Are we the last technologically advanced civilisation ever on Earth?
It’s possible.
Humanity has risen to the position of the dominant species on the planet, 8 billion
strong.
We have planes, cars, robotics, advanced computers, and the capacity to send our spacecraft to
distant celestial objects; and soon maybe we will even travel there ourselves.
And yet Rome wasn’t built in a day, nor without cost.
It has taken billions of tons of coal, oil, and natural gas to fuel the industrial revolutions
that have made society into what it is today.
Those resources are not infinite; and they will take millions of years to replenish themselves.
Which begs an interesting question: Was this a one-time deal?
If something were to happen to civilisation – if some cataclysm or nuclear holocaust
were to send us all technologically back to the stone age, or even wipe us out completely
– are there enough resources left that some future civilisation could rebuild?
Or are we now the first and last civilisation birthed by our Earth that will ever reach
for the stars?
And if so, why?
I’m Alex McColgan, and you’re watching Astrum.
And today we will explore the rise of our technologically advanced society, and learn
what materials you need to build what we now have.
And then we will discover how much of those vital ingredients are left.
But for the sake of this thought experiment, let’s start by activating doomsday right
now.
Boom.
In one fell swoop, humanity has been sent back to the stone age.
All technology has been annihilated, perhaps in a horrific nuclear exchange.
Human society has collapsed.
Whoever survived is now tasked with rebuilding civilisation in a world with no buildings,
no machines, no books and (perhaps worst of all) no internet.
Let us say for the sake of this thought experiment that natural resources are unharmed, but nothing
can be salvaged from the civilisation before.
Like the ultimate survival game, everything must be built from scratch.
Once our survivors have gotten over the shock of this horrifying turn of events, they will
quickly realise that they need at least three vital things if they want to live: food, clothing
and shelter.
And fortunately, these are all accessible through various renewable sources.
These will not be the limiting factors when it comes to restarting civilisation.
With wood, you have building materials.
Wool or cotton can be woven into clothing.
Animals, vegetables and fruit can be hunted and gathered for sustenance.
Conveniently, these natural resources can be accessed with some very simple tools – some
sharp sticks for hunting and fishing, and some simple axes and knives for chopping and
fashioning wood, made out of nothing more than sharp stones tied to sticks with hempen
rope.
With this as its base, a civilisation that develops after us could absolutely and easily
reach a thriving hunter-gatherer society . It should even be possible to get further than
that, although if our civilisation is ever going to get to the stars again they will
need to start by stepping up from stone tools to bronze and iron.
For bronze – an alloy made from mixing tin and copper – wood burning fires will be
enough to get by.
Metal ores extracted from the ground need to be melted, to separate the rock and impurities.
Smelting tin requires temperatures of 230°C, and smelting copper needs a little under 1100°C.
Fortunately, a large wood-based bonfire can reach temperatures of 1100°C, making bronze
just about accessible to our new civilisation.
But it is with iron that the problem comes into a focus.
Iron is tricky.
While this metal is extremely plentiful in the Earth’s crust, its melting point of
1,583°C means our fledgling civilisation would need to do more than just place it on
a wood-based bonfire to be able to smelt it.
Fortunately, there are workarounds to this problem.
By partially burning wood in low oxygen conditions you can make charcoal, which burns at a higher
temperature than the wood it’s formed from due to the fact that the initial combustion
cost of getting rid of all that water and sap has already been paid.
This can be further enhanced by placing your fire in a kiln, and controlling air flows.
With the right flow, even a wood-burning fire can reach temperatures of 1500°C, such as
with the record-breaking Zhunan Snake kiln in Taiwan.
But using charcoal comes at a cost – you need a lot of forestry if you’re going to
get enough wood to support a metal-hungry civilisation.
It will need to be re-planted regularly, but more crucially, you won’t be able to turn
that land into farmland – something your civilisation will also need if it wants to
grow and develop.
This is why most nations use fossil fuels to produce their steel.
Coal or methane gas can be used to create incredibly hot fires, without requiring you
to give up your farmland.
You might be wondering if our new civilisation could do without these fossil fuels.
If we just grew a little more slowly, with a smaller population, couldn’t we make charcoal
work?
Charcoal is carbon neutral, as the trees that create it grow by removing carbon from the
atmosphere.
Couldn’t a new civilisation reach our level and get to space again without using fossil
fuels in their production?
The answer is no.
The absence of fossil fuels would be devastating for a civilisation trying to reach for the
stars.
This may be an uncomfortable thought, but just consider for a moment the degree to which
our own civilisation uses coal, oil and gas.
Now, I’m not advocating that we don’t need to do better - just because we currently
use a lot of fossil fuels as a species doesn’t mean we shouldn’t try and reduce and care
better for the planet.
At the end of the video, I’ll talk about Planet Wild, a channel that goes into that
in more detail.
However, when we talk about using fossil fuels, it’s easy to think about them only in terms
of electricity production – which our new civilisation would need to get to if it wanted
to get back to space-travel.
In fairness, fossil fuels remain the world’s primary energy source – in 2022, 83% of
the world’s energy came from these sources.
But fossil fuels are also incredibly important in the production of four other vital ingredients
for our civilisation.
I’ve already mentioned steel, for which our current global demand sits at 1.8 billion
tons a year due to its strength and durability as a building material; but there is also
concrete, plastic, ammonia and silicon.
Can you imagine our world without concrete?
Without fossil fuels, you would probably have to.
The sand and gravel that makes concrete up are easy enough to acquire, but the cement
that binds it all together – made from a mixture of limestone and clay – requires
temperatures of 1400°C to melt them together properly.
If our new civilisation wanted to make concrete (which would be useful, as it’s an extremely
malleable, durable building material, useful for building a space port for launches and
many other buildings and platforms), they would need to find a fuel that could burn
at that temperature.
The civilisation that comes after us would need a lot of charcoal to fill the gap if
fossil fuels were no longer on the table.
But that’s not even an option for silicon.
Silicon has widespread use in our society – from ceramics to brickwork – but by
far its most influential trait is that, once refined and purified, it is the element used
to make computer chips thanks to its abundance and its properties as a semi-conductor.
It’s extremely easy to find in its raw form, but refining it is a complex process that
requires temperatures of 2350°C. Charcoal does not burn that hot.
Not for nothing have the last 100 years been referred to by some as the silicon age.
Can you imagine our world without computer chips?
In terms of getting to space, the computers that guide and control the launch of a rocket
would certainly struggle without computer chips.
There’s more.
Ignoring materials that simply need high heat to smelt or refine, fossil fuels are literally
a building material we use to make our products and feed our population.
While we sometimes express concern about the amount of plastic being used in the world,
there’s no denying its importance to modern civilisation.
It makes keyboards, boxes, sterile tubes and syringes for medical applications, polyester
clothing, car bumpers, windmill turbines.
Yes, even “green” energy sources like wind turbines are made out of materials that
require fossil fuels.
A wind turbine is around 70% steel, and 10% plastic.
Both are fossil fuel reliant.
Plastics are also used in rocketry.
Having a lightweight material that’s easy to mould, fairly rigid, and above all light
is extremely useful for rockets that are trying to shave every gram of weight off.
Launching without plastics makes rockets much heavier, requiring more fuel or smaller payloads.
Finally, let’s consider ammonia.
While you might think we could do without plastic in our lives, without ammonia, it
is likely that about half of the Earth’s present population would starve to death;
which, while not directly related to getting to space, is a bit of a problem on its own.
Ammonia is used in fertiliser.
Although other natural fertilisers exist, they lack the potency provided by ammonia.
Without ammonia, we simply would not be able to sustain the amount of food production that
we need to support the global population; not by half.
And ammonia is made from methane, which is mainly sourced from natural gases.
When viewed through this lens, it’s easy to see the scale of the challenge that would
be faced by a civilisation trying to reach a technological level where they could explore
space, if they didn’t want to or didn’t have access to fossil fuels.
And let’s be honest.
The easiest to get to fossil fuels on Earth are now mostly gone.
You need serious equipment to get to the fossil fuels we are now extracting, which required
fossil fuels in the first place to build.
Our civilisation has been built on the back of fossil fuels.
They provide our plastic, our steel, our concrete for our buildings, and our energy.
Without them, we would struggle to produce the metal for a rocket, or the fuel that powers
it, or the computers that guide it.
And so, for the sake of our thought experiment, how much fossil fuels have we used?
And is there enough left so that a civilisation that came after us could do it all again,
if they had to?
It’s difficult to find estimates that accurately lay out how much fossil fuels have been used
up by this point.
Our current usage is at around 15 billion metric tons per year, although this figure
has been climbing for some time so will likely continue to increase as our population does.
However, by projecting our current usage back across the past, and by factoring in the increase
in demand over time since 1800, when the industrial revolution roughly began, it’s possible
to arrive at a ballpark estimate of 750 billion metric tons of fossil fuels consumed by the
human race to get to where we are now, by multiplying our current yearly usage by the
number of years between 1800 and now and then approximately quartering the result, to reflect
the fact that demand was considerably lower for most of that time.
Now we do not know how much fossil fuels we have left.
Current estimates based on proven reserves suggest that we will start running out of
fossil fuels in just 50 years time.
Coal will last longer – coal reserves should keep the lights on for up to 130 years – but
oil and natural gas could potentially be all used up in the lifetime of people around today.
Calculating based on our current usage, this works out to at least another 750 billion
tons of fossil fuels remaining – the same amount that got us to this point, only we’re
currently burning through it much faster.
Of course, this number could be much higher.
This estimate is based only on proven reserves.
If more oil fields are found, or technology is developed that can allow us to access fossil
fuels better, the amount of fossil fuels available in the planet could be a lot higher than current
estimates.
Still, this is enough information to provide us with our answer.
A civilisation that rises after us would indeed have enough resources to get to the same technological
level that we are currently at.
But, they would likely find it much harder, as much of those untapped fossil fuel reserves
are buried at much deeper depths than the ones our own civilisation found.
We have burned the supplies that were easy to get to already.
In 1950, the average depth you needed to drill to access oil was 1.1km.
This now stands at 1.8km, but some oil and gas fields are as deep as 9.1km.
It wouldn’t be easy.
But the resources are there.
For now.
If we ask this question again in 50 years time, we might arrive at a different answer.
It might be necessary for future civilisations to get used to the idea of a more comfortable,
arable existence.
Still, if there is a ray of hope to shine on this, it is that necessity is the master
of innovation.
The materials we use are the most effective at what they do, but that’s not to say that
with sufficient will, a new civilisation that comes after us couldn’t get to the stars
again even without fossil fuels.
They might need to go slower, their population might never reach our levels, and many would
have to make do with rougher tools or suboptimal materials.
But where there is a will, there is a way.
Perhaps a future civilisation will one day harvest methane from bio-waste.
Methane can be used as a rocket fuel.
Without fossil fuels, the civilisations that came after us would look very different from
our own.
They would have different priorities, and would perhaps use their land with a different
focus in mind.
But perhaps they could get to the stars in their own way.
All this talk about fossil fuels might have left a sour taste in your mouth, but it’s
important to recognise that there’s still incredible things people are doing to fix
our planet, too.
For today’s video we’ve partnered up with another YouTube channel called Planet Wild.
Their environmental action channel shows incredible rewilding missions they go on – a new one
every month – to rewild our planet and fix the damage that humans have done to our environments.
Here’s an awesome video about them reforesting a dying forest in Germany, and here’s one
where they save Europe’s cutest bird from extinction.
Their videos are super entertaining, as they combine education with real world environmental
action.
And it’s all driven by a community that anyone can join, to help our planet bounce
back – go give them a watch!
Thanks for watching.
Want more thought experiments?
Check out this playlist here.
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All the best, and see you next time.