The secrets I find on the mysterious ocean floor
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0:01 - 0:02Well, I'm an ocean chemist.
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0:02 - 0:04I look at the chemistry
of the ocean today. -
0:04 - 0:07I look at the chemistry
of the ocean in the past. -
0:07 - 0:09The way I look back in the past
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0:09 - 0:13is by using the fossilized remains
of deepwater corals. -
0:13 - 0:15You can see an image of one
of these corals behind me. -
0:15 - 0:20It was collected from close to Antarctica,
thousands of meters below the sea, -
0:20 - 0:22so, very different
than the kinds of corals -
0:22 - 0:26you may have been lucky enough to see
if you've had a tropical holiday. -
0:26 - 0:28So I'm hoping that this talk will give you
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0:28 - 0:30a four-dimensional view of the ocean.
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0:30 - 0:33Two dimensions, such as this
beautiful two-dimensional image -
0:33 - 0:35of the sea surface temperature.
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0:35 - 0:39This was taken using satellite,
so it's got tremendous spatial resolution. -
0:40 - 0:43The overall features are extremely
easy to understand. -
0:43 - 0:46The equatorial regions are warm
because there's more sunlight. -
0:46 - 0:49The polar regions are cold
because there's less sunlight. -
0:49 - 0:52And that allows big icecaps
to build up on Antarctica -
0:52 - 0:54and up in the Northern Hemisphere.
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0:54 - 0:58If you plunge deep into the sea,
or even put your toes in the sea, -
0:58 - 1:00you know it gets colder as you go down,
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1:00 - 1:04and that's mostly because the deep waters
that fill the abyss of the ocean -
1:04 - 1:07come from the cold polar regions
where the waters are dense. -
1:08 - 1:11If we travel back in time
20,000 years ago, -
1:11 - 1:13the earth looked very much different.
-
1:13 - 1:16And I've just given you a cartoon version
of one of the major differences -
1:16 - 1:19you would have seen
if you went back that long. -
1:19 - 1:20The icecaps were much bigger.
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1:20 - 1:24They covered lots of the continent,
and they extended out over the ocean. -
1:24 - 1:26Sea level was 120 meters lower.
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1:27 - 1:30Carbon dioxide [levels] were very
much lower than they are today. -
1:30 - 1:34So the earth was probably about three
to five degrees colder overall, -
1:34 - 1:37and much, much colder
in the polar regions. -
1:38 - 1:39What I'm trying to understand,
-
1:39 - 1:42and what other colleagues of mine
are trying to understand, -
1:42 - 1:45is how we moved from that
cold climate condition -
1:45 - 1:48to the warm climate condition
that we enjoy today. -
1:48 - 1:50We know from ice core research
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1:50 - 1:53that the transition from these
cold conditions to warm conditions -
1:53 - 1:58wasn't smooth, as you might predict
from the slow increase in solar radiation. -
1:58 - 2:01And we know this from ice cores,
because if you drill down into ice, -
2:01 - 2:05you find annual bands of ice,
and you can see this in the iceberg. -
2:05 - 2:07You can see those blue-white layers.
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2:07 - 2:10Gases are trapped in the ice cores,
so we can measure CO2 -- -
2:10 - 2:13that's why we know CO2
was lower in the past -- -
2:13 - 2:16and the chemistry of the ice
also tells us about temperature -
2:16 - 2:17in the polar regions.
-
2:17 - 2:21And if you move in time
from 20,000 years ago to the modern day, -
2:21 - 2:23you see that temperature increased.
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2:23 - 2:24It didn't increase smoothly.
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2:24 - 2:26Sometimes it increased very rapidly,
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2:26 - 2:28then there was a plateau,
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2:28 - 2:29then it increased rapidly.
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2:29 - 2:31It was different in the two polar regions,
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2:31 - 2:34and CO2 also increased in jumps.
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2:35 - 2:38So we're pretty sure the ocean
has a lot to do with this. -
2:38 - 2:40The ocean stores huge amounts of carbon,
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2:40 - 2:43about 60 times more
than is in the atmosphere. -
2:43 - 2:46It also acts to transport heat
across the equator, -
2:46 - 2:50and the ocean is full of nutrients
and it controls primary productivity. -
2:50 - 2:53So if we want to find out
what's going on down in the deep sea, -
2:53 - 2:55we really need to get down there,
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2:55 - 2:56see what's there
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2:56 - 2:57and start to explore.
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2:57 - 3:00This is some spectacular footage
coming from a seamount -
3:00 - 3:03about a kilometer deep
in international waters -
3:03 - 3:06in the equatorial Atlantic, far from land.
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3:06 - 3:09You're amongst the first people
to see this bit of the seafloor, -
3:09 - 3:10along with my research team.
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3:11 - 3:13You're probably seeing new species.
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3:13 - 3:14We don't know.
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3:14 - 3:18You'd have to collect the samples
and do some very intense taxonomy. -
3:18 - 3:20You can see beautiful bubblegum corals.
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3:20 - 3:22There are brittle stars
growing on these corals. -
3:22 - 3:25Those are things that look
like tentacles coming out of corals. -
3:25 - 3:28There are corals made of different forms
of calcium carbonate -
3:28 - 3:32growing off the basalt of this
massive undersea mountain, -
3:32 - 3:35and the dark sort of stuff,
those are fossilized corals, -
3:35 - 3:37and we're going to talk
a little more about those -
3:37 - 3:39as we travel back in time.
-
3:39 - 3:42To do that, we need
to charter a research boat. -
3:42 - 3:45This is the James Cook,
an ocean-class research vessel -
3:45 - 3:46moored up in Tenerife.
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3:46 - 3:47Looks beautiful, right?
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3:48 - 3:49Great, if you're not a great mariner.
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3:50 - 3:52Sometimes it looks
a little more like this. -
3:52 - 3:55This is us trying to make sure
that we don't lose precious samples. -
3:55 - 3:58Everyone's scurrying around,
and I get terribly seasick, -
3:58 - 4:01so it's not always a lot of fun,
but overall it is. -
4:01 - 4:04So we've got to become
a really good mapper to do this. -
4:04 - 4:08You don't see that kind of spectacular
coral abundance everywhere. -
4:08 - 4:11It is global and it is deep,
-
4:11 - 4:13but we need to really find
the right places. -
4:13 - 4:16We just saw a global map,
and overlaid was our cruise passage -
4:16 - 4:17from last year.
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4:18 - 4:19This was a seven-week cruise,
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4:19 - 4:21and this is us, having made our own maps
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4:21 - 4:26of about 75,000 square kilometers
of the seafloor in seven weeks, -
4:26 - 4:28but that's only a tiny fraction
of the seafloor. -
4:28 - 4:30We're traveling from west to east,
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4:30 - 4:33over part of the ocean that would
look featureless on a big-scale map, -
4:33 - 4:37but actually some of these mountains
are as big as Everest. -
4:37 - 4:39So with the maps that we make on board,
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4:39 - 4:41we get about 100-meter resolution,
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4:41 - 4:44enough to pick out areas
to deploy our equipment, -
4:44 - 4:45but not enough to see very much.
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4:46 - 4:48To do that, we need to fly
remotely-operated vehicles -
4:48 - 4:50about five meters off the seafloor.
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4:51 - 4:54And if we do that, we can get maps
that are one-meter resolution -
4:54 - 4:56down thousands of meters.
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4:56 - 4:58Here is a remotely-operated vehicle,
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4:58 - 5:00a research-grade vehicle.
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5:00 - 5:03You can see an array
of big lights on the top. -
5:03 - 5:06There are high-definition cameras,
manipulator arms, -
5:06 - 5:09and lots of little boxes and things
to put your samples. -
5:09 - 5:13Here we are on our first dive
of this particular cruise, -
5:13 - 5:15plunging down into the ocean.
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5:15 - 5:17We go pretty fast to make sure
the remotely operated vehicles -
5:17 - 5:19are not affected by any other ships.
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5:19 - 5:20And we go down,
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5:20 - 5:23and these are the kinds of things you see.
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5:23 - 5:26These are deep sea sponges, meter scale.
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5:27 - 5:31This is a swimming holothurian --
it's a small sea slug, basically. -
5:31 - 5:32This is slowed down.
-
5:32 - 5:35Most of the footage I'm showing
you is speeded up, -
5:35 - 5:37because all of this takes a lot of time.
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5:37 - 5:40This is a beautiful holothurian as well.
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5:41 - 5:44And this animal you're going to see
coming up was a big surprise. -
5:44 - 5:47I've never seen anything like this
and it took us all a bit surprised. -
5:47 - 5:51This was after about 15 hours of work
and we were all a bit trigger-happy, -
5:51 - 5:54and suddenly this giant
sea monster started rolling past. -
5:54 - 5:57It's called a pyrosome
or colonial tunicate, if you like. -
5:57 - 5:59This wasn't what we were looking for.
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5:59 - 6:01We were looking for corals,
deep sea corals. -
6:02 - 6:04You're going to see a picture
of one in a moment. -
6:05 - 6:07It's small, about five centimeters high.
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6:07 - 6:10It's made of calcium carbonate,
so you can see its tentacles there, -
6:11 - 6:13moving in the ocean currents.
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6:13 - 6:16An organism like this probably lives
for about a hundred years. -
6:16 - 6:20And as it grows, it takes in
chemicals from the ocean. -
6:20 - 6:22And the chemicals,
or the amount of chemicals, -
6:22 - 6:25depends on the temperature;
it depends on the pH, -
6:25 - 6:26it depends on the nutrients.
-
6:26 - 6:30And if we can understand how
these chemicals get into the skeleton, -
6:30 - 6:32we can then go back,
collect fossil specimens, -
6:32 - 6:35and reconstruct what the ocean
used to look like in the past. -
6:35 - 6:39And here you can see us collecting
that coral with a vacuum system, -
6:39 - 6:41and we put it into a sampling container.
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6:41 - 6:43We can do this very
carefully, I should add. -
6:43 - 6:46Some of these organisms live even longer.
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6:46 - 6:49This is a black coral called Leiopathes,
an image taken by my colleague, -
6:49 - 6:53Brendan Roark, about 500
meters below Hawaii. -
6:53 - 6:55Four thousand years is a long time.
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6:55 - 6:58If you take a branch from one
of these corals and polish it up, -
6:58 - 7:00this is about 100 microns across.
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7:01 - 7:03And Brendan took some analyses
across this coral -- -
7:03 - 7:05you can see the marks --
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7:05 - 7:08and he's been able to show
that these are actual annual bands, -
7:08 - 7:10so even at 500 meters deep in the ocean,
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7:10 - 7:13corals can record seasonal changes,
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7:13 - 7:15which is pretty spectacular.
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7:15 - 7:18But 4,000 years is not enough to get
us back to our last glacial maximum. -
7:18 - 7:20So what do we do?
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7:20 - 7:22We go in for these fossil specimens.
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7:22 - 7:25This is what makes me really unpopular
with my research team. -
7:25 - 7:26So going along,
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7:26 - 7:28there's giant sharks everywhere,
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7:28 - 7:30there are pyrosomes,
there are swimming holothurians, -
7:30 - 7:32there's giant sponges,
-
7:32 - 7:34but I make everyone go down
to these dead fossil areas -
7:34 - 7:38and spend ages kind of shoveling
around on the seafloor. -
7:38 - 7:41And we pick up all these corals,
bring them back, we sort them out. -
7:41 - 7:44But each one of these is a different age,
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7:44 - 7:46and if we can find out how old they are
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7:46 - 7:48and then we can measure
those chemical signals, -
7:48 - 7:50this helps us to find out
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7:50 - 7:52what's been going on
in the ocean in the past. -
7:53 - 7:54So on the left-hand image here,
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7:54 - 7:57I've taken a slice through a coral,
polished it very carefully -
7:57 - 7:59and taken an optical image.
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7:59 - 8:00On the right-hand side,
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8:01 - 8:04we've taken that same piece of coral,
put it in a nuclear reactor, -
8:04 - 8:05induced fission,
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8:05 - 8:06and every time there's some decay,
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8:06 - 8:08you can see that marked out in the coral,
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8:08 - 8:10so we can see the uranium distribution.
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8:10 - 8:12Why are we doing this?
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8:12 - 8:14Uranium is a very poorly regarded element,
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8:14 - 8:15but I love it.
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8:15 - 8:18The decay helps us find out
about the rates and dates -
8:18 - 8:20of what's going on in the ocean.
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8:20 - 8:22And if you remember from the beginning,
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8:22 - 8:25that's what we want to get at
when we're thinking about climate. -
8:25 - 8:27So we use a laser to analyze uranium
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8:27 - 8:29and one of its daughter products,
thorium, in these corals, -
8:29 - 8:32and that tells us exactly
how old the fossils are. -
8:33 - 8:35This beautiful animation
of the Southern Ocean -
8:35 - 8:38I'm just going to use illustrate
how we're using these corals -
8:38 - 8:42to get at some of the ancient
ocean feedbacks. -
8:42 - 8:45You can see the density
of the surface water -
8:45 - 8:47in this animation by Ryan Abernathey.
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8:47 - 8:50It's just one year of data,
-
8:50 - 8:52but you can see how dynamic
the Southern Ocean is. -
8:52 - 8:56The intense mixing,
particularly the Drake Passage, -
8:56 - 8:58which is shown by the box,
-
8:58 - 9:01is really one of the strongest
currents in the world -
9:01 - 9:03coming through here,
flowing from west to east. -
9:03 - 9:05It's very turbulently mixed,
-
9:05 - 9:08because it's moving over those
great big undersea mountains, -
9:08 - 9:12and this allows CO2 and heat to exchange
with the atmosphere in and out. -
9:12 - 9:16And essentially, the oceans are breathing
through the Southern Ocean. -
9:17 - 9:22We've collected corals from back and forth
across this Antarctic passage, -
9:22 - 9:25and we've found quite a surprising thing
from my uranium dating: -
9:25 - 9:28the corals migrated from south to north
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9:28 - 9:31during this transition from the glacial
to the interglacial. -
9:31 - 9:32We don't really know why,
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9:32 - 9:35but we think it's something
to do with the food source -
9:35 - 9:37and maybe the oxygen in the water.
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9:38 - 9:39So here we are.
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9:39 - 9:42I'm going to illustrate what I think
we've found about climate -
9:42 - 9:44from those corals in the Southern Ocean.
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9:44 - 9:47We went up and down sea mountains.
We collected little fossil corals. -
9:47 - 9:49This is my illustration of that.
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9:49 - 9:50We think back in the glacial,
-
9:50 - 9:52from the analysis
we've made in the corals, -
9:52 - 9:55that the deep part of the Southern Ocean
was very rich in carbon, -
9:55 - 9:58and there was a low-density
layer sitting on top. -
9:58 - 10:01That stops carbon dioxide
coming out of the ocean. -
10:02 - 10:04We then found corals
that are of an intermediate age, -
10:04 - 10:09and they show us that the ocean mixed
partway through that climate transition. -
10:09 - 10:11That allows carbon to come
out of the deep ocean. -
10:12 - 10:15And then if we analyze corals
closer to the modern day, -
10:15 - 10:18or indeed if we go down there today anyway
-
10:18 - 10:20and measure the chemistry of the corals,
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10:20 - 10:24we see that we move to a position
where carbon can exchange in and out. -
10:24 - 10:26So this is the way
we can use fossil corals -
10:26 - 10:28to help us learn about the environment.
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10:30 - 10:32So I want to leave you
with this last slide. -
10:32 - 10:36It's just a still taken out of that first
piece of footage that I showed you. -
10:36 - 10:38This is a spectacular coral garden.
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10:38 - 10:41We didn't even expect
to find things this beautiful. -
10:41 - 10:43It's thousands of meters deep.
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10:43 - 10:44There are new species.
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10:44 - 10:46It's just a beautiful place.
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10:46 - 10:48There are fossils in amongst,
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10:48 - 10:50and now I've trained you
to appreciate the fossil corals -
10:50 - 10:52that are down there.
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10:52 - 10:55So next time you're lucky enough
to fly over the ocean -
10:55 - 10:56or sail over the ocean,
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10:56 - 10:59just think -- there are massive
sea mountains down there -
10:59 - 11:01that nobody's ever seen before,
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11:01 - 11:02and there are beautiful corals.
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11:02 - 11:03Thank you.
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11:03 - 11:08(Applause)
- Title:
- The secrets I find on the mysterious ocean floor
- Speaker:
- Laura Robinson
- Description:
-
Hundreds of meters below the surface of the ocean, Laura Robinson probes the steep slopes of massive undersea mountains. She's on the hunt for thousand-year-old corals that she can test in a nuclear reactor to discover how the ocean changes over time. By studying the history of the earth, Robinson hopes to find clues of what might happen in the future.
- Video Language:
- English
- Team:
- closed TED
- Project:
- TEDTalks
- Duration:
- 11:21
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Brian Greene
This transcript was updated on March 25, 2016.
The subtitle beginning at 8:53 was corrected. It now reads:
The intense mixing,
particularly the Drake Passage,