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(soft dramatic music)
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Earth is born out of chaos and catastrophe.
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Despite such hostile conditions,
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life emerges on our planet.
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But it must withstand deadly disasters again and again.
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Planet Earth is a wild world
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shaken by unimaginable impacts,
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volcanic eruptions that flood the landscape,
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and drastic climate changes that lead to ice ages
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that freeze the world from pole to pole.
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Yet each assault creates a path for something new.
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Life always finds a way
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despite being constantly put to the test.
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Without these catastrophes,
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life as we know it would not exist
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on our "Fateful Planet."
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According to scientific theory,
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a long time ago,
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our planet experienced an ice age of epic proportions,
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a period of extreme global glaciation.
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It is thought that the ice extended
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from the poles to the equator,
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that our entire planet was covered in ice,
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including the oceans and land masses.
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A global catastrophe known as Snowball Earth.
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If our planet was really struck
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by an all-encompassing ancient ice age,
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traces of this dramatic event might have survived the eons.
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Western Australia, in the Pilbara region,
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temperatures can reach more than 120 degrees Fahrenheit.
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Nothing much can survive here,
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but the dryness has helped preserve ancient sediments.
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3 1/2 billion years in age,
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these Archean rocks are some of the oldest in the world.
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Professor Nora Noffke and a team of international geologists
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have come here to search for clues
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that will shed light on what our planet looked like
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in these ancient times
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and what may have created conditions for a snowball Earth.
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(gentle music)
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Well, here we have an excellent window
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of the really early Earth.
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I mean, 3 1/2 billion years ago, how was it?
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Earth was different at that time.
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And so this formation here provides
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a very small glimpse into really completely strange worlds
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of the beginning of our planet,
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and that makes it so great being here.
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In this unique ancient landscape,
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the scientists are looking for fossils
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of the earliest microbes.
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Using a combination of modern techniques
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and decades of experience gained in the field,
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it's not long before Nora Noffke spots something.
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That's what we call ripple marks.
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If we find something like that in an area like here,
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it's a clue which says shallow water
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which was moving not too fast but also not too slow,
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that means that the water probably was very clear,
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and that is a nice indicator for very, very early life
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that existed on Earth at that time.
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This entire landscape
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was once an ancient shallow sea,
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warm pools of water raging from just a few inches
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to a few feet in depth,
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enough for the warm rays of the sun
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to penetrate through the gentle waves.
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And these conditions created the optimal environment
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for early life to thrive.
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This is gorgeous, look at that view.
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So let's go measure a little bit from here upward,
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and then we get an idea what actually is in the rocks,
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what's the story they're going to tell us.
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Many ancient rocks
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are so distorted through time
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that the clues Nora is looking for are long gone.
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But here in the Pilbara,
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the sediments are undeformed
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and thus might have preserved evidence
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of the earliest forms of life.
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Look at that.
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Wow, look at that.
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Now, that is spectacular.
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So this is really what I was looking for here.
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Basically, colonies, assemblages of very small organisms,
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microscopic small, bacteria you could say,
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and they were living on the seafloor at that time.
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The colonies of bacteria clustered together
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and formed what are known as microbial mats.
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So we know that this is not geological.
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What we're looking at here it's biology
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because we have here those round-shaped lobes basically
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in the outline of those fragments.
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These bacterial mat colonies
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are examples of Earth's earliest life forms.
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Recording the evidence of the colonies,
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the team can build up a picture
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of early life here in the Pilbara.
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Life in these shallow pools,
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although primitive, is efficient.
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Simple creatures that feed on carbon compounds
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that are accumulating in Earth's early oceans.
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We have very similar carpets, biological carpets,
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in the modern nowadays, all along our beaches,
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all along the Atlantic Ocean, for instance.
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So it's very common nowadays.
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And now we have here 3 1/2 billion-years-old material,
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and we see some of the earliest life
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that we have here on Planet Earth.
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The microbial mats are not the only evidence
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of early life in the Pilbara.
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The entire region is filled with precious fossil traces
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of ancient life.
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These sedimentary structures known as stromatolites
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are formed by ancient bacteria
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and were discovered by Noffke's colleagues in the 70s.
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So you see this little dome there,
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it's now quite weathered,
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so this is a historical site
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with respect to science history,
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so this one was the first life form detected
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in those really, really old rocks.
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3 1/2 billion years ago,
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life was beginning to thrive on Planet Earth,
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but catastrophe was looming.
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In the ancient rocks,
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Nora Noffke detects a clue
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indicating a dramatic shift in environmental conditions
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that could have spelled dire consequences
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for the early forms of life.
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It does not look like much,
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but indeed it tells us a lot
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about a very important event in Earth history.
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So these red lines here essentially are rust.
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That's a mineral that contains a lot of iron.
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And in order to produce that, we need oxygen.
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In the first billion years,
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there was virtually no free oxygen on Planet Earth.
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Live had evolved without it.
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But the ancient rust Nora has found
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only forms when iron comes in contact with free oxygen.
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The banded iron formation,
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as the ancient striped rock is known,
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is a hint that our planet was changing in a major way.
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Earth now had enough free oxygen
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to entirely transform a geological landscape
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to such an extent
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that its effects can still be seen today.
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The change was so drastic,
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something catastrophic must have happened.
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What impact did it have on early life
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and where did this oxygen come from?
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The answer may be found deep in the heart of Europe.
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Lake Alat in Germany.
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Many myths surround the lake
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because its turquoise waters frequently turn blood red.
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Biologists Patrick Jung and Michael Lakatos
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believe the strange coloration might have to do
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with some of the earliest forms of life on our planet.
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By finding them, they hope to discover
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how early life was affected by the oxygen
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and how it may have contributed
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to the complete glaciation of our planet.
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Lake Alat is surrounded by mountains
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and lies in a basin.
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This is very rare for lakes.
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It's also very deep.
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Through this constellation,
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we hope to find the clues in the depths.
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If there is ancient life down there,
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it might unveil what happened in the past.
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Using a special glass container,
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the biologists want to bring water from the deep
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to the surface.
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In the lower section of the lake, they suspect an anomaly.
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It's coming.
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That's the bottle, watch out.
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Look at that, oh my god.
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The water in the container is all pink.
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To find out why,
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Michael and Patrick are using a probe
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to measure the oxygen content of the water sample
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to determine its composition.
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[Patrick's Translator] What's the oxygen level?
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[Michael's Translator] It's only 1.3.
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[Patrick's Translator] Wow, there's almost no oxygen left
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in the water.
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First, the pink color.
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Second, the smell of hydrogen sulfide.
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And finally, the lack of oxygen indicates
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that we are dealing with very, very old bacteria,
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so-called sulfur purple bacteria.
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Within the depths of Lake Alat
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lies a layer that is deadly to most forms of life.
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It contains virtually no oxygen.
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Just like the deep water we recovered here,
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we have to imagine the oceans billions of years ago
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because they were also oxygen-free.
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Around 4 billion years ago,
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our Earth was a completely different place.
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The so-called Archean Eon was hostile
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to most forms of life we know today.
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Even though water already covered most parts of the Earth,
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there was no free oxygen available,
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neither in the water nor in the atmosphere.
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So the question is, where did the oxygen come from?
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On the shore of Lake Alat,
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the biologists are searching for the answer.
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A layer of slime is accumulated at the edge
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that looks promising.
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The biologists suspect that the green slime
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is also an ancient microorganism known as cyanobacteria.
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[Patrick's Translator] Now look at this.
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Okay, these really are cyanobacteria.
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They form long filaments
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and are found in masses here on the shore.
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The cyanobacteria are ancient.
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They're almost as old as the sulfur bacteria
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and even evolved from them.
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What's special is that we can find them here
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in the shore area
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and not 18 meters deep, which is oxygen free.
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We want to find out why with further analysis.
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The scientists measure the oxygen concentration
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of the shoreline water sample.
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[Patrick's Translator] It's around 8 milligrams per liter.
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That corresponds to the surface water.
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[Michael's Translator] Okay, let's put it in the sun
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and see what happens.
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The biologists believe
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that the power of the sun will affect their sample.
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After a short amount of time,
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the oxygen level increases drastically.
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The cyanobacteria have brought along
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an innovative metabolism
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and developed the so-called oxygen photosynthesis.
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In this process, oxygen is released as a byproduct,
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and this oxygen has changed the Earth forever.
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While purple bacteria depend on sulfur
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and could only survive in niches
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like the deep water layer and Lake Alat,
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cyanobacteria only need light,
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carbon dioxide and water to survive,
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things that are available nearly everywhere
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in the Archean world.
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Scientists are sure that this must have paved the way
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for a global spread of cyanobacteria,
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a story that should again be written in the rocks.
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South Africa, in the dusty plains of Griqualand,
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scientists hope to decipher the events
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that unfolded at this early stage of Earth's history.
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The rocks in this billion-year-old landscape
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act like an archive for field geologists
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like Professor Tony Prave.
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You know, when you say a rock to most people,
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they think, yeah, just a rock.
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When I look at a rock, it holds a story.
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And in many respects, that story is in some ways very poetic
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because it's the history of our planet,
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it's a record of what happened on Earth at that place
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at that particular time in the past.
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(gentle music)
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Professor Prave is looking for rock formations
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from about 2.4 billion years,
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a time when our planet is supposed to have turned
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into a snowball.
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Oh my.
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These features that you see in the rock,
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these curvy plainer surfaces, these are stromatolites.
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These are beautiful examples of stromatolites.
271
00:14:57,870 --> 00:14:59,550
And these stromatolites
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00:14:59,550 --> 00:15:03,150
have been generated by cyanobacteria.
273
00:15:03,150 --> 00:15:05,130
And it's the cyanobacteria,
274
00:15:05,130 --> 00:15:07,251
is part of the evidence that
275
00:15:07,251 --> 00:15:09,330
we want to talk about the genesis of oxygen,
276
00:15:09,330 --> 00:15:12,390
free oxygen that would go into the water column
277
00:15:12,390 --> 00:15:15,930
and could ultimately change climate on Earth
278
00:15:15,930 --> 00:15:17,550
2.4 billion years ago.
279
00:15:17,550 --> 00:15:19,980
One of the reasons why I'm in South Africa
280
00:15:19,980 --> 00:15:22,560
is to find these types of fossils,
281
00:15:22,560 --> 00:15:25,170
but also because these fossils represent
282
00:15:25,170 --> 00:15:28,680
a fundamental change in the chemistry of the oceans
283
00:15:28,680 --> 00:15:30,630
and in the chemistry of the atmosphere.
284
00:15:32,160 --> 00:15:34,020
Stromatolites provide a record
285
00:15:34,020 --> 00:15:39,020
of primordial microbial activity and sediment accumulation.
286
00:15:41,160 --> 00:15:45,180
Despite their ancient origins dating back billions of years,
287
00:15:45,180 --> 00:15:47,460
stromatolites can still be found
288
00:15:47,460 --> 00:15:50,400
in certain aquatic environments today,
289
00:15:50,400 --> 00:15:55,020
providing invaluable insights into early Earth ecosystems
290
00:15:55,020 --> 00:15:57,063
and the evolution of life.
291
00:15:59,490 --> 00:16:04,350
Myriads of tiny cyanobacteria carry out photosynthesis,
292
00:16:04,350 --> 00:16:07,860
converting sunlight, carbon dioxide, and water
293
00:16:07,860 --> 00:16:09,840
into organic matter,
294
00:16:09,840 --> 00:16:12,633
releasing oxygen as a byproduct.
295
00:16:14,190 --> 00:16:18,300
They form sticky biofilms or microbial mats,
296
00:16:18,300 --> 00:16:21,000
which are thin layers of microorganisms
297
00:16:21,000 --> 00:16:24,663
that attach to surfaces such as rocks or sediment.
298
00:16:27,030 --> 00:16:30,270
Over time, these layers build up,
299
00:16:30,270 --> 00:16:32,463
creating a stratified structure.
300
00:16:34,200 --> 00:16:36,693
What is left are stromatolites.
301
00:16:38,512 --> 00:16:42,143
Professor Prave can find them in all sizes.
302
00:16:45,540 --> 00:16:46,950
You know, I'm smiling to myself
303
00:16:46,950 --> 00:16:48,693
because I've seen stromatolites
304
00:16:48,693 --> 00:16:50,430
that are the size of cabbages
305
00:16:50,430 --> 00:16:53,670
and I've seen larger ones that are almost the size of me.
306
00:16:53,670 --> 00:16:58,267
This rock that I'm on is a massive stromatolite.
307
00:17:01,830 --> 00:17:04,020
Cyanobacteria have formed
308
00:17:04,020 --> 00:17:06,450
this colossal structure.
309
00:17:06,450 --> 00:17:08,850
2.4 billion years ago,
310
00:17:08,850 --> 00:17:12,873
they generated oxygen on an unimaginable scale.
311
00:17:15,210 --> 00:17:18,180
As a result of their extensive expansion,
312
00:17:18,180 --> 00:17:21,903
earlier life forms were placed under increasing pressure.
313
00:17:23,670 --> 00:17:26,880
In the Archean oceans,
314
00:17:26,880 --> 00:17:29,400
cyanobacteria were real killers.
315
00:17:29,400 --> 00:17:32,400
Because life was not adapted to oxygen at that time,
316
00:17:32,400 --> 00:17:34,530
it wiped out almost all life.
317
00:17:34,530 --> 00:17:37,923
A real catastrophe was triggered here, a mass extinction.
318
00:17:39,960 --> 00:17:43,020
The ancestors of the sulfur purple bacteria
319
00:17:43,020 --> 00:17:45,540
and other anoxic ancient forms of life
320
00:17:45,540 --> 00:17:50,130
are driven away to places which the oxygen could not reach.
321
00:17:50,130 --> 00:17:52,380
But those who cannot escape
322
00:17:52,380 --> 00:17:54,633
are wiped out by the deadly poison.
323
00:17:55,920 --> 00:17:59,163
And that was not the only harmful effect of the oxygen.
324
00:18:02,460 --> 00:18:04,980
The oxygen produced by the cyanobacteria
325
00:18:04,980 --> 00:18:06,750
first saturated the oceans
326
00:18:06,750 --> 00:18:09,240
and then diffused into the atmosphere,
327
00:18:09,240 --> 00:18:12,450
which was then changed by the accumulating oxygen.
328
00:18:12,450 --> 00:18:13,650
As a consequence,
329
00:18:13,650 --> 00:18:15,960
the Earth cooled down more and more,
330
00:18:15,960 --> 00:18:19,650
which led to the formation of ice and snow at the poles.
331
00:18:19,650 --> 00:18:22,410
These glaciers then advanced to the equator
332
00:18:22,410 --> 00:18:25,233
so that the Earth turned into a real snowball.
333
00:18:28,003 --> 00:18:31,530
(soft ominous music)
334
00:18:31,530 --> 00:18:34,530
Some scientists believe this critical change
335
00:18:34,530 --> 00:18:38,460
ended up having a catastrophic impact on the planet,
336
00:18:38,460 --> 00:18:41,250
plunging it into a deep freeze
337
00:18:41,250 --> 00:18:44,340
and quite possibly a snowball Earth,
338
00:18:44,340 --> 00:18:47,130
wiping out nearly all life.
339
00:18:47,130 --> 00:18:50,793
But if this really happened, it should have left traces.
340
00:18:55,850 --> 00:18:59,010
Vatnajokull Glacier in Iceland.
341
00:18:59,010 --> 00:19:01,080
The rugged landscape provides a glimpse
342
00:19:01,080 --> 00:19:04,023
of what this frozen world might have looked like.
343
00:19:06,210 --> 00:19:09,990
Here, Geologist Professor Colin Devey wants to find out
344
00:19:09,990 --> 00:19:13,353
if Earth really witnessed an ancient ice age.
345
00:19:16,410 --> 00:19:19,740
I'm looking for traces of snowball Earth,
346
00:19:19,740 --> 00:19:21,180
and if you want to do that,
347
00:19:21,180 --> 00:19:23,430
then you come to a very big glacier.
348
00:19:23,430 --> 00:19:25,530
And this is Europe's biggest glacier,
349
00:19:25,530 --> 00:19:28,680
a land of snow and ice.
350
00:19:28,680 --> 00:19:32,130
And I'm hoping to find evidence here
351
00:19:32,130 --> 00:19:34,500
of processes that happened in the glacier
352
00:19:34,500 --> 00:19:36,660
so that I can compare it to evidence we have
353
00:19:36,660 --> 00:19:38,070
from way back in time
354
00:19:38,070 --> 00:19:41,253
when the Earth was probably covered totally in ice.
355
00:19:42,690 --> 00:19:45,120
Scientists believe that snowball Earth
356
00:19:45,120 --> 00:19:48,330
was caused by changes in the chemical composition
357
00:19:48,330 --> 00:19:50,400
of the Earth's atmosphere.
358
00:19:50,400 --> 00:19:52,320
It coincided with the occurrence
359
00:19:52,320 --> 00:19:55,380
of the so-called Great Oxidation Event
360
00:19:55,380 --> 00:19:58,833
that happened at the beginning of the Paleoproterozoic era.
361
00:20:00,060 --> 00:20:01,350
Prior to that point,
362
00:20:01,350 --> 00:20:03,210
the atmosphere on our planet
363
00:20:03,210 --> 00:20:06,090
was far different than it is today.
364
00:20:06,090 --> 00:20:09,060
If I was on the Earth 2.4 billion years ago,
365
00:20:09,060 --> 00:20:10,800
and I really aren't that old,
366
00:20:10,800 --> 00:20:13,410
I would need a spacesuit to sit here.
367
00:20:13,410 --> 00:20:16,680
The atmosphere of the Earth contained almost no,
368
00:20:16,680 --> 00:20:18,840
really no, no, no oxygen.
369
00:20:18,840 --> 00:20:23,840
It was made of sort of nitrogen, lots of methane, and CO2.
370
00:20:23,910 --> 00:20:26,310
But then life came along.
371
00:20:26,310 --> 00:20:27,143
The atmosphere went
372
00:20:27,143 --> 00:20:29,580
from something I couldn't possibly breathe
373
00:20:29,580 --> 00:20:31,680
to being full of oxygen.
374
00:20:31,680 --> 00:20:33,780
Then something happened to the methane,
375
00:20:33,780 --> 00:20:35,700
which we call oxidation.
376
00:20:35,700 --> 00:20:39,090
The methane molecules get attacked by the oxygen
377
00:20:39,090 --> 00:20:41,280
and get turned into carbon dioxide.
378
00:20:41,280 --> 00:20:43,260
Carbon dioxide is also a greenhouse gas
379
00:20:43,260 --> 00:20:44,613
but much less potent.
380
00:20:47,340 --> 00:20:50,490
By producing oxygen through photosynthesis,
381
00:20:50,490 --> 00:20:53,490
life changed the world it was living in
382
00:20:53,490 --> 00:20:55,920
in a revolutionary way.
383
00:20:55,920 --> 00:20:57,900
It's a milestone in the history of the Earth.
384
00:20:57,900 --> 00:21:01,080
It changed the planet completely,
385
00:21:01,080 --> 00:21:03,690
changed our atmosphere completely,
386
00:21:03,690 --> 00:21:04,860
and made our atmosphere
387
00:21:04,860 --> 00:21:07,530
from a very, very nice greenhouse atmosphere
388
00:21:07,530 --> 00:21:09,870
to something with a lot less greenhouse potential.
389
00:21:09,870 --> 00:21:13,320
It was like taking a down jacket off the Earth.
390
00:21:13,320 --> 00:21:15,360
Methane is a really good greenhouse gas
391
00:21:15,360 --> 00:21:16,830
and if you take it away,
392
00:21:16,830 --> 00:21:19,650
even if you turn it into CO2 into large parts,
393
00:21:19,650 --> 00:21:22,593
you're still one jacket less than you were before.
394
00:21:23,520 --> 00:21:24,630
As a consequence,
395
00:21:24,630 --> 00:21:27,300
scientists believe the Earth cooled significantly,
396
00:21:27,300 --> 00:21:30,330
forming glaciers at the poles that grew and grew
397
00:21:30,330 --> 00:21:34,800
until the whole planet was covered in snow and ice.
398
00:21:34,800 --> 00:21:35,700
To prove this,
399
00:21:35,700 --> 00:21:39,420
Colin Devey is analyzing the behavior of glaciers.
400
00:21:39,420 --> 00:21:41,190
It's important to understand
401
00:21:41,190 --> 00:21:43,020
that although they look static,
402
00:21:43,020 --> 00:21:46,263
they are constantly moving like a very slow river.
403
00:21:47,640 --> 00:21:49,950
Glaciers move all the time.
404
00:21:49,950 --> 00:21:53,640
Not as fast as water, but much faster than tectonic plates.
405
00:21:53,640 --> 00:21:56,700
Accumulates snow high up in the mountains,
406
00:21:56,700 --> 00:21:58,440
lots of snow falls up there,
407
00:21:58,440 --> 00:22:00,360
and it gets so deep and thick
408
00:22:00,360 --> 00:22:03,780
that it compress itself down into really solid ice.
409
00:22:03,780 --> 00:22:04,830
But that ice moves
410
00:22:04,830 --> 00:22:06,810
because the next lot of snow is coming on top,
411
00:22:06,810 --> 00:22:08,960
so it's being constantly pushed from above.
412
00:22:11,520 --> 00:22:14,280
Glaciers end up reforming the landscape
413
00:22:14,280 --> 00:22:16,290
they travel across.
414
00:22:16,290 --> 00:22:18,960
The force of the ice acts like a bulldozer
415
00:22:18,960 --> 00:22:20,703
for everything in its way.
416
00:22:21,810 --> 00:22:24,510
At Vatnajokull, Devey wants to check
417
00:22:24,510 --> 00:22:27,213
which traces the glacier left behind.
418
00:22:30,450 --> 00:22:33,300
I'm in front here rather than on top of the ice
419
00:22:33,300 --> 00:22:37,080
because when the ice is gone, what's left are stones.
420
00:22:37,080 --> 00:22:38,010
And for a geologist,
421
00:22:38,010 --> 00:22:40,200
the stones are the things that tell the story.
422
00:22:40,200 --> 00:22:41,580
If you look at the rocks,
423
00:22:41,580 --> 00:22:44,340
you see that many of them are scratched,
424
00:22:44,340 --> 00:22:46,440
and that's because the ice has used them as tools
425
00:22:46,440 --> 00:22:48,930
to grind down the landscape.
426
00:22:48,930 --> 00:22:51,510
And if you get down to the bedrock,
427
00:22:51,510 --> 00:22:54,840
then you'll see the bedrock has been scraped really badly
428
00:22:54,840 --> 00:22:57,180
and has what we call in geology striations.
429
00:22:57,180 --> 00:23:00,210
It looks if somebody's gone with pretty hard fingernails
430
00:23:00,210 --> 00:23:02,550
across it and just scratched it.
431
00:23:02,550 --> 00:23:05,280
And for glacial processes,
432
00:23:05,280 --> 00:23:07,920
the stones are absolutely characteristic,
433
00:23:07,920 --> 00:23:10,410
because the glacier is the only thing
434
00:23:10,410 --> 00:23:13,803
that can pick up stones and rub them together.
435
00:23:14,820 --> 00:23:16,680
This process can be observed
436
00:23:16,680 --> 00:23:18,210
throughout the ages.
437
00:23:18,210 --> 00:23:20,640
If there had been glaciers in the past,
438
00:23:20,640 --> 00:23:24,090
this would've been recorded in the landscape.
439
00:23:24,090 --> 00:23:25,860
Glaciers are hugely powerful.
440
00:23:25,860 --> 00:23:27,990
If a glacier's been in a landscape,
441
00:23:27,990 --> 00:23:29,550
you can see the traces of it.
442
00:23:29,550 --> 00:23:33,330
When ice goes away, it leaves almost a signature
443
00:23:33,330 --> 00:23:35,073
on the surface of the planet.
444
00:23:36,190 --> 00:23:39,270
If the Earth really turned into a snowball,
445
00:23:39,270 --> 00:23:42,963
the glacial signature should be found in ancient rocks.
446
00:23:45,060 --> 00:23:48,780
South Africa, the signs for primordial ice sheets
447
00:23:48,780 --> 00:23:51,930
are not always where you would expect to find them.
448
00:23:51,930 --> 00:23:55,500
In the dry, dusty plains north of the Karoo Desert,
449
00:23:55,500 --> 00:23:59,220
Professor Tony Prave is trying to unravel the story
450
00:23:59,220 --> 00:24:01,803
behind our planet's icy past.
451
00:24:03,000 --> 00:24:05,820
You could think of it as being in part like a detective,
452
00:24:05,820 --> 00:24:07,770
and that aspect is fascinating
453
00:24:07,770 --> 00:24:10,950
because it makes you feel a bit like Sherlock Holmes
454
00:24:10,950 --> 00:24:13,440
taking disparate pieces of evidence
455
00:24:13,440 --> 00:24:17,550
and building to make a case to come to an understanding
456
00:24:17,550 --> 00:24:20,550
of a particular process that happened in the past.
457
00:24:20,550 --> 00:24:23,100
And when we're talking about the past, in this case,
458
00:24:23,100 --> 00:24:25,439
we're talking billions of years ago.
459
00:24:25,439 --> 00:24:27,900
In the 2.4-billion-year-old rocks
460
00:24:27,900 --> 00:24:28,980
in this region,
461
00:24:28,980 --> 00:24:32,280
the geologist finds banded iron formations
462
00:24:32,280 --> 00:24:34,950
similar to the ones found in Australia.
463
00:24:34,950 --> 00:24:38,370
This is step one in our understanding
464
00:24:38,370 --> 00:24:42,600
of how climate could have changed 2.4 billion years ago.
465
00:24:42,600 --> 00:24:45,750
So it's important for us then in step two
466
00:24:45,750 --> 00:24:49,710
to go to younger rocks that would be on top of these rocks
467
00:24:49,710 --> 00:24:54,060
to see if there is that evidence for the global cooling
468
00:24:54,060 --> 00:24:55,743
in the so-called snowball Earth.
469
00:24:58,860 --> 00:25:01,110
A cliff in the vicinity
470
00:25:01,110 --> 00:25:04,143
has caught the attention of the geologist.
471
00:25:06,660 --> 00:25:10,890
Ah, now this, this is what we've been looking for.
472
00:25:10,890 --> 00:25:13,500
Here we have this rock unit and it's massive,
473
00:25:13,500 --> 00:25:16,140
it forms this entire cliff that we saw below.
474
00:25:16,140 --> 00:25:18,570
And it's composed of diamictite,
475
00:25:18,570 --> 00:25:20,670
these pebbles that you can see
476
00:25:20,670 --> 00:25:22,773
that are sitting in a mud matrix.
477
00:25:23,640 --> 00:25:26,730
That mud matrix and those pebbles
478
00:25:26,730 --> 00:25:29,250
can be formed by a couple of different processes.
479
00:25:29,250 --> 00:25:31,710
One is mud flows, but the other is glaciers.
480
00:25:31,710 --> 00:25:34,980
And the extent and size and scale of this deposit
481
00:25:34,980 --> 00:25:37,860
makes us really think it has to be a glacial deposit
482
00:25:37,860 --> 00:25:39,930
formed by the movement of ice.
483
00:25:39,930 --> 00:25:43,380
But the key line of evidence that I want to find
484
00:25:43,380 --> 00:25:45,330
would be striations,
485
00:25:45,330 --> 00:25:46,920
and that is what I want to see,
486
00:25:46,920 --> 00:25:50,223
if I could find that associated with this rock.
487
00:25:53,580 --> 00:25:56,010
Tony Prave is scanning the rocks
488
00:25:56,010 --> 00:25:58,320
in the vicinity for scratches,
489
00:25:58,320 --> 00:26:00,750
clues that would prove the presence
490
00:26:00,750 --> 00:26:03,243
of former glaciers in this region.
491
00:26:07,350 --> 00:26:09,750
This surface shows these very fine lines,
492
00:26:09,750 --> 00:26:11,850
these very fine striae.
493
00:26:11,850 --> 00:26:13,890
Those striae are formed
494
00:26:13,890 --> 00:26:16,650
by ice moving over Earth's land surface,
495
00:26:16,650 --> 00:26:20,670
and we know then that that movement of ice
496
00:26:20,670 --> 00:26:23,223
was what deposited this diamictite.
497
00:26:24,690 --> 00:26:25,710
This proves
498
00:26:25,710 --> 00:26:30,710
that glaciers covered this landscape 2.4 billion years ago.
499
00:26:32,970 --> 00:26:34,170
But here we are
500
00:26:34,170 --> 00:26:38,550
in the middle of a very hot, dry, South African desert
501
00:26:38,550 --> 00:26:41,973
and it seems crazy to have ice and snow here.
502
00:26:42,930 --> 00:26:47,580
But we also know plate tectonics shift Earth's land masses.
503
00:26:47,580 --> 00:26:49,920
Just think 2.4 billion years ago
504
00:26:49,920 --> 00:26:51,780
what the Earth may have looked like.
505
00:26:51,780 --> 00:26:55,050
We need to find out where this land surface was
506
00:26:55,050 --> 00:26:56,853
2.4 billion years ago.
507
00:26:58,020 --> 00:26:59,340
To find out more,
508
00:26:59,340 --> 00:27:03,570
Tony Prave is meeting geologist Professor Nick Beukes
509
00:27:03,570 --> 00:27:06,390
from the University of Johannesburg.
510
00:27:06,390 --> 00:27:09,510
He is an expert on early Earth history
511
00:27:09,510 --> 00:27:12,693
and knows the area here like the back of his hand.
512
00:27:14,520 --> 00:27:15,720
Hi Nick, good to see you again.
513
00:27:15,720 --> 00:27:17,010
Tony, yeah, it's nice to see you.
514
00:27:17,010 --> 00:27:17,910
Thanks for meeting me.
515
00:27:17,910 --> 00:27:21,250
So today I'd like you to be able to tell us
516
00:27:22,140 --> 00:27:24,660
how we could find out where South Africa was
517
00:27:24,660 --> 00:27:26,430
at that time of the glaciation.
518
00:27:26,430 --> 00:27:28,800
Tony, I think if we look around
519
00:27:28,800 --> 00:27:31,170
and you look at the far distance there,
520
00:27:31,170 --> 00:27:35,580
we have this very thick and very extensive flat basalt.
521
00:27:35,580 --> 00:27:36,930
I see, I see, okay.
522
00:27:36,930 --> 00:27:38,730
Which is a lava succession.
523
00:27:38,730 --> 00:27:40,863
And if we can go and look at that,
524
00:27:40,863 --> 00:27:44,970
then we can try and figure out the question that you asked,
525
00:27:44,970 --> 00:27:47,610
where the glaciation happened.
526
00:27:47,610 --> 00:27:49,160
And that's where we have to go.
527
00:27:51,240 --> 00:27:54,030
Lava from a large-scale eruption,
528
00:27:54,030 --> 00:27:57,060
a so-called flood basalt event,
529
00:27:57,060 --> 00:27:59,550
covered the ancient glacial sediments
530
00:27:59,550 --> 00:28:01,503
soon after they were formed.
531
00:28:04,110 --> 00:28:06,210
It is these volcanic rocks
532
00:28:06,210 --> 00:28:08,880
that the scientists now want to analyze
533
00:28:08,880 --> 00:28:13,738
to answer the question where these glaciers once existed.
534
00:28:13,738 --> 00:28:16,488
(drill whirring)
535
00:28:18,510 --> 00:28:21,150
So Tony, this is it.
536
00:28:21,150 --> 00:28:23,700
The special thing about lava sediments
537
00:28:23,700 --> 00:28:26,340
is that they contain precise information
538
00:28:26,340 --> 00:28:29,400
about the latitude in which they were formed.
539
00:28:29,400 --> 00:28:32,280
The magnetic signature that's preserved in this rock
540
00:28:32,280 --> 00:28:35,850
is found in very small crystals that when this lava cools,
541
00:28:35,850 --> 00:28:39,270
those crystals align themselves to Earth's magnetic field
542
00:28:39,270 --> 00:28:42,300
and the orientation of Earth's magnetic field.
543
00:28:42,300 --> 00:28:45,870
And in this rock, the signature that has been analyzed
544
00:28:45,870 --> 00:28:48,480
is that the angle of Earth's magnetic field
545
00:28:48,480 --> 00:28:50,310
is plus or minus 10 degrees,
546
00:28:50,310 --> 00:28:53,823
which means that we have to be close to the equator.
547
00:28:56,280 --> 00:28:57,840
The lava cooled on rocks
548
00:28:57,840 --> 00:29:01,724
that immediately before had been covered with glaciers.
549
00:29:01,724 --> 00:29:04,320
And the palaeomagnetic measurements show
550
00:29:04,320 --> 00:29:09,320
that this happened very close to or directly at the equator.
551
00:29:09,600 --> 00:29:13,970
If we have ice, as we saw in that glacial diamictite,
552
00:29:13,970 --> 00:29:17,700
at the hottest latitudes on the planet, the tropics,
553
00:29:17,700 --> 00:29:19,710
then that means we must have ice
554
00:29:19,710 --> 00:29:24,270
across the coldest regions of the planet, ice everywhere.
555
00:29:24,270 --> 00:29:26,820
And this then is confirmation
556
00:29:26,820 --> 00:29:29,670
that the glaciation was global in scale
557
00:29:29,670 --> 00:29:31,850
and hence a snowball Earth.
558
00:29:31,850 --> 00:29:33,900
(gentle music)
559
00:29:33,900 --> 00:29:36,300
Earth had cooled to such an extent
560
00:29:36,300 --> 00:29:38,580
that the glaciers that formed at the poles
561
00:29:38,580 --> 00:29:40,500
extended even further
562
00:29:40,500 --> 00:29:42,570
until they reached the equator
563
00:29:42,570 --> 00:29:45,933
and the whole planet was covered in snow and ice.
564
00:29:47,190 --> 00:29:49,953
It had become a snowball Earth.
565
00:29:52,740 --> 00:29:55,710
Some scientists believe such a dramatic change
566
00:29:55,710 --> 00:29:57,720
could not have been caused by an increase
567
00:29:57,720 --> 00:29:59,493
in oxygen levels alone.
568
00:30:00,630 --> 00:30:03,510
If so, what else could have contributed
569
00:30:03,510 --> 00:30:05,587
to the global freeze?
570
00:30:05,587 --> 00:30:09,004
(gentle music continues)
571
00:30:11,940 --> 00:30:15,570
Switzerland, the Jungfraujoch region is home
572
00:30:15,570 --> 00:30:17,763
to some of the highest peaks in Europe.
573
00:30:18,870 --> 00:30:22,740
The world up here is frozen all year round.
574
00:30:22,740 --> 00:30:25,530
For Patrick Jung and Michael Lakatos,
575
00:30:25,530 --> 00:30:27,480
this is the perfect environment
576
00:30:27,480 --> 00:30:31,263
to uncover the secrets surrounding snowball Earth.
577
00:30:33,450 --> 00:30:35,490
We traveled here to find out
578
00:30:35,490 --> 00:30:38,973
how an entire planet could turn into snow and ice.
579
00:30:42,844 --> 00:30:46,011
(inspirational music)
580
00:30:47,340 --> 00:30:49,380
As temperatures continued to drop,
581
00:30:49,380 --> 00:30:51,510
a tipping point had been reached.
582
00:30:51,510 --> 00:30:54,090
Ice sheets formed and enveloped the Earth
583
00:30:54,090 --> 00:30:56,969
as the world had never experienced before.
584
00:30:56,969 --> 00:31:00,753
The big question is, how this icehouse effect came about?
585
00:31:02,370 --> 00:31:03,750
The scientists are sure
586
00:31:03,750 --> 00:31:06,390
that there must have been some kind of mechanism
587
00:31:06,390 --> 00:31:09,270
besides chemical changes in the atmosphere
588
00:31:09,270 --> 00:31:11,493
that drove the global glaciation.
589
00:31:13,620 --> 00:31:15,210
The eternal ice and snow
590
00:31:15,210 --> 00:31:17,640
could be clues to what happened back then,
591
00:31:17,640 --> 00:31:19,530
because different surfaces of the Earth
592
00:31:19,530 --> 00:31:21,930
reflect light in different ways.
593
00:31:21,930 --> 00:31:24,513
This could be a key to what happened at that time.
594
00:31:28,260 --> 00:31:30,930
Patrick and Michael have a theory.
595
00:31:30,930 --> 00:31:33,570
As our planet became wider and wider,
596
00:31:33,570 --> 00:31:37,260
it was less and less able to store solar energy,
597
00:31:37,260 --> 00:31:41,253
which eventually intensified the cooling of our planet.
598
00:31:42,330 --> 00:31:43,980
The scientists have brought along
599
00:31:43,980 --> 00:31:45,930
special measuring instruments
600
00:31:45,930 --> 00:31:47,433
to prove their idea.
601
00:31:48,758 --> 00:31:52,350
This is the so-called albedometer.
602
00:31:52,350 --> 00:31:55,740
Up here, the global radiation from above is measured,
603
00:31:55,740 --> 00:31:58,080
which radiates onto the Earth.
604
00:31:58,080 --> 00:32:00,930
And down here, the reflected radiation is measured.
605
00:32:00,930 --> 00:32:01,763
In other words,
606
00:32:01,763 --> 00:32:04,503
the amount of radiation that the snow reflects back up.
607
00:32:07,260 --> 00:32:09,990
From the measurement of the so-called albedo,
608
00:32:09,990 --> 00:32:12,300
the researchers hope to draw conclusions
609
00:32:12,300 --> 00:32:15,573
about the icy events in the early days of our planet.
610
00:32:19,110 --> 00:32:21,360
The albedo describes the amount of sunlight
611
00:32:21,360 --> 00:32:23,520
that is reflected by a certain surface.
612
00:32:23,520 --> 00:32:26,403
So the greater the albedo, the more light is reflected.
613
00:32:27,365 --> 00:32:30,782
(gentle music continues)
614
00:32:35,190 --> 00:32:36,813
Alright, I'll see what it says.
615
00:32:39,690 --> 00:32:41,670
Our albedo measurement here has shown
616
00:32:41,670 --> 00:32:45,060
that about 90% of the incoming light is reflected.
617
00:32:45,060 --> 00:32:47,410
This is the highest value we can find on Earth.
618
00:32:50,820 --> 00:32:52,080
A high reflectivity
619
00:32:52,080 --> 00:32:56,370
not only means that light is reflected back into space.
620
00:32:56,370 --> 00:33:00,363
In addition, the much-needed thermo energy is lost.
621
00:33:02,130 --> 00:33:04,980
For comparison, the researchers now want to measure
622
00:33:04,980 --> 00:33:07,233
the albedo of a dark surface.
623
00:33:12,060 --> 00:33:14,460
We have measured an extremely low albedo
624
00:33:14,460 --> 00:33:17,790
of about 20% on this dark rock.
625
00:33:17,790 --> 00:33:19,980
That means the dark surface absorbs
626
00:33:19,980 --> 00:33:22,380
about 80% of the solar radiation
627
00:33:22,380 --> 00:33:24,003
and thus heats up strongly.
628
00:33:25,050 --> 00:33:26,940
This is roughly how we have to imagine
629
00:33:26,940 --> 00:33:30,900
the function of the oceans 2.4 billion years ago.
630
00:33:30,900 --> 00:33:33,420
They covered about 2/3 of the planet
631
00:33:33,420 --> 00:33:36,573
and they had a much lower albedo than this rock does now.
632
00:33:37,560 --> 00:33:40,170
This means that they could store much more heat
633
00:33:40,170 --> 00:33:41,763
and thus heat the planet.
634
00:33:45,330 --> 00:33:47,850
2.4 billion years ago,
635
00:33:47,850 --> 00:33:50,520
right before the global glaciation,
636
00:33:50,520 --> 00:33:53,133
Earth looked very different from ours today.
637
00:33:54,090 --> 00:33:56,790
But the temperatures were comparable.
638
00:33:56,790 --> 00:34:00,243
The dark oceans acted as heat reservoirs.
639
00:34:02,710 --> 00:34:05,580
Normally, the Earth keeps itself warm
640
00:34:05,580 --> 00:34:08,190
by absorbing an enormous amount of heat energy
641
00:34:08,190 --> 00:34:09,870
from the dark surfaces
642
00:34:09,870 --> 00:34:13,140
and slowly releasing it over a long period of time.
643
00:34:13,140 --> 00:34:15,360
But while ice and snow have spread further
644
00:34:15,360 --> 00:34:16,560
across the planet,
645
00:34:16,560 --> 00:34:19,230
more heat energy has been radiated back.
646
00:34:19,230 --> 00:34:21,240
This amount of heat was lost,
647
00:34:21,240 --> 00:34:23,433
and thus the Earth finally cooled down.
648
00:34:25,320 --> 00:34:27,000
By massively decreasing
649
00:34:27,000 --> 00:34:29,760
the amount of strong greenhouse gases,
650
00:34:29,760 --> 00:34:32,610
the oxygen production of cyanobacteria
651
00:34:32,610 --> 00:34:34,920
had changed the chemical composition
652
00:34:34,920 --> 00:34:38,010
of Earth's atmosphere fundamentally.
653
00:34:38,010 --> 00:34:41,760
The resulting cooling led to the glaciation of the poles
654
00:34:41,760 --> 00:34:45,000
from which ice sheets moved further towards the equator
655
00:34:45,000 --> 00:34:45,963
bit by bit.
656
00:34:46,830 --> 00:34:51,480
And, at a certain point, it was the nature of the ice itself
657
00:34:51,480 --> 00:34:54,453
that ensured that there was no turning back.
658
00:34:56,820 --> 00:34:58,770
The highly reflective ice layers
659
00:34:58,770 --> 00:35:01,530
set an unstoppable cycle in motion.
660
00:35:01,530 --> 00:35:03,810
More and more sunlight was reflected.
661
00:35:03,810 --> 00:35:05,100
There was less heat.
662
00:35:05,100 --> 00:35:06,570
The ice sheets grew.
663
00:35:06,570 --> 00:35:09,540
This process was unstoppable, and in the end,
664
00:35:09,540 --> 00:35:13,350
Earth went into a true catastrophe for the very first time
665
00:35:13,350 --> 00:35:15,423
and was enveloped in a snowball.
666
00:35:17,760 --> 00:35:20,130
2.4 billion years ago,
667
00:35:20,130 --> 00:35:22,923
our planet found itself in a deadly trap.
668
00:35:23,910 --> 00:35:25,440
With most of the sun's energy
669
00:35:25,440 --> 00:35:28,380
now being reflected back into space,
670
00:35:28,380 --> 00:35:30,570
how could Earth ever free itself
671
00:35:30,570 --> 00:35:32,733
from the snowball's icy grip?
672
00:35:33,572 --> 00:35:36,155
(gentle music)
673
00:35:37,170 --> 00:35:41,313
White as far as the eyes can see.
674
00:35:43,110 --> 00:35:47,073
The world is locked in snow and ice for millions of years.
675
00:35:48,450 --> 00:35:51,900
Iceland's snow-covered landscape provides a glimpse
676
00:35:51,900 --> 00:35:55,083
of what the snowball Earth might have looked like.
677
00:35:57,450 --> 00:35:59,010
Scientists aren't sure
678
00:35:59,010 --> 00:36:03,750
how our planet could have broken free from its icy bonds,
679
00:36:03,750 --> 00:36:06,573
but Professor Colin Devey has an idea.
680
00:36:07,650 --> 00:36:09,920
In the ice of Europe's biggest glacier,
681
00:36:09,920 --> 00:36:12,273
he is hoping to find the answer.
682
00:36:13,174 --> 00:36:16,400
(gentle music continues)
683
00:36:16,400 --> 00:36:18,330
(water whooshing)
684
00:36:18,330 --> 00:36:22,200
So I'm here at the toe of a tongue
685
00:36:22,200 --> 00:36:26,130
from Vatnajokull Glacier.
686
00:36:26,130 --> 00:36:30,330
And as you can see, the ice is gray.
687
00:36:30,330 --> 00:36:32,310
There's lots of water.
688
00:36:32,310 --> 00:36:34,230
This glacier is melting.
689
00:36:34,230 --> 00:36:36,960
The reason it's gray is it's ash,
690
00:36:36,960 --> 00:36:39,840
it's volcanic ash lying on the ice.
691
00:36:39,840 --> 00:36:44,340
So we've got ash on ice, it's melting.
692
00:36:44,340 --> 00:36:46,140
Is that the end of a snowball Earth?
693
00:36:51,300 --> 00:36:54,543
Could volcanic corruptions have melted the ice?
694
00:36:56,520 --> 00:36:58,530
Like the rest of the Earth,
695
00:36:58,530 --> 00:37:00,900
the primordial volcanoes were buried
696
00:37:00,900 --> 00:37:03,900
under masses of ice and snow,
697
00:37:03,900 --> 00:37:07,983
so an eruption would've had to take place under ice.
698
00:37:11,670 --> 00:37:14,100
Volcanoes can definitely erupt under ice.
699
00:37:14,100 --> 00:37:15,450
We know it from Iceland.
700
00:37:15,450 --> 00:37:18,900
Grimsvotn up there erupted in 1996
701
00:37:18,900 --> 00:37:22,080
under 800 meters of glacier,
702
00:37:22,080 --> 00:37:24,600
and it managed to melt all that ice
703
00:37:24,600 --> 00:37:26,940
into a huge lake full of water
704
00:37:26,940 --> 00:37:30,600
which then raced down the side of Iceland,
705
00:37:30,600 --> 00:37:32,160
devastating all the coast here,
706
00:37:32,160 --> 00:37:33,990
washing away roads and bridges
707
00:37:33,990 --> 00:37:36,660
and power lines and all sorts of stuff.
708
00:37:36,660 --> 00:37:41,610
But after that, the volcano was in the open air.
709
00:37:41,610 --> 00:37:43,710
So it managed to free itself of that much ice,
710
00:37:43,710 --> 00:37:45,963
that's no problem for a volcano.
711
00:37:49,860 --> 00:37:53,250
The power of volcanoes is immense
712
00:37:53,250 --> 00:37:57,333
and the heat of the magma can easily melt snow and ice.
713
00:37:58,200 --> 00:38:01,800
But are there really enough volcanoes on our planet
714
00:38:01,800 --> 00:38:04,293
to put an end to a snowball Earth?
715
00:38:05,346 --> 00:38:08,763
(gentle music continues)
716
00:38:11,160 --> 00:38:13,530
I mean, it would be possible to melt the snowball
717
00:38:13,530 --> 00:38:16,020
if you had vulcanism all over the planet
718
00:38:16,020 --> 00:38:18,150
at the same time everywhere.
719
00:38:18,150 --> 00:38:21,270
But then I'd see the rocks, and I don't,
720
00:38:21,270 --> 00:38:24,788
there isn't vulcanism all over the planet at that time.
721
00:38:24,788 --> 00:38:27,750
There's always volcanoes going off on this planet,
722
00:38:27,750 --> 00:38:30,750
but not more than at any other time.
723
00:38:30,750 --> 00:38:33,030
So no vulcanism,
724
00:38:33,030 --> 00:38:35,070
just the heat of the magma coming out
725
00:38:35,070 --> 00:38:37,563
could not have melted a snowball Earth.
726
00:38:40,500 --> 00:38:41,790
At some spots,
727
00:38:41,790 --> 00:38:45,210
the volcanoes may have melted little parts,
728
00:38:45,210 --> 00:38:48,210
but the snowball Earth remained frozen
729
00:38:48,210 --> 00:38:50,283
despite the magma flows.
730
00:38:51,810 --> 00:38:53,970
In fact, as I said,
731
00:38:53,970 --> 00:38:57,090
it's unlikely that that's how you end a snowball Earth.
732
00:38:57,090 --> 00:39:02,090
But volcanoes are not just producing molten rock as magma.
733
00:39:02,280 --> 00:39:04,620
They produce other things
734
00:39:04,620 --> 00:39:07,473
that may help us to get out of a snowball Earth.
735
00:39:09,480 --> 00:39:12,240
Professor Devey is heading for a volcano
736
00:39:12,240 --> 00:39:14,070
in the southwest of Iceland
737
00:39:14,070 --> 00:39:16,260
that has recently erupted.
738
00:39:16,260 --> 00:39:20,733
Here, he wants to see what it spews out apart from lava.
739
00:39:21,713 --> 00:39:24,796
(soft ominous music)
740
00:39:32,760 --> 00:39:35,210
Yeah, that's really what fresh lava looks like.
741
00:39:36,630 --> 00:39:40,170
It's a really good place to examine fresh lava.
742
00:39:40,170 --> 00:39:42,060
This is probably one of the youngest lavas
743
00:39:42,060 --> 00:39:43,350
on our planet at the moment.
744
00:39:43,350 --> 00:39:45,150
This is the youngest one on Iceland.
745
00:39:46,020 --> 00:39:47,490
It's still warm, actually,
746
00:39:47,490 --> 00:39:49,440
in several places here where I'm standing.
747
00:39:49,440 --> 00:39:53,370
And this is probably a really good place to find out
748
00:39:53,370 --> 00:39:55,383
how snowball Earth ended.
749
00:39:56,910 --> 00:39:58,470
With a special instrument,
750
00:39:58,470 --> 00:40:01,230
Professor Devey wants to analyze the vapors
751
00:40:01,230 --> 00:40:03,183
that rise from the hot rocks.
752
00:40:04,050 --> 00:40:06,120
This is a gas flux meter.
753
00:40:06,120 --> 00:40:09,840
It sucks air out of this pot here
754
00:40:09,840 --> 00:40:12,120
and measures the gases inside this box,
755
00:40:12,120 --> 00:40:17,010
particularly CO2 is what I'm looking at at the moment.
756
00:40:17,010 --> 00:40:20,220
Up in the air like this, we're about 400 PPM CO2,
757
00:40:20,220 --> 00:40:22,870
that's what the air has on this planet at the moment.
758
00:40:25,080 --> 00:40:26,520
And we go down onto here
759
00:40:26,520 --> 00:40:30,693
and we're now at 405, 6, 7, 800, 900.
760
00:40:32,370 --> 00:40:33,600
It's going up and up and up.
761
00:40:33,600 --> 00:40:35,430
Okay, we're at 1,500 PPM.
762
00:40:35,430 --> 00:40:39,240
That's four times the normal CO2 concentration
763
00:40:39,240 --> 00:40:40,110
of the atmosphere,
764
00:40:40,110 --> 00:40:43,263
so there's a lot of CO2 coming out of the ground here.
765
00:40:44,640 --> 00:40:47,370
A subglacial eruption of many volcanoes
766
00:40:47,370 --> 00:40:49,680
during the snowball Earth period
767
00:40:49,680 --> 00:40:53,010
would've significantly increased the greenhouse gas level
768
00:40:53,010 --> 00:40:54,243
in the atmosphere.
769
00:40:55,380 --> 00:40:59,820
It's very difficult to get an icy Earth to melt again.
770
00:40:59,820 --> 00:41:02,310
So probably the only way to get out of it,
771
00:41:02,310 --> 00:41:04,470
or at least one of the few ways to get out of it,
772
00:41:04,470 --> 00:41:07,050
is to make the atmosphere into a greenhouse,
773
00:41:07,050 --> 00:41:08,280
to actually warm the planet
774
00:41:08,280 --> 00:41:10,710
by increasing carbon dioxide in the atmosphere.
775
00:41:10,710 --> 00:41:11,910
The volcanoes can do it,
776
00:41:11,910 --> 00:41:15,000
and so that's probably how snowball Earth ended.
777
00:41:15,000 --> 00:41:17,010
Increased carbon dioxide in the atmosphere,
778
00:41:17,010 --> 00:41:19,593
a greenhouse climate, the ice melts.
779
00:41:20,910 --> 00:41:23,100
The volcanoes have freed the Earth
780
00:41:23,100 --> 00:41:24,630
from the snowball,
781
00:41:24,630 --> 00:41:27,330
not by their magma melting the ice,
782
00:41:27,330 --> 00:41:30,363
but by the greenhouse gases they release.
783
00:41:32,010 --> 00:41:34,920
Through them, our atmosphere is transformed
784
00:41:34,920 --> 00:41:38,703
so that heat can accumulate and thaw the snowball.
785
00:41:39,750 --> 00:41:43,770
But as the ice melts, one question remains.
786
00:41:43,770 --> 00:41:45,570
How could any life survive
787
00:41:45,570 --> 00:41:48,903
after millions of years in such a deep freeze?
788
00:41:51,780 --> 00:41:54,780
The eternal ice on the highest peaks of the Alps
789
00:41:54,780 --> 00:41:57,780
forms an environment that is comparable to our Earth
790
00:41:57,780 --> 00:42:00,240
2.4 billion years ago
791
00:42:00,240 --> 00:42:03,153
when it was firmly in the grip of snow and ice.
792
00:42:04,500 --> 00:42:07,020
Patrick Jung and Michael Lakatos
793
00:42:07,020 --> 00:42:09,783
therefore want to search for clues right here,
794
00:42:10,920 --> 00:42:12,540
on the roof of Europe.
795
00:42:12,540 --> 00:42:15,780
They wanna find out how life was able to survive
796
00:42:15,780 --> 00:42:18,093
in the deep freeze of the snowball Earth.
797
00:42:22,848 --> 00:42:24,748
Look at this landscape.
798
00:42:27,750 --> 00:42:29,190
We came to the Aletsch Glacier
799
00:42:29,190 --> 00:42:31,230
to find out if we could find life
800
00:42:31,230 --> 00:42:32,640
in this hostile environment
801
00:42:32,640 --> 00:42:34,950
completely covered by ice and snow
802
00:42:34,950 --> 00:42:36,423
as far as the eye can see.
803
00:42:40,230 --> 00:42:42,840
The scientists are led by a mountain guide,
804
00:42:42,840 --> 00:42:45,630
as dangerous crevices plunge into the depths
805
00:42:45,630 --> 00:42:47,043
beneath the snow cover.
806
00:42:50,550 --> 00:42:52,050
With the help of a drone,
807
00:42:52,050 --> 00:42:56,103
the two biologists scan the area for any signs of life.
808
00:42:57,099 --> 00:42:59,849
(dramatic music)
809
00:43:08,576 --> 00:43:10,080
[Patrick's Translator] Turn a little more to the left,
810
00:43:10,080 --> 00:43:11,093
Michael.
Okay.
811
00:43:12,872 --> 00:43:13,705
[Patrick's Translator] That could be something.
812
00:43:14,638 --> 00:43:15,848
[Michael's Translator] Oh yeah, you're right.
813
00:43:15,848 --> 00:43:17,430
[Patrick's Translator] This black formation looks good.
814
00:43:17,430 --> 00:43:18,730
That's where we should go.
815
00:43:22,655 --> 00:43:24,570
To really be able to say
816
00:43:24,570 --> 00:43:26,970
whether we can find organisms on the rock face,
817
00:43:26,970 --> 00:43:29,340
Michael will climb up and take a sample,
818
00:43:29,340 --> 00:43:31,490
because that's the only way we can clarify.
819
00:43:35,400 --> 00:43:37,470
The climb is risky.
820
00:43:37,470 --> 00:43:39,840
The rock face is steep.
821
00:43:39,840 --> 00:43:41,310
But without the sample,
822
00:43:41,310 --> 00:43:44,343
the scientists can't evaluate their discovery.
823
00:43:45,963 --> 00:43:46,950
[Patrick's Translator] Further to the right.
824
00:43:46,950 --> 00:43:47,853
Yeah, right there.
825
00:43:52,380 --> 00:43:53,730
You think you can reach it?
826
00:43:54,578 --> 00:43:58,161
(dramatic music continues)
827
00:44:01,223 --> 00:44:04,056
(hammer thudding)
828
00:44:07,108 --> 00:44:10,525
(gentle music continues)
829
00:44:13,586 --> 00:44:17,253
[Michael's Translator] I've got something.
830
00:44:20,805 --> 00:44:23,236
[Patrick's Translator] Oh, cool. Wow.
831
00:44:23,236 --> 00:44:24,069
[Michael's Translator] You can see
832
00:44:24,069 --> 00:44:25,000
the entire structure here.
833
00:44:26,473 --> 00:44:27,450
[Patrick's Translator] And it's nice and black
834
00:44:27,450 --> 00:44:28,443
on the surface.
835
00:44:29,430 --> 00:44:31,770
Okay, let me rub some of that off.
836
00:44:31,770 --> 00:44:33,330
Oh yeah, look.
837
00:44:33,330 --> 00:44:34,980
There's some brown color on here.
838
00:44:35,970 --> 00:44:37,950
Could be organic.
It definitely gives us
839
00:44:37,950 --> 00:44:39,060
a good indication,
840
00:44:39,060 --> 00:44:41,110
but I think we should take a closer look.
841
00:44:43,140 --> 00:44:44,970
Using a magnifying glass,
842
00:44:44,970 --> 00:44:47,913
the biologists inspect the rock sample closer.
843
00:44:50,947 --> 00:44:52,140
[Patrick's Translator] Well, Michael,
844
00:44:52,140 --> 00:44:53,280
I'm pretty sure about that.
845
00:44:53,280 --> 00:44:54,630
I can see it quite clearly
846
00:44:54,630 --> 00:44:56,640
by the color and the shape of the growth.
847
00:44:56,640 --> 00:44:58,503
These are actually cyanobacteria.
848
00:45:02,010 --> 00:45:03,870
The same ancient bacteria
849
00:45:03,870 --> 00:45:05,970
that caused the global ice age
850
00:45:05,970 --> 00:45:07,773
are clinging to the rock face.
851
00:45:08,670 --> 00:45:10,740
To determine if they are alive,
852
00:45:10,740 --> 00:45:13,173
the researchers take another measurement.
853
00:45:18,896 --> 00:45:19,950
[Patrick's Translator] With this device,
854
00:45:19,950 --> 00:45:21,870
we can measure photosynthesis.
855
00:45:21,870 --> 00:45:23,190
If it shows something,
856
00:45:23,190 --> 00:45:26,377
it would be a clear indication that we have found life.
857
00:45:26,377 --> 00:45:27,840
[Michael's Translator] Let me switch this
858
00:45:27,840 --> 00:45:29,040
so we can see something.
859
00:45:31,499 --> 00:45:34,980
[Patrick's Translator] Yes, it's everywhere.
860
00:45:34,980 --> 00:45:37,920
Here where it lights up red, those are signals.
861
00:45:37,920 --> 00:45:39,873
That looks alive, it's a lot.
862
00:45:41,760 --> 00:45:45,333
Life amidst a world of snow and ice.
863
00:45:48,840 --> 00:45:50,400
During the snowball Earth phase,
864
00:45:50,400 --> 00:45:52,890
many life forms actually perished.
865
00:45:52,890 --> 00:45:55,830
Those that survived have retreated to certain regions
866
00:45:55,830 --> 00:45:57,933
like these cyanobacteria stains.
867
00:46:01,620 --> 00:46:03,300
Ancient microbial life
868
00:46:03,300 --> 00:46:07,173
has found a way to survive in this hostile environment.
869
00:46:09,840 --> 00:46:11,970
Cyanobacteria and life in general
870
00:46:11,970 --> 00:46:14,370
have a very hard time developing and growing
871
00:46:14,370 --> 00:46:16,170
in a world without water.
872
00:46:16,170 --> 00:46:17,310
Here on the other hand,
873
00:46:17,310 --> 00:46:20,850
the cyanobacteria grow on these black formations.
874
00:46:20,850 --> 00:46:23,160
These rocks remain free of ice and snow
875
00:46:23,160 --> 00:46:24,630
for a very long time,
876
00:46:24,630 --> 00:46:26,433
simply because they are too steep.
877
00:46:27,300 --> 00:46:29,883
But ice regularly melts off the overhang.
878
00:46:30,720 --> 00:46:32,940
This water forms a drainage channel
879
00:46:32,940 --> 00:46:35,790
and cyanobacteria can thrive in it.
880
00:46:35,790 --> 00:46:39,273
That's exactly how it must have been 2.4 billion years ago.
881
00:46:40,140 --> 00:46:43,470
The cyanobacteria survived in ice-free niches
882
00:46:43,470 --> 00:46:45,183
like the one we found here today.
883
00:46:49,583 --> 00:46:50,970
By this strategy,
884
00:46:50,970 --> 00:46:55,230
life was able to outlast the snowball Earth phases.
885
00:46:55,230 --> 00:46:57,510
Two more times in Earth's history
886
00:46:57,510 --> 00:47:01,440
almost the entire planet was to freeze over.
887
00:47:01,440 --> 00:47:04,533
Each time, many species died out.
888
00:47:06,060 --> 00:47:09,213
But some of them survived on the edge of the ice world.
889
00:47:11,940 --> 00:47:14,100
Scientists believe that even during
890
00:47:14,100 --> 00:47:16,290
the snowball Earth phases
891
00:47:16,290 --> 00:47:18,750
there were small areas on Earth
892
00:47:18,750 --> 00:47:21,273
that were not completely covered with ice.
893
00:47:23,100 --> 00:47:27,270
These niches may have provided safe havens for early life
894
00:47:27,270 --> 00:47:29,553
with oxygen and liquid water.
895
00:47:31,200 --> 00:47:36,200
Tiny oases where life could survive the global ice ages.
896
00:47:36,540 --> 00:47:40,500
(dramatic music continues)
897
00:47:40,500 --> 00:47:45,500
After the last global glaciation 580 million years ago,
898
00:47:45,600 --> 00:47:48,450
the time had come for life to flourish
899
00:47:48,450 --> 00:47:50,283
on an unprecedented level.
900
00:47:52,650 --> 00:47:56,883
It now began to evolve into evermore complex forms.
901
00:47:59,160 --> 00:48:03,090
Snowball Earth and all the catastrophes that followed
902
00:48:03,090 --> 00:48:05,220
were the kind of apocalyptic events
903
00:48:05,220 --> 00:48:08,103
that life on Earth has always benefited from.
904
00:48:11,970 --> 00:48:14,340
Without these catastrophes,
905
00:48:14,340 --> 00:48:17,543
we literally would not be here today.
906
00:48:21,071 --> 00:48:24,238
(soft dramatic music)
907
00:48:51,120 --> 00:48:55,120
(soft dramatic music continues)
908
00:49:17,639 --> 00:49:18,745
(music fades out)