…we don't know how - that doesn't matter.
What we'd like to know is...
What would a world without humans be like?
Within days, the electricity grid fails as fuel supplies run out
and there's nobody to override the powerstation's failsafe mechanisms.
Within a week the subways we've built under the water table flood.
The 47 million litres of water
that was pumped out of the London Underground every day
inundates tunnels.
Without heating or air conditioning
mould flourishes on moist surfaces in homes and offices
and ice bursts pipes.
Within weeks, plants begin to take over buildings
as the strongest species compete for space.
No-one's there to cut them back.
Fast forward in time.
The lines between city and countryside are blurred.
Windows fall out of rotten frames and wildlife recolonises towns.
Farmland is blanketed by scrub and then trees,
and scattered on the surface are the things that will never degrade.
Metals corrode. Plastics start to break down and disperse.
But stainless steel pans, stranded granite work tops
and billions of car tyres remain.
Nuclear facilities fail as their fabric degrades.
Some explode, irradiating the local ecosystem
and causing many animals to die.
The radiation leads to mutations in others
creating new evolutionary lines.
Meanwhile, the tiniest of plants
are stubbornly breaking up even the motorways.
Mosquitos are having a great time.
They've lost their enemy in us
but they've moved on to other animals.
And they're busy pollinating plants as they love nectar as well as blood.
Endangered animals have a chance and space to multiply again.
Lions and elephants could even reach Europe,
the strongest swimming across the Suez Canal.
Massive whirlpool islands of plastic carry on spinning in our oceans.
Each piece of plastic is ground down
until microscopic grains of it are everywhere.
Bacteria may evolve to digest plastic,
but this will take millions of years.
Could the Earth ever recover?
Atmospheric carbon dioxide is absorbed
by the vegetation that carpets the land.
Global temperatures and sea levels begin to fall.
As chemical pollutants break down and sink into the earth,
rivers become cleaner.
Animals and plants flourish.
Is this a new Eden?
Perhaps.
The Earth is a breathing organism
that has lived with us for a fraction of its life.
Our human ingenuity has led to extraordinary changes to the world.
The planet would survive, indeed thrive, without us.
But it would never be able to forget us.
We'd have left our mark.
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