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Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
Dialogue: 0,0:00:00.00,0:00:18.90,Default,,0000,0000,0000,,{\i1}36C3 preroll music{\i0}
Dialogue: 0,0:00:19.74,0:00:23.64,Default,,0000,0000,0000,,Herald: ... so I'm looking forward and I\Nhope you are, too. I am looking forward to
Dialogue: 0,0:00:23.64,0:00:29.92,Default,,0000,0000,0000,,be told the difference between..\N{\i1}laughs{\i0} ... we will all be told the
Dialogue: 0,0:00:29.92,0:00:34.73,Default,,0000,0000,0000,,difference between an input model and a\Nclimate model, and we are going to be told
Dialogue: 0,0:00:34.73,0:00:38.98,Default,,0000,0000,0000,,this difference by karlabyrinth. \NThere you go.
Dialogue: 0,0:00:38.98,0:00:48.41,Default,,0000,0000,0000,,{\i1}applause{\i0}
Dialogue: 0,0:00:48.41,0:00:55.08,Default,,0000,0000,0000,,karlabyrinth: Thank you. Hello and\Nwelcome, everyone. I would like to see my
Dialogue: 0,0:00:55.08,0:01:07.26,Default,,0000,0000,0000,,slides. Are the slides ...? Ah, OK.\N{\i1}laughs{\i0} nice. So welcome, everyone, to my
Dialogue: 0,0:01:07.26,0:01:13.70,Default,,0000,0000,0000,,talk about Climate Modeling - the science\Nbehind climate reports. First of all, I
Dialogue: 0,0:01:13.70,0:01:19.24,Default,,0000,0000,0000,,will shortly introduce myself and what I\Ndo. I work at the UFZ. That's the
Dialogue: 0,0:01:19.24,0:01:25.20,Default,,0000,0000,0000,,Helmholtz Center for Environmental\NResearch in Leipzig and I work for the ESM
Dialogue: 0,0:01:25.20,0:01:32.39,Default,,0000,0000,0000,,project, which is short for 'advanced earth\Nsystem' modelling capacity. I am also a PhD
Dialogue: 0,0:01:32.39,0:01:39.57,Default,,0000,0000,0000,,student at the University of Potsdam and I\Nam part of the developer team for the
Dialogue: 0,0:01:39.57,0:01:45.40,Default,,0000,0000,0000,,middle scale hydrologic model, which is an\Nimpact model. And I'm also a scientist for
Dialogue: 0,0:01:45.40,0:01:54.21,Default,,0000,0000,0000,,future and an artist. So what this talk is\Nabout? This talk is partitioned into three
Dialogue: 0,0:01:54.21,0:01:59.42,Default,,0000,0000,0000,,sections, mainly. First is the\Nintroduction where I will introduce some
Dialogue: 0,0:01:59.42,0:02:05.60,Default,,0000,0000,0000,,nomenclature like what is weather, what is\Nclimate and what we can say about
Dialogue: 0,0:02:05.60,0:02:10.97,Default,,0000,0000,0000,,predictions. For example, why we can't\Ntell the weather in three years but we can
Dialogue: 0,0:02:10.97,0:02:16.56,Default,,0000,0000,0000,,say something about the climate, and what\Nare climate models. Then the second part
Dialogue: 0,0:02:16.56,0:02:20.76,Default,,0000,0000,0000,,will be the longest, the science behind\Nwarming graphs. I will show you a graph
Dialogue: 0,0:02:20.76,0:02:26.94,Default,,0000,0000,0000,,that's typically shown when people tell\Nyou about climate change, and I will
Dialogue: 0,0:02:26.94,0:02:35.93,Default,,0000,0000,0000,,explain that graph in detail and what is\Nbehind it. The third part would be
Dialogue: 0,0:02:35.93,0:02:39.75,Default,,0000,0000,0000,,installing an impact model to your local\NPC if there is time. If there is no time I
Dialogue: 0,0:02:39.75,0:02:46.87,Default,,0000,0000,0000,,will skip that. And in the end, there is, as\Nalways, a summary and conclusion. So
Dialogue: 0,0:02:46.87,0:02:54.28,Default,,0000,0000,0000,,starting with the introduction. Weather is\Ndefined as the physical state of the
Dialogue: 0,0:02:54.28,0:03:01.18,Default,,0000,0000,0000,,atmosphere at a given time whilst climate\Nis averaged weather. Most of the time a
Dialogue: 0,0:03:01.18,0:03:07.17,Default,,0000,0000,0000,,time period of 30 years is taken for that\Naveraging but also other time periods
Dialogue: 0,0:03:07.17,0:03:14.97,Default,,0000,0000,0000,,could be taken. So, while, the main\Nquestion was, while we
Dialogue: 0,0:03:14.97,0:03:18.39,Default,,0000,0000,0000,,are not able to predict whether at a\Nspecific date in a
Dialogue: 0,0:03:18.39,0:03:24.19,Default,,0000,0000,0000,,decade, for example, let's say the 27th of\NDecember in 50 years or so. Why does it
Dialogue: 0,0:03:24.19,0:03:28.92,Default,,0000,0000,0000,,still make sense to propose general trends\Nfor the climate? That is a question that
Dialogue: 0,0:03:28.92,0:03:39.21,Default,,0000,0000,0000,,often arises when... and I'll answer that.\NSo, first of all, it is about average.
Dialogue: 0,0:03:39.21,0:03:45.22,Default,,0000,0000,0000,,Average cloud coverage gives us\Ninformation on average reflection. And
Dialogue: 0,0:03:45.22,0:03:50.87,Default,,0000,0000,0000,,average reflection is ... has an impact on\Nthe warmth on the earth. And the same is
Dialogue: 0,0:03:50.87,0:03:57.33,Default,,0000,0000,0000,,true for another scenario. For example,\Naverage precipitation - meaning rain or snow
Dialogue: 0,0:03:57.33,0:04:01.78,Default,,0000,0000,0000,,and temperature - has an impact on\Nvegetation and vegetation influences the
Dialogue: 0,0:04:01.78,0:04:06.96,Default,,0000,0000,0000,,carbon cycle. And that again influences\Nthe warming or cooling and that has an
Dialogue: 0,0:04:06.96,0:04:11.47,Default,,0000,0000,0000,,influence on the ice coverage. And that,\Nagain, on the reflection. So there are
Dialogue: 0,0:04:11.47,0:04:16.62,Default,,0000,0000,0000,,lots of processes that are connected to\Neach other and if we know something about
Dialogue: 0,0:04:16.62,0:04:22.39,Default,,0000,0000,0000,,the average of some of these physical\Nstate of the atmosphere, we can say
Dialogue: 0,0:04:22.39,0:04:31.05,Default,,0000,0000,0000,,something about the climate trends. So the\Nquestion is, what is a climate model? And
Dialogue: 0,0:04:31.05,0:04:37.82,Default,,0000,0000,0000,,the AR5 defines a climate model is a\Nnumerical representation of the climate
Dialogue: 0,0:04:37.82,0:04:44.11,Default,,0000,0000,0000,,system. The AR5 is a source I will cite\Nquite often. So I have one slide
Dialogue: 0,0:04:44.11,0:04:50.97,Default,,0000,0000,0000,,with the whole citation. It's the fifth\NIPCC report. IPCC is the
Dialogue: 0,0:04:50.97,0:04:57.69,Default,,0000,0000,0000,,Intergovernmental Panel on Climate Change\Nand the fifth assessment report is, yeah,
Dialogue: 0,0:04:57.69,0:05:04.72,Default,,0000,0000,0000,,so AR5 is the abbreviation for fifth\Nassessment report. But coming back to a
Dialogue: 0,0:05:04.72,0:05:08.95,Default,,0000,0000,0000,,climate model. So a climate model could,\Nfor example, be a GCM - a general
Dialogue: 0,0:05:08.95,0:05:15.35,Default,,0000,0000,0000,,circulation model - which is a global\Nclimate model that usually consists of an
Dialogue: 0,0:05:15.35,0:05:24.90,Default,,0000,0000,0000,,ocean and atmosphere circulation. An RCM\Nis not a GCM but it's a regional climate
Dialogue: 0,0:05:24.90,0:05:30.03,Default,,0000,0000,0000,,model, meaning a climate model at a\Nlimited area, and mainly it has a higher
Dialogue: 0,0:05:30.03,0:05:34.61,Default,,0000,0000,0000,,resolution. And for it is at a limited\Narea, that usually means that there is
Dialogue: 0,0:05:34.61,0:05:40.83,Default,,0000,0000,0000,,some input and output going in because\Nit's not a closed system. And an impact
Dialogue: 0,0:05:40.83,0:05:46.90,Default,,0000,0000,0000,,model again has usually a higher\Nresolution in time and space and it's not
Dialogue: 0,0:05:46.90,0:05:50.28,Default,,0000,0000,0000,,a climate model, but it's for simulating\Nextreme weather events
Dialogue: 0,0:05:50.28,0:05:56.69,Default,,0000,0000,0000,,like floods. So if you want to build a\Ndam or a dike and you want to know how
Dialogue: 0,0:05:56.69,0:06:02.79,Default,,0000,0000,0000,,high this dike or dam should be, then you\Nwould usually run an impact model that
Dialogue: 0,0:06:02.79,0:06:11.64,Default,,0000,0000,0000,,gives you information about water height\Nover decades or longer or so. And then
Dialogue: 0,0:06:11.64,0:06:18.73,Default,,0000,0000,0000,,you would decide on the height. So this is\Nthe use for impact models. So that's for
Dialogue: 0,0:06:18.73,0:06:24.14,Default,,0000,0000,0000,,the introduction part. Now I come to the\Nmain part and I will start with a
Dialogue: 0,0:06:24.14,0:06:31.81,Default,,0000,0000,0000,,question: is it proven? Or with a climate\Ngraph. As that, I will show you a graph, a
Dialogue: 0,0:06:31.81,0:06:36.53,Default,,0000,0000,0000,,typical image people would show you when\Nthey address climate change. This graph
Dialogue: 0,0:06:36.53,0:06:42.65,Default,,0000,0000,0000,,has an x-axis with a time scale and you\Nsee it's reaching far into the future. And
Dialogue: 0,0:06:42.65,0:06:49.51,Default,,0000,0000,0000,,it also has three or four regions\Nand the first region is only in the past.
Dialogue: 0,0:06:49.51,0:06:57.57,Default,,0000,0000,0000,,And the y-axis is the global surface\Ntemperature change, meaning how much
Dialogue: 0,0:06:57.57,0:07:05.17,Default,,0000,0000,0000,,degrees in Celsius or in Kelvin, if it's\Ndifferent it's the same, we will have in
Dialogue: 0,0:07:05.17,0:07:13.51,Default,,0000,0000,0000,,future or we had already. And then, you\Nsee several lines and different colors and
Dialogue: 0,0:07:13.51,0:07:21.13,Default,,0000,0000,0000,,with the names RCP something. And I will\Nexplain all the numbers and everything
Dialogue: 0,0:07:21.13,0:07:27.19,Default,,0000,0000,0000,,about that graph because it's a pretty\Nimportant graph. So first of all, I will
Dialogue: 0,0:07:27.19,0:07:30.60,Default,,0000,0000,0000,,tell you... no, no. I will tell you\Nsomething about the numbers and
Dialogue: 0,0:07:30.60,0:07:38.59,Default,,0000,0000,0000,,uncertainties. The uncertainties are the\Ntransparent colors behind the lines. I
Dialogue: 0,0:07:38.59,0:07:43.23,Default,,0000,0000,0000,,will tell you something about the\Nrepresentative concentration pathways,
Dialogue: 0,0:07:43.23,0:07:51.07,Default,,0000,0000,0000,,which is short RCP, and so it's reflecting\Nthe colors of the lines. I will tell you
Dialogue: 0,0:07:51.07,0:07:55.34,Default,,0000,0000,0000,,something about the source of the graphs.\NSo where does this graph actually come
Dialogue: 0,0:07:55.34,0:08:01.76,Default,,0000,0000,0000,,from? So I will tell you something about\Nthe assessment report. And first of all, I
Dialogue: 0,0:08:01.76,0:08:07.13,Default,,0000,0000,0000,,will answer the question: is it proven or\Nis there scientific evidence that we will
Dialogue: 0,0:08:07.13,0:08:15.60,Default,,0000,0000,0000,,face that climate change? So, you will see\Nthat graph quite often. First of all, I
Dialogue: 0,0:08:15.60,0:08:22.65,Default,,0000,0000,0000,,took a definition for proof, for\Nscientific evidence, from Wikipedia. The
Dialogue: 0,0:08:22.65,0:08:26.83,Default,,0000,0000,0000,,strength of scientific evidence is\Ngenerally based on the results of
Dialogue: 0,0:08:26.83,0:08:31.58,Default,,0000,0000,0000,,statistical analysis and the strength of\Nscientific controls.
Dialogue: 0,0:08:31.58,0:08:37.86,Default,,0000,0000,0000,,Meaning, you make an experiment over and\Nover again and you change basically some
Dialogue: 0,0:08:37.86,0:08:43.42,Default,,0000,0000,0000,,influences on the experiments where you\Nwant to know that this does not influence
Dialogue: 0,0:08:43.42,0:08:50.24,Default,,0000,0000,0000,,the output. So you can narrow it down and\Nknow what is the source of your results
Dialogue: 0,0:08:50.24,0:08:56.44,Default,,0000,0000,0000,,and so you can prove a physical law or\Nsomething. Yeah, I took this comic from
Dialogue: 0,0:08:56.44,0:09:04.01,Default,,0000,0000,0000,,xkcd because it's a nice... it's somehow\Nconnected. So there is a person who pulls
Dialogue: 0,0:09:04.01,0:09:09.70,Default,,0000,0000,0000,,a trigger and then gets struck by a bolt\Nor some something. Something bad happens,
Dialogue: 0,0:09:09.70,0:09:16.55,Default,,0000,0000,0000,,for example climate change. And then,\Nyeah, there are two scenarios. For
Dialogue: 0,0:09:16.55,0:09:23.47,Default,,0000,0000,0000,,example, a person usually would decide,\Nokay, I would not pull the lever again.
Dialogue: 0,0:09:23.47,0:09:29.63,Default,,0000,0000,0000,,But scientists usually or more often would\Nsay, okay, maybe: Does that happen every
Dialogue: 0,0:09:29.63,0:09:38.05,Default,,0000,0000,0000,,time if I do so? Because yeah, that's\Nbasically how you prove something. That's
Dialogue: 0,0:09:38.05,0:09:42.88,Default,,0000,0000,0000,,experiments. But in case of climate\Nchange, even scientists say you shouldn't.
Dialogue: 0,0:09:42.88,0:09:47.25,Default,,0000,0000,0000,,Although it's pretty interesting for us\Nfrom a scientific perspective. But the
Dialogue: 0,0:09:47.25,0:09:53.75,Default,,0000,0000,0000,,problem is we only have one earth. We\Ncannot do this experiment very often,
Dialogue: 0,0:09:53.75,0:09:57.91,Default,,0000,0000,0000,,except we had a time machine. Then we\Ncould go back, but we haven't so we
Dialogue: 0,0:09:57.91,0:10:05.19,Default,,0000,0000,0000,,shouldn't do that experiment. And that's\Nsomething scientists before, long ago in
Dialogue: 0,0:10:05.19,0:10:10.98,Default,,0000,0000,0000,,1957 said already: "Human beings are now\Ncarrying out a large-scale geophysical
Dialogue: 0,0:10:10.98,0:10:17.10,Default,,0000,0000,0000,,experiment of a kind that could not have\Nhappened in the past nor be reproduced in
Dialogue: 0,0:10:17.10,0:10:26.31,Default,,0000,0000,0000,,the future." So another question is, yeah,\Nif you ask this question if it is proven
Dialogue: 0,0:10:26.31,0:10:32.32,Default,,0000,0000,0000,,or that it probably is not happening or so\Nto climate deniers, they usually would
Dialogue: 0,0:10:32.32,0:10:36.94,Default,,0000,0000,0000,,tell you: Okay, maybe it's not happening.\NAnd the other side would take the position
Dialogue: 0,0:10:36.94,0:10:40.89,Default,,0000,0000,0000,,and ask you, okay, if you stand in front\Nof a road and you want to cross the road
Dialogue: 0,0:10:40.89,0:10:45.74,Default,,0000,0000,0000,,and there's a car approaching very fast,\Nwould you cross that road? Because it
Dialogue: 0,0:10:45.74,0:10:52.17,Default,,0000,0000,0000,,could happen that the car stops or makes a\NU-turn or something. But well, usually it
Dialogue: 0,0:10:52.17,0:10:59.65,Default,,0000,0000,0000,,doesn't. And sadly, we know lots about\Nthis experiment, because it's done very
Dialogue: 0,0:10:59.65,0:11:03.60,Default,,0000,0000,0000,,often before. We know\Nsomething about traffic, and that it's
Dialogue: 0,0:11:03.60,0:11:08.98,Default,,0000,0000,0000,,pretty dangerous. So let's change the\Nfactors a little so that we don't know so
Dialogue: 0,0:11:08.98,0:11:13.99,Default,,0000,0000,0000,,much about that situation. Let's say a\Ncube approaches us with a high velocity on
Dialogue: 0,0:11:13.99,0:11:20.91,Default,,0000,0000,0000,,something that is maybe not a road. Would\Nyou still cross that something? The answer
Dialogue: 0,0:11:20.91,0:11:27.04,Default,,0000,0000,0000,,is you still probably wouldn't. And why\Nwouldn't you do so although you know
Dialogue: 0,0:11:27.04,0:11:32.69,Default,,0000,0000,0000,,nothing about this situation? Well, you do\Nknow something. You know conservation of
Dialogue: 0,0:11:32.69,0:11:37.78,Default,,0000,0000,0000,,the momentum, which is a physical law you\Nknow about. So you have a situation, you
Dialogue: 0,0:11:37.78,0:11:43.05,Default,,0000,0000,0000,,know not so much about. You have never had\Nan experience before, but you still are
Dialogue: 0,0:11:43.05,0:11:48.80,Default,,0000,0000,0000,,able to make some assumptions because you\Nknow the physical laws behind it. And
Dialogue: 0,0:11:48.80,0:11:58.14,Default,,0000,0000,0000,,that's basically the same we do with, in\Nfact, in the context of climate. So we
Dialogue: 0,0:11:58.14,0:12:06.00,Default,,0000,0000,0000,,have, let's say, just an earth and the sun\Nand the sun has some radiation and that
Dialogue: 0,0:12:06.00,0:12:10.76,Default,,0000,0000,0000,,comes to the earth and gets partially\Nreflected and the earth radiates itself
Dialogue: 0,0:12:10.76,0:12:15.93,Default,,0000,0000,0000,,because it has some temperature. We know\Nsomething about this sun. We know the
Dialogue: 0,0:12:15.93,0:12:24.56,Default,,0000,0000,0000,,solar insolation. And we know parts of the\Nlight is reflected. And the factor that is
Dialogue: 0,0:12:24.56,0:12:30.06,Default,,0000,0000,0000,,reflected is usually called albedo. And so\Nthe reflected energy is albedo times the
Dialogue: 0,0:12:30.06,0:12:39.21,Default,,0000,0000,0000,,solar insulation and albedo is something\Nabout 30 percent. And we know then that
Dialogue: 0,0:12:39.21,0:12:44.98,Default,,0000,0000,0000,,the light that is absorbed must be all the\Nremaining energy. So the energy of the
Dialogue: 0,0:12:44.98,0:12:51.99,Default,,0000,0000,0000,,surface is 1 minus albedo times the solar\Ninsolation. Then knowing Stefan-Boltzmann
Dialogue: 0,0:12:51.99,0:12:58.07,Default,,0000,0000,0000,,law for energy emissions where the\Ntemperature goes in to the power of four
Dialogue: 0,0:12:58.07,0:13:05.60,Default,,0000,0000,0000,,and with the Stefan-Boltzmann constant we\Ncan actually find find out the surface
Dialogue: 0,0:13:05.60,0:13:12.97,Default,,0000,0000,0000,,temperature which then is derived to -19.5\Ndegrees Celsius. Well, we know, probably
Dialogue: 0,0:13:12.97,0:13:18.85,Default,,0000,0000,0000,,we know, that the earth is much warmer,\Nand that's because our model in this case,
Dialogue: 0,0:13:18.85,0:13:27.76,Default,,0000,0000,0000,,which is maybe a climate model, is far too\Nsimple. So we change something about that.
Dialogue: 0,0:13:27.76,0:13:37.01,Default,,0000,0000,0000,,We add atmosphere, and atmosphere has some\Ninteresting impact. So atmosphere has some
Dialogue: 0,0:13:37.01,0:13:42.75,Default,,0000,0000,0000,,trace greenhouse gases,\Nfor example CO2 but also H2O, ozone,
Dialogue: 0,0:13:42.75,0:13:52.65,Default,,0000,0000,0000,,methane, O2 and nitrous oxide. And these\Ngreenhouse gases reflect the radiation of
Dialogue: 0,0:13:52.65,0:14:00.78,Default,,0000,0000,0000,,earth back to earth, partially. Meaning\Nthe atmosphere has a transparency and this
Dialogue: 0,0:14:00.78,0:14:05.69,Default,,0000,0000,0000,,transparency we call t is something\Nbetween 15 percent and 30 percent. So it's
Dialogue: 0,0:14:05.69,0:14:14.02,Default,,0000,0000,0000,,not fixed. And that's another interesting\Nfact. The atmosphere emits energy, which
Dialogue: 0,0:14:14.02,0:14:22.57,Default,,0000,0000,0000,,we call j atmos, and that goes out in\Nspace and to earth and the energy that
Dialogue: 0,0:14:22.57,0:14:31.27,Default,,0000,0000,0000,,goes into the atmosphere is 1 minus the\Ntransparency times the energy. So we know
Dialogue: 0,0:14:31.27,0:14:35.55,Default,,0000,0000,0000,,two equations. The first is the energy\Nthat goes into the atmosphere also goes
Dialogue: 0,0:14:35.55,0:14:43.62,Default,,0000,0000,0000,,out of the atmosphere. The second is that\Nthe surface energy of the earth
Dialogue: 0,0:14:43.62,0:14:46.76,Default,,0000,0000,0000,,is the term we had before,\N1 minus albedo times the solar
Dialogue: 0,0:14:46.76,0:14:51.88,Default,,0000,0000,0000,,insolation plus the one part of the energy\Nthat is reflected by the atmosphere. And
Dialogue: 0,0:14:51.88,0:14:56.75,Default,,0000,0000,0000,,so we have two formulas, two equations\Nwith two unknowns and with the Stefan-
Dialogue: 0,0:14:56.75,0:15:01.54,Default,,0000,0000,0000,,Boltzmann law from before we can derive\Nthe surface temperature, which is 15
Dialogue: 0,0:15:01.54,0:15:07.50,Default,,0000,0000,0000,,degrees of Celsius. And that actually is\Nnot so far from what it actually is. In
Dialogue: 0,0:15:07.50,0:15:15.06,Default,,0000,0000,0000,,2000 it was measured that the surface\Ntemperature is 14.5 degrees. So, I did
Dialogue: 0,0:15:15.06,0:15:23.32,Default,,0000,0000,0000,,this for a specific t which is 22.5\Npercent but when we change that t a little
Dialogue: 0,0:15:23.32,0:15:27.95,Default,,0000,0000,0000,,to, for example, 20 percent, so we add\Nmore CO2 because, for example, we would
Dialogue: 0,0:15:27.95,0:15:35.66,Default,,0000,0000,0000,,add a factory that would do carbon\Nemissions. Then the transparency goes down
Dialogue: 0,0:15:35.66,0:15:43.02,Default,,0000,0000,0000,,and the temperature rises to, for example,\N16.6 degrees in case of 20 percent. This
Dialogue: 0,0:15:43.02,0:15:52.96,Default,,0000,0000,0000,,is also a very old knowledge. So this is\Nmaybe a little much on a slide but it is
Dialogue: 0,0:15:52.96,0:15:58.08,Default,,0000,0000,0000,,still very interesting because it is\Ncopied directly from a paper that was
Dialogue: 0,0:15:58.08,0:16:05.40,Default,,0000,0000,0000,,published from Svante Arrhenius in 1896\Nalready. And it's on the influence of
Dialogue: 0,0:16:05.40,0:16:09.88,Default,,0000,0000,0000,,carbon acid in the air upon the\Ntemperature of the ground. And carbon acid
Dialogue: 0,0:16:09.88,0:16:18.49,Default,,0000,0000,0000,,is the old term for carbon dioxide. So if\Nwe have a look to the percentage... So he
Dialogue: 0,0:16:18.49,0:16:25.96,Default,,0000,0000,0000,,investigated: What if we change\Ncarbon dioxide? So what is the impact of
Dialogue: 0,0:16:25.96,0:16:34.74,Default,,0000,0000,0000,,our behavior? Let's say carbon dioxide\Nin our atmosphere would
Dialogue: 0,0:16:34.74,0:16:41.76,Default,,0000,0000,0000,,double, so would increase by a factor of\N2, then the average temperature rise in
Dialogue: 0,0:16:41.76,0:16:50.21,Default,,0000,0000,0000,,Leipzig in December, so I choose the\Nregion for Leipzig, would be 6.1 degrees.
Dialogue: 0,0:16:50.21,0:16:55.55,Default,,0000,0000,0000,,Well, that's probably a little high, but\Nwhat we can't see is already that
Dialogue: 0,0:16:55.55,0:17:02.05,Default,,0000,0000,0000,,Arrhenius back then already knew that\Nthere is a seasonal impact on
Dialogue: 0,0:17:02.05,0:17:11.80,Default,,0000,0000,0000,,climate... that climate change is seasonal\Nand also spatial. So it is not just one...
Dialogue: 0,0:17:11.80,0:17:20.96,Default,,0000,0000,0000,,not the average temperature is the only\Ninteresting knowledge we get. So
Dialogue: 0,0:17:20.96,0:17:27.81,Default,,0000,0000,0000,,Arrhenius said something like the\Ntemperature in case of carbon acid doubled
Dialogue: 0,0:17:27.81,0:17:35.81,Default,,0000,0000,0000,,would be around four to six degrees. And\Nthe current models predict something like
Dialogue: 0,0:17:35.81,0:17:45.61,Default,,0000,0000,0000,,an increase of two to four degrees for\Nthat scenario. So there is maybe overlap
Dialogue: 0,0:17:45.61,0:17:55.68,Default,,0000,0000,0000,,already with that simple model from back\Nthen. So, then I come to the question...
Dialogue: 0,0:17:55.68,0:17:59.44,Default,,0000,0000,0000,,a climate model represents physical laws.\NThat's what we learned. Where do the
Dialogue: 0,0:17:59.44,0:18:05.46,Default,,0000,0000,0000,,uncertainties come from? So if we know all\Nthe physics laws and we would just
Dialogue: 0,0:18:05.46,0:18:09.82,Default,,0000,0000,0000,,calculate everything with this physics\Nlaws, why are there even uncertainties?
Dialogue: 0,0:18:09.82,0:18:13.69,Default,,0000,0000,0000,,And there are some reasons for that. For\Nexample, the initial conditions is one
Dialogue: 0,0:18:13.69,0:18:18.66,Default,,0000,0000,0000,,main source of uncertainties, meaning how\Nis the current state of the climate system
Dialogue: 0,0:18:18.66,0:18:24.33,Default,,0000,0000,0000,,now? How fast does something move? \NWhere are the clouds exactly?
Dialogue: 0,0:18:24.33,0:18:27.32,Default,,0000,0000,0000,,And so on. We don't\Nknow these precise initial
Dialogue: 0,0:18:27.32,0:18:33.52,Default,,0000,0000,0000,,conditions and therefore errors \Noccure. Second, would be the
Dialogue: 0,0:18:33.52,0:18:41.75,Default,,0000,0000,0000,,resolution of a model. So the\Ntemporal and spatial step length, meaning
Dialogue: 0,0:18:41.75,0:18:47.93,Default,,0000,0000,0000,,we can't... always represent our\Nclimate system with differential equations
Dialogue: 0,0:18:47.93,0:18:55.37,Default,,0000,0000,0000,,and we approximate everything. We have not\Nthe movement of every molecule but we have
Dialogue: 0,0:18:55.37,0:19:03.25,Default,,0000,0000,0000,,some average on cells. And if we increase\Nthe resolution then usually the
Dialogue: 0,0:19:03.25,0:19:08.84,Default,,0000,0000,0000,,uncertainties go down. But sometimes they\Neven don't for some question, for some
Dialogue: 0,0:19:08.84,0:19:12.26,Default,,0000,0000,0000,,questions it's better to have a lower\Nresolution. But mostly it's better to have
Dialogue: 0,0:19:12.26,0:19:15.55,Default,,0000,0000,0000,,a higher. Then, truncation, so we have
Dialogue: 0,0:19:15.55,0:19:23.05,Default,,0000,0000,0000,,computational limits. And lack of\Nunderstanding, for example, clouds. Clouds
Dialogue: 0,0:19:23.05,0:19:28.18,Default,,0000,0000,0000,,are not understood pretty well. And when I\Nread the fifth assessment report, I found
Dialogue: 0,0:19:28.18,0:19:35.60,Default,,0000,0000,0000,,a sentence a little amusing:\NClimate model... Clouds in climate models
Dialogue: 0,0:19:35.60,0:19:47.03,Default,,0000,0000,0000,,usually tend to rain too early. Yeah, so\Nbut if you know all these sources of
Dialogue: 0,0:19:47.03,0:19:52.25,Default,,0000,0000,0000,,uncertainty, why is there no such thing as\Nthe one best climate model? Meaning, why
Dialogue: 0,0:19:52.25,0:20:01.13,Default,,0000,0000,0000,,can't we go to the highest resolution and\Nto the best... the best computer we get
Dialogue: 0,0:20:01.13,0:20:07.32,Default,,0000,0000,0000,,and do everything just in the best way and\Nthen we would have our best climate model?
Dialogue: 0,0:20:07.32,0:20:13.22,Default,,0000,0000,0000,,And there are some reasons for that. For\Nexample, the so-called dynamic core,
Dialogue: 0,0:20:13.22,0:20:19.05,Default,,0000,0000,0000,,including the method for differential \Nequations or something like grids.
Dialogue: 0,0:20:19.05,0:20:25.96,Default,,0000,0000,0000,,For example, if we have a triangular \Ngrid or a rectangular grid. On a
Dialogue: 0,0:20:25.96,0:20:31.96,Default,,0000,0000,0000,,rectangular grid we usually can\Ncalculate faster but on a triangular grid
Dialogue: 0,0:20:31.96,0:20:37.74,Default,,0000,0000,0000,,we could, for example, increase the\Nresolution locally. That might be
Dialogue: 0,0:20:37.74,0:20:44.94,Default,,0000,0000,0000,,differences. And both have advantages and\Ndisadvantages. Also, the parametrization:
Dialogue: 0,0:20:44.94,0:20:51.68,Default,,0000,0000,0000,,parameters in our last slide were for\Nexample the t and the albedo which will
Dialogue: 0,0:20:51.68,0:20:55.26,Default,,0000,0000,0000,,probably be not the final parameters\Nbecause they are derived from other
Dialogue: 0,0:20:55.26,0:21:00.55,Default,,0000,0000,0000,,parameters, but physical laws or something\Nare often represented by rules with
Dialogue: 0,0:21:00.55,0:21:07.43,Default,,0000,0000,0000,,parameters, and these parameters can be\Nestimated. And they can be calibrated with
Dialogue: 0,0:21:07.43,0:21:11.66,Default,,0000,0000,0000,,different error measures.\NAnd there this is another reason for
Dialogue: 0,0:21:11.66,0:21:16.72,Default,,0000,0000,0000,,uncertainties and differences in climate\Nmodels and then their schemes. For
Dialogue: 0,0:21:16.72,0:21:20.69,Default,,0000,0000,0000,,example, there are different formulations\Nof physical processes, for example, that
Dialogue: 0,0:21:20.69,0:21:29.15,Default,,0000,0000,0000,,again, clouds. And last the truncation,\Nagain, we can also decide how we limit due
Dialogue: 0,0:21:29.15,0:21:37.32,Default,,0000,0000,0000,,to our lack of computational power. So,\Nyeah, what do we do? We investigate all
Dialogue: 0,0:21:37.32,0:21:44.22,Default,,0000,0000,0000,,the models we have. So there are different\Nclimate models that are representing our
Dialogue: 0,0:21:44.22,0:21:48.96,Default,,0000,0000,0000,,climate and we take all the models that\Nmatch certain conditions - I come to that
Dialogue: 0,0:21:48.96,0:21:53.46,Default,,0000,0000,0000,,later - and we average the output and then\Nwe
Dialogue: 0,0:21:53.46,0:22:05.44,Default,,0000,0000,0000,,get a climate prediction and also that\Nuncertainty band you see. So what climate
Dialogue: 0,0:22:05.44,0:22:12.99,Default,,0000,0000,0000,,models do we investigate? They are so-\Ncalled coordinated GCMS. So climate models
Dialogue: 0,0:22:12.99,0:22:18.28,Default,,0000,0000,0000,,are compared in so-called coupled model\Nintercomparison projects in different
Dialogue: 0,0:22:18.28,0:22:24.26,Default,,0000,0000,0000,,phases. These coupled model\Nintercomparison projects are called CMIP
Dialogue: 0,0:22:24.26,0:22:34.54,Default,,0000,0000,0000,,4, 5 and 6. So there might have been four\Nearlier ones. But currently, for the AR6,
Dialogue: 0,0:22:34.54,0:22:45.30,Default,,0000,0000,0000,,so for the sixth assessment report CMIP6 \Ninvestigated. And I showed you on the
Dialogue: 0,0:22:45.30,0:22:52.93,Default,,0000,0000,0000,,map the research centers which took part\Nin CMIP6, so which take part in the 6th
Dialogue: 0,0:22:52.93,0:23:00.46,Default,,0000,0000,0000,,assessment report. These research centers\Nare mainly specialized research centers,
Dialogue: 0,0:23:00.46,0:23:06.77,Default,,0000,0000,0000,,university and metereological offices, but\Ngenerally it's open for any institution to
Dialogue: 0,0:23:06.77,0:23:11.90,Default,,0000,0000,0000,,participate, as long as they follow a\Nprotocol for their contribution, where
Dialogue: 0,0:23:11.90,0:23:18.48,Default,,0000,0000,0000,,there are some rules so you cannot just do\Nanything. These institutions
Dialogue: 0,0:23:18.48,0:23:23.35,Default,,0000,0000,0000,,need to produce variables for a set of\Ndefined experiments and a historical
Dialogue: 0,0:23:23.35,0:23:31.02,Default,,0000,0000,0000,,simulation from 1850 to present. This blue\Npart is a link, so if you go to my slides
Dialogue: 0,0:23:31.02,0:23:37.46,Default,,0000,0000,0000,,afterwards, you can see these variables\Nyou need to reproduce and then you can do
Dialogue: 0,0:23:37.46,0:23:45.32,Default,,0000,0000,0000,,something like this. So we have a graph\Nhere again. On the x axis, we see again a
Dialogue: 0,0:23:45.32,0:23:52.37,Default,,0000,0000,0000,,timescale that reaches from 1850 to today.\NAnd on the y axis we again see the
Dialogue: 0,0:23:52.37,0:24:01.02,Default,,0000,0000,0000,,temperature anomaly or the temperature\Ndifference between.. so, exactly the
Dialogue: 0,0:24:01.02,0:24:11.44,Default,,0000,0000,0000,,temperature difference, so how much the\Nearth has warmed up. We see CMIP3 and CMIP5
Dialogue: 0,0:24:11.44,0:24:21.27,Default,,0000,0000,0000,,compared, which were the models that were\Ninvestigated for the AR5. So we see a
Dialogue: 0,0:24:21.27,0:24:29.42,Default,,0000,0000,0000,,band. This uncertainty with the yellow and\Nbluish and the background and then we see
Dialogue: 0,0:24:29.42,0:24:38.21,Default,,0000,0000,0000,,these two lines, the blue and the red one\Nfrom CMIP3 and CMIP5 and then we see the
Dialogue: 0,0:24:38.21,0:24:43.76,Default,,0000,0000,0000,,black one. And that is what actually was\Nobserved. And we see that this differs
Dialogue: 0,0:24:43.76,0:24:50.41,Default,,0000,0000,0000,,quite a lot. And that's due to there was\Nonly investigated the natural forces,
Dialogue: 0,0:24:50.41,0:24:54.86,Default,,0000,0000,0000,,meaning excluded what the human did. And\Nif we
Dialogue: 0,0:24:54.86,0:25:01.34,Default,,0000,0000,0000,,also put the human forces into it, then\Nit's quite matching. And that is the best
Dialogue: 0,0:25:01.34,0:25:09.76,Default,,0000,0000,0000,,kind of proof we can get. And again, I\Nsaid we investigate the physical laws and
Dialogue: 0,0:25:09.76,0:25:19.36,Default,,0000,0000,0000,,the physical laws were actually results of\Nscientific experiments. And so, yeah,
Dialogue: 0,0:25:19.36,0:25:30.25,Default,,0000,0000,0000,,there's this kind of proof. And yeah. So\Nmaybe a little addition. There are also
Dialogue: 0,0:25:30.25,0:25:40.61,Default,,0000,0000,0000,,other coordinated model intercomparisons\Nprojects that are outside of the IPCC and
Dialogue: 0,0:25:40.61,0:25:45.89,Default,,0000,0000,0000,,so the ones that are inside the IPCC\Nwhere the scientific focus is on a
Dialogue: 0,0:25:45.89,0:25:53.17,Default,,0000,0000,0000,,subtopic, on something like land surface\Nfor example (and that's what I do). And
Dialogue: 0,0:25:53.17,0:26:01.89,Default,,0000,0000,0000,,they're also published work\Noutside from IPCC. So back to the graph.
Dialogue: 0,0:26:01.89,0:26:10.38,Default,,0000,0000,0000,,We talked about the part: Is it proven?\NAnd I hope I convinced you that it is. And
Dialogue: 0,0:26:10.38,0:26:16.82,Default,,0000,0000,0000,,now I will talk about the sources of the\Ngraph. So I talked a lot about the IPCC.
Dialogue: 0,0:26:16.82,0:26:26.97,Default,,0000,0000,0000,,The IPCC, the Intergovernmental Panel on\NClimate Change, publishes reports. So for
Dialogue: 0,0:26:26.97,0:26:31.57,Default,,0000,0000,0000,,example, the 5th assessment report and\Nwhat you see here is part of the cover.
Dialogue: 0,0:26:31.57,0:26:41.16,Default,,0000,0000,0000,,But there have been 4 ones before, as the\Nname 5th suggests, the first assessment
Dialogue: 0,0:26:41.16,0:26:51.44,Default,,0000,0000,0000,,report FAR was published in 1990. The\Nsecond SAR in 1995. Then there was the TAR
Dialogue: 0,0:26:51.44,0:26:56.38,Default,,0000,0000,0000,,and then for the 4th assessment report\Nthey changed the name scheme for some
Dialogue: 0,0:26:56.38,0:27:03.59,Default,,0000,0000,0000,,reason to AR4 and then there was AR5,\Nwhich I'm talking about. The IPCC consists
Dialogue: 0,0:27:03.59,0:27:09.41,Default,,0000,0000,0000,,of several working groups, including\NWorking Group 1 to 3, providing the
Dialogue: 0,0:27:09.41,0:27:14.53,Default,,0000,0000,0000,,assessment reports and I mainly focus on\Nthe assessment report from a working group
Dialogue: 0,0:27:14.53,0:27:20.26,Default,,0000,0000,0000,,1, which investigates the scientific\Naspects of the climate system and climate
Dialogue: 0,0:27:20.26,0:27:28.08,Default,,0000,0000,0000,,change. But there is also a working group\Ninvestigating on vulnerability and
Dialogue: 0,0:27:28.08,0:27:33.95,Default,,0000,0000,0000,,economic impact. And the third one on the\Noptions of limiting greenhouse gas
Dialogue: 0,0:27:33.95,0:27:44.29,Default,,0000,0000,0000,,emissions and others. So I totally show\Nyou a history of the climate models. In
Dialogue: 0,0:27:44.29,0:27:50.71,Default,,0000,0000,0000,,something like the 70s, climate models\Nwere investigated where there was just an
Dialogue: 0,0:27:50.71,0:27:56.64,Default,,0000,0000,0000,,atmosphere, the sun, rain - clouds were\Nmissing - and CO2 emissions. And
Dialogue: 0,0:27:56.64,0:28:02.99,Default,,0000,0000,0000,,I hope you believe that the sun is behind\Nthe atmosphere and not in this atmosphere.
Dialogue: 0,0:28:02.99,0:28:09.78,Default,,0000,0000,0000,,In the mid 80s there was prescribed\Nice added and already clouds and land
Dialogue: 0,0:28:09.78,0:28:16.55,Default,,0000,0000,0000,,surfaces and yeah, you see a nice mountain.\NBut actually in that time the resolution
Dialogue: 0,0:28:16.55,0:28:25.15,Default,,0000,0000,0000,,was so low that the Alps only had one or\Ntwo grid cells, meaning that was not so
Dialogue: 0,0:28:25.15,0:28:33.22,Default,,0000,0000,0000,,much about land surface, but it was added.\NAnd for the first assessment report there
Dialogue: 0,0:28:33.22,0:28:39.39,Default,,0000,0000,0000,,was a swamp ocean added, meaning an ocean\Nwas added, but it was had no depth. For
Dialogue: 0,0:28:39.39,0:28:46.14,Default,,0000,0000,0000,,the second assessment report, the ocean\Ngot some depth. So it was a normal ocean
Dialogue: 0,0:28:46.14,0:28:53.04,Default,,0000,0000,0000,,with surface circulation and there was\Nadded volcano activity and sulphates. For
Dialogue: 0,0:28:53.04,0:29:01.83,Default,,0000,0000,0000,,the third assessment report, there was\Nadded... So this is all about which kind of
Dialogue: 0,0:29:01.83,0:29:10.72,Default,,0000,0000,0000,,processes were there in the climate models\Nthat were investigated in these assessment
Dialogue: 0,0:29:10.72,0:29:16.83,Default,,0000,0000,0000,,reports. Meaning there were climate models\Nbefore that already had those processes
Dialogue: 0,0:29:16.83,0:29:22.21,Default,,0000,0000,0000,,included, but they were not investigated\Nin the assessment reports. So this is a
Dialogue: 0,0:29:22.21,0:29:25.71,Default,,0000,0000,0000,,history of which climate models or which\Nprocesses and climate models were
Dialogue: 0,0:29:25.71,0:29:30.65,Default,,0000,0000,0000,,investigated in assessment reports. And\Nthe third assessment report, there was
Dialogue: 0,0:29:30.65,0:29:35.36,Default,,0000,0000,0000,,another circulation edit for the ocean,\Nthe overturning circulations. And there
Dialogue: 0,0:29:35.36,0:29:41.58,Default,,0000,0000,0000,,were rivers added, which is interesting\Nbecause I do something with rivers and
Dialogue: 0,0:29:41.58,0:29:46.58,Default,,0000,0000,0000,,there were aerosols added and a carbon\Ncycle, meaning that the carbon that goes
Dialogue: 0,0:29:46.58,0:29:54.70,Default,,0000,0000,0000,,into the atmosphere also goes out. But\Nyeah, not everything, or that half-time is
Dialogue: 0,0:29:54.70,0:30:02.06,Default,,0000,0000,0000,,not so good. For the AR5, er 4, there was\Nchemistry added in the atmosphere and
Dialogue: 0,0:30:02.06,0:30:08.91,Default,,0000,0000,0000,,interactive vegetation, and for the AR5\Nthere was ozone added and biomass burning
Dialogue: 0,0:30:08.91,0:30:15.93,Default,,0000,0000,0000,,emissions. And there is a history of\Nprocesses, but there is also a history of
Dialogue: 0,0:30:15.93,0:30:21.47,Default,,0000,0000,0000,,computer modeling that might be really\Ninteresting. It started more or less in
Dialogue: 0,0:30:21.47,0:30:31.09,Default,,0000,0000,0000,,1904 with Vilhelm Bjerknes, who found\Nequations that could be solved to obtain
Dialogue: 0,0:30:31.09,0:30:37.65,Default,,0000,0000,0000,,future states of the atmosphere. And he\Nthought about that maybe these equations
Dialogue: 0,0:30:37.65,0:30:41.44,Default,,0000,0000,0000,,are really hard to\Nsolve and that task should be split and
Dialogue: 0,0:30:41.44,0:30:48.17,Default,,0000,0000,0000,,distributed to many people. So he\Nbasically mentioned a human computer and
Dialogue: 0,0:30:48.17,0:30:54.59,Default,,0000,0000,0000,,then Lewis Fry Richardson came in 1922 and\Ndid actually calculate all this.
Dialogue: 0,0:30:54.59,0:31:03.58,Default,,0000,0000,0000,,This did a six hour forecast solving the\Nequations by hand, alone. And 42 days user
Dialogue: 0,0:31:03.58,0:31:09.06,Default,,0000,0000,0000,,time, meaning he himself calculated 42\Ndays on it. But those 42 days were
Dialogue: 0,0:31:09.06,0:31:17.79,Default,,0000,0000,0000,,distributed over two years in total. So he\Nwas a little behind the weather, only to
Dialogue: 0,0:31:17.79,0:31:24.73,Default,,0000,0000,0000,,find out that it didn't give the correct\Nanswer. {\i1}audience laughs{\i0} That was long
Dialogue: 0,0:31:24.73,0:31:32.92,Default,,0000,0000,0000,,forgotten. But people said, yea, that's\Nnot quite practical. We cannot do that.
Dialogue: 0,0:31:32.92,0:31:38.89,Default,,0000,0000,0000,,But then computers came. In 1950, the\Nfirst successful weather model was run on
Dialogue: 0,0:31:38.89,0:31:45.24,Default,,0000,0000,0000,,a computer called ENIAC, and in 1950,\Nweather predictions were run twice a day
Dialogue: 0,0:31:45.24,0:31:53.15,Default,,0000,0000,0000,,on an IBM 701. Nowadays we use\Nsupercomputers much larger and there's a
Dialogue: 0,0:31:53.15,0:31:59.47,Default,,0000,0000,0000,,whole list and rank and I will shortly\Nintroduce JEWELS to you: the Jülich Wizard
Dialogue: 0,0:31:59.47,0:32:03.82,Default,,0000,0000,0000,,for European Leadership Science. That's a\Nsupercomputer in Jülich and I would have
Dialogue: 0,0:32:03.82,0:32:09.96,Default,,0000,0000,0000,,shown you a picture, but you are not\Nallowed, you are not simply allowed to
Dialogue: 0,0:32:09.96,0:32:16.64,Default,,0000,0000,0000,,take pictures on that campus. But since\Nsuper computers are fancy shiny cupboards
Dialogue: 0,0:32:16.64,0:32:24.94,Default,,0000,0000,0000,,anyway, I thought this is OK. So we have\Nthese cupboards that look at shiny covers
Dialogue: 0,0:32:24.94,0:32:31.10,Default,,0000,0000,0000,,and then this covers their blades and each\Nblade is called a standard node and
Dialogue: 0,0:32:31.10,0:32:39.76,Default,,0000,0000,0000,,consists of, in case of JEWELS, 2 times 24\Ncores with 2.7 GHz and it's hyper-
Dialogue: 0,0:32:39.76,0:32:45.44,Default,,0000,0000,0000,,threaded, meaning you can actually run 96\Nthreads or processes on one of these
Dialogue: 0,0:32:45.44,0:32:56.36,Default,,0000,0000,0000,,nodes. And these notes have 12 times 8 GB\Nof memory. And that's not quite much if
Dialogue: 0,0:32:56.36,0:33:00.78,Default,,0000,0000,0000,,you want to run a climate model but\NI'll come to that a little later. And in
Dialogue: 0,0:33:00.78,0:33:07.47,Default,,0000,0000,0000,,fact, in case of JEWELS, you have like\Nthree rows of five of these cupboards or
Dialogue: 0,0:33:07.47,0:33:18.04,Default,,0000,0000,0000,,something. And so there are in total 2271\Nstandard nodes, 240 large memory nodes and
Dialogue: 0,0:33:18.04,0:33:26.03,Default,,0000,0000,0000,,56 accelerated nodes having something like\NGPUs. And I tell you about JEWELS, not
Dialogue: 0,0:33:26.03,0:33:29.90,Default,,0000,0000,0000,,because it's the\Nfastest, actually, it's maybe the 30th,
Dialogue: 0,0:33:29.90,0:33:34.34,Default,,0000,0000,0000,,not even because it's the fastest in\NGermany - it was when it was built but
Dialogue: 0,0:33:34.34,0:33:41.44,Default,,0000,0000,0000,,that's a while ago - but I told you about\Nthat because JEWELS provides actually
Dialogue: 0,0:33:41.44,0:33:46.47,Default,,0000,0000,0000,,computing budget for the ESM project, the\NAdvanced Earth System Modelling Capacity.
Dialogue: 0,0:33:46.47,0:33:53.56,Default,,0000,0000,0000,,And so there are actually earth system\Nmodels run on that machine. So what I told
Dialogue: 0,0:33:53.56,0:33:57.04,Default,,0000,0000,0000,,you before, there is not so much memory on\Neach node.
Dialogue: 0,0:33:57.04,0:34:00.47,Default,,0000,0000,0000,,So what you need to do is you need to cut\Ndown your problem and distribute them over
Dialogue: 0,0:34:00.47,0:34:07.13,Default,,0000,0000,0000,,the nodes. And then there needs to be some\Ncommunication. So usually if the task
Dialogue: 0,0:34:07.13,0:34:13.85,Default,,0000,0000,0000,,is so simple, you can cut down your grid\Nand put a number of grid cells to each
Dialogue: 0,0:34:13.85,0:34:18.99,Default,,0000,0000,0000,,node. And then there's communication\Nbetween the nodes on the boundaries to
Dialogue: 0,0:34:18.99,0:34:25.59,Default,,0000,0000,0000,,solve the differential equations. Talking\Nabout grids, I would talk about the
Dialogue: 0,0:34:25.59,0:34:30.16,Default,,0000,0000,0000,,resolution. Also, again, a history of\Nresolution of the climate models. For the
Dialogue: 0,0:34:30.16,0:34:36.40,Default,,0000,0000,0000,,1st assessment report, the region\Nresolution was 500 kilometers times 500
Dialogue: 0,0:34:36.40,0:34:44.64,Default,,0000,0000,0000,,kilometers. And as I said before, you see\Nthese two yellow yellowish cells in the
Dialogue: 0,0:34:44.64,0:34:51.97,Default,,0000,0000,0000,,middle that are the Alps. For the second\Nassessment report, the resolution already
Dialogue: 0,0:34:51.97,0:34:59.73,Default,,0000,0000,0000,,doubled or halved, depends on how you want\Nto phrase it. For the TAR, it was 180
Dialogue: 0,0:34:59.73,0:35:09.41,Default,,0000,0000,0000,,kilometers for AR4, it\Nwas 120 kilometers. For the AR5, it's a
Dialogue: 0,0:35:09.41,0:35:17.23,Default,,0000,0000,0000,,little bit a different section I show you.\NAnd also, I show you two resolutions.
Dialogue: 0,0:35:17.23,0:35:23.19,Default,,0000,0000,0000,,There's a resolution for the higher\Nmodels, which is 87, for example, 87.5
Dialogue: 0,0:35:23.19,0:35:30.44,Default,,0000,0000,0000,,kilometers. And for the very high\Nresolution, 30 kilometers. And that's
Dialogue: 0,0:35:30.44,0:35:35.36,Default,,0000,0000,0000,,because climate models are not just one\Nmodel, but they are different kinds of
Dialogue: 0,0:35:35.36,0:35:41.05,Default,,0000,0000,0000,,models that are coupled. And each model\Nhas its own resolution. So it's more or
Dialogue: 0,0:35:41.05,0:35:45.87,Default,,0000,0000,0000,,less like something like this. So we have\Na model for ice, we have a model for
Dialogue: 0,0:35:45.87,0:35:51.86,Default,,0000,0000,0000,,atmosphere, for ocean and for terrestrial.\NAnd this is coupled. So they all sent
Dialogue: 0,0:35:51.86,0:35:57.13,Default,,0000,0000,0000,,their data to a coupler or something. And\Nthat set was there as an input to the
Dialogue: 0,0:35:57.13,0:36:02.36,Default,,0000,0000,0000,,other model. So this is more or\Nless like how climate models look.
Dialogue: 0,0:36:02.36,0:36:11.60,Default,,0000,0000,0000,,And each of the models, again, has several\Nlayers. For example, the terrestrial layer
Dialogue: 0,0:36:11.60,0:36:18.01,Default,,0000,0000,0000,,has a ground water part and the\Natmosphere. And so there's some input from
Dialogue: 0,0:36:18.01,0:36:23.91,Default,,0000,0000,0000,,the atmosphere to the soil and plant\Nsystem. And then there's some water that
Dialogue: 0,0:36:23.91,0:36:30.74,Default,,0000,0000,0000,,is sinking into the groundwater and then\Ncoming out to the rivers. And yeah. So
Dialogue: 0,0:36:30.74,0:36:36.33,Default,,0000,0000,0000,,then we have the runoff. So meaning rivers\Nget water. And then if you have a look to
Dialogue: 0,0:36:36.33,0:36:44.21,Default,,0000,0000,0000,,rivers and want to parallelize rivers,\Nthen it's not so easy because we have a
Dialogue: 0,0:36:44.21,0:36:48.18,Default,,0000,0000,0000,,source somewhere and the water has to go\Nfrom the source or something that happens
Dialogue: 0,0:36:48.18,0:36:55.50,Default,,0000,0000,0000,,at the source has an impact to the sink,\Nmeaning this has to communicate all the
Dialogue: 0,0:36:55.50,0:37:05.99,Default,,0000,0000,0000,,way along to the sink. And that's where I\Ncome in. I actually do. So I show you the
Dialogue: 0,0:37:05.99,0:37:11.95,Default,,0000,0000,0000,,Danube, which you probably know better\Nwith the name Donau. At a resolution of
Dialogue: 0,0:37:11.95,0:37:22.47,Default,,0000,0000,0000,,five kilometers and basically cut down the\NDanube into sub river domains. And we
Dialogue: 0,0:37:22.47,0:37:28.85,Default,,0000,0000,0000,,need. If we parallelize these we need to\Ncalculate the subriver domains that are
Dialogue: 0,0:37:28.85,0:37:36.47,Default,,0000,0000,0000,,farther away from the sink first and it\Nuses that in the first graph a little. So
Dialogue: 0,0:37:36.47,0:37:44.06,Default,,0000,0000,0000,,the grayish areas are calculated first and\Nthen it goes down farther to the sink. So
Dialogue: 0,0:37:44.06,0:37:52.13,Default,,0000,0000,0000,,just to tell you about what I do. So now\Nwe come back to the main question. So we
Dialogue: 0,0:37:52.13,0:37:59.27,Default,,0000,0000,0000,,answered where the sources of the graphs\Ncome from. Now we answer the questions:
Dialogue: 0,0:37:59.27,0:38:06.73,Default,,0000,0000,0000,,What is a representative concentration\Npathway? Meaning what we all did before
Dialogue: 0,0:38:06.73,0:38:13.46,Default,,0000,0000,0000,,was more or less telling how we get to\Nthat black line in the first section. And
Dialogue: 0,0:38:13.46,0:38:26.15,Default,,0000,0000,0000,,now we concentrate on the colored part\Nwhere we have more graphs than one. So the
Dialogue: 0,0:38:26.15,0:38:31.16,Default,,0000,0000,0000,,working group 1 of the IPCC generally\Ntests the selection of coupled models, that
Dialogue: 0,0:38:31.16,0:38:36.20,Default,,0000,0000,0000,,is what I told you before, matching\Nspecific conditions and investigates the
Dialogue: 0,0:38:36.20,0:38:40.74,Default,,0000,0000,0000,,output assuming different emission\Nscenarios. Meaning we have a couple of
Dialogue: 0,0:38:40.74,0:38:46.00,Default,,0000,0000,0000,,climate models that are somehow different,\Nfor example in their grid. And then we
Dialogue: 0,0:38:46.00,0:38:53.13,Default,,0000,0000,0000,,have input data. The input scenarios would\Nbe, for example, the first one where we
Dialogue: 0,0:38:53.13,0:38:58.62,Default,,0000,0000,0000,,just do business as\Nusual and don't reduce carbon emissions.
Dialogue: 0,0:38:58.62,0:39:05.64,Default,,0000,0000,0000,,The second would be we start with our way\Nwe do it today, but we would slowly change
Dialogue: 0,0:39:05.64,0:39:10.98,Default,,0000,0000,0000,,to renewable energy. And the third one\Nwould be a scenario where we do it
Dialogue: 0,0:39:10.98,0:39:15.87,Default,,0000,0000,0000,,spontaneously now or so. And that is an\Ninput scenario that we put into the
Dialogue: 0,0:39:15.87,0:39:22.73,Default,,0000,0000,0000,,systems and then we get out a model output,\Nthat says something about the future. So
Dialogue: 0,0:39:22.73,0:39:29.09,Default,,0000,0000,0000,,there is a black line that says, OK, this\Nwas our history until today. And from that
Dialogue: 0,0:39:29.09,0:39:35.73,Default,,0000,0000,0000,,on, we have three scenarios and they are\Nrepresented upper to lower. So the upper,
Dialogue: 0,0:39:35.73,0:39:47.48,Default,,0000,0000,0000,,upper and right line represents the way\Nwhere we do nothing or so. So this is
Dialogue: 0,0:39:47.48,0:39:55.68,Default,,0000,0000,0000,,basically what we do with scenarios. And\Nthe RCPs, Representative Concentration
Dialogue: 0,0:39:55.68,0:40:00.60,Default,,0000,0000,0000,,Pathways are scenarios that include time\Nseries of emissions and concentrations of
Dialogue: 0,0:40:00.60,0:40:06.78,Default,,0000,0000,0000,,the full suite of greenhouse gases and\Naerosols and chemical active gases as well
Dialogue: 0,0:40:06.78,0:40:16.07,Default,,0000,0000,0000,,as land use and land cover. So that is\Nanother graph from the AR5 and it shows
Dialogue: 0,0:40:16.07,0:40:21.66,Default,,0000,0000,0000,,again in the X-axis the years, it's the\Nsame timescale as before, but on the Y-
Dialogue: 0,0:40:21.66,0:40:28.60,Default,,0000,0000,0000,,axis we now have the rate of forcing, that\Nis basically having this impact on our
Dialogue: 0,0:40:28.60,0:40:36.37,Default,,0000,0000,0000,,climate. And so each of the RCP scenarios\Nhas some kind of equivalent in
Dialogue: 0,0:40:36.37,0:40:42.69,Default,,0000,0000,0000,,radiative forcing.\NYeah. So we have a 4 of these scenarios.
Dialogue: 0,0:40:42.69,0:40:52.92,Default,,0000,0000,0000,,The data for the RCP scenarios is\Ncoordinated by again the input4MIPS: input
Dialogue: 0,0:40:52.92,0:40:57.01,Default,,0000,0000,0000,,datasets for model and intercomparison\Nprojects that I told you before. And most
Dialogue: 0,0:40:57.01,0:41:01.89,Default,,0000,0000,0000,,of it is freely available and I gave you\Nthe link. So if you want to run your own
Dialogue: 0,0:41:01.89,0:41:07.61,Default,,0000,0000,0000,,climate model and test it with these\Ninput, you can find it there. And now I
Dialogue: 0,0:41:07.61,0:41:11.33,Default,,0000,0000,0000,,will explain the last part. The numbers\Nand uncertainties.
Dialogue: 0,0:41:11.33,0:41:16.91,Default,,0000,0000,0000,,So first of all, again, to the graph from\Nbefore the numbers behind the RCP refer to
Dialogue: 0,0:41:16.91,0:41:24.00,Default,,0000,0000,0000,,the radiative forcing at the end of the\Nmodeling period of 2100. Meaning if you
Dialogue: 0,0:41:24.00,0:41:30.82,Default,,0000,0000,0000,,follow one of these lines, for example,\Nthe red one to where it crosses the 2100
Dialogue: 0,0:41:30.82,0:41:45.91,Default,,0000,0000,0000,,line, then the number there is 8.5. So\NRCP8.5 is the name for this RCP scenario.
Dialogue: 0,0:41:45.91,0:41:52.77,Default,,0000,0000,0000,,But then the numbers of these different\Nsections are the numbers of models used
Dialogue: 0,0:41:52.77,0:42:02.79,Default,,0000,0000,0000,,for this scenario in this time period.\NYes. So as I said, there are lots of
Dialogue: 0,0:42:02.79,0:42:09.87,Default,,0000,0000,0000,,models intercompared and we even have\Ndifferent models for the different time
Dialogue: 0,0:42:09.87,0:42:19.32,Default,,0000,0000,0000,,periods. So until 2100 there are 39 models\Nfor the RCP8.5. And of all the all the
Dialogue: 0,0:42:19.32,0:42:28.89,Default,,0000,0000,0000,,rest, there are 12. And you see this\Nlittle gap, this line break at 2100. And
Dialogue: 0,0:42:28.89,0:42:34.82,Default,,0000,0000,0000,,that is caused by the change of numbers of\Nmodels that took took part in this
Dialogue: 0,0:42:34.82,0:42:40.78,Default,,0000,0000,0000,,project. And another interesting thing\Nthat we see here, and maybe the most
Dialogue: 0,0:42:40.78,0:42:48.72,Default,,0000,0000,0000,,important, is we have quite huge model\Nuncertainties. So if we compare all the
Dialogue: 0,0:42:48.72,0:42:55.39,Default,,0000,0000,0000,,models, there's a huge band where we can't\Nexactly say, OK, it's like this or that.
Dialogue: 0,0:42:55.39,0:43:05.98,Default,,0000,0000,0000,,But this band is still... About human\Nuncertainties are more important, than this
Dialogue: 0,0:43:05.98,0:43:13.46,Default,,0000,0000,0000,,model uncertainties. We see tiny overlap,\Nbut mainly we can say how will the human
Dialogue: 0,0:43:13.46,0:43:22.93,Default,,0000,0000,0000,,behave derives our future. And that there\Nwill be this climate change we are talking
Dialogue: 0,0:43:22.93,0:43:31.15,Default,,0000,0000,0000,,about. So that was the main part about\Nthis three parts. And it's also it is also
Dialogue: 0,0:43:31.15,0:43:38.47,Default,,0000,0000,0000,,the most important part. Now, I could\Nprobably show you how you can install an
Dialogue: 0,0:43:38.47,0:43:44.26,Default,,0000,0000,0000,,impact model to your local PC, but\Nprobably I will have maybe something like
Dialogue: 0,0:43:44.26,0:43:53.34,Default,,0000,0000,0000,,three minutes left. So we'll switch to the\Nconclusion. And yeah, maybe if it's
Dialogue: 0,0:43:53.34,0:44:02.09,Default,,0000,0000,0000,,arising as a question, I can do it. So\Nwhat have we learned? Weather is the
Dialogue: 0,0:44:02.09,0:44:06.46,Default,,0000,0000,0000,,physical state of the atmosphere at a\Ngiven time, while climate is average weather
Dialogue: 0,0:44:06.46,0:44:13.65,Default,,0000,0000,0000,,over 30 years. A climate model as a\Nnumerical representation of the climate
Dialogue: 0,0:44:13.65,0:44:23.91,Default,,0000,0000,0000,,system. And we learned that the main\Nuncertainty is the way we solve a
Dialogue: 0,0:44:23.91,0:44:29.55,Default,,0000,0000,0000,,differential equations. I would probably\Nhave told you what a differential equation
Dialogue: 0,0:44:29.55,0:44:36.56,Default,,0000,0000,0000,,is in particular, but that would have\Ntaken maybe another lecture. Climate
Dialogue: 0,0:44:36.56,0:44:42.69,Default,,0000,0000,0000,,change is not proven throughout repeating\None real experiment over and over again.
Dialogue: 0,0:44:42.69,0:44:45.49,Default,,0000,0000,0000,,So there is only one earth it is said. But\Nmodels simulate our
Dialogue: 0,0:44:45.49,0:44:50.64,Default,,0000,0000,0000,,past climate pretty, well based \Non physical laws that were proven in real
Dialogue: 0,0:44:50.64,0:44:58.80,Default,,0000,0000,0000,,experiments. And then maybe the most\Nimportant message. Human behavior
Dialogue: 0,0:44:58.80,0:45:03.69,Default,,0000,0000,0000,,is the primary source of climate change.\NTherefore, we talk about projections and
Dialogue: 0,0:45:03.69,0:45:12.44,Default,,0000,0000,0000,,not predictions. Meaning if we wanted to\Npredict the climate, then we needed to
Dialogue: 0,0:45:12.44,0:45:18.39,Default,,0000,0000,0000,,simulate all human minds. And what we will\Ndecide on future. But we don't. That would
Dialogue: 0,0:45:18.39,0:45:28.03,Default,,0000,0000,0000,,be another talk again. We take what humans\Nwill decide in future as an input
Dialogue: 0,0:45:28.03,0:45:32.68,Default,,0000,0000,0000,,scenario, and with these input scenarios\Nwe create different output scenarios. So
Dialogue: 0,0:45:32.68,0:45:37.13,Default,,0000,0000,0000,,with different inputs scenarios, we get\Nthese different output scenarios. Where we
Dialogue: 0,0:45:37.13,0:45:43.34,Default,,0000,0000,0000,,can tell, OK, when we behave like that,\Nthis is the output. And human behavior
Dialogue: 0,0:45:43.34,0:45:51.71,Default,,0000,0000,0000,,scenarios dominate model uncertainties,\Nmeaning the question is what do we want?
Dialogue: 0,0:45:51.71,0:45:55.100,Default,,0000,0000,0000,,And if you go to a demonstration, the\Nanswer is usually climate justice. And I
Dialogue: 0,0:45:55.100,0:46:10.78,Default,,0000,0000,0000,,think that's a good answer. Thank you.
Dialogue: 0,0:58:43.81,0:58:44.22,Default,,0000,0000,0000,,{\i1}postroll music{\i0}
Dialogue: 0,0:58:44.22,0:58:44.64,Default,,0000,0000,0000,,subtitles created by c3subtitles.de\Nin the year 2020. Join, and help us!