0:00:00.000,0:00:06.930 i'm going to give you a an overview of 0:00:02.820,0:00:10.620 what it is that that we do as a as a 0:00:06.930,0:00:13.830 group and what we do collectively as 0:00:10.620,0:00:16.830 scientists to try and understand what 0:00:13.830,0:00:19.109 we're dealing with with with climate and 0:00:16.830,0:00:25.560 the climate system and climate change 0:00:19.109,0:00:28.529 the world is extremely complex and 0:00:25.560,0:00:32.339 dynamic the patterns that you can see 0:00:28.529,0:00:34.140 here in these clouds which is not real 0:00:32.340,0:00:37.350 where this is a computer simulations is 0:00:34.140,0:00:41.520 not this is this isn't a this is in a on 0:00:37.350,0:00:43.260 a laptop not on a non a satellite but 0:00:41.520,0:00:44.640 the patterns that you can see a very 0:00:43.260,0:00:48.599 similar to the ones that you see in the 0:00:44.640,0:00:52.469 satellite you can see storms you can see 0:00:48.600,0:00:54.449 convection you can see waves going 0:00:52.469,0:00:56.430 through you can see things repeating but 0:00:54.449,0:00:58.320 not quite right 0:00:56.430,0:00:59.609 that's the essence of the system that 0:00:58.320,0:01:02.340 were talking about it's a it's a 0:00:59.609,0:01:05.400 complicated chaotic dynamic system it 0:01:02.340,0:01:06.540 never quite repeats and yet all of the 0:01:05.400,0:01:08.490 processes that are going on the 0:01:06.540,0:01:10.890 underlying all of the things that are 0:01:08.490,0:01:13.770 going on with these clouds there 0:01:10.890,0:01:15.119 understandable there are computable we 0:01:13.770,0:01:17.610 can go and measure all of those 0:01:15.119,0:01:23.100 different individual things how do we 0:01:17.610,0:01:26.340 deal with that the challenge is is one 0:01:23.100,0:01:29.850 of scale the scales of the climate 0:01:26.340,0:01:32.579 system range from micrometers for small 0:01:29.850,0:01:36.449 aerosol particles that are from the 0:01:32.579,0:01:38.639 nuclei of clouds in the atmosphere all 0:01:36.450,0:01:40.950 the way out to the size of the planet 0:01:38.640,0:01:42.780 itself which is about 10 to the 8th 0:01:40.950,0:01:45.869 meters that's about 14 orders of 0:01:42.780,0:01:48.329 magnitude that's an enormous scale range 0:01:45.869,0:01:52.530 in which to encapsulate all the things 0:01:48.329,0:01:54.210 that are going on and even in time you 0:01:52.530,0:01:56.490 know you're going from things that are 0:01:54.210,0:01:57.779 happening on micro second scales to 0:01:56.490,0:02:01.140 things that are happening over millennia 0:01:57.780,0:02:04.170 again 14 orders of magnitude an enormous 0:02:01.140,0:02:06.900 range of scales to comprehend them play 0:02:04.170,0:02:09.690 everything together that's enormous 0:02:06.900,0:02:12.360 challenge what you have when you build a 0:02:09.690,0:02:13.800 model then is-is-is you have some 0:02:12.360,0:02:17.940 fundamental concerns we don't have 0:02:13.800,0:02:21.150 infinite computer power right so how 0:02:17.940,0:02:23.100 does that work well with weather models 0:02:21.150,0:02:24.720 right the ones that produce the forecast 0:02:23.100,0:02:26.820 that you see every day 0:02:24.720,0:02:28.290 the kind that the kind of result physics 0:02:26.820,0:02:30.720 the things that we can expressly 0:02:28.290,0:02:33.900 included in these models go from the 0:02:30.720,0:02:35.400 global scale down to about the 0:02:33.900,0:02:38.820 50-kilometer scale right that's only a 0:02:35.400,0:02:41.190 very small part of that huge range of 0:02:38.820,0:02:43.530 scales that that actually impact of 0:02:41.190,0:02:45.000 climate and the weather right the stuff 0:02:43.530,0:02:46.860 that we can resolve the stuff that we 0:02:45.000,0:02:49.140 can say okay we totally understand that 0:02:46.860,0:02:51.570 we can put in the exact equations is 0:02:49.140,0:02:54.420 just that small part all the rest of it 0:02:51.570,0:02:57.810 is what we call these subscale processes 0:02:54.420,0:03:00.149 now that stuff is is how a cloud 0:02:57.810,0:03:02.250 actually forms how rainfall actually 0:03:00.150,0:03:05.400 comes from a cloud system how 0:03:02.250,0:03:07.950 evaporation works at other very very 0:03:05.400,0:03:10.320 small scale and all of those things need 0:03:07.950,0:03:14.220 to be approximated in some way we need 0:03:10.320,0:03:17.880 to have some empirical phenomenological 0:03:14.220,0:03:20.580 approximation to that physics to allow 0:03:17.880,0:03:23.400 the rest of it to work and that's a real 0:03:20.580,0:03:25.290 challenge right there's this is this is 0:03:23.400,0:03:27.959 turbulence this is a small-scale 0:03:25.290,0:03:30.329 heterogeneity this is small mountains 0:03:27.959,0:03:32.100 and small hills and small lakes all of 0:03:30.330,0:03:34.380 those things have to be squeezed into 0:03:32.100,0:03:37.440 our approximation of those subscale 0:03:34.380,0:03:40.200 processes so there's no guarantee that 0:03:37.440,0:03:42.750 this works right there's no guarantee 0:03:40.200,0:03:47.880 that this is even a program that will 0:03:42.750,0:03:50.459 lead to successful predictions and so 0:03:47.880,0:03:52.829 the test all of this program is whether 0:03:50.459,0:03:53.790 it does actually produce successful 0:03:52.830,0:03:56.310 predictions 0:03:53.790,0:03:58.290 now you might not like the weather 0:03:56.310,0:03:59.580 forecast that you get you might think 0:03:58.290,0:04:01.380 that they're terrible but actually 0:03:59.580,0:04:03.930 they're much much better than they used 0:04:01.380,0:04:07.140 to be where the models are skillful of 0:04:03.930,0:04:10.410 producing forecasts three four five six 0:04:07.140,0:04:13.500 days almost 10 days out in ways that 0:04:10.410,0:04:16.168 were unforeseen able even 20 years ago 0:04:13.500,0:04:19.858 now climate models are slightly 0:04:16.168,0:04:22.919 different beast climate models have to 0:04:19.858,0:04:24.990 use longer timescales because time is a 0:04:22.919,0:04:26.729 longer time scale and so that compromise 0:04:24.990,0:04:27.520 they make is they don't go to quite such 0:04:26.729,0:04:29.200 fine detail 0:04:27.520,0:04:31.750 and so back in the nineteen nineties 0:04:29.200,0:04:33.849 climate models really only occupied that 0:04:31.750,0:04:38.199 very small part of that of that space 0:04:33.849,0:04:40.659 now we can go a little bit further so in 0:04:38.199,0:04:42.400 the 20,000 tens that so the models that 0:04:40.659,0:04:45.190 were working with now you know we're 0:04:42.400,0:04:47.770 coming out about the same spatial 0:04:45.190,0:04:49.870 resolution as the weather models and 0:04:47.770,0:04:52.210 we're taking up more times you know 0:04:49.870,0:04:53.620 we're going out for a thousand years and 0:04:52.210,0:04:56.289 working on the physics at the same 0:04:53.620,0:04:58.659 potential and yet we still have this 0:04:56.289,0:05:00.550 large large range of subjects scale 0:04:58.659,0:05:07.840 processes that we still have to include 0:05:00.550,0:05:09.370 this is a climate model I this is an old 0:05:07.840,0:05:11.948 tram or you'll be pleased to know we 0:05:09.370,0:05:14.409 don't use punch cards anymore it's a 0:05:11.949,0:05:16.120 single line of Fortran we still do you 0:05:14.409,0:05:18.280 use for transfer any of the old-timers 0:05:16.120,0:05:19.870 here who think that that their skills 0:05:18.280,0:05:21.758 are no longer valid 0:05:19.870,0:05:25.240 they asked a valid yes you can have a 0:05:21.759,0:05:26.740 job with each of these colored bands 0:05:25.240,0:05:28.719 with a single subroutine a single 0:05:26.740,0:05:30.699 calculation of some physical aspect of 0:05:28.719,0:05:32.770 the code arm and you would put them into 0:05:30.699,0:05:33.880 a machine one at a time and if you got 0:05:32.770,0:05:36.250 them in the wrong order you have to 0:05:33.880,0:05:39.849 start over again it would take months to 0:05:36.250,0:05:42.390 produce any output arm and it was a very 0:05:39.849,0:05:44.289 very clunky thing and so obviously if 0:05:42.390,0:05:46.150 you have to write out every line using 0:05:44.289,0:05:48.550 punch cards you don't include or of 0:05:46.150,0:05:49.508 comments so you know we inherited this 0:05:48.550,0:05:50.919 code and we're going 0:05:49.509,0:05:52.990 what does this go do we have no idea 0:05:50.919,0:05:57.940 anyway so it doesn't quite look like 0:05:52.990,0:06:00.520 that anymore but the the essence the the 0:05:57.940,0:06:02.740 idea of what we're doing is directly 0:06:00.520,0:06:04.990 related to what we did back in the 0:06:02.740,0:06:08.680 nineteen eighties and in the missus 0:06:04.990,0:06:10.750 before that 1970 ok so how do we 0:06:08.680,0:06:13.150 actually go around building a model we 0:06:10.750,0:06:16.539 do it one piece of the time and i use 0:06:13.150,0:06:17.770 the a jigsaw analogy by the beginning 0:06:16.539,0:06:20.830 and I'll kind of work with that a little 0:06:17.770,0:06:26.198 bit now it's very much like putting 0:06:20.830,0:06:28.539 together pieces of a jigsaw so this is a 0:06:26.199,0:06:31.719 piece of the jigsaw it's a picture of 0:06:28.539,0:06:34.389 arctic sea ice taken from a flight going 0:06:31.719,0:06:36.820 across the North Pole each of those ice 0:06:34.389,0:06:38.919 floes that you can barely see there are 0:06:36.820,0:06:39.860 a few tens of kilometers across and you 0:06:38.919,0:06:42.169 can see leads 0:06:39.860,0:06:43.520 the middle i was the summertime so the 0:06:42.169,0:06:46.188 ice is breaking up 0:06:43.520,0:06:47.659 and so there's a lot of physics is going 0:06:46.189,0:06:50.300 on there right there is the physics of 0:06:47.659,0:06:51.530 the Sun coming in reflecting off the ice 0:06:50.300,0:06:53.810 because it's white 0:06:51.530,0:06:56.599 there's the physics of the of the the 0:06:53.810,0:06:58.159 heat being absorbed in the ice melting 0:06:56.599,0:07:00.200 it from the top and is melting from the 0:06:58.159,0:07:02.240 bottom going on at the same time there's 0:07:00.200,0:07:04.370 dynamics how each of the ice floes 0:07:02.240,0:07:07.390 interacts with each other all of those 0:07:04.370,0:07:10.390 things can be encapsulated measured and 0:07:07.390,0:07:11.389 put into some kind of formula so here 0:07:10.390,0:07:18.529 are some of the formulas 0:07:11.389,0:07:20.569 yeah so physics you know I don't expect 0:07:18.529,0:07:22.580 you two to look at these your critique 0:07:20.569,0:07:23.750 these are but this is basically what we 0:07:22.580,0:07:25.609 do we write down what the boundary 0:07:23.750,0:07:28.520 conditions are we use calculus we use 0:07:25.610,0:07:31.390 basic conservation of energy that's 0:07:28.520,0:07:34.849 that's a big deal and for each of those 0:07:31.390,0:07:37.680 different things we then take some code 0:07:34.849,0:07:39.110 and you get lots and lots of lines of 0:07:37.690,0:07:42.500 code there are some comments now that 0:07:39.110,0:07:45.349 that's pleasing arm mr. the last bit 0:07:42.500,0:07:49.400 that there's some melting and we make 0:07:45.349,0:07:51.650 that one piece into like a component and 0:07:49.400,0:07:52.940 so okay well when we do see ice that's 0:07:51.650,0:07:56.628 the piece of code that we're going to 0:07:52.940,0:07:58.789 use and we can add in lots of different 0:07:56.629,0:08:01.159 processes so that was the sea-ice 0:07:58.789,0:08:04.219 process now there's one other processes 0:08:01.159,0:08:08.930 associated with clouds there's a process 0:08:04.219,0:08:10.460 associated with radiation and the solar 0:08:08.930,0:08:12.319 radiation coming through the atmosphere 0:08:10.460,0:08:14.568 and being absorbed at the different 0:08:12.319,0:08:19.639 layers of the atmosphere that's one more 0:08:14.569,0:08:23.120 piece there are other pieces the winds 0:08:19.639,0:08:25.699 and the way use and other pieces the 0:08:23.120,0:08:27.560 flow of water through plants the flow of 0:08:25.699,0:08:31.189 water and rivers back down to the ocean 0:08:27.560,0:08:35.240 so the point is that each of those bits 0:08:31.189,0:08:37.849 makes up part of the picture of the 0:08:35.240,0:08:40.700 climate system now I've left and pieces 0:08:37.849,0:08:42.799 out because our picture of the timing 0:08:40.700,0:08:46.430 system is not complete right we don't 0:08:42.799,0:08:51.109 know everything about the system and yet 0:08:46.430,0:08:53.479 when we put it all together we end up 0:08:51.110,0:08:56.870 with a simulation 0:08:53.480,0:09:00.139 that has all of the emergent properties 0:08:56.870,0:09:03.790 that we can see in the real world right 0:09:00.139,0:09:05.720 so these storm systems in the Southern 0:09:03.790,0:09:07.279 Ocean you can anybody has been to the 0:09:05.720,0:09:09.440 Southern Ocean knows exactly what they 0:09:07.279,0:09:11.600 look like or storms in the North 0:09:09.440,0:09:16.100 Atlantic Kevin can tell you about those 0:09:11.600,0:09:19.790 tropical cyclones in in the Pacific the 0:09:16.100,0:09:21.380 convective bands in in the was a couple 0:09:19.790,0:09:23.839 of tropical cyclones are going to cycle 0:09:21.380,0:09:29.600 around each other kind of meat 0:09:23.839,0:09:32.329 yeah now within the code there was no 0:09:29.600,0:09:35.149 code that says hey do an atmospheric 0:09:32.329,0:09:37.910 River that hits Oregon there's no code 0:09:35.149,0:09:40.160 that says do tropical cyclones and make 0:09:37.910,0:09:42.260 them dance around each other right 0:09:40.160,0:09:45.230 all of these things are emergent 0:09:42.260,0:09:47.360 properties that just arise from the fact 0:09:45.230,0:09:50.290 that the system that you're modeling is 0:09:47.360,0:09:51.589 chaotic is dynamic and all of the 0:09:50.290,0:09:54.949 different processes that we put together 0:09:51.589,0:10:04.579 intersect and interact in ways that you 0:09:54.949,0:10:09.439 can't predict a priori now just having 0:10:04.579,0:10:12.800 done that i think is a intellectual 0:10:09.440,0:10:14.810 endeavor worthy of of of Cato 0:10:12.800,0:10:16.939 and-and-and Chomsky right trying to 0:10:14.810,0:10:18.589 understand exactly what's going on in 0:10:16.940,0:10:21.620 such a complex system and being 0:10:18.589,0:10:24.500 successful at doing so is an enormous 0:10:21.620,0:10:28.399 challenge and i think one we can rightly 0:10:24.500,0:10:31.519 be proud of but we're not just doing it 0:10:28.399,0:10:35.149 to understand the system we're doing it 0:10:31.519,0:10:37.610 because that system can be kicked in 0:10:35.149,0:10:40.310 many many different ways and right now 0:10:37.610,0:10:43.190 humans are kicking this system in a very 0:10:40.310,0:10:44.930 particular way so let's look at some 0:10:43.190,0:10:47.000 ways in which the system can be kept 0:10:44.930,0:10:49.880 right so there are waffles in the 0:10:47.000,0:10:51.860 Earth's orbit these bubbles kind of make 0:10:49.880,0:10:54.529 a difference on ten thousand two hundred 0:10:51.860,0:10:57.740 thousand year time scales and a big 0:10:54.529,0:10:59.660 driver of the of the of the Ice Age 0:10:57.740,0:11:04.690 cycle that we've been seeing for the 0:10:59.660,0:11:05.569 past 2.5 million years right so Iceland 0:11:04.690,0:11:06.979 used to have a lot more ice 0:11:05.569,0:11:10.130 it's not quite as I see 0:11:06.980,0:11:14.209 as it used to be and and and it will get 0:11:10.130,0:11:15.470 messy as well with 10,000 years ago 0:11:14.209,0:11:16.849 20,000 years ago 0:11:15.470,0:11:20.360 Iceland was almost completely emaciated 0:11:16.850,0:11:21.860 right all right yeah and that's due to 0:11:20.360,0:11:24.589 these bubbles so that's that's a very 0:11:21.860,0:11:26.300 powerful kick to the system right that's 0:11:24.589,0:11:29.660 everything changed 0:11:26.300,0:11:32.389 you know can we understand that ok there 0:11:29.660,0:11:35.290 are changes because of the Sun the Sun 0:11:32.389,0:11:37.190 has cycles that has activity and it's 0:11:35.290,0:11:40.459 over its lifetime of the lifetime of the 0:11:37.190,0:11:42.470 earth has expanded and become more 0:11:40.459,0:11:44.599 active by about thirty percent over the 0:11:42.470,0:11:46.880 last four billion years that has an 0:11:44.600,0:11:50.890 impact on the climate the set the solar 0:11:46.880,0:11:52.220 cycles an 11-year cycle have an impact 0:11:50.890,0:11:58.400 on the climate we need to understand 0:11:52.220,0:12:00.800 those things volcanoes as have also well 0:11:58.400,0:12:02.689 aware have an impact on the climate not 0:12:00.800,0:12:06.229 just locally but they can have a global 0:12:02.690,0:12:07.820 impact on the climate by the injection 0:12:06.230,0:12:10.130 of sulfates into the stratosphere 0:12:07.820,0:12:11.420 changing the albedo of the palette 0:12:10.130,0:12:14.180 changing the amount of energy coming 0:12:11.420,0:12:16.399 into the system right so you're getting 0:12:14.180,0:12:20.779 the idea there are lots of different 0:12:16.399,0:12:23.600 ways in which we can change the climate 0:12:20.779,0:12:25.430 right or the system itself can be 0:12:23.600,0:12:28.100 changed whether its biomass burning 0:12:25.430,0:12:31.579 ozone depletion land-use change 0:12:28.100,0:12:35.449 contrails or of course greenhouse gases 0:12:31.579,0:12:37.579 all of these change the balances and the 0:12:35.449,0:12:39.380 flows of energy in the system and when 0:12:37.579,0:12:40.969 you change the balances and flows of 0:12:39.380,0:12:49.100 energy in the system you change the 0:12:40.970,0:12:51.190 climate so what we need to understand is 0:12:49.100,0:12:53.600 whether the simulations that i discussed 0:12:51.190,0:12:56.180 before where the weather models are the 0:12:53.600,0:12:57.768 climate models whether they have skill I 0:12:56.180,0:12:59.719 want to be very clear about this 0:12:57.769,0:13:02.510 these models are not complete right 0:12:59.720,0:13:04.250 there were holes in the jigsaw there's 0:13:02.510,0:13:07.610 whole bunches of things that we have to 0:13:04.250,0:13:10.519 and empirically fill-in write the word 0:13:07.610,0:13:12.680 that we can't predict from a priori 0:13:10.519,0:13:16.339 considerations 0:13:12.680,0:13:17.300 so why do we think that these things are 0:13:16.339,0:13:19.310 useful 0:13:17.300,0:13:20.258 we think that they're useful because 0:13:19.310,0:13:24.608 they have 0:13:20.259,0:13:26.979 demonstrated skill skill is I model 0:13:24.609,0:13:28.689 results skillful if it's better than 0:13:26.979,0:13:31.569 what you would have had otherwise 0:13:28.689,0:13:34.540 that's not to say it's perfect it's not 0:13:31.569,0:13:36.219 to say that there are uncertainties but 0:13:34.540,0:13:38.858 it's something that's better than what 0:13:36.220,0:13:41.889 you had before with the weather forecast 0:13:38.859,0:13:43.720 you could stick your finger in the air 0:13:41.889,0:13:46.539 and predict what the weather is going to 0:13:43.720,0:13:48.549 be tomorrow based on just persistence of 0:13:46.539,0:13:50.559 the weather today that probably doesn't 0:13:48.549,0:13:54.390 work very well here but it works quite 0:13:50.559,0:13:56.319 well in New York but we can do better 0:13:54.390,0:13:58.779 than that with models right weather 0:13:56.319,0:14:00.189 models a skillful despite the fact that 0:13:58.779,0:14:03.189 there was that whole range of things 0:14:00.189,0:14:05.919 that we had to empirically include and 0:14:03.189,0:14:09.399 so we need to demonstrate that climate 0:14:05.919,0:14:11.649 models are skillful at estimating the 0:14:09.399,0:14:13.720 changes to the climate when you kick 0:14:11.649,0:14:15.789 that system in all of the different 0:14:13.720,0:14:16.600 myriad ways that that system can be 0:14:15.789,0:14:19.239 kicked 0:14:16.600,0:14:22.290 okay so is that true is there are the 0:14:19.239,0:14:24.999 models skillful so well they know 0:14:22.290,0:14:27.759 volcanoes are a current topic of 0:14:24.999,0:14:29.289 interest in in Iceland I said well 0:14:27.759,0:14:31.660 actually not not anymore right we're 0:14:29.289,0:14:33.850 done with the volcanoes right so that's 0:14:31.660,0:14:36.999 it for the next week right 0:14:33.850,0:14:40.590 remember no more volcanoes ok 0:14:36.999,0:14:42.519 all models skillful with respect to big 0:14:40.590,0:14:45.129 volcanic forces so the large big volcano 0:14:42.519,0:14:47.190 that we had that had a global impact was 0:14:45.129,0:14:51.369 magnitude but went off in june nineteen 0:14:47.190,0:14:54.399 ninety one arm and this is a graph of 0:14:51.369,0:14:56.889 how much stuff basically there was in 0:14:54.399,0:14:59.169 the stratosphere are from the main 0:14:56.889,0:15:01.359 eruption and then it took like three or 0:14:59.169,0:15:02.980 four years for all that stuff to kind of 0:15:01.359,0:15:05.289 fall out of the atmosphere 0:15:02.980,0:15:07.749 ok so this is actually quite a large 0:15:05.289,0:15:09.669 amount of stuff right on the amount of 0:15:07.749,0:15:13.329 stuff that that is there that's the 0:15:09.669,0:15:17.100 technical term stuff and got some people 0:15:13.329,0:15:21.209 pay attention okay 0:15:17.100,0:15:24.450 the amount of stuff that was there cause 0:15:21.210,0:15:26.640 the radiation to be from the Sun to be 0:15:24.450,0:15:28.530 significantly less than it was right 0:15:26.640,0:15:31.710 because each of those little particles 0:15:28.530,0:15:33.360 is white and so when the Sun shines on a 0:15:31.710,0:15:35.910 white particle it reflects back to space 0:15:33.360,0:15:37.560 and that reduces the total amount of 0:15:35.910,0:15:39.569 energy coming in the amount of energy 0:15:37.560,0:15:41.459 going out was pretty much the same and 0:15:39.570,0:15:43.650 so you have less energy coming into the 0:15:41.460,0:15:46.620 system right so basic conservation of 0:15:43.650,0:15:48.660 energy suggest that that would lead to a 0:15:46.620,0:15:51.930 cooling of the planet but by how much 0:15:48.660,0:15:53.819 how much should the planet call with a 3 0:15:51.930,0:15:57.239 watt per meter squared energy imbalance 0:15:53.820,0:15:59.160 over a few years you have to do the 0:15:57.240,0:16:02.100 calculation and the climate models allow 0:15:59.160,0:16:04.410 you to do that calculation so what do 0:16:02.100,0:16:06.990 they suggest well what they suggested 0:16:04.410,0:16:09.300 are the the little thin lines that you 0:16:06.990,0:16:10.350 can see there's a bit of noise because 0:16:09.300,0:16:13.140 of the different weather and each of 0:16:10.350,0:16:14.670 those models and then the red line there 0:16:13.140,0:16:17.850 is what actually happened 0:16:14.670,0:16:21.270 so the models were able to estimate 0:16:17.850,0:16:23.160 quite precisely the rate at which this 0:16:21.270,0:16:26.760 the climate called because of this 0:16:23.160,0:16:28.949 forcing and we know that is better than 0:16:26.760,0:16:30.180 what we could just worked out by doing a 0:16:28.950,0:16:32.430 calculation on the back of the envelope 0:16:30.180,0:16:35.280 and in fact the first time that we did 0:16:32.430,0:16:39.510 that calculation we did it in October 0:16:35.280,0:16:41.970 1991 and made this prediction before any 0:16:39.510,0:16:45.300 of those changes had actually occurred 0:16:41.970,0:16:47.370 the model was skillful and it wasn't 0:16:45.300,0:16:49.589 just fearful estimating the global 0:16:47.370,0:16:51.330 cooling which you know kind of my energy 0:16:49.590,0:16:54.540 balance arguments you might argue was 0:16:51.330,0:16:58.350 the easy part but it was also skillful 0:16:54.540,0:17:01.500 at predicting that in the wintertime you 0:16:58.350,0:17:03.570 got a strange pattern in Europe where 0:17:01.500,0:17:06.210 you actually get winter warming after a 0:17:03.570,0:17:08.970 big volcano and that turns out to be a 0:17:06.210,0:17:10.770 dynamic response changes in the winds 0:17:08.970,0:17:13.800 that are affected by the temperature 0:17:10.770,0:17:17.670 changes our loft that actually push more 0:17:13.800,0:17:19.680 warm water over more warm air over over 0:17:17.670,0:17:21.450 Europe during the wintertime and that is 0:17:19.680,0:17:24.000 also captured by the model and the 0:17:21.450,0:17:26.099 models are skillful even with the 0:17:24.000,0:17:29.280 dynamics and the radiation and the 0:17:26.099,0:17:30.169 temperature there are lots of other 0:17:29.280,0:17:32.299 example 0:17:30.169,0:17:34.159 solar cycles you know we can measure and 0:17:32.299,0:17:36.200 calculate the change in ozone in the 0:17:34.159,0:17:38.419 stratosphere because of this change in 0:17:36.200,0:17:41.840 the sun with models are skillful because 0:17:38.419,0:17:44.179 of that in overall changes those wobbles 0:17:41.840,0:17:46.369 in the Earth's orbit like even 6,000 0:17:44.179,0:17:48.139 years ago they were relatively important 0:17:46.369,0:17:50.629 and we can look at that difference and 0:17:48.139,0:17:52.908 the models are skillful estimating how 0:17:50.629,0:17:55.129 the northern hemisphere temperatures got 0:17:52.909,0:17:58.399 better because our change because of 0:17:55.129,0:18:01.700 that ok 0:17:58.399,0:18:03.139 the response to the ice sheets 20,000 0:18:01.700,0:18:04.129 years ago the models are successful are 0:18:03.139,0:18:06.289 getting that right 0:18:04.129,0:18:07.908 the 20th century multi-decade all trends 0:18:06.289,0:18:10.940 were successful getting that right 0:18:07.909,0:18:12.109 models are skillful even bizarre things 0:18:10.940,0:18:14.629 that have happened to the climate about 0:18:12.109,0:18:17.590 8,000 years ago there was a huge great 0:18:14.629,0:18:18.590 lake that covered most of Manitoba and 0:18:17.590,0:18:20.749 Ontario much larger than all of the 0:18:18.590,0:18:25.369 great lakes that exists right now and it 0:18:20.749,0:18:27.980 was kept in place by the remnant by the 0:18:25.369,0:18:30.350 remnant ice sheet that was kind of 0:18:27.980,0:18:32.929 standing over hudson bay about 8,000 0:18:30.350,0:18:34.519 years ago that I sheet finally broke and 0:18:32.929,0:18:37.900 all of that water that was kept in that 0:18:34.519,0:18:38.629 Lake rushed into hudson bay and into the 0:18:37.900,0:18:41.659 labrador sea and into the North Atlantic 0:18:38.629,0:18:43.730 around here and at that same time there 0:18:41.659,0:18:46.190 is evidence of a cooling event that 0:18:43.730,0:18:48.350 happened in the Greenland ice cause in 0:18:46.190,0:18:49.850 Europe and in Newfoundland and all 0:18:48.350,0:18:52.189 around here and I'm sure that they would 0:18:49.850,0:18:55.340 a nice and have been affected as well 0:18:52.190,0:18:57.799 the models are skillful at responding to 0:18:55.340,0:19:00.619 that water going in by changing the 0:18:57.799,0:19:01.908 circulation in the in the ocean and by 0:19:00.619,0:19:03.379 changing the temperatures in the 0:19:01.909,0:19:05.600 rainfall patterns associated with that 0:19:03.379,0:19:08.209 the models are skillful across a whole 0:19:05.600,0:19:09.320 range of different ways that we can kick 0:19:08.210,0:19:14.130 that system 0:19:09.320,0:19:17.610 ok 0:19:14.130,0:19:20.910 and that system is complicated and 0:19:17.610,0:19:23.969 global right this is a simulation again 0:19:20.910,0:19:25.110 of tiny little atmospheric particles and 0:19:23.970,0:19:28.590 all the different kinds of particles 0:19:25.110,0:19:31.500 that you can have these orange swirls 0:19:28.590,0:19:33.300 are dust coming from the Sahara Desert 0:19:31.500,0:19:35.909 and you can see them affecting the 0:19:33.300,0:19:37.770 climate and affecting a deposition of 0:19:35.910,0:19:41.430 stuff all the way across the Atlantic 0:19:37.770,0:19:43.320 the white wispy parts over over Europe 0:19:41.430,0:19:45.270 you can see that's atmospheric pollution 0:19:43.320,0:19:47.220 sulfates right and you can see that 0:19:45.270,0:19:50.760 what's happens in Europe does not stay 0:19:47.220,0:19:53.250 in Europe the green and the Reds 0:19:50.760,0:19:54.780 indicate where there is our where there 0:19:53.250,0:19:57.000 are fires and whether its biomass 0:19:54.780,0:19:58.470 burning and where is organic carbon and 0:19:57.000,0:20:01.170 black carbon being put into the 0:19:58.470,0:20:02.940 atmosphere and again these things don't 0:20:01.170,0:20:04.950 just stay where they are stuck there 0:20:02.940,0:20:08.190 they started you can see the pollution 0:20:04.950,0:20:12.480 over China that again does not just stay 0:20:08.190,0:20:15.300 in China the blue dots associated with 0:20:12.480,0:20:17.850 the big tropical storms are associated 0:20:15.300,0:20:20.610 with sea salt particles so as the winds 0:20:17.850,0:20:23.280 whip up the waves small particles of sea 0:20:20.610,0:20:26.370 salt which are a key element in the 0:20:23.280,0:20:28.440 production of low-level clouds you can 0:20:26.370,0:20:32.159 see them again in the in the Southern 0:20:28.440,0:20:35.610 Ocean all of these things are connected 0:20:32.160,0:20:38.250 and important and we can answer now with 0:20:35.610,0:20:40.500 the click with the with the computer 0:20:38.250,0:20:42.300 models that we have we can answer 0:20:40.500,0:20:43.860 questions that associate that are 0:20:42.300,0:20:47.700 associated with all of those things 0:20:43.860,0:20:52.979 how does pollution change climate and 0:20:47.700,0:20:55.530 air quality all at the same time I love 0:20:52.980,0:20:57.240 this but this this animation that they 0:20:55.530,0:20:59.970 they did a really nice job here this is 0:20:57.240,0:21:01.470 my colleagues at NASA Goddard Space 0:20:59.970,0:21:03.510 Flight Center and now there's another 0:21:01.470,0:21:06.450 volcano in Madagascar that just went off 0:21:03.510,0:21:08.400 and so you can include all thoughts of 0:21:06.450,0:21:10.560 things in these models and answer all 0:21:08.400,0:21:15.460 sorts of actually quite subtle and 0:21:10.560,0:21:19.990 interesting nuance questions 0:21:15.460,0:21:22.570 how things work over the 20th century 0:21:19.990,0:21:25.590 when we've seen an amount of global 0:21:22.570,0:21:28.590 warming right so is this is a model 0:21:25.590,0:21:30.789 simulation this is the observations you 0:21:28.590,0:21:32.620 can see the patterns of whether you know 0:21:30.789,0:21:35.649 they're not correlated the weather isn't 0:21:32.620,0:21:38.490 predictable 50 years in advance but the 0:21:35.649,0:21:40.239 emerging patterns have changed that you 0:21:38.490,0:21:41.950 see towards the end of the 20th century 0:21:40.240,0:21:45.399 and that we end up where we are today 0:21:41.950,0:21:47.559 those patterns are predictable they are 0:21:45.399,0:21:49.959 predicted by the models the models are 0:21:47.559,0:21:51.970 skillful at getting these patterns right 0:21:49.960,0:21:53.799 this warming in the Arctic compared to 0:21:51.970,0:21:55.270 the Antarctic the warming over land 0:21:53.799,0:21:57.549 compared to the ocean the warming in the 0:21:55.270,0:22:04.210 North versus the woman in the south 0:21:57.549,0:22:06.700 these are skillful models but then let's 0:22:04.210,0:22:09.100 think about the real reason why we need 0:22:06.700,0:22:12.668 models right and then this this comes 0:22:09.100,0:22:14.620 from a rebuttal that the two scientists 0:22:12.669,0:22:17.799 wrote when somebody you know they talked 0:22:14.620,0:22:20.200 about modeling of of future tropical 0:22:17.799,0:22:21.580 cyclones and somebody wrote a response 0:22:20.200,0:22:24.100 to them they say well why are you 0:22:21.580,0:22:28.149 looking observations and they responded 0:22:24.100,0:22:30.340 i think quite finally what if we had 0:22:28.149,0:22:32.590 observations of the future we obviously 0:22:30.340,0:22:36.610 would trust them more than models but 0:22:32.590,0:22:40.449 unfortunately observations of the future 0:22:36.610,0:22:43.360 and not available at this time and 0:22:40.450,0:22:45.429 that's funny but it's actually the real 0:22:43.360,0:22:49.000 reason why we build models we want to 0:22:45.429,0:22:51.130 have predictive capability of situations 0:22:49.000,0:22:53.649 where we don't yet have any observations 0:22:51.130,0:22:55.720 so that we can make plans accordingly 0:22:53.649,0:22:57.610 whether it's a weather forecast whether 0:22:55.720,0:22:59.830 it's a climate forecasts whether it's an 0:22:57.610,0:23:03.908 economic projection which we could get 0:22:59.830,0:23:06.939 into is as well but Sir what we want our 0:23:03.909,0:23:10.270 is an ability to make informed decisions 0:23:06.940,0:23:12.460 about the future right so predictable 0:23:10.270,0:23:15.668 lity and predicting the future is the 0:23:12.460,0:23:16.929 absolute fundamental reason why we're 0:23:15.669,0:23:18.309 looking at models right that's what 0:23:16.929,0:23:21.159 science is all about making predictions 0:23:18.309,0:23:22.570 testing your theories adapting them 0:23:21.159,0:23:26.799 making them better making them more 0:23:22.570,0:23:27.679 predictive so what does the future hold 0:23:26.799,0:23:31.430 what we have 0:23:27.680,0:23:34.700 in the future of course our choices and 0:23:31.430,0:23:37.580 we don't have to fall down one 0:23:34.700,0:23:40.220 particular line the economic an economy 0:23:37.580,0:23:42.350 technology how we structure societies 0:23:40.220,0:23:44.810 these things are not written in stone 0:23:42.350,0:23:50.510 we have choices society has choices you 0:23:44.810,0:23:52.700 individuals have choices and these 0:23:50.510,0:23:55.850 aren't you know completely accurate 0:23:52.700,0:23:58.400 labels we don't know really what will 0:23:55.850,0:24:02.000 happen if we just continue as we go 0:23:58.400,0:24:03.830 along this is an estimate of that we 0:24:02.000,0:24:06.170 have a pretty good idea of what it would 0:24:03.830,0:24:09.230 take to bring everything kind of back 0:24:06.170,0:24:12.650 down to the level that it was you know 0:24:09.230,0:24:16.550 at the beginning of this century this 0:24:12.650,0:24:18.350 aggressive mitigation i am kevin will 0:24:16.550,0:24:21.860 tell you this is not going to happen 0:24:18.350,0:24:25.340 this is the under two-degree world that 0:24:21.860,0:24:26.270 people talk about sometimes business as 0:24:25.340,0:24:29.720 usual 0:24:26.270,0:24:31.160 that's a 56 degree world that's a 0:24:29.720,0:24:33.140 totally different planet 0:24:31.160,0:24:34.580 remember how different the ice age was 0:24:33.140,0:24:36.950 to today 0:24:34.580,0:24:39.439 well that is just as different but in 0:24:36.950,0:24:42.140 the opposite direction the ice age was a 0:24:39.440,0:24:44.510 different planet different organization 0:24:42.140,0:24:47.510 of ecosystems where people lived where 0:24:44.510,0:24:50.480 things live where things grew the same 0:24:47.510,0:24:53.870 will be true for the business-as-usual 0:24:50.480,0:24:58.490 planet where were more likely to end up 0:24:53.870,0:25:00.649 in my opinion is some effort serious 0:24:58.490,0:25:02.840 mitigation not today not tomorrow maybe 0:25:00.650,0:25:05.450 in the next 10 years 20 years 30 is 0:25:02.840,0:25:08.990 armed and now I'll still be a planet 0:25:05.450,0:25:11.390 that has significantly warmer 0:25:08.990,0:25:13.700 temperatures particularly on land 0:25:11.390,0:25:16.760 particularly in the North particularly 0:25:13.700,0:25:19.520 in the Arctic this will be a radically 0:25:16.760,0:25:22.640 different planet as well but exactly how 0:25:19.520,0:25:26.210 different is still to be determined but 0:25:22.640,0:25:31.430 the choices are really ours to make 0:25:26.210,0:25:33.740 now I'm a scientist and and I spend my 0:25:31.430,0:25:35.750 time working on those small scale 0:25:33.740,0:25:37.400 processes and the encapsulation of all 0:25:35.750,0:25:39.299 of that physics that you store in those 0:25:37.400,0:25:42.360 animations 0:25:39.299,0:25:47.999 and these projections these predictions 0:25:42.360,0:25:50.758 put us in a very odd position and it was 0:25:47.999,0:25:56.639 very clearly encapsulated by showed 0:25:50.759,0:25:59.820 Rowland who are was the one of the the 0:25:56.639,0:26:01.738 chemists who discovered the reactions 0:25:59.820,0:26:03.960 that led to ozone depletion and some of 0:26:01.739,0:26:06.389 you here will remember spray cans and 0:26:03.960,0:26:09.480 freon and the Montreal Protocol and how 0:26:06.389,0:26:12.748 that was negotiated and how that changed 0:26:09.480,0:26:15.600 so sure Roland understood quite clearly 0:26:12.749,0:26:17.730 the consequences of having made 0:26:15.600,0:26:22.259 scientific discoveries that have 0:26:17.730,0:26:25.409 real-world implications and he said in 0:26:22.259,0:26:27.389 an interview what's the use of having 0:26:25.409,0:26:30.989 developed a science well enough to make 0:26:27.389,0:26:33.269 predictions if in the end all willing to 0:26:30.989,0:26:37.109 do is stand around and wait for them to 0:26:33.269,0:26:41.279 come true and that's really the dilemma 0:26:37.109,0:26:44.699 that people like me fais do we just 0:26:41.279,0:26:46.649 continue to make predictions or do we go 0:26:44.700,0:26:49.649 out and tell people about what these 0:26:46.649,0:26:51.779 predictions mean do we go and help 0:26:49.649,0:26:53.998 people work out what they should do 0:26:51.779,0:26:57.119 about the energy system i'm not an 0:26:53.999,0:26:58.679 expert in energy systems you know should 0:26:57.119,0:27:00.590 we use nuclear power should be used 0:26:58.679,0:27:01.109 geothermal power should we do this 0:27:00.590,0:27:04.408 should we do that 0:27:01.109,0:27:08.399 those are decisions that are not up to 0:27:04.409,0:27:11.609 me though I would like to think that the 0:27:08.399,0:27:14.639 information that we produce informs the 0:27:11.609,0:27:16.918 decisions that you make individually and 0:27:14.639,0:27:22.529 that you make as a city or as a country 0:27:16.919,0:27:28.590 and as the world and I don't know what 0:27:22.529,0:27:34.440 our future will hold arm but i'm i'm 0:27:28.590,0:27:37.289 hopeful that whatever future we choose 0:27:34.440,0:27:42.529 it's an informed future so thank you 0:27:37.289,0:27:42.529 very much