Thanks to Linode for supporting  this episode of SciShow.  You can go to linode.com/scishow  to learn more and get a  $100 60-day credit on a new Linode account. [♪ INTRO]  55 million years ago, just  10 million years after the  extinction of nearly all the  dinosaurs, Earth’s average  temperature shot up, and fast.

This warm period is known as the Paleocene-Eocene  Thermal Maximum, or PETM. We know it was caused   by a massive amount of carbon entering Earth’s atmosphere, and that this warming  happened over a comparatively short time.

So, the PETM is the closest   thing we have in Earth’s history to the modern climate crisis.  Except, instead of all that  carbon coming from human  activity, a 2022 study suggests  it could have come from an  entire continent splitting apart. The PETM has been a big mystery   for paleoclimatologists who are scientists who   study the climate in Earth’s past. During this event, temperatures   at the oceans’ surface suddenly shot up by about   5 degrees Celsius on average, and the ocean acidified to the   point that many deep-sea species were wiped out.  It’s one of the most extreme  heating events in Earth’s  history, and while scientists  have been studying it for  decades, they still don’t know  definitively what caused it.  They do know that the warming was driven by extra carbon in the atmosphere, and especially extra   carbon dioxide.  That’s because the oceans  both warmed and acidified.  And while many gases can warm the planet, only CO2 dissolves in the ocean to make it more acidic.  But it would’ve taken more  than just like a quick burst of  gas to cause this kind of  warming.

In fact, researchers  calculated that it would have  taken 10 to 15 trillion tonnes  of carbon. That’s four to six times   more than what humans have released since 1850.   And what we’ve done already, here, is enough to start wreaking havoc on the planet.  Now, the cause of the modern  climate crisis is clear and  straightforward: Our world  revolves around fossil fuels, and  burning them releases gasses that warm the Earth. But 55 million years ago,   it’s not like ancient birds were sitting around burning tons of oil and coal.  Instead, for that much carbon  to enter the atmosphere  naturally, scientists know  it had to come from multiple  sources.

They’re just not  sure what all of them are.  They do know that volcanoes  were part of it, but the total  amount of volcanism happening  at this time only accounts  for about a fifth of the carbon. So, the bulk of it had   to come from somewhere else. And a study published in 2022 might have found where.  In their paper, researchers  looked at volcanic rocks from  sediment cores: cylindrical  samples of material drilled  from the seafloor.

The material in these   cores forms as sediment from the water’s surface drifts down to the   seafloor and builds up over time. So,   they tell us what sorts of material was floating around the oceans as far back as   millions of years ago.  These cores in particular  were taken from the North  Atlantic Ocean in the 1980s.  But they had basically been  sitting around in a warehouse  since then, waiting to be  analyzed. And when the COVID-19 pandemic shut down most  normal research, it was finally  their time to shine.

Scientists  took the opportunity to dive  into the archives to dust off  these samples. They found that   the core sections that came from around the time of the PETM were full of ash   deposits, indicating a lot of volcanism. Now   that sounds a lot like support for the theory that the PETM was caused by volcanoes.  But when they looked at the  chemistry of lava deposits that  occurred around the same time  as the ash deposits, they  found something strange about  the chemistry of the lava.  Lava deposits from around  the same time as the PETM  were oddly high in elements  like titanium and magnesium.  Eventually, these elements  disappeared from the cores  and the rest of the lava  deposits from this time looked  more like normal lava deposits.

But that initial spike of high   magnesium, high titanium lava led the researchers to think that   some of the volcanism might have come from   a different source than normal. And that made them look at the subcontinental  lithospheric mantle, which  is a deep layer of the earth  between the crust and mantle. This layer is high in carbonates,   minerals with a high amount of carbon and oxygen in them.  But here’s the weird thing:  This layer of the crust normally  exists way deeper in the  planet than we can get to with  conventional tools.

So, for these metals   to have made it to the sediment cores, something must have been happening to take those  carbonates from deep in the  Earth, and throw them all the  way up to the surface, where  they could eventually drift  down to the seafloor. And scientists think   this happened during one particular, dramatic geological event: the break-up of a  supercontinent. Before the continents   got to their modern positions, all the land on Earth was bunched up into one enormous  supercontinent, called Pangea.

Eventually, it split apart in three   stages. The last stage formed what’s now   the North Atlantic Ocean, and that occurred at roughly the same time as the PETM.  This was a violent time, and  material from deep in the  planet could’ve been brought  up to the surface, including  those carbonates. And if that  happened, a lot of carbon  would have been released into the air.

Because these minerals   formed at super high pressures deep in the Earth. So, when they reached lower  pressures at the surface,  they would’ve broken apart,  releasing that CO2. The release of carbon   dioxide would have been short-lived, like a really big burp.

But in   that time, a lot of carbon would have gotten into the atmosphere.  If this is true, it could  explain where a lot of the carbon  released during the PETM came from! That said, other researchers not   involved with the study were quick to point out   that the PETM was still likely caused by more than one event.  So, while the breakup of Pangea could have been a significant factor, other effects   might have put even more carbon in the atmosphere.  For example, as the planet  warmed, frozen soils called  permafrosts could’ve started  melting, releasing their  stored carbon into the air. But this research adds another   piece to the story.

And with Earth’s climate changing rapidly,   and scientists doing their best to learn what this   means for our future, understanding extreme warming events like the PETM   is more important than ever.  This kind of climate research  can involve some really big  datasets to see how things  change over time. And Linode  can handle big datasets. This SciShow video is supported by Linode, a cloud  computing company from Akamai.

Linode can provide high memory   servers to work with really big databases   and get into large scale projects that require terabytes or more of storage.  Linode offers dedicated  cloud resources for when you  need fast processing of a lot  of information. That way, you  don’t need to compete with  other users to access the same  server at the same time. Linode can handle the   needs of large organizations and researchers working with giant   datasets.

They’ll give you high level performance 24/7.  To explore what the cloud can  do for you, you can click the  link in the description or head  to linode.com/scishow for a  $100 60-day credit on a new Linode account. [♪ OUTRO]