Well, I'm an ocean chemist. I look at the chemistry of the ocean today. I look at the chemistry of the ocean in the past. The way I look back in the past is by using the fossilized remains of deepwater corals. You can see an image of one of these corals behind me. It was collected from close to Antarctica, thousands of meters below the sea, so, very different than the kinds of corals you may have been lucky enough to see if you've had a tropical holiday.
Son química mariña. Estudo as propiedades químicas actuais dos océanos. E as propiedades químicas dos océanos no pasado. Para observar o pasado, utilizo restos fósiles de corais de augas profundas. Detrás de min tedes unha imaxe dun destes corais. Foi recollido cerca da Antártida, a miles de metros de profundidade. Moi distinto, polo tanto, do tipo de corais que se cadra tivestes a sorte de atopar se fostes de vacacións ao trópico.
So I'm hoping that this talk will give you a four-dimensional view of the ocean. Two dimensions, such as this beautiful two-dimensional image of the sea surface temperature. This was taken using satellite, so it's got tremendous spatial resolution. The overall features are extremely easy to understand. The equatorial regions are warm because there's more sunlight. The polar regions are cold because there's less sunlight. And that allows big icecaps to build up on Antarctica and up in the Northern Hemisphere. If you plunge deep into the sea, or even put your toes in the sea, you know it gets colder as you go down, and that's mostly because the deep waters that fill the abyss of the ocean come from the cold polar regions where the waters are dense.
Con esta charla espero ofrecervos unha visión do océano en catro dimensións. Dúas dimensións, como as desta fermosa imaxe, que representa a temperatura superficial do mar. Tomouse vía satélite, polo que ten unha resolución espacial altísima. Os trazos xerais son moi doados de entender. As rexións ecuatoriais están máis quentes porque reciben máis luz solar. As rexións polares están frías porque reciben menos luz. Iso permite que se formen grandes capas de xeo na Antártida e no extremo do hemisferio norte. Se nos mergullamos no mar a gran profundidade, ou só metemos o pé, notamos máis frío canto máis descendemos, e iso ocorre sobre todo porque as augas profundas do abismo oceánico proceden das frías rexións polares onde a densidade da auga é alta.
If we travel back in time 20,000 years ago, the earth looked very much different. And I've just given you a cartoon version of one of the major differences you would have seen if you went back that long. The icecaps were much bigger. They covered lots of the continent, and they extended out over the ocean. Sea level was 120 meters lower. Carbon dioxide [levels] were very much lower than they are today. So the earth was probably about three to five degrees colder overall, and much, much colder in the polar regions.
Se retrocedésemos no tempo uns 20.000 anos, a Terra tería un aspecto moi distinto. Este debuxo representa unha das diferenzas máis importantes que veríamos se retrocedésemos todo ese tempo. As capas de xeo eran moito maiores. Cubrían gran parte do continente e estendíanse polo océano. O nivel do mar era 120 metros máis baixo. Os niveis de dióxido de carbono eran moi inferiores aos actuais. Así que a temperatura media da Terra era entre tres e cinco graos máis baixa, e moitísimo máis baixa nas rexións polares.
What I'm trying to understand, and what other colleagues of mine are trying to understand, is how we moved from that cold climate condition to the warm climate condition that we enjoy today. We know from ice core research that the transition from these cold conditions to warm conditions wasn't smooth, as you might predict from the slow increase in solar radiation. And we know this from ice cores, because if you drill down into ice, you find annual bands of ice, and you can see this in the iceberg. You can see those blue-white layers. Gases are trapped in the ice cores, so we can measure CO2 -- that's why we know CO2 was lower in the past -- and the chemistry of the ice also tells us about temperature in the polar regions. And if you move in time from 20,000 years ago to the modern day, you see that temperature increased. It didn't increase smoothly. Sometimes it increased very rapidly, then there was a plateau, then it increased rapidly. It was different in the two polar regions, and CO2 also increased in jumps.
O que trato de entender, coma outros colegas meus, é como pasamos daquelas condicións climáticas frías ás condicións máis cálidas das que gozamos hoxe. Sabemos pola análise de mostras de xeo que a transición destas condicións frías a outras máis cálidas non foi gradual, como cabería predicir polo lento aumento da radiación solar. Sabémolo polas mostras de xeo, porque, ao perforar o xeo, atopamos bandas anuais, como podedes observar neste iceberg. Son esas capas azuis e brancas. Os gases quedan atrapados no xeo, polo que podemos medir o CO2 -- por iso sabemos que había menos CO2 no pasado-- e a composición química do xeo dinos a temperatura das rexións polares. Se avanzamos dende hai 20.000 anos ata hoxe, vemos que a temperatura aumentou. Non aumentou de xeito gradual. Ás veces aumentaba moi rápido, logo estabilizábase, logo aumentaba rápido. Era distinta nas dúas rexións polares, e o CO2 tamén aumentou a tiróns.
So we're pretty sure the ocean has a lot to do with this. The ocean stores huge amounts of carbon, about 60 times more than is in the atmosphere. It also acts to transport heat across the equator, and the ocean is full of nutrients and it controls primary productivity.
Así que estamos convencidos de que o océano ten moito que ver. O océano almacena cantidades enormes de carbono, 60 veces máis do que hai na atmosfera. Tamén intervén no transporte de calor dun lado ao outro do ecuador, e está cheo de nutrientes e controla a produtividade primaria.
So if we want to find out what's going on down in the deep sea, we really need to get down there, see what's there and start to explore. This is some spectacular footage coming from a seamount about a kilometer deep in international waters in the equatorial Atlantic, far from land. You're amongst the first people to see this bit of the seafloor, along with my research team. You're probably seeing new species. We don't know. You'd have to collect the samples and do some very intense taxonomy. You can see beautiful bubblegum corals. There are brittle stars growing on these corals. Those are things that look like tentacles coming out of corals. There are corals made of different forms of calcium carbonate growing off the basalt of this massive undersea mountain, and the dark sort of stuff, those are fossilized corals, and we're going to talk a little more about those as we travel back in time.
Así que se queremos saber o que pasa nas profundidades do mar, temos que baixar alí, ver o que hai e comezar a explorar. Estas son imaxes espectaculares obtidas nun monte submarino a un quilómetro de profundidade en augas internacionais na zona ecuatorial do Atlántico, lonxe de terra firme. Sodes dos primeiros en ver este anaco de fondo mariño, xunto co meu equipo. Igual estades vendo especies novas. Non o sabemos. Habería que recoller as mostras e facer unha análise taxonómica rigorosa. Aquí vedes o fermoso Paragorgia arborea. Nestes corais viven ofiuras. Son esas cousas con forma de tentáculo que saen dos corais. Corais de distintas formas de carbonato de calcio viven no basalto deste enorme monte submarino, e o material escuro que se ve son corais fosilizados, dos que imos falar un pouco máis ao retrocedermos no tempo.
To do that, we need to charter a research boat. This is the James Cook, an ocean-class research vessel moored up in Tenerife. Looks beautiful, right? Great, if you're not a great mariner. Sometimes it looks a little more like this. This is us trying to make sure that we don't lose precious samples. Everyone's scurrying around, and I get terribly seasick, so it's not always a lot of fun, but overall it is.
Para iso temos que fretar un barco de investigación. Este é o James Cook, un buque oceánico de investigación atracado en Tenerife. Precioso, non si? Fantástico, se un non é un gran mariño. En ocasións ten máis ben estoutro aspecto. Estes somos nós tratando de non perder mostras moi valiosas. Todos á carreira, e eu maréome moitísimo, así que non sempre é divertido, aínda que en xeral, si.
So we've got to become a really good mapper to do this. You don't see that kind of spectacular coral abundance everywhere. It is global and it is deep, but we need to really find the right places. We just saw a global map, and overlaid was our cruise passage from last year. This was a seven-week cruise, and this is us, having made our own maps of about 75,000 square kilometers of the seafloor in seven weeks, but that's only a tiny fraction of the seafloor. We're traveling from west to east, over part of the ocean that would look featureless on a big-scale map, but actually some of these mountains are as big as Everest. So with the maps that we make on board, we get about 100-meter resolution, enough to pick out areas to deploy our equipment, but not enough to see very much. To do that, we need to fly remotely-operated vehicles about five meters off the seafloor. And if we do that, we can get maps that are one-meter resolution down thousands of meters. Here is a remotely-operated vehicle, a research-grade vehicle. You can see an array of big lights on the top. There are high-definition cameras, manipulator arms, and lots of little boxes and things to put your samples.
Para dedicarse a isto hai que ser moi bos cartógrafos. Non se atopa en calquera sitio esa espectacular abundancia de coral. É global e está a gran profundidade, pero hai que buscala nos lugares adecuados. Acabamos de ver un mapamundi, no que sinalamos a travesía do ano pasado. Foron sete semanas de viaxe, e este é o mapa que nós fixemos en sete semanas duns 75.000 quilómetros cadrados de fondo mariño, unha porción diminuta do fondo do mar. Desprazámonos de oeste a leste, sobre unha zona da que un mapa a gran escala non mostraría nada, aínda que algúns destes montes teñen o tamaño do Everest. Cos mapas que facemos a bordo, obtemos unha resolución duns 100 metros, o que abonda para decidir onde despregar o equipo, pero non permite ver gran cousa. Para facer isto precisamos dispositivos con control remoto que se desprazan a uns cinco metros do fondo. Dese xeito podemos obter mapas cunha resolución dun metro a miles de metros de profundidade. Este é un deses dispositivos remotos, un vehículo de máxima precisión. Dispón de grandes focos na parte superior, cámaras de alta definición, brazos robóticos, e múltiples caixiñas e cousas para gardar as mostras.
Here we are on our first dive of this particular cruise, plunging down into the ocean. We go pretty fast to make sure the remotely operated vehicles are not affected by any other ships. And we go down, and these are the kinds of things you see. These are deep sea sponges, meter scale. This is a swimming holothurian -- it's a small sea slug, basically. This is slowed down. Most of the footage I'm showing you is speeded up, because all of this takes a lot of time. This is a beautiful holothurian as well. And this animal you're going to see coming up was a big surprise. I've never seen anything like this and it took us all a bit surprised. This was after about 15 hours of work and we were all a bit trigger-happy, and suddenly this giant sea monster started rolling past. It's called a pyrosome or colonial tunicate, if you like. This wasn't what we were looking for. We were looking for corals, deep sea corals. You're going to see a picture of one in a moment. It's small, about five centimeters high. It's made of calcium carbonate, so you can see its tentacles there, moving in the ocean currents. An organism like this probably lives for about a hundred years. And as it grows, it takes in chemicals from the ocean. And the chemicals, or the amount of chemicals, depends on the temperature; it depends on the pH, it depends on the nutrients. And if we can understand how these chemicals get into the skeleton, we can then go back, collect fossil specimens, and reconstruct what the ocean used to look like in the past. And here you can see us collecting that coral with a vacuum system, and we put it into a sampling container. We can do this very carefully, I should add.
Esta era a nosa primeira inmersión nesta expedición concreta. Estámonos mergullando. Imos rápido para que outros barcos non afecten aos nosos dispositivos con control remoto. Imos descendendo, e estas son as cousas que se ven. Estas son esponxas de augas profundas, a escala dun metro. Aquí vemos unha holoturia nadando -- en esencia, unha pequena lesma mariña. Esta está a cámara lenta. A maioría das imaxes que amoso están aceleradas, porque todo isto leva moito tempo. Esta é outra fermosa holoturia. E o animal que ides ver agora foi unha gran sorpresa. Nunca vira algo así e colleunos a todos un pouco por sorpresa. Levabamos unhas 15 horas traballando e estabamos algo sobreexcitados e de repente este monstro pasou a rolos por diante de nós Chámase pirosoma, ou tamén tunicado colonial. Non era isto o que buscabamos. Nós andabamos á procura de corais de augas profundas. Ides ver deseguida unha imaxe dun destes. É pequeno, duns cinco centímetros de alto. Está composto de carbonato de calcio e vemos os seus tentáculos, que se moven coa corrente. Un organismo coma este vive probablemente uns cen anos. Ao medrar, vai tomando substancias químicas do océano. E a cantidade destas substancias depende da temperatura, do pH e dos nutrientes. Se logramos entender como se integran estas substancias no esqueleto, podemos voltar, recoller espécimes fósiles e reconstruír como era o océano no pasado. Aquí estamos recollendo ese coral cun sistema de baleiro, para poñelo nun recipiente de mostras. Debo engadir que o facemos con moitísimo coidado.
Some of these organisms live even longer. This is a black coral called Leiopathes, an image taken by my colleague, Brendan Roark, about 500 meters below Hawaii. Four thousand years is a long time. If you take a branch from one of these corals and polish it up, this is about 100 microns across. And Brendan took some analyses across this coral -- you can see the marks -- and he's been able to show that these are actual annual bands, so even at 500 meters deep in the ocean, corals can record seasonal changes, which is pretty spectacular.
Algúns destes organismos viven aínda máis tempo. Esta é unha foto dun coral negro chamado leiopathes. Foi tomada por un colega, Brendan Roark, en Hawaii, a 500 metros de profundidade. Catro mil anos é moito tempo. Se collemos unha póla dun destes corais e a pulimos, isto son uns 100 microns. Brendan analizou varias seccións deste coral --pódense ver as marcas-- e puido demostrar que en realidade se trata de franxas anuais, de modo que mesmo a 500 metros de profundidade os corais poden rexistrar cambios estacionais. o cal é bastante espectacular.
But 4,000 years is not enough to get us back to our last glacial maximum. So what do we do? We go in for these fossil specimens. This is what makes me really unpopular with my research team. So going along, there's giant sharks everywhere, there are pyrosomes, there are swimming holothurians, there's giant sponges, but I make everyone go down to these dead fossil areas and spend ages kind of shoveling around on the seafloor. And we pick up all these corals, bring them back, we sort them out. But each one of these is a different age, and if we can find out how old they are and then we can measure those chemical signals, this helps us to find out what's been going on in the ocean in the past.
Pero 4.000 anos non abonda para chegar ao punto máximo da última glaciación. Que facemos entón? Pois imos por estes espécimes fósiles. Por isto non lle caio moi ben ao meu equipo. Cando nos mergullamos, vemos moitos tiburóns xigantes, pirosomas, holoturias nadando, esponxas xigantes, pero eu obrígoos a baixar ás zonas mortas dos fósiles, onde pasan horas remexendo o fondo mariño. Recollemos todos estes corais, subímolos e clasificámolos. Son de distintas idades, e se logramos determinar a de cada espécime e medir eses sinais químicos, iso axúdanos a saber que aconteceu no océano en épocas pasadas.
So on the left-hand image here, I've taken a slice through a coral, polished it very carefully and taken an optical image. On the right-hand side, we've taken that same piece of coral, put it in a nuclear reactor, induced fission, and every time there's some decay, you can see that marked out in the coral, so we can see the uranium distribution. Why are we doing this? Uranium is a very poorly regarded element, but I love it. The decay helps us find out about the rates and dates of what's going on in the ocean. And if you remember from the beginning, that's what we want to get at when we're thinking about climate. So we use a laser to analyze uranium and one of its daughter products, thorium, in these corals, and that tells us exactly how old the fossils are.
Para obter a imaxe da esquerda, collín unha sección de coral, pulina con moito coidado e fotografeina. Para a imaxe da dereita puxemos o mesmo anaco de coral nun reactor nuclear, inducimos a fisión e cada vez que hai desintegración queda unha marca no coral, e así podemos ver a distribución do uranio. Por que facemos isto? O uranio é un elemento con moi mala reputación, pero a min encántame. A desintegración axúdanos a coñecer os ritmos e as datas do que acontece no océano. Se lembrades o que dixen ao comezo, iso é o que queremos saber cando pensamos no clima. Así que aplicamos un láser a estes corais para analizar o uranio e un dos seus produtos fillos, o torio, e iso dinos con exactitude a idade dos fósiles.
This beautiful animation of the Southern Ocean I'm just going to use illustrate how we're using these corals to get at some of the ancient ocean feedbacks. You can see the density of the surface water in this animation by Ryan Abernathey. It's just one year of data, but you can see how dynamic the Southern Ocean is. The intense mixing, particularly the Drake Passage, which is shown by the box, is really one of the strongest currents in the world coming through here, flowing from west to east. It's very turbulently mixed, because it's moving over those great big undersea mountains, and this allows CO2 and heat to exchange with the atmosphere in and out. And essentially, the oceans are breathing through the Southern Ocean. We've collected corals from back and forth across this Antarctic passage, and we've found quite a surprising thing from my uranium dating: the corals migrated from south to north during this transition from the glacial to the interglacial. We don't really know why, but we think it's something to do with the food source and maybe the oxygen in the water.
Esta fermosa animación do Océano Antártico servirame para ilustrar como empregamos estes corais para obter información sobre o océano arcaico. Podedes ver a densidade das augas superficiais nesta imaxe animada creada por Ryan Abernathey. Mostra os datos dun só ano pero pódese ver o dinámico que é o Océano Antártico. A intensa mestura, sobre todo o Paso de Drake, sinalado cun recadro, é de feito unha das correntes máis fortes do mundo a que flúe por aquí de oeste a leste. A mestura é moi turbulenta, porque circula sobre eses enormes montes submarinos, o cal permite o intercambio de calor e CO2 coa atmosfera. En esencia, os océanos respiran a través do Océano Antártico. Recollimos corais ao longo de todo este paso antártico, e descubrimos algo bastante sorprendente grazas á datación do uranio: os corais migraron de sur a norte durante esta transición da glaciación ao período interglaciar. Non sabemos ben por que, pero pensamos que ten que ver coas fontes de alimento e se cadra coa concentración de osíxeno na auga.
So here we are. I'm going to illustrate what I think we've found about climate from those corals in the Southern Ocean. We went up and down sea mountains. We collected little fossil corals. This is my illustration of that. We think back in the glacial, from the analysis we've made in the corals, that the deep part of the Southern Ocean was very rich in carbon, and there was a low-density layer sitting on top. That stops carbon dioxide coming out of the ocean. We then found corals that are of an intermediate age, and they show us that the ocean mixed partway through that climate transition. That allows carbon to come out of the deep ocean. And then if we analyze corals closer to the modern day, or indeed if we go down there today anyway and measure the chemistry of the corals, we see that we move to a position where carbon can exchange in and out. So this is the way we can use fossil corals to help us learn about the environment.
Neste punto nos atopamos. Vou ilustrar o que penso que levamos descuberto sobre o clima grazas aos corais do Océano Antártico. Subimos e baixamos montes submarinos. Recollimos pequenos fósiles de coral. Así o represento eu. Pensamos que durante a glaciación, segundo as nosas análises dos corais, a zona profunda do Océano Antártico era moi rica en carbono e había unha capa de baixa densidade xusto encima que impedía que o carbono saíse do océano. Entón atopamos corais dunha idade intermedia que demostran que o océano se mesturou no medio desa transición climática. Iso permite ao carbono saír da zona máis profunda. E se analizamos corais máis próximos á época moderna, ou se baixamos hoxe mesmo alí e medimos as propiedades químicas dos corais, vemos que pasamos a unha situación na que pode haber intercambio de carbono. Este é o modo en que os corais fósiles nos axudan a aprender cousas sobre o medio.
So I want to leave you with this last slide. It's just a still taken out of that first piece of footage that I showed you. This is a spectacular coral garden. We didn't even expect to find things this beautiful. It's thousands of meters deep. There are new species. It's just a beautiful place. There are fossils in amongst, and now I've trained you to appreciate the fossil corals that are down there.
Déixovos cunha última diapositiva. É unha imaxe fixa tirada da primeira gravación que mostrei. É un xardín de corais espectacular. Non esperabamos atopar algo tan fermoso. Está a miles de metros de profundidade. Hai especies novas. É simplemente un lugar fermoso. Tamén hai fósiles, e veño de prepararvos para valorar os fósiles de coral que se atopan aló abaixo.
So next time you're lucky enough to fly over the ocean or sail over the ocean, just think -- there are massive sea mountains down there that nobody's ever seen before, and there are beautiful corals.
A próxima vez que teñades a sorte de voar sobre o océano ou de navegar por el, lembrade que aló abaixo hai enormes montes submarinos que ninguén viu aínda, e fermosos corais.
Thank you.
Grazas.
(Applause)
(Aplausos)