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The Anthropocene – Humanity as a Geological Force · Talking Science

0:00
Welcome to the deep dive. Whether you are prepping
0:03
for a meeting, commuting, or just, you know,
0:05
insanely curious about the world, you are in
0:08
the right place. Yeah, we have a really fascinating
0:10
one today. We really do. So today we are taking
0:12
a stack of really profound source material and
0:15
unpacking an idea that, well... it might just
0:19
shift how you see your entire existence on this
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planet. Which I know sounds like a massive promise,
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but the concepts here are just wild. Right. So
0:28
to get into the right headspace for this, I want
0:30
you to just imagine the Earth as this massive
0:34
ancient archivist, like just this silent librarian
0:38
methodically writing down literally everything
0:41
that ever happens on the planet. Obviously, you
0:43
know, it's not using paper and ink. Yeah, no,
0:45
no paper. It is logging the shifting continents,
0:48
the ice ages and, you know, the occasional catastrophic
0:51
asteroid impacts all in layers of mud, ice and
0:55
stone. It's just a completely impartial record
0:57
keeper. I mean, the planet simply absorbed whatever
0:59
happens on the surface and permanently presses
1:01
it into the rock layers for the rest of time.
1:03
Right. And for billions of years, that process
1:06
was driven entirely by blind natural forces.
1:09
But the source material for our deep dive today,
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it forces us to confront this staggering concept.
1:17
Yeah, the idea that we are no longer just living
1:18
on the Earth. Exactly. The argument on the table
1:21
is that human beings have become a geological
1:23
force so overwhelmingly powerful that, well,
1:27
we are changing the planet on a scale that will
1:30
be perfectly legible in the rocks millions of
1:32
years. We are essentially the ones writing in
1:35
the Earth a diary now. And this brings us to
1:38
the core concept of our exploration today, which
1:40
is the Anthropocene. The Anthropocene. Yeah.
1:42
It's a term you might have heard, like bleeding
1:44
out of academic geology and into just everyday
1:46
conversation. So Anthropo, meaning human, and
1:49
scene. referring to a geological epoch. It's
1:53
just such a heavy, provocative idea. So our mission
1:55
today is to take an unhurried, you know, jargon
1:58
-free look at what it actually means. Absolutely.
2:00
We're going to break down how time actually works
2:03
for a planet, what specific evidence we are currently,
2:06
like, burying in the dirt for future geologists
2:10
to find, and perhaps most surprisingly, the fascinating
2:13
scientific drama over whether this new era is
2:16
actually officially real. Let's start with the
2:19
foundational piece here because... To understand
2:23
how humans are supposedly hijacking the geological
2:25
record, we really first have to understand how
2:27
the Earth actually keeps time. Right, which is
2:30
totally different from human history. Oh, completely.
2:32
We have to step out of the realm of human history
2:35
and into what geologists call deep time. I mean,
2:38
the Earth is about four and a half billion years
2:40
old. Which is just a number our brains simply
2:42
aren't wired to comprehend. No, not at all. It's
2:44
too big. I was reading about this in the sources,
2:46
and the way geologists manage this immense span
2:50
of time is through, like, this nested hierarchy
2:53
of named time intervals. Yeah, it helps break
2:55
it down into manageable chunks. Right. So you
2:58
start with the largest chunks called eons, and
3:00
those are broken down into eras, which are broken
3:02
into periods, which finally break down into epochs.
3:05
Think of it like the folders on your computer
3:09
or just a basic calendar. That's a great way
3:11
to put it. Yeah. So years contain months, months
3:14
contain weeks, weeks contain days. It's all nested.
3:17
And to visualize how they actually read this
3:19
calendar. You know, you have to think about stratigraphy,
3:22
which is the study of rock layers. Okay. So when
3:25
a geologist looks at a canyon wall or, say, a
3:28
deep core sample taken from the ocean floor,
3:31
they are essentially looking at the spine of
3:33
a massive book. Over millions of years, dirt,
3:36
sand, organic matter, it all settles at the bottom
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of lakes and oceans. Just piling up slowly over
3:42
time. Exactly. And the immense pressure from
3:45
the earth compresses that sediment into solid
3:47
rock. As the environment changes, the type of
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sediment changes. Yeah. And that creates these
3:52
distinct visible bands or strata. So the boundaries
3:56
between an era or an epoch, they aren't just
3:58
arbitrary dates we picked. It's not like the
4:00
boundary between December 31st and January 1st
4:03
on our calendar. Right. Nature didn't just print
4:05
a new calendar page. In geology, these boundaries
4:08
are massive, unmistakable physical lines in the
4:11
stone. Yeah, they mark genuine planet -wide physical
4:15
changes. Like for a new geological time interval
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to be formally recognized, there has to be a
4:21
distinct signature preserved in those rock layers.
4:23
And it has to be everywhere, right? Exactly.
4:26
It must be clear and global enough that a geologist
4:29
digging in, I don't know, Australia and another
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one digging in Canada can both point to the exact
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same anomaly. Wow. OK, so what kind of anomalies
4:38
are we talking about? Well, we are talking about
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things like the sudden rise or fall of huge groups
4:42
of life, mass extinctions, dramatic shifts in
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the Earth's climate or massive changes to the
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composition of the atmosphere. Which brings us
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to the geological folder we currently occupy.
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Because officially, according to the current
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geological calendar, we live in an epoch called
4:58
the Holocene. Right. And the Holocene began nearly
5:00
12 ,000 years ago, just right at the end of the
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last ice age when massive glaciers finally retreated.
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And the sources made a really interesting point
5:09
here. When geologists look at the rock and ice
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core layers from the Holocene, the defining characteristic
5:14
they see is just incredible stability. Yes. It
5:19
has been this remarkably warm, quiet, stable
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stretch of planetary time. And the significance
5:25
of that stability for you listening right now,
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it honestly cannot be overstated. That quiet
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stretch of 12 ,000 years. is literally the cozy
5:34
cradle in which all of human civilization has
5:37
flourished. It really is. I mean, it's essentially
5:39
been the Goldilocks zone for humanity. Right,
5:41
because every farm, every city, every written
5:44
word, every empire that rose and fell, all of
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it only happened because the Holocene provided
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a stable climate window. The predictable seasons
5:50
allowed us to invent agriculture. And that allowed
5:53
for static populations, which, you know, eventually
5:56
allowed for the modern world. But, and here's
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the massive pivot. If the Holocene is defined
6:00
by that beautiful, quiet stability, the whole
6:02
proposal of the Anthropocene argues that human
6:05
activity has violently ended that quiet period.
6:08
Right. The argument is that we have pushed the
6:10
Earth into a brand new, fundamentally different
6:12
chapter. But I want to dig into the mechanism
6:14
of this. Because if geological boundaries require
6:18
a permanent physical marker in the rock, you
6:22
know, like the iridium layer left by the asteroid
6:24
that wiped out the dinosaurs. What on earth are
6:27
humans laying down today that will survive the
6:30
shifting tectonic plates? That's the big question.
6:33
Like, are future geologists going to find fossilized
6:35
smartphones millions of years in the future?
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Well, I mean, probably not an intact smartphone.
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Yeah. But it really all comes down to permanence.
6:44
What is going to become the rocks of tomorrow?
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Okay, so let's methodically walk through the
6:49
evidence detailed in our source material, starting
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with something we use every day, plastics. Right,
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plastics. We manufacture plastic on such a colossal
6:57
scale, and as we all know, it takes so incredibly
6:59
long to degrade. So it's now spread across literally
7:02
every corner of the planet. Yeah, the sources
7:04
mention it's not just sitting in landfills anymore.
7:07
Microplastics have made their way all the way
7:09
down into deep ocean sediments. And that's crucial.
7:12
Because when those ocean sediments slowly pile
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up and eventually get subjected to the immense
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heat and pressure of the Earth's crust over millions
7:20
of years, they bake into sedimentary rocks. Because
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the plastic becomes part of the rock. Exactly.
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The synthetic polymers of our plastic trash will
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get permanently locked into that rock matrix.
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They won't look like a perfectly preserved water
7:34
bottle, but they will form a distinct... carbon
7:38
-heavy chemical band that has just never existed
7:41
in nature before. Wow. And some geologists call
7:44
these technofossils, right? Yes, technofossils.
7:47
It's a weird synthetic band of rock just wrapping
7:50
around the entire globe. That is wild to picture.
7:53
And then the sources detail the impact of concrete.
7:56
Which, if you think about it, is essentially
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just an artificial rock that we invented. Yeah,
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that's exactly what it is. And we have poured
8:01
such a staggering volume of concrete that it
8:04
basically coats the planet's surface in a way
8:07
nothing in nature ever naturally has. So it's
8:09
this dense footprint that will absolutely leave
8:12
a massive scar in the geological record. Absolutely.
8:15
And it's not just the solid stuff on the ground.
8:18
We're also leaving permanent markers in the atmosphere
8:21
and the oceans. Okay. How does that work? Like,
8:23
how does air become rock? Well, think about the
8:26
slow carbon cycle. Normally, the Earth regulates
8:29
its temperature over millions of years. Carbon
8:31
gets locked in rocks. It's slowly released by
8:34
volcanoes into the atmosphere, absorbed by rain,
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washed into the oceans, and eventually settles
8:39
back into the rocks. A very slow, balanced loop.
8:42
Exactly. But humans have dug up hundreds of millions
8:45
of years worth of stored carbon -like coal and
8:48
oil, and we've burned it in a matter of just
8:50
a few decades. Which drastically alters the atmospheric
8:53
chemistry really fast. Right. And by changing
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the air so quickly, we are changing the ocean's
8:59
chemistry. As the oceans absorb all that excess
9:02
carbon, they become more acidic. And the sources
9:04
say that acidification changes how certain microscopic
9:07
sea creatures form their shells? Yes, it fundamentally
9:10
alters their biology. So when those trillions
9:14
of creatures die and fall to the ocean floor,
9:17
the actual makeup of that sediment is changed.
9:20
Future geologists will see a sudden, really sharp
9:23
shift in the chemical composition of the limestone
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and chalk that's forming right now. That is just,
9:28
wow. So we are changing the air, which changes
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the water, which changes the mud, which eventually
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becomes the stone. It's like this domino effect
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of permanence. It really is. Everything is connected.
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But, okay. One of the most memorable details
9:41
from the source material, for me anyway, is the
9:43
fingerprint of agriculture. I was just totally
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fascinated by how industrial farming is going
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to look to a paleontologist. Two million years
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from now. Oh, the fossil record of the present
9:53
day is going to look incredibly strange to them.
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I mean, future paleontologists will find this
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overwhelming, globally distributed presence of
10:00
billions of domestic animals. Specifically cows,
10:03
pigs, and chickens, right? Yes, specifically
10:05
them. The sheer biomass of domestic animals completely
10:08
dwarfs all wild mammals and birds today. The
10:11
stat that blew my mind was the chickens. We are
10:14
essentially laying down a global layer of chicken
10:17
bones. Yeah, it sounds almost funny, but it's
10:19
true. Because of the incredible scale of industrial
10:22
poultry farming, the modern broiler chicken is
10:25
actually the most numerous bird on the planet.
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Its bones are going to be absolutely everywhere
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in the fossil record. Just a global stratum of
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chicken bones. That is crazy to think about.
10:36
And right alongside those bones, you have the
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chemical footprint of farming. Our use of artificial
10:42
fertilizers has been so extensive that we have
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actually doubled the natural flow of elements
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like nitrogen and phosphorus through the environment.
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Doubled it. Globally. Yeah. Those chemicals run
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off our fields, they enter the river systems,
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and they settle into the sediment. So that massive
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chemical spike will also be permanently locked
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into the rock. Okay, I also want to make sure
11:02
we bring up the 1950s atomic tests. Because of
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all the evidence in the source material, this
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seems like the most dramatic piece. Oh, it is
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arguably the sharpest marker of all of them.
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In the mid -20th century, humanity began detonating
11:14
nuclear weapons above ground. Right, the atmospheric
11:17
tests. Yeah. And those tests sprinkled radioactive
11:19
isotopes worldwide within a span of just a few
11:22
short years. And just to clarify for everyone,
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an isotope is basically a variant of an element
11:27
that has extra neutrons, which makes it unstable
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and radioactive, right? Yes, exactly. And the
11:32
key thing for geology is that they decay at a
11:35
very specific predictable rate. So they act like
11:38
a built -in clock in the rock. Oh, that's incredibly
11:41
useful for future scientists. It is. When future
11:44
geologists examine our layer, they won't just
11:46
see a gradual shift in chemistry like with the
11:49
carbon cycle. They will see a razor -sharp global
11:52
marker of radioactive isotopes like plutonium
11:55
-239 that just suddenly appear everywhere all
11:58
at once. So if we take all of this together,
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the techno fossils from plastic, the sheer volume
12:03
of concrete, the chemical shift from carbon fertilizers,
12:06
the global layer of chicken bones and the radioactive
12:09
fallout. I mean, these create exactly the kind
12:12
of clear, global, lasting signals that geologists
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use to mark the boundaries of deep time. They
12:18
really do. The evidence points to a massive planetary
12:21
transition. The end of an epoch is almost always
12:24
marked by something sudden and dramatic in the
12:27
rock. Like we mentioned earlier, the asteroid
12:29
impact that ended the age of the dinosaurs. Right.
12:32
Except in this case, the geological force reshaping
12:35
the biosphere isn't coming from space. The cause
12:38
is us, which, and this is where the story gets
12:40
really interesting, leads us to a fascinating
12:43
scientific plot twist. Yeah, the plot twist.
12:47
Because with all this staggering planet -wide
12:49
evidence, you would naturally assume that declaring
12:52
the Anthropocene an official epoch is just a
12:54
settled fact. You'd think the textbooks are already
12:56
being updated. You would think so, yes. But science
12:58
requires rigorous honesty, and as of right now,
13:01
based on the sources we're looking at, the Anthropocene
13:03
is actually not an officially recognized division
13:06
of geological time. No, it is not. The International
13:09
Scientific Bodies The specific committees of
13:12
stratigraphers who formerly governed the geological
13:14
timescale, they actually recently declined to
13:17
ratify the Anthropocene as a new epoch. Wait,
13:20
really? So they voted it down. I think this is
13:23
where the scientific community is actually fractured
13:25
right now, which is just fascinating, because
13:27
it's crucial to understand that the formal rejection
13:29
by these committees is absolutely not a group
13:32
of scientists saying humans aren't having an
13:34
impact. Oh, no, not at all. Let's be very clear
13:37
about that. The broad scientific reality of human
13:40
transformation is completely undisputed by these
13:43
groups. No one is denying what's happening to
13:46
the environment. OK, so if the evidence is literally
13:49
written in concrete and radiation, why isn't
13:52
it official yet? What is the debate actually
13:54
about? The debate entirely centers on the nuance
13:57
of how geology actually works as a bureaucratic
14:01
and scientific discipline. Administrative rules,
14:03
basically. Exactly. To create an official epoch,
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you cannot just point to a general trend of environmental
14:08
change and say, look, things are different. The
14:11
rules of stratigraphy require strict, very rigid
14:14
thresholds. globally agreed upon starting marker
14:19
in the rock. Oh, I read about this. In geology,
14:22
this is affectionately called a golden spike,
14:24
right? Yes, a golden spike. Or, if you want the
14:28
official term, a global boundary stratotype section
14:31
and point. I think we'll stick with Golden Spike,
14:34
but that is a literal specific location on Earth,
14:37
isn't it? Like maybe a specific cliff face in
14:39
Italy or a lake bed in Canada. Right. It's a
14:42
real place where geologists can point to one
14:45
exact millimeter of rock and say, right here
14:47
at this specific line, the epoch officially began.
14:51
So that level of precision has to be the heart
14:54
of the problem here. It is. Finding a single
14:57
synchronous marker for human impact is incredibly
15:00
difficult. Why? Because human history is terribly
15:03
messy and asynchronous. Right. We didn't all
15:05
do the same things at the exact same time. Exactly.
15:08
For example, some scientists argue the Anthropocene
15:10
should start with the agricultural revolution
15:12
thousands of years ago. Because, you know, that's
15:15
when we started clearing forests en masse and
15:17
raising methane -producing livestock. But the
15:19
agricultural revolution didn't happen everywhere
15:21
at once. It took thousands of years to spread
15:24
across the globe. So it doesn't leave a clean,
15:26
single line in the global rock record. Precisely.
15:30
Other scientists argue it should start with the
15:32
Industrial Revolution in the 1800s when we started
15:34
burning coal. But again, industrialization was
15:37
gradual. It was regional. So what did the group
15:40
pushing for the Anthropocene propose? They argued
15:43
that the best golden spike is actually the radioactive
15:45
fallout from those 1950s atomic tests we talked
15:48
about. Because it is sudden, it is global, and
15:51
it leaves a permanent chemical line everywhere
15:53
simultaneously. Okay, but if you use the 1950s
15:57
as the official starting line for the Anthropocene,
15:59
you're essentially telling the historical record
16:02
that all the massive human impacts before 1950
16:05
don't count as part of the human epoch. And that
16:08
is the exact tension that caused it to be voted
16:11
down. It ignores thousands of years of deforestation,
16:13
the extinction of countless species, the entire
16:16
Industrial Revolution. Right. The stratigraphers
16:18
voting against it were making a careful, highly
16:21
technical judgment. They felt that pinning the
16:24
entire human transformation of Earth to a single
16:26
date in the 1950s was just too restrictive. It
16:29
didn't accurately reflect the long... really
16:32
complex history of our interaction with the planet.
16:34
So they were basically arguing over administrative
16:37
boundary lines, not denying the reality of what
16:40
we are doing to the Earth. Yes, exactly. The
16:43
analogy from the source material that perfectly
16:45
summarizes this administrative tension is thinking
16:48
about a house renovation. Oh, the house analogy
16:50
is great. Yeah. So imagine a new family moves
16:54
into an old house and immediately starts knocking
16:57
down walls, tearing up the floorboards, painting
17:00
everything neon green. Everyone in the neighborhood
17:03
can clearly see the sledgehammers. The physical
17:06
transformation of the house is totally obvious
17:08
and undeniable. Down at the city council. Right.
17:12
Down at the city council, the bureaucrats are
17:14
locked in this heated, endless debate over the
17:17
exact millisecond. The new residency officially
17:19
began for tax purposes. Did it start when they
17:22
signed the mortgage? when they move the first
17:24
couch in, or when they knock down the first wall.
17:27
And the paperwork of geology just requires a
17:29
level of synchronous precision that makes the
17:32
Anthropocene really difficult to formalize right
17:34
now. But it's worth noting that even the scientists
17:38
who opposed the formal designation still use
17:41
the word Anthropocene. in their daily work. So
17:44
it's still a highly relevant concept. Oh, very
17:46
much so. They see it as a profoundly legitimate
17:49
way to describe this age of human influence.
17:52
They just don't think it fits neatly into the
17:54
rigid filing cabinet of a formal geological epoch
17:57
based on the current traditional rules. So the
18:00
honest summary for you listening right now is
18:03
this. The human impact on the Earth is real,
18:06
it is actively being written in the stones, and
18:08
it is widely accepted by the scientific community.
18:11
The rigorous debate over how to categorize it
18:13
is simply a reflection of scientists taking their
18:16
discipline really seriously. Yeah, that's exactly
18:18
the right way to frame it. Which brings us to
18:19
the final piece of our deep dive today. Because
18:22
whether or not the Anthropocene ever gets a formal
18:24
golden spike on a chart somewhere, the deeper
18:27
reality of this concept fundamentally changes
18:29
our understanding of ourselves. It really does.
18:32
We have to weigh human actions against the entirety
18:35
of Earth's history. I mean, for almost all of
18:38
that 4 .5 billion year timeline, the great forces
18:42
shaping the planet were entirely blind and unthinking.
18:46
Right. A dinosaur couldn't stop a wandering ice
18:48
age. No. Early sea life couldn't halt the drifting
18:51
of tectonic plates. Life just had to adapt to
18:54
whatever the Earth blindly decided to do. But
18:56
the source material highlights this awe -inspiring
18:59
and honestly slightly terrifying fact. If you
19:02
compress Earth's entire history into a single
19:05
24 -hour clock, human beings show up in just
19:08
the last few seconds before midnight. So a tiny
19:11
blip. A tiny blip. Yet in that fraction of a
19:13
fraction of time, our mining, our construction,
19:15
and our agriculture now move more rock and soil.
19:18
around the surface of the Earth than all the
19:21
natural rivers combined. Think about that. A
19:23
single species has joined the ranks of ice ages
19:26
and tectonic plates. We have literally become
19:28
a force of nature. And understanding the scale
19:31
isn't just about, you know, memorizing facts
19:33
to sound informed at a dinner party. The argument
19:35
for science itself is that this knowledge allows
19:37
us to see our own massive effects clearly. And
19:40
to weigh them honestly. With that staggering
19:43
planetary level power comes an incredible responsibility.
19:46
Absolutely. The Anthropocene is essentially a
19:49
mirror held up to our species. It's a geological
19:52
record being written right now, today, about
19:55
what we chose to do with our brief moment of
19:57
enormous power. We are the very first species
20:00
in the history of the entire planet to actually
20:02
be aware that we are leaving a layer in the rock.
20:05
We have the unique capability to study our own
20:07
impact in real time. Which is an incredible privilege,
20:10
but a huge burden. It is. Which leaves us with
20:14
a final thought to mull over as you go about
20:16
your day. Think back to that massive silent librarian
20:19
we talked about at the very beginning of the
20:21
deep dive, methodically recording everything
20:23
in the Earth's stone diary. Still writing, even
20:26
right now. Millions of years from now, if some
20:28
future geologists, whatever they might look like,
20:31
if they examine the rock layer we are leaving
20:33
behind in this exact moment, what story will
20:36
it tell? Will they see a chaotic, polluted layer
20:38
of plastic and radiation that eventually stabilized
20:41
and thinned out because we learned to balance
20:43
our tremendous power? Or will the Anthropocene
20:46
just be a thin, abrupt, devastating boundary
20:49
line marking our sudden, dramatic end. It's quite
20:52
a question to leave people with. It is. The geological
20:54
record is still being written, and thankfully
20:56
for now, the pen is still in our hands.