the problem that we're facing with the oceans,

you have to think about the biology

at the same time you think about the physics.

We can't solve the problems

unless we start studying the ocean

in a very much more interdisciplinary way.

So I'm going to demonstrate that through

discussion of some of the climate change things that are going on in the ocean.

We'll look at sea level rise.

We'll look at ocean warming.

And then the last thing on the list there, ocean acidification --

if you were to ask me, you know, "What do you worry about the most?

What frightens you?"

for me, it's ocean acidification.

And this has come onto the stage pretty recently.

So I will spend a little time at the end.

I was in Copenhagen in December

like a number of you in this room.

And I think we all found it, simultaneously,

an eye-opening

and a very frustrating experience.

I sat in this large negotiation hall,

at one point, for three or four hours,

without hearing the word "oceans" one time.

It really wasn't on the radar screen.

The nations that brought it up

when we had the speeches of the national leaders --

it tended to be the leaders of the small island states,

the low-lying island states.

And by this weird quirk

of alphabetical order of the nations,

a lot of the low-lying states,

like Kiribati and Nauru,

they were seated at the very end of these immensely long rows.

You know, they were marginalized

in the negotiation room.

One of the problems

is coming up with the right target.

It's not clear what the target should be.

And how can you figure out how to fix something

if you don't have a clear target?

Now, you've heard about "two degrees":

that we should limit temperature rise to no more than two degrees.

But there's not a lot of science behind that number.

We've also talked about

concentrations of carbon dioxide in the atmosphere.

Should it be 450? Should it be 400?

There's not a lot of science behind that one either.

Most of the science that is behind these numbers,

these potential targets,

is based on studies on land.

And I would say, for the people that work in the ocean

and think about what the targets should be,

we would argue that they must be much lower.

You know, from an oceanic perspective,

450 is way too high.

Now there's compelling evidence

that it really needs to be 350.

We are, right now, at 390 parts per million

of CO2 in the atmosphere.

We're not going to put the brakes on in time to stop at 450,

so we've got to accept we're going to do an overshoot,

and the discussion as we go forward

has to focus on how far the overshoot goes

and what's the pathway back to 350.

Now, why is this so complicated?

Why don't we know some of these things a little bit better?

Well, the problem is that

we've got very complicated forces in the climate system.

There's all kinds of natural causes of climate change.

There's air-sea interactions.

Here in Galapagos,

we're affected by El Ninos and La Nina.

But the entire planet warms up when there's a big El Nino.

Volcanoes eject aerosols into the atmosphere.

That changes our climate.

The ocean contains most of the exchangeable heat on the planet.

So anything that influences

how ocean surface waters mix with the deep water

changes the ocean of the planet.

And we know the solar output's not constant through time.

So those are all natural causes of climate change.

And then we have the human-induced causes

of climate change as well.

We're changing the characteristics of the surface of the land,

the reflectivity.

We inject our own aerosols into the atmosphere,

and we have trace gases, and not just carbon dioxide --

it's methane, ozone,

oxides of sulfur and nitrogen.

So here's the thing. It sounds like a simple question.

Is CO2 produced by man's activities

causing the planet to warm up?

But to answer that question,

to make a clear attribution to carbon dioxide,

you have to know something about

all of these other agents of change.

But the fact is we do know a lot about all of those things.

You know, thousands of scientists

have been working on understanding

all of these man-made causes

and the natural causes.

And we've got it worked out, and we can say,

"Yes, CO2 is causing the planet to warm up now."

Now, we have many ways to study natural variability.

I'll show you a few examples of this now.

This is the ship that I spent the last three months on in the Antarctic.

It's a scientific drilling vessel.

We go out for months at a time and drill into the sea bed

to recover sediments

that tell us stories of climate change, right.

Like one of the ways to understand our greenhouse future

is to drill down in time

to the last period

where we had CO2 double what it is today.

And so that's what we've done with this ship.

This was -- this is south of the Antarctic Circle.

It looks downright tropical there.

One day where we had calm seas and sun,

which was the reason I could get off the ship.

Most of the time it looked like this.

We had a waves up to 50 ft.

and winds averaging

about 40 knots for most of the voyage

and up to 70 or 80 knots.

So that trip just ended,

and I can't show you too many results from that right now,

but we'll go back one more year,

to another drilling expedition I've been involved in.

This was led by Ross Powell and Tim Naish.

It's the ANDRILL project.

And we made the very first bore hole

through the largest floating ice shelf on the planet.

This is a crazy thing, this big drill rig wrapped in a blanket

to keep everybody warm,

drilling at temperatures of minus 40.

And we drilled in the Ross Sea.

That's the Ross Sea Ice Shelf on the right there.

So, this huge floating ice shelf

the size of Alaska

comes from West Antarctica.

Now, West Antarctica is the part of the continent

where the ice is grounded on sea floor

as much as 2,000 meters deep.

So that ice sheet is partly floating,

and it's exposed to the ocean, to the ocean heat.

This is the part of Antarctica that we worry about.

Because it's partly floating, you can imagine,

is sea level rises a little bit,

the ice lifts off the bed, and then it can break off and float north.

When that ice melts, sea level rises by six meters.

So we drill back in time to see how often that's happened,

and exactly how fast that ice can melt.

Here's the cartoon on the left there.

We drilled through a hundred meters of floating ice shelf

then through 900 meters of water

and then 1,300 meters into the sea floor.

So it's the deepest geological bore hole ever drilled.

It took about 10 years to put this project together.

And here's what we found.

Now, there's 40 scientists working on this project,

and people are doing all kinds of really complicated

and expensive analyses.

But it turns out, you know, the thing that told the best story

was this simple visual description.

You know, we saw this in the core samples as they came up.

We saw these alternations

between sediments that look like this --

there's gravel and cobbles in there

and a bunch of sand.

That's the kind of material in the deep sea.

It can only get there if it's carried out by ice.

So we know there's an ice shelf overhead.

And that alternates with a sediment that looks like this.

This is absolutely beautiful stuff.

This sediment is 100 percent made up

of the shells of microscopic plants.

And these plants need sunlight,

so we know when we find that sediment

there's no ice overhead.

And we saw about 35 alternations

between open water and ice-covered water,

between gravels and these plant sediments.

So what that means is, what it tells us

is that the Ross Sea region, this ice shelf,

melted back and formed anew

about 35 times.

And this is in the past four million years.

This was completely unexpected.

Nobody imagined that the West Antarctic Ice Sheet

was this dynamic.

In fact, the lore for many years has been,

"The ice formed many tens of millions of years ago,

and it's been there ever since."

And now we know that in our recent past

it melted back and formed again,

and sea level went up and down, six meters at a time.

What caused it?

Well, we're pretty sure that it's very small changes

in the amount of sunlight reaching Antarctica,

just caused by natural changes in the orbit of the Earth.

But here's the key thing:

you know, the other thing we found out

is that the ice sheet passed a threshold,

that the planet warmed up enough --

and the number's about one degree to one and a half degrees Centigrade --

the planet warmed up enough that it became ...

that ice sheet became very dynamic

and was very easily melted.

And you know what?

We've actually changed the temperature in the last century

just the right amount.

So many of us are convinced now

that West Antarctica, the West Antarctic Ice Sheet, is starting to melt.

We do expect to see a sea-level rise

on the order of one to two meters by the end of this century.

And it could be larger than that.

This is a serious consequence

for nations like Kiribati,

you know, where the average elevation

is about a little over a meter above sea level.

Okay, the second story takes place here in Galapagos.

This is a bleached coral,

coral that died during the 1982-'83 El Nino.

This is from Champion Island.

It's about a meter tall Pavona clavus colony.

And it's covered with algae. That's what happens.

When these things die,

immediately, organisms come in

and encrust and live on that dead surface.

And so, when a coral colony is killed

by an El Nino event,

it leaves this indelible record.

You can go then and study corals

and figure out how often do you see this.

So one of the things thought of in the '80s

was to go back and take cores

of coral heads throughout the Galapagos

and find out how often was there a devastating event.

And just so you know, 1982-'83,

that El Nino killed 95 percent

of all the corals here in Galapagos.

Then there was similar mortality in '97-'98.

And what we found

after drilling back in time two to 400 years

was that these were unique events.