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  • If you really want to understand

  • 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.

  • We saw no other mass mortality events.

  • So these events in our recent past really are unique.

  • So they're either just truly monster El Ninos,

  • or they're just very strong El Ninos

  • that occurred against a backdrop of global warming.

  • Either case, it's bad news

  • for the corals of the Galapagos Islands.

  • Here's how we sample the corals.