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The Deep-Sea Conveyor Belt · The Climate Translation

• 0:00
  Most of the time, when we talk about climate change, we look up.
• 0:11
  We talk about the air, the clouds, and the sun.
• 0:15
  But what if one of the biggest drivers of first long-term climate isn't happening above
• 0:21
  us at all?
• 0:22
  What if it's happening deep below our feet and the slow, crushing movement of the planet
• 0:28
  itself?
• 0:30
  New research is changing how scientists understand Earth's natural, temperature control system.
• 0:37
  We've always known that tectonic plates move, what we're learning now is how they pull
• 0:42
  apart and collide helps to regulate the planet's climate over millions of years.
• 0:48
  Today we're going to explore the deep sea conveyor belt.
• 0:52
  Welcome to the podcast.
• 0:53
  I'm Dr. Mac, and this is the Climate Translation.
• 1:03
  When we talk about the carbon cycle, we usually picture trees pulling carbon dioxide out
• 1:08
  of the air, or the ocean absorbing it at the surface, and they're important processes.
• 1:15
  But there's a larger, much slower carbon cycle happening far below us.
• 1:21
  This call it the deep carbon cycle, and it's one of the main ways Earth has managed
• 1:26
  its temperature for billions of years.
• 1:30
  This isn't a fast system.
• 1:32
  It runs on a million-year time scales, but over a deep time, it's incredibly powerful.
• 1:39
  To visualize it, imagine Earth's surface as a giant conveyor belt.
• 1:44
  The bottom of the ocean is covered in a thick layer of sediment, mostly the crushed shells
• 1:50
  of the microscopic sea creatures and organic material that are around.
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  Over time, the shells lock carbon into solid rock.
• 2:00
  Think of the sea floor as a massive sponge, slowly pulling carbon dioxide out of the atmosphere
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  and storing it away.
• 2:09
  That sponge doesn't stay in place forever though.
• 2:12
  As tectonic plates move, parts of the ocean floor are pushed underneath continents, and
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  what we call subduction zones.
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  This is the trash compactor phase of the cycle.
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  The carbon-rich rock is dragged deep into the Earth where it's crushed and heated under
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  enormous pressure.
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  Eventually, some of that buried carbon melts into magma, and when magma reaches the surface
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  through volcanoes, the planet exhales.
• 2:42
  Carbon dioxide is released back into the atmosphere, completing the loop.
• 2:47
  For a long time, scientists thought these volcanic exhaust pipes were the main control on
• 2:53
  the system, but new research has revealed a surprising twist.
• 2:58
  It turns out the places where tectonic plates pull apart and new plate is created, especially
• 3:04
  at mid-ocean ridges, play a much bigger role than we realized.
• 3:10
  When plates move faster and spread more actively, fresh ocean crust forms in a way that
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  allows the seafloor sponge to trap more carbon.
• 3:20
  That pulls more carbon dioxide out of the atmosphere and cools the planet.
• 3:25
  When plate motion slows, less carbon gets locked away, more stays in the air and the planet
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  warms.
• 3:33
  It's a delicate balance of inhaling and exhaling that takes millions of years to complete.
• 3:41
  That finding was a missing piece of the climate puzzle.
• 3:44
  Scientists had focused on the exhaust pipes, volcanoes, but they had underestimated how
• 3:50
  much control the storage system had over the whole process.
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  Volcanoes still matter, they're still part of the cycle, but they aren't a straight
• 4:00
  pipe where carbon immediately comes back out.
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  Some carbon stays underground far longer than expected.
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  Sometimes it never makes it back up at all.
• 4:10
  So instead of a simple loop, the deep carbon cycle looks more like a leaky recycling
• 4:15
  system, where one plate motion determines how much carbon stays buried and how much escapes.
• 4:23
  And here's why the discovery is so important.
• 4:25
  It helps explain why Earth's climate has shifted so dramatically in the distant past, long
• 4:31
  before humans existed.
• 4:34
  Slow changes in plate motion could quietly change how much carbon stayed locked away, nudging
• 4:40
  the planet warmer or cooler over several million years.
• 4:45
  Now this is usually the moment when someone stops me and says, okay, Dr. Mac, if the
• 4:50
  Earth has this massive natural thermostat, it's been working for billions of years, why
• 4:55
  are we worried about what's happening now?
• 4:58
  It's a great question and it's the heart of the translation.
• 5:02
  The difference between Earth's natural carbon cycle and what humans are doing today comes
• 5:07
  down to one thing, and you probably can guess what it is.
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  It's something I brought up many times over several podcasts.
• 5:16
  It's speed.
• 5:17
  It's helpful to revisit the analogy of thinking of deep carbon cycling like breathing.
• 5:23
  Over millions of years, Earth slowly entails carbon dioxide out of the atmosphere by locking
• 5:29
  it into carbon in ocean sediments, dragging it underground, and then eventually exhales
• 5:36
  it back through volcanoes.
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  Inhale, exhale, slowly, steadily.
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  That rhythm has kept the planet temperature within a livable range from most of its history.
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  Now compare that to what we've been doing recently.
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  By burning fossil fuels, we're taking carbon that the planet carefully buried over tens
• 5:58
  to hundreds of millions of years and releasing it back to the atmosphere in just a few decades.
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  It's not breathing anymore, that's a coughing fit, and a violent one at that.
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  Imagine someone calmly breathing for a few seconds and then suddenly coughing out all
• 6:15
  their air at once, their lungs are overwhelmed, and the rhythm is gone.
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  That's what happens to the carbon cycle.
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  The deep sea conveyor belt is still running.
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  The ocean floor is still absorbing carbon, tectonic plates are still moving.
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  Canos are still recycling material back into the atmosphere, but none of those systems
• 6:37
  were built to keep up with the changes so fast.
• 6:41
  Here's another way to picture it.
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  Think of the Earth's carbon system like a long-term savings account.
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  For millions of years, carbon was slowly deposited into that account, a little at a time, locked
• 6:54
  away in coal, oil, and natural gas, and rocks like limestone.
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  The deep carbon cycle acts like a very slow, responsible withdrawal plan, releasing small
• 7:05
  amounts back into the atmosphere over enormous spans of time.
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  What humans have done is walked up to that bank account, gone into the ATM, and emptied
• 7:15
  it all at once, dumping it straight back into the atmosphere.
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  And now the planet is trying to figure out how to handle the balance.
• 7:24
  The ocean sponge can absorb some of it, but not instantly.
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  The tectonic conveyor belt can bury carbon again, but not on a human time scale.
• 7:35
  Those systems are measured in millions of years, not human lifetimes.
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  That's why the new research on plate movement and mid-ocean ridges matter so much.
• 7:46
  It shows us the Earth does have a way to regulate carbon and the climate, but it only works
• 7:52
  when changes happen slowly, when the system is nudged, not shoved.
• 7:59
  What you might ask, if Earth has been removing carbon naturally for billions of years, why
• 8:04
  don't we try to mimic what the Earth does?
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  That question comes up more and more as scientists and engineers talk about carbon removal, things
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  like mineralizing carbon in rock, or storing carbon under the ground, or accelerating in
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  the natural weathering processes.
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  And deep carbon cycles give us a valuable reality check.
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  Carbon is good at removing carbon, but it's good at it because it plays the very long
• 8:30
  game.
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  The deep carbon cycle works by spreading the job across enormous areas, enormous pressures,
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  and enormous spans of time.
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  Carbon doesn't just disappear, it gets slowly locked into minerals, sediments, and other
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  rocks over tens to thousands to millions of years.
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  The time scale is the secret.
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  When carbon gets buried naturally, it doesn't require pumps and pipelines and containment
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  vaults.
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  The planet uses gravity, pressure, chemistry, and time.
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  A lot of time.
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  Now contrast that with what humans are trying to do.
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  We're trying to find ways to cheat and quickly remove carbon on the scale of decades, not
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  millennia.
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  We want fast results, measurable progress, and systems that can be turned on and off.
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  With the Earth's method, it was never designed for speed, it was designed for stability.
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  Think of it like composting.
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  If you toss scraps of food into the backyard compost pile, nature will break them down beautifully,
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  given enough time.
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  But try to force that process to finish overnight, and you'll quickly learn that speed introduces
• 9:42
  complications, heat, the imbalance, leaks, and unintended byproducts.
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  Some removal works the same way.
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  Enhanced rock weathering, for instance, tries to mimic what happens naturally when fresh
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  rock is exposed to air and water.
• 10:00
  Over time those reactions lock carbon into minerals, but over time is doing a lot of work
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  in that sentence.
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  In nature, those reactions happen across entire continents and ocean basins.
• 10:13
  When we try to accelerate them, we run into limits.
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  Technology costs, material availability, land use, and chemistry that doesn't always
• 10:23
  behave the way we hope at human speed.
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  Geological carbon storage faces a similar challenge.
• 10:31
  Yeah.
• 10:32
  Earth stores carbon underground, but it does so in places shaped by millions of years of
• 10:38
  tectonic movement, pressure, and sealing rock layers.
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  Finding locations that are stable on those timescales and proving they'll remain stable
• 10:47
  isn't simple.
• 10:49
  The deep carbon cycle shows us something important.
• 10:53
  Nature doesn't remove carbon by controlling it, it removes carbon by outlasting it, and
• 10:58
  that's a crucial distinction.
• 11:00
  Now, it doesn't mean that carbon removal is pointless or impossible.
• 11:04
  In fact, I applaud scientists that are out on the front line and innovating in new ways
• 11:11
  and using new techniques to try to help address the issue.
• 11:16
  But we have to be honest about what these approaches can and can't do, and how fast
• 11:22
  they can realistically work.
• 11:24
  We cannot engineer our way out of this completely, and then continue to maintain the same lifestyle
• 11:31
  we have now.
• 11:32
  The new research on plate motion in mid-ocean ridges reinforces this lesson.
• 11:38
  It shows that Earth's most effective carbon storage mechanisms depend on slow, continuous
• 11:44
  movement, and vast geologic timescales.
• 11:47
  They're not switches you can flip.
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  Their process is we can learn from, but we can't really easily replicate them.
• 11:54
  So when we talk about climate solutions, this research adds an important layer of realism.
• 12:01
  It reminds us that while technology can help, there's no shortcut that replaces the basic
• 12:06
  physics of time, scale, and chemistry.
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  Any solution that claims to fix the problem instantly should raise questions, not hope.
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  In a way, it brings us back to where this episode began.
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  Earth has a remarkable carbon management system.
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  It just doesn't work on human schedules.
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  Understanding that doesn't make the problem hopeless, it just makes it more clear.
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  Because the lesson of the deep carbon cycle isn't that the solutions are impossible, it's
• 12:36
  just addressing the root causes of carbon production may be far easier than trying to lock
• 12:42
  it all away after.
• 12:45
  That insight rooted in the slow movement of the planet itself may be one of the most important
• 12:50
  translations climate science has to offer.
• 13:01
  One of the things I love most about science is it keeps us honest.
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  Every so often new research forces us to zoom out and rethink about what we thought we
• 13:10
  understood.
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  That's what this discovery about Earth's deep carbon cycle does.
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  It reminds us that climate just isn't something that happens in the air above our heads.
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  It's shaped by slow movements below our feet, by the steady creation and destruction of
• 13:25
  the ocean crust, by systems so patient and so powerful that they've regulated this
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  planet long before humans existed.
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  But it reminds us of something else.
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  Earth's carbon management system works because it's slow and it spreads the work across
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  vast spaces and emits spans of time.
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  That's where the contrast with today becomes clear.
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  We don't need to outsmart the planet, we need to understand this system we're part of
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  and respect the limits of how fast it can move.
• 13:56
  This is Dr. Mac and this has been the Climate Translation.
• 14:02
  If you have a question about the climate that you've been too afraid to ask or if you
• 14:05
  have a different opinion, please let me know, I can use your viewpoints in future episodes.
• 14:11
  You can reach me at the climate translation at gmail.com.
• 14:15
  I'll see you next time.