We live in a very complex environment: complexity and dynamism and patterns of evidence from satellite photographs, from videos. You can even see it outside your window. It's endlessly complex, but somehow familiar, but the patterns kind of repeat, but they never repeat exactly. It's a huge challenge to understand. The patterns that you see are there at all of the different scales, but you can't chop it into one little bit and say, "Oh, well let me just make a smaller climate." I can't use the normal products of reductionism to get a smaller and smaller thing that I can study in a laboratory and say, "Oh, now that's something I now understand." It's the whole or it's nothing.
Živimo u vrlo složenom okruženju - složenost i dinamičnost i obrasci dokaza sa satelitskih snimaka, videa. Možemo ih čak videti i sa našeg prozora. Beskonačno su složeni, ali nekako poznati, ali obrasci se nekako ponavljaju. ali nikad u potpunosti. To je veliki izazov za razumeti. Obrasci koje vidite postoje u svim različitim razmerama, ali, ne možete izdvojiti jedan mali delić i reći: "Hajde da napravim manju klimu." Ne mogu da koristim uobičajene metode redukcije da bih dobio što manji delić koji mogu da proučavam u laboratoriji, i kažem: "Oh, pa to je nešto što konačno razumem." Ili je celo ili nije ništa.
The different scales that give you these kinds of patterns range over an enormous range of magnitude, roughly 14 orders of magnitude, from the small microscopic particles that seed clouds to the size of the planet itself, from 10 to the minus six to 10 to the eight, 14 orders of spatial magnitude. In time, from milliseconds to millennia, again around 14 orders of magnitude.
Različite razmere koje proizvode ovakve vrste obrazaca kreću se preko ogromnog raspona veličina, otprilike 14 redova veličine, od malih mikroskopskih čestica oko kojih se formiraju oblaci do veličine same planete, od 10 na minus šesti do 10 na osmi, 14 redova veličine u prostoru. U vremenu, od milisekunda do milenijuma, i opet, oko 14 redova veličine.
What does that mean? Okay, well if you think about how you can calculate these things, you can take what you can see, okay, I'm going to chop it up into lots of little boxes, and that's the result of physics, right? And if I think about a weather model, that spans about five orders of magnitude, from the planet to a few kilometers, and the time scale from a few minutes to 10 days, maybe a month. We're interested in more than that. We're interested in the climate. That's years, that's millennia, and we need to go to even smaller scales. The stuff that we can't resolve, the sub-scale processes, we need to approximate in some way. That is a huge challenge. Climate models in the 1990s took an even smaller chunk of that, only about three orders of magnitude. Climate models in the 2010s, kind of what we're working with now, four orders of magnitude. We have 14 to go, and we're increasing our capability of simulating those at about one extra order of magnitude every decade. One extra order of magnitude in space is 10,000 times more calculations. And we keep adding more things, more questions to these different models.
Šta to znači? Pa dobro, ako mislite na to kako da izračunate ove stvari, možete uzeti ono što vidite, OK, usitniću to na mnogo malih kutijica, a to je rezultat fizike, zar ne? A ako govorimo o klimatskom modelu, koji obuhvata oko 5 redova veličine, počevši od planete do nekoliko kilometara, i vremenska skala od nekoliko minuta do 10 dana, možda jedan mesec. Interesuje nas više od toga. Nas interesuje klima. U pitanju su godine, milenijumi, moramo da idemo u još sitnije razmere. Deliće koje ne možemo dalje rastaviti, najsitnije procese moramo da aproksimiramo na neki način. To je ogroman izazov. Klimatski modeli 90-tih posmatrali su još manji deo svega, samo tri reda veličine. Klimatski modeli posle 2010, ono sa čime danas radimo, četiri reda veličine. Ostalo nam je još 14 i uvećavamo našu sposobnost da ih simuliramo za otprilike 1 red veličine, svake decenije. Jedan dodatni red veličine u prostoru znači 10.000 puta više izračunavanja. A mi nastavljamo da dodajemo stvari, sve više pitanja za različite modele.
So what does a climate model look like? This is an old climate model, admittedly, a punch card, a single line of Fortran code. We no longer use punch cards. We do still use Fortran. New-fangled ideas like C really haven't had a big impact on the climate modeling community.
Dobro, kako izgleda klimatski model? Doduše, ovo je stari klimatski model, bušena kartica, jedan red Fortran koda. Više ne koristimo bušene kartice. Ali još uvek koristimo Fortran. Novotarije poput C nisu imale veliki uticaj na zajednicu koja pravi klimatske modele.
But how do we go about doing it? How do we go from that complexity that you saw to a line of code? We do it one piece at a time. This is a picture of sea ice taken flying over the Arctic. We can look at all of the different equations that go into making the ice grow or melt or change shape. We can look at the fluxes. We can look at the rate at which snow turns to ice, and we can code that. We can encapsulate that in code. These models are around a million lines of code at this point, and growing by tens of thousands of lines of code every year.
Ali, kako mi to radimo? Kako preći sa složenosti koju ste videli na jedan red koda? Radimo to parče po parče. Ovo je slika morskog leda napravljena iz aviona iznad Arktika. Možemo da gledamo sve ove razne jednačine koje predstavljaju rast leda ili topljenje, ili promenu oblika. Možemo posmatrati tokove. Možemo posmatrati brzinu kojom se sneg pretvara u led, i to možemo da kodiramo. To možemo da obuhvatimo kodom. Ovi modeli imaju oko milion redova koda u ovom trenutku, i rastu za desetine hiljada redova koda svake godine.
So you can look at that piece, but you can look at the other pieces too. What happens when you have clouds? What happens when clouds form, when they dissipate, when they rain out? That's another piece. What happens when we have radiation coming from the sun, going through the atmosphere, being absorbed and reflected? We can code each of those very small pieces as well. There are other pieces: the winds changing the ocean currents. We can talk about the role of vegetation in transporting water from the soils back into the atmosphere. And each of these different elements we can encapsulate and put into a system. Each of those pieces ends up adding to the whole.
Dakle, možemo da posmatramo ovo parče, ali možemo da posmatramo i druge delove. Šta se dešava kad imamo oblake? Šta se dešava kad se oblaci formiraju, kad se raspšuju, kad iz njih pada kiša? To je još jedan delić. Šta se dešava kad imamo radijaciju koja od sunca prodire kroz atmosferu i upija se ili odbija? I ove, vrlo male deliće takođe možemo da kodiramo. Ima još delova: vetrovi koji menjaju okeanske struje. Možemo govoriti o ulozi vegetacije u transportu vode sa površine zemlje natrag u atmosferu. I svaki od ovih različitih elemenata možemo da obuhvatimo i postavimo u sistem. Svaki od ovih delova doprinosi celini.
And you get something like this. You get a beautiful representation of what's going on in the climate system, where each and every one of those emergent patterns that you can see, the swirls in the Southern Ocean, the tropical cyclone in the Gulf of Mexico, and there's two more that are going to pop up in the Pacific at any point now, those rivers of atmospheric water, all of those are emergent properties that come from the interactions of all of those small-scale processes I mentioned. There's no code that says, "Do a wiggle in the Southern Ocean." There's no code that says, "Have two tropical cyclones that spin around each other." All of those things are emergent properties.
I dobićete nešto ovako: dobićete divan prikaz onoga što se dešava u klimatskom sistemu, gde svaki od ovih proizašlih oblika koje vidite, kovitlaci u Južnom okeanu, tropski ciklon u Meksičkom zalivu, i još dva koja će tek da se pojave u Tihom okeanu u svakom trenutku, ove reke atmosferske vode, sve to su nova svojstva koja proističu iz interakcija svih ovih malih procesa koje sam pominjao. Ne postoji taj kod koji će da kaže: "Talasaj u Južnom okeanu". Ne postoji kod koji kaže: "Uzmite dva tropska ciklona koja se okreću jedan oko drugog". Sve ove pojave su nova svojstva.
This is all very good. This is all great. But what we really want to know is what happens to these emergent properties when we kick the system? When something changes, what happens to those properties? And there's lots of different ways to kick the system. There are wobbles in the Earth's orbit over hundreds of thousands of years that change the climate. There are changes in the solar cycles, every 11 years and longer, that change the climate. Big volcanoes go off and change the climate. Changes in biomass burning, in smoke, in aerosol particles, all of those things change the climate. The ozone hole changed the climate. Deforestation changes the climate by changing the surface properties and how water is evaporated and moved around in the system. Contrails change the climate by creating clouds where there were none before, and of course greenhouse gases change the system.
Sve je ovo dobro. Sve je ovo odlično. Ali stvarno želimo da znamo šta se dešava sa ovim novim svojstvima kada udarimo na sistem. Kada se nešto promeni, šta se dešava sa svojstvima? A postoji mnogo načina da udarimo sistem. Imamo kolebanja u Zemljinoj orbiti već stotinama hiljada godina koja utiču na promenu klime. Postoje promene u solarnim ciklusima, svakih 11 godina ili duže, koje takođe menjaju klimu. Erupcije velikih vulkana menjaju klimu. Promene u sagorevlju biomase, u dimu, u aerosolnim česticama, sve ove pojave utiču na promenu klime. Ozonska rupa je promenila klimu. Krčenje šuma menja klimu promenom svojstava zemljine površine i načina na koji voda isparava i kako se kreće u sistemu. Kondenzacioni tragovi aviona menjaju klimu stvarajući oblake tamo gde ih nije bilo. i naravno, efekat staklene bašte utiče i menja sistem.
Each of these different kicks provides us with a target to evaluate whether we understand something about this system. So we can go to look at what model skill is. Now I use the word "skill" advisedly: Models are not right or wrong; they're always wrong. They're always approximations. The question you have to ask is whether a model tells you more information than you would have had otherwise. If it does, it's skillful. This is the impact of the ozone hole on sea level pressure, so low pressure, high pressures, around the southern oceans, around Antarctica. This is observed data. This is modeled data. There's a good match because we understand the physics that controls the temperatures in the stratosphere and what that does to the winds around the southern oceans.
Svaki od ovih različitih udaraca postavlja nam za cilj da procenimo da li smo razumeli nešto o ovom sistemu. Tako, možemo da pogledamo sta je veština pravljenja modela. Reč "veština" koristim promišljeno. Modeli nisu u pravu ili ne; nikad nisu u pravu. Oni su uvek samo aproksimacije. Pitanje koje treba postaviti je da li nam model daje više informacija nego što bi ih imali inače. Ako da, onda je vešto napravljen. Ovo je uticaj ozonske rupe na pritisak na nivou mora, nizak pritisak, visok pritisak u južnim okeanima, oko Antarktika. Ovo su podaci posmatranja. Ovo su podaci iz modela. Postoji dobro podudaranje zato što mi razumemo fiziku koja kontroliše temperaturu u stratosferi i kako to utiče na vetrove u južnim okeanima.
We can look at other examples. The eruption of Mount Pinatubo in 1991 put an enormous amount of aerosols, small particles, into the stratosphere. That changed the radiation balance of the whole planet. There was less energy coming in than there was before, so that cooled the planet, and those red lines and those green lines, those are the differences between what we expected and what actually happened. The models are skillful, not just in the global mean, but also in the regional patterns.
Pogledajmo druge primere. Erupcija vulkana Maunt Pinatubo 1991. izbacila je ogromnu količinu aerosola, sitnih čestica, u stratosferu. To je promenilo ravnotežu zračenja na celoj planeti. Manje energije je dolazilo nego pre. što je ohladilo planetu, i ove crvene linije, i zelene linije to su razlike između onoga što smo očekivali i šta se stvarno dogodilo. Modeli su vešto napravljeni, ne samo kao globalna srednja vrednost, već i u regionalnim oblicima.
I could go through a dozen more examples: the skill associated with solar cycles, changing the ozone in the stratosphere; the skill associated with orbital changes over 6,000 years. We can look at that too, and the models are skillful. The models are skillful in response to the ice sheets 20,000 years ago. The models are skillful when it comes to the 20th-century trends over the decades. Models are successful at modeling lake outbursts into the North Atlantic 8,000 years ago. And we can get a good match to the data.
Mogao bih da prođem kroz još tuce primera: veština vezana za solarne cikluse, promena ozona u stratosferi; veština vezana za promenu orbite u toku 6000 godina. I to možemo da posmatramo, a modeli su vešti. Modeli su vešti u reakciji na slojeve leda od pre 20,000 godina. Modeli su vešti što se tiče trendova 20-tog veka tokom decenija. Modeli su uspešni u modeliranju pojava jezera u severnom Atlantiku pre 8.000 godina Možemo dobiti dobro podudaranje sa podacima.
Each of these different targets, each of these different evaluations, leads us to add more scope to these models, and leads us to more and more complex situations that we can ask more and more interesting questions, like, how does dust from the Sahara, that you can see in the orange, interact with tropical cyclones in the Atlantic? How do organic aerosols from biomass burning, which you can see in the red dots, intersect with clouds and rainfall patterns? How does pollution, which you can see in the white wisps of sulfate pollution in Europe, how does that affect the temperatures at the surface and the sunlight that you get at the surface?
Svaki od ovih različitih ciljeva, svaka od ovih procena, dovodi do toga da dodajemo širi pogled na ove modele, i vodi nas ka sve složenijim situacijama pa možemo da postavljamo sve interesantnija pitanja. Na primer, kako prašina iz Sahare koju možete da vidite u narandžastoj, utiče na tropske ciklone u Atlantiku? Kako organski aerosoli koji nastaju sagorevanjem biomase, koje ovde vidite kao crvene tačke, utiču na oblake i obrasce padavina? Kako zagađenje, koje vidite kao bele kovitlace sulfatnog zagađenja u Evropi, kako to utiče na temperature na površini i količinu sunčeve svetlosti koje dobijamo na površini?
We can look at this across the world. We can look at the pollution from China. We can look at the impacts of storms on sea salt particles in the atmosphere. We can see the combination of all of these different things happening all at once, and we can ask much more interesting questions. How do air pollution and climate coexist? Can we change things that affect air pollution and climate at the same time? The answer is yes.
Ovo možemo da posmatramo širom sveta. Možemo da vidimo zagađenje iz Kine. Možemo da vidimo uticaj oluja na čestice morske soli u atmosferi. Možemo da vidimo kombinaciju svih ovih različitih stvari koje se dešavaju, sve odjednom i možemo postavljati mnogo interesantnija pitanja. Kako zagađenje vazduha i klima koegzistiraju? Da li možemo da izmenimo stvari koje utiču na zagađenje vazduha i klimu u isto vreme? Odgovor je, da.
So this is a history of the 20th century. The first one is the model. The weather is a little bit different to what actually happened. The second one are the observations. And we're going through the 1930s. There's variability, there are things going on, but it's all kind of in the noise. As you get towards the 1970s, things are going to start to change. They're going to start to look more similar, and by the time you get to the 2000s, you're already seeing the patterns of global warming, both in the observations and in the model.
Ovo je istorija 20-tog veka. prvi je model. Vreme je nešto drugačije od onoga što se zaista desilo. Drugi su posmatranja. Idemo kroz 30-te. Ovde imamo varijabilnost, stvari se dešavaju. Ali sve to je nekako u pozadini. Kako se približavamo 70-tim, stvari počinju da se menjaju. Počinju sve više da liče, i do trenutka kad dođemo u 2000-te, već počinjemo da uočavamo obrasce globalnog zagrevanja, i u pravim posmatranjima i u modelu.
We know what happened over the 20th century. Right? We know that it's gotten warmer. We know where it's gotten warmer. And if you ask the models why did that happen, and you say, okay, well, yes, basically it's because of the carbon dioxide we put into the atmosphere. We have a very good match up until the present day.
Znamo šta se dogodilo u 20-tom veku. Zar ne? Znamo da je postalo toplije. Znamo i zašto je postalo toplije. I ako pitate modele zašto se to dogodilo, i kažete, ok, pa da, u osnovi to je zbog ugljen-dioksida koga ispuštamo u atmosferu. Imamo baš dobro podudaranje sve do današnjih dana.
But there's one key reason why we look at models, and that's because of this phrase here. Because if we had observations of the future, we obviously would trust them more than models, But unfortunately, observations of the future are not available at this time.
Ako postoji jedan ključni razlog zašto gledamo u modele, to je zbog ove fraze ovde: da imamo rezultate opažanja iz budućnosti, očigledno bi im verovali više nego modelima, Ali, na žalost, opažanja iz budućnosti u ovom trenutku nisu nam dostupna.
So when we go out into the future, there's a difference. The future is unknown, the future is uncertain, and there are choices. Here are the choices that we have. We can do some work to mitigate the emissions of carbon dioxide into the atmosphere. That's the top one. We can do more work to really bring it down so that by the end of the century, it's not much more than there is now. Or we can just leave it to fate and continue on with a business-as-usual type of attitude. The differences between these choices can't be answered by looking at models.
Zato, kad idemo u budućnost, postoji razlika. Budućnost je nepoznata, budućnost je nesigurna, ali postoje izbori. Ovo su izbori koje imamo. Možemo nešto uraditi da ublažimo emisiju ugljen-dioksida u atmosferu. To je osnovni izbor. Možemo još više uraditi da ga zaista smanjimo tako da ga krajem veka, ne bude mnogo više nego što je sada. Ili ga možemo samo prepustiti sudbini i nastaviti da se ponašamo po starom. Razlika između ovih izbora ne može se videti iz modela.
There's a great phrase that Sherwood Rowland, who won the Nobel Prize for the chemistry that led to ozone depletion, when he was accepting his Nobel Prize, he asked this question: "What is the use of having developed a science well enough to make predictions if, in the end, all we're willing to do is stand around and wait for them to come true?" The models are skillful, but what we do with the information from those models is totally up to you.
Postoji divna fraza koju je stvorio Šervud Roland dobitnik Nobelovu nagrade za hemiju vezano za otkriće ozonskog omotača. Kada je primao Nobelovu Nagradu, postavio je pitanje: "Kakva je korist razviti nauku toliko da može da pravi predviđanja, kada, na kraju, samo stojimo po strani i čekamo da se ona obistine?" Modeli su vešti, ali ono što ćemo da uradimo sa informacijama iz tih modela potpuno zavisi samo od nas.
Thank you.
Hvala.
(Applause)
(Aplauz)