Translator: Hiroko Kawano Reviewer: Cristina Bufi-Pöcksteiner
This is our planet.
This is planet Earth.
What a curious name for a planet!
I mean, there's very little earth on it.
Only 29% of the surface of this planet is actually earth, land.
(Laughter)
We need to challenge our human-centric perspective of where we live.
This is an oceanic planet.
The oceans is where most of the life on this planet lives.
The oceans control our weather.
The oceans control our climate.
When ocean circulation changes, the climate changes.
The oceans are present absorbing excess CO2 and heat from our atmosphere.
Yet, we know very little about our oceans.
So what I want to do is I want to tell you about some discoveries
that me and my research team and some colleagues have made in the ocean.
I want to tell you a story about climate change.
And I want to tell you a story about a grain of sand,
a grain of sand that was discovered in the deep ocean,
and a grain of sand that was actually discovered
deep below the seabed in the deep ocean.
When I was a boy I was a lot cuter than I am today.
(Laughter)
Now I have a distinct memory of standing on a beach
and looking out to sea and thinking,
"I wonder what it'd be like if I just kept walking."
"I wonder what it would be like if I walk down across the bay."
"If I walked out across the shelf and down into the deep abyss,
I wonder what it's like down there."
As a boy, I had a dream
that one day man would walk upon not the moon but the seabed,
because the seabed, the deep ocean is our final frontier.
We haven't explored it properly yet.
We've hardly started.
Well, I'm a little bit more grown-up and I was following my dreams.
I am a marine geologist.
And that means I'm passionate about finding out
what rocks and sediments can tell us about how the Earth functions.
We live on a very dynamic planet, a planet that's constantly changing.
And as sediments accumulate on the seabed, sand and mud,
they record changes in the ocean.
And geologists can look back through those sediments
and discover what's been going on.
I'm not interested in what happened hundreds of millions of years ago.
I'm interested in what's happening now.
And I'm interested in what processes have brought us to where we are now,
and where we're going to go in the future.
I'm also an ocean explorer.
I'm interested in discovering bits of the ocean
that no one's looked at before.
I've seen many places for the first time that anyone's ever seen.
And I'm going there and finding what's down there, what's going on.
And to do that,
it involves going out on research vessels,
and we might go out to sea for maybe a week.
We may even go out for a month.
It's a big place out there, you've got to get out there.
And that means that if a storm comes along,
well, maybe you just have to ride out that storm,
and when it calms down, you can get on working.
Although I'd say that the most dangerous thing out there is not really the weather,
it's being stuck on a small boat with a bunch of crazy scientists
and succumbing to cabin fever.
(Laughter)
No, seriously.
The depths of water I'm interested in exploring are deep.
Scuba divers go down 40 meters, 50 meters, maybe a little bit more.
I'm interested in what happens in the deep ocean,
maybe 1,000 meters down, maybe 5,000 meters down.
And at those kind of depths humans simply implode,
so we use robotic instruments like the one behind me,
that become our arms to take samples,
and the cameras on these become our eyes to look around.
So this is our oceanic planet.
And this map of our ocean is the kind of standard public-domain map
that you get on your smartphones through Google Earth.
And it's fairly state-of-the-art.
It depicts actually the resolution that we know most of our oceans at.
We have spent centuries mapping our land.
We've mapped our countries, we've mapped our towns, our streets,
We even have plans of our own houses.
Yet, less than 10% of our ocean seabed is properly mapped.
That means 90% of our ocean is very poorly mapped,
or simply undiscovered.
I want to tell you the story about this grain of sand
which we discovered here.
And if we zoom into that area,
this is what the map of that bit of seabed looks like.
A one pixel here.
You could fit Central Park of Manhattan in that pixel.
That's how poor that map is.
And that's pretty much standard for most of our ocean.
Now, this bit of seabed has been mapped in detail
by scientists who've bothered to go out there and have a look.
If you do that -
We're going to view it from this direction because it just looks a little bit better.
If you do that, it looks like this.
There's a whole landscape down there.
There's a series of channels that go into a bigger channel
that goes off even deeper off of the map.
That red square there is our Central Park size pixel,
and there are hills down here.
And these hills are a 100 meters tall.
They're as big as office blocks.
And if we take camera systems, we dive down and we look at those hills
and find out what's on the surface,
we find they're covered in cold-water coral reefs.
So if we bother to look at west of Ireland about a kilometer below the surface,
we have coral existing at about 4 ℃ in the perpetual darkness.
Now, in 1998 I was fortunate in being one of the first people
to see these coral reefs in Irish waters
as a collaboration with Russian scientists.
And since then I have been very very interested in this habitat.
And I'm interested in it
not so much because of the organisms that live there that are very important.
But what fascinated me was:
if these coral reefs sit on top of these 100-meter-tall hills,
does that mean all of that hill is made by coral reef?
And if so, what record do they contain of our Earth's past?
So the most significant discovery that I think I've made here
is this grain of sand.
And we didn't discover this grain of sand from on top of one of those reefs.
We discovered it right at the very, very base
of one of those 100-meter-plus mounds.
And to do that, we needed to get out there, we needed to drill.
And we collected a continuous core all the way down through that mound.
At the very bottom of it, there was a very interesting layer of sand.
The sand grains on the left
are what you usually expect to find in the marine environment.
They're kind of rounded,
they've been rolling around on the seabed they've had the corners knocked off.
The layer of sand that we found is over on the right.
And to a geologist's eye this looks very different.
This sand is really quite angular,
and it shows evidence of being crushed or shattered.
This sand has been in a glacier.
It's been in ice and it's been crushed in a glacier,
and somehow found its way out
and deposited on this coral reef deep on the seabed.
That's not so fanciful because this happens all the time today.
And if glaciers exit down to sea level, they break apart,
and they produce dirty icebergs that float out across the ocean,
and as they melt, they drop all this sand and mud down on the seabed
and look very much like that grain down there.
So that's okay.
So we had an iceberg floating out into the deep ocean long time ago,
and depositing sediment in this coral reef.
But how old is that layer of sand?
It's 145 meters down,
it must be quite old.
But if we took that core -
it's full of coral, it's all coral reef -
we could date the individual bits of coral.
And it looks something like this.
On the vertical axis,
you see depth below the seabed going down through that mound.
On the bottom, there's age in millions of years.
This shows triangles that have a date from this bit of coral.
And at 145 meters down where a layer of sand is,
it comes out at 2.5 million years,
which is a very, very interesting time.
Sorry to throw graphs at you, this is another graph.
On the vertical axis we have mean global temperature,
the average temperature of our planet.
And on the bottom is five million years to present.
So, you can see our global temperature on our planet
has been going up and down quite a bit.
And in the last five million years, it's been slowly cooling down.
Our planet has been cooling down, okay?
And if you look at the far side at zero, that's present-day,
we've just come out of a glaciation, and we've gone up,
and that's present-day temperature there.
We worry that it might be going up even more.
When you get to this temperature here, as our planet cools down,
something interesting happens.
Snow that falls in winter doesn't melt in summer
because it gets too cool up in northern latitudes.
And this is the start of glaciation.
This is when glaciers first started forming
in the northern hemisphere in the relatively recent time.
And that is 2.5 million years ago.
Now, we didn't get widespread glaciation
into Europe and into Britain and Ireland and from Canada into North America
till about 1.4 million years ago.
And you can see after that, our climate curve really yo-yos,
and we get these really cold periods, these big full glaciations.
So what we're saying is,
2.5 million years ago, there was a glacier that liberated some icebergs,
and they floated all the way down from Scandinavia or Canada
all the way south to west of Ireland.
That's a long long way to go.
Is that realistic?
Uh, perhaps.
So we wanted to find out where did this grain of sand come from.
And this is where the real forensics kicks in
because we could isotopically fingerprint this grain of sand
and match it to the rocks that it eroded from.
So if you take a rock made of crystals and you erode it, you break it up,
you create grains of sand made of individual crystals,
and they are made of a regular arrangement of elements,
and elements are made of electrons with protons and neutrons,
and some elements can carry slightly more neutrons in them.
They're called the isotopes.
If we look at the ratio of isotopes,
we can get really quite a unique isotopic signature for different rocks
depending on how old they are, or where they come from.
So if we look to the isotopic signature of strontium and neodymium for our rock,
we can distinguish Iceland and Greenland from Canada, from the British Irish Isles,
from the gulfs and lands from Scandinavia.
And our layer of sand, 2.5 million years ago,
plots right in the middle of the British Irish Isles,
perhaps a little bit close to the Scandinavia domain.
But if you look at lead isotopes,
well, it's pretty convincing, it comes from Northwest Ireland.
Now, that's really quite surprising.
What we're saying is, 2.5 million years ago,
when we had the very, very start of glaciation,
the very first icebergs floating around in the Atlantic,
when they should have been way up in Scandinavia or northern Canada,
we've got glaciers in Ireland,
a million years too early, so big that they're actually exiting at sea level
and floating out and then melting a deposit of this sand in this early reef
that eventually gets buried.
That's really quite surprising, and is that feasible?
Well, maybe, because if you look at the west coast of Ireland today,
it's pretty mountainous.
It's pretty rugged.
And 2.5 million years of glaciation, or even 1.4 for that matter,
those mountains would have been considerably higher
before those glaciers eroded them down.
So right at the side of glaciation,
with really, really tall mountains on the west of Ireland,
we may have had permanent snow caps
getting those lovely wet westerlies that we loved in Ireland,
falling as permanent snowfall and getting so much snowfall
that they were producing glaciers that pumped down to sea level,
rather like Patagonia today in southern Chile and Argentina.
Okay, well, that's an interesting bit of detective work.
It's a story about the Earth's past.
And it's important that we understand the past
if we're to understand what's possible in the future.
It's a story of a radical rewrite of our understanding of glaciation
in the northern hemisphere.
It's a story about sensitivity of ice caps to climate change,
in this case, global cooling.
But we're very worried today about what ice caps are doing
with global warming.
It's only part of a jigsaw
of trying to understand how this planet works.
But the message that I want to leave you with today
is if we can learn so much from one small grain of sand,
what could we do if we bothered to explore 90% of our oceans
that we haven't really looked at?
And I really, really think we should.
Thank you.
(Applause)