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In northeast Siberia, there’s a hole so massive
it’s been nicknamed the Doorway to the Underworld.
As of 2023, it’s about 88 hectares big, or
a little less than one square kilometer.
But here’s the thing: since
it appeared in the 1960s,
that doorway has been growing,
releasing tons of greenhouse gasses
into the atmosphere and
pollutants into the local river.
Which, ya know, sounds pretty bad, and it is.
But while some researchers dread the consequences
of this doorway opening up,
others have found a silver lining.
Because as it turns out, there's
something useful in the Underworld.
[♪ INTRO]
The Doorway to the Underworld
goes by several other names,
from the innocuous “cave-in”,
to the much more scientific
but no less catchy “retrogressive thaw megaslump”.
It is, in fact, the most
mega megaslump in the world…
by which I mean it’s the largest.
But the Doorway to the Underworld
is most often called the Batagay
or Batagaika Crater, because it is
located near a small town called Batagay.
And with the name “crater”, you
might think that it was created
by a massive asteroid impact or
something similar falling from space.
But you’ve seen this thing.
Like, we’ve showed it to you.
The hole is vaguely shaped
like a stingray or a tadpole,
measuring 2700 meters long from head
to tail, and 990 meters at its widest.
And that wonky shape suggests
it was created by something
other than a giant space hamster missing
its belly flop into the Arctic Ocean.
The creator of this megaslump is, in fact, us.
See, the terrain in this area
is basically the biggest,
but worst tasting, ice
cream cake you’ve ever seen.
It’s made of several layers of permafrost,
which is like really wet land that’s been
continuously frozen for at least 2 years.
And before the crater formed,
those layers added up to
something around 75 meters thick.
There’s a bedrock base at the bottom, and then
alternating layers of stuff that’s either
a bit more icy or a bit more sandy.
And the sandy layers have layers inside
of them, too, made of woody material,
peat, and other biomass like
pollen and insect remains.
Delicious! Om nom nom.
Geologists hypothesize that this cake
was assembled over thousands of years.
As the permafrost formed, sand was getting
blown over from a nearby floodplain.
But because of those alternating layers, we know
this wasn’t happening consistently.
The region must have gone
through cycles of freezing
and relative warming…during which time you’d get
stuff like meadows and coniferous forests growing.
Now before the Crater formed, you could expect
to see some amount of seasonal melting.
But if the upper layers of a
permafrost cake melt too much,
it could initiate a dangerous feedback loop.
For example, higher surface
temperature might cause the snow that’s
covering the upper permafrost layers to melt.
And without the snow to reflect the Sun’s
toasty light back into space, the darker,
newly-exposed layers would absorb more
light and start to thaw themselves.
And once a layer of permafrost has
done a bit more thawing than usual,
it’s much more likely to continue
doing so in subsequent years.
But that’s not all. These warmer
temperatures also wake up bacteria
in the ground that have been
hanging out in what’s basically
a non-SciFi version of suspended animation.
Then, they get to work decomposing
organic material in the permafrost,
producing greenhouse gasses as byproducts.
And when the permafrost melts
and collapses, those gasses are
released into the atmosphere…making
things warm up even faster.
Now, typically, melted permafrost will
form massive puddles on the surface.
But the region that Batagay Crater calls
home isn’t sitting at one single elevation.
The “tail” part is much lower, so when
all that ice melts, the water and eroded
sediments can drain into the nearest
river…leaving a massive hole behind.
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But how old is that hole?
Like if you could time travel back to the 1960s,
you’d find yourself standing
in a seemingly harmless ravine.
But the Soviets had recently
cleared a nearby forest
to search for good places to mine
a bunch of different minerals.
Without tree roots, the landscape
became more susceptible to erosion.
And without tree cover, it was a lot
easier for the Sun to warm the ground.
In other words, the sudden
lack of trees kicked off
a vicious cycle of permafrost melting.
We actually have satellite images
that show the ravine gradually
expanding over the decades, taking
on its stingray-slash-tadpole shape.
And by 1991, it had grown so large that scientists
could officially call it a megaslump.
And it’s kind of shocking
how quickly the slump has
grown in just the past few decades.
Like between 2019 and 2023, the edge of
the crater’s bowl retreated by 53 meters,
at an average rate of around 12 meters per year.
Since 1991, Batagay Crater has lost an
estimated 35 million cubic meters of matter.
Two-thirds of that has been meltwater,
with the rest being a mix of
sand and biomass that was layered
throughout the permafrost.
Each year, the melted permafrost also releases
4,000 to 5000 tons of previously
sequestered organic carbon.
But the growing megaslump isn’t
just creating environmental problems
by releasing a bunch of CO2
and methane into the air.
The runoff has also made the river
water unsuitable for drinking,
affecting the residents in Batagay and clogging
the waterway down to the sea it drains into.
Unfortunately, there is nothing
we can immediately do to stop
Batagay Crater’s growth, but it might
stop expanding on its own within
just a few decades, because the situation
is literally about to hit rock bottom.
Below and at its sides, the
crater is about to hit bedrock.
It’s running out of permafrost to melt.
But all that melting permafrost is actually
a good thing in one particular way.
Basically, the Batagay Crater is
self-excavating, and each year it reveals new,
well-defined cross-sections
of its geological history.
At the head of the proverbial stingray,
there’s a sheer cliff that’s 55 meters tall,
perfectly exposing the permafrost’s layers.
Geologists can sample the ice
structure, sediment composition,
and biomass remains from each
layer of the permafrost cake,
and compile a history of the region
that stretches back 650,000 years.
They’ve even discovered animal
remains…from the remnants of ants
and mushroom-inhabiting beetles,
to bones from much more charismatic
fauna like cave lions, wooly mammoths, and bison.
And in 2018, one team found a
roughly 40,000-year old foal that was
so well-preserved by the icy permafrost,
it still had hair and muscle!
Meanwhile, a different study found lemming remains
that researchers estimated to
be around 330,000 years old!
As Batagay Crater grows, scientists can paint
an ever-more detailed picture of the past.
And if you want in on that action, you
could dedicate your life to earth science
and join one of the teams that
regularly samples the Crater’s walls!
The Institute of Applied Ecology of the North
organizes scientific expeditions to the Crater.
You just gotta watch out for
all the animals in the region
that are still very much
alive…like bears, mosquitos,
and all those ancient microorganisms
that have just woken up!
[♪ OUTRO]
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