion tonnes, which by one careful accounting outweighed all life on Earth.¹⁸ We were adding about 30 billion tonnes more every year.

Buried and squeezed, it becomes rock. Concrete would look like an odd conglomerate. Aluminium, which nature almost never makes pure, could survive as glinting flecks. Some plastics may flatten into thin films of carbon, the way fossil leaves do.¹⁹

A geologist of the far future might find a band only centimetres thick across open country, and metres thick under old cities and landfills. It would hold strange minerals, carbon with an unmistakable isotope fingerprint, and bones, an enormous number of chicken bones.²⁰ Hover or tap the rock to read its layers.

Life will long since have rebuilt its variety. After the great extinctions of the past, including the asteroid, that took on the order of ten million years.²¹ The creatures of that world will walk over the line without knowing what it means.

Already on its way

XII

The last message

One thing we made may outlast life on Earth itself. Two small spacecraft, Voyager 1 and 2, are more than 20 billion kilometres away and still going. Bolted to each is a gold-plated record of Earth: rain, a heartbeat, a kiss, greetings in 55 languages, Bach and Chuck Berry.

Its makers expected the record to survive for more than a billion years.²² Around then, a slowly brightening Sun is expected to start boiling Earth's oceans away. The record will still be drifting between the stars, playing to no one, a letter with no return address.

Earth doesn't need us. It recovered from the asteroid and from the ice, and it will recover from us. But it will remember us for a long time: in a line in the rock, in the air for a hundred thousand years, in a golden record among the stars.

So the thought experiment leaves one question, and it is about now. What would we like that line in the rock to say?