1 00:00:00,000 --> 00:00:06,930 i'm going to give you a an overview of 2 00:00:02,820 --> 00:00:10,620 what it is that that we do as a as a 3 00:00:06,930 --> 00:00:13,830 group and what we do collectively as 4 00:00:10,620 --> 00:00:16,830 scientists to try and understand what 5 00:00:13,830 --> 00:00:19,109 we're dealing with with with climate and 6 00:00:16,830 --> 00:00:25,560 the climate system and climate change 7 00:00:19,109 --> 00:00:28,529 the world is extremely complex and 8 00:00:25,560 --> 00:00:32,339 dynamic the patterns that you can see 9 00:00:28,529 --> 00:00:34,140 here in these clouds which is not real 10 00:00:32,340 --> 00:00:37,350 where this is a computer simulations is 11 00:00:34,140 --> 00:00:41,520 not this is this isn't a this is in a on 12 00:00:37,350 --> 00:00:43,260 a laptop not on a non a satellite but 13 00:00:41,520 --> 00:00:44,640 the patterns that you can see a very 14 00:00:43,260 --> 00:00:48,599 similar to the ones that you see in the 15 00:00:44,640 --> 00:00:52,469 satellite you can see storms you can see 16 00:00:48,600 --> 00:00:54,449 convection you can see waves going 17 00:00:52,469 --> 00:00:56,430 through you can see things repeating but 18 00:00:54,449 --> 00:00:58,320 not quite right 19 00:00:56,430 --> 00:00:59,609 that's the essence of the system that 20 00:00:58,320 --> 00:01:02,340 were talking about it's a it's a 21 00:00:59,609 --> 00:01:05,400 complicated chaotic dynamic system it 22 00:01:02,340 --> 00:01:06,540 never quite repeats and yet all of the 23 00:01:05,400 --> 00:01:08,490 processes that are going on the 24 00:01:06,540 --> 00:01:10,890 underlying all of the things that are 25 00:01:08,490 --> 00:01:13,770 going on with these clouds there 26 00:01:10,890 --> 00:01:15,119 understandable there are computable we 27 00:01:13,770 --> 00:01:17,610 can go and measure all of those 28 00:01:15,119 --> 00:01:23,100 different individual things how do we 29 00:01:17,610 --> 00:01:26,340 deal with that the challenge is is one 30 00:01:23,100 --> 00:01:29,850 of scale the scales of the climate 31 00:01:26,340 --> 00:01:32,579 system range from micrometers for small 32 00:01:29,850 --> 00:01:36,449 aerosol particles that are from the 33 00:01:32,579 --> 00:01:38,639 nuclei of clouds in the atmosphere all 34 00:01:36,450 --> 00:01:40,950 the way out to the size of the planet 35 00:01:38,640 --> 00:01:42,780 itself which is about 10 to the 8th 36 00:01:40,950 --> 00:01:45,869 meters that's about 14 orders of 37 00:01:42,780 --> 00:01:48,329 magnitude that's an enormous scale range 38 00:01:45,869 --> 00:01:52,530 in which to encapsulate all the things 39 00:01:48,329 --> 00:01:54,210 that are going on and even in time you 40 00:01:52,530 --> 00:01:56,490 know you're going from things that are 41 00:01:54,210 --> 00:01:57,779 happening on micro second scales to 42 00:01:56,490 --> 00:02:01,140 things that are happening over millennia 43 00:01:57,780 --> 00:02:04,170 again 14 orders of magnitude an enormous 44 00:02:01,140 --> 00:02:06,900 range of scales to comprehend them play 45 00:02:04,170 --> 00:02:09,690 everything together that's enormous 46 00:02:06,900 --> 00:02:12,360 challenge what you have when you build a 47 00:02:09,690 --> 00:02:13,800 model then is-is-is you have some 48 00:02:12,360 --> 00:02:17,940 fundamental concerns we don't have 49 00:02:13,800 --> 00:02:21,150 infinite computer power right so how 50 00:02:17,940 --> 00:02:23,100 does that work well with weather models 51 00:02:21,150 --> 00:02:24,720 right the ones that produce the forecast 52 00:02:23,100 --> 00:02:26,820 that you see every day 53 00:02:24,720 --> 00:02:28,290 the kind that the kind of result physics 54 00:02:26,820 --> 00:02:30,720 the things that we can expressly 55 00:02:28,290 --> 00:02:33,900 included in these models go from the 56 00:02:30,720 --> 00:02:35,400 global scale down to about the 57 00:02:33,900 --> 00:02:38,820 50-kilometer scale right that's only a 58 00:02:35,400 --> 00:02:41,190 very small part of that huge range of 59 00:02:38,820 --> 00:02:43,530 scales that that actually impact of 60 00:02:41,190 --> 00:02:45,000 climate and the weather right the stuff 61 00:02:43,530 --> 00:02:46,860 that we can resolve the stuff that we 62 00:02:45,000 --> 00:02:49,140 can say okay we totally understand that 63 00:02:46,860 --> 00:02:51,570 we can put in the exact equations is 64 00:02:49,140 --> 00:02:54,420 just that small part all the rest of it 65 00:02:51,570 --> 00:02:57,810 is what we call these subscale processes 66 00:02:54,420 --> 00:03:00,149 now that stuff is is how a cloud 67 00:02:57,810 --> 00:03:02,250 actually forms how rainfall actually 68 00:03:00,150 --> 00:03:05,400 comes from a cloud system how 69 00:03:02,250 --> 00:03:07,950 evaporation works at other very very 70 00:03:05,400 --> 00:03:10,320 small scale and all of those things need 71 00:03:07,950 --> 00:03:14,220 to be approximated in some way we need 72 00:03:10,320 --> 00:03:17,880 to have some empirical phenomenological 73 00:03:14,220 --> 00:03:20,580 approximation to that physics to allow 74 00:03:17,880 --> 00:03:23,400 the rest of it to work and that's a real 75 00:03:20,580 --> 00:03:25,290 challenge right there's this is this is 76 00:03:23,400 --> 00:03:27,959 turbulence this is a small-scale 77 00:03:25,290 --> 00:03:30,329 heterogeneity this is small mountains 78 00:03:27,959 --> 00:03:32,100 and small hills and small lakes all of 79 00:03:30,330 --> 00:03:34,380 those things have to be squeezed into 80 00:03:32,100 --> 00:03:37,440 our approximation of those subscale 81 00:03:34,380 --> 00:03:40,200 processes so there's no guarantee that 82 00:03:37,440 --> 00:03:42,750 this works right there's no guarantee 83 00:03:40,200 --> 00:03:47,880 that this is even a program that will 84 00:03:42,750 --> 00:03:50,459 lead to successful predictions and so 85 00:03:47,880 --> 00:03:52,829 the test all of this program is whether 86 00:03:50,459 --> 00:03:53,790 it does actually produce successful 87 00:03:52,830 --> 00:03:56,310 predictions 88 00:03:53,790 --> 00:03:58,290 now you might not like the weather 89 00:03:56,310 --> 00:03:59,580 forecast that you get you might think 90 00:03:58,290 --> 00:04:01,380 that they're terrible but actually 91 00:03:59,580 --> 00:04:03,930 they're much much better than they used 92 00:04:01,380 --> 00:04:07,140 to be where the models are skillful of 93 00:04:03,930 --> 00:04:10,410 producing forecasts three four five six 94 00:04:07,140 --> 00:04:13,500 days almost 10 days out in ways that 95 00:04:10,410 --> 00:04:16,168 were unforeseen able even 20 years ago 96 00:04:13,500 --> 00:04:19,858 now climate models are slightly 97 00:04:16,168 --> 00:04:22,919 different beast climate models have to 98 00:04:19,858 --> 00:04:24,990 use longer timescales because time is a 99 00:04:22,919 --> 00:04:26,729 longer time scale and so that compromise 100 00:04:24,990 --> 00:04:27,520 they make is they don't go to quite such 101 00:04:26,729 --> 00:04:29,200 fine detail 102 00:04:27,520 --> 00:04:31,750 and so back in the nineteen nineties 103 00:04:29,200 --> 00:04:33,849 climate models really only occupied that 104 00:04:31,750 --> 00:04:38,199 very small part of that of that space 105 00:04:33,849 --> 00:04:40,659 now we can go a little bit further so in 106 00:04:38,199 --> 00:04:42,400 the 20,000 tens that so the models that 107 00:04:40,659 --> 00:04:45,190 were working with now you know we're 108 00:04:42,400 --> 00:04:47,770 coming out about the same spatial 109 00:04:45,190 --> 00:04:49,870 resolution as the weather models and 110 00:04:47,770 --> 00:04:52,210 we're taking up more times you know 111 00:04:49,870 --> 00:04:53,620 we're going out for a thousand years and 112 00:04:52,210 --> 00:04:56,289 working on the physics at the same 113 00:04:53,620 --> 00:04:58,659 potential and yet we still have this 114 00:04:56,289 --> 00:05:00,550 large large range of subjects scale 115 00:04:58,659 --> 00:05:07,840 processes that we still have to include 116 00:05:00,550 --> 00:05:09,370 this is a climate model I this is an old 117 00:05:07,840 --> 00:05:11,948 tram or you'll be pleased to know we 118 00:05:09,370 --> 00:05:14,409 don't use punch cards anymore it's a 119 00:05:11,949 --> 00:05:16,120 single line of Fortran we still do you 120 00:05:14,409 --> 00:05:18,280 use for transfer any of the old-timers 121 00:05:16,120 --> 00:05:19,870 here who think that that their skills 122 00:05:18,280 --> 00:05:21,758 are no longer valid 123 00:05:19,870 --> 00:05:25,240 they asked a valid yes you can have a 124 00:05:21,759 --> 00:05:26,740 job with each of these colored bands 125 00:05:25,240 --> 00:05:28,719 with a single subroutine a single 126 00:05:26,740 --> 00:05:30,699 calculation of some physical aspect of 127 00:05:28,719 --> 00:05:32,770 the code arm and you would put them into 128 00:05:30,699 --> 00:05:33,880 a machine one at a time and if you got 129 00:05:32,770 --> 00:05:36,250 them in the wrong order you have to 130 00:05:33,880 --> 00:05:39,849 start over again it would take months to 131 00:05:36,250 --> 00:05:42,390 produce any output arm and it was a very 132 00:05:39,849 --> 00:05:44,289 very clunky thing and so obviously if 133 00:05:42,390 --> 00:05:46,150 you have to write out every line using 134 00:05:44,289 --> 00:05:48,550 punch cards you don't include or of 135 00:05:46,150 --> 00:05:49,508 comments so you know we inherited this 136 00:05:48,550 --> 00:05:50,919 code and we're going 137 00:05:49,509 --> 00:05:52,990 what does this go do we have no idea 138 00:05:50,919 --> 00:05:57,940 anyway so it doesn't quite look like 139 00:05:52,990 --> 00:06:00,520 that anymore but the the essence the the 140 00:05:57,940 --> 00:06:02,740 idea of what we're doing is directly 141 00:06:00,520 --> 00:06:04,990 related to what we did back in the 142 00:06:02,740 --> 00:06:08,680 nineteen eighties and in the missus 143 00:06:04,990 --> 00:06:10,750 before that 1970 ok so how do we 144 00:06:08,680 --> 00:06:13,150 actually go around building a model we 145 00:06:10,750 --> 00:06:16,539 do it one piece of the time and i use 146 00:06:13,150 --> 00:06:17,770 the a jigsaw analogy by the beginning 147 00:06:16,539 --> 00:06:20,830 and I'll kind of work with that a little 148 00:06:17,770 --> 00:06:26,198 bit now it's very much like putting 149 00:06:20,830 --> 00:06:28,539 together pieces of a jigsaw so this is a 150 00:06:26,199 --> 00:06:31,719 piece of the jigsaw it's a picture of 151 00:06:28,539 --> 00:06:34,389 arctic sea ice taken from a flight going 152 00:06:31,719 --> 00:06:36,820 across the North Pole each of those ice 153 00:06:34,389 --> 00:06:38,919 floes that you can barely see there are 154 00:06:36,820 --> 00:06:39,860 a few tens of kilometers across and you 155 00:06:38,919 --> 00:06:42,169 can see leads 156 00:06:39,860 --> 00:06:43,520 the middle i was the summertime so the 157 00:06:42,169 --> 00:06:46,188 ice is breaking up 158 00:06:43,520 --> 00:06:47,659 and so there's a lot of physics is going 159 00:06:46,189 --> 00:06:50,300 on there right there is the physics of 160 00:06:47,659 --> 00:06:51,530 the Sun coming in reflecting off the ice 161 00:06:50,300 --> 00:06:53,810 because it's white 162 00:06:51,530 --> 00:06:56,599 there's the physics of the of the the 163 00:06:53,810 --> 00:06:58,159 heat being absorbed in the ice melting 164 00:06:56,599 --> 00:07:00,200 it from the top and is melting from the 165 00:06:58,159 --> 00:07:02,240 bottom going on at the same time there's 166 00:07:00,200 --> 00:07:04,370 dynamics how each of the ice floes 167 00:07:02,240 --> 00:07:07,390 interacts with each other all of those 168 00:07:04,370 --> 00:07:10,390 things can be encapsulated measured and 169 00:07:07,390 --> 00:07:11,389 put into some kind of formula so here 170 00:07:10,390 --> 00:07:18,529 are some of the formulas 171 00:07:11,389 --> 00:07:20,569 yeah so physics you know I don't expect 172 00:07:18,529 --> 00:07:22,580 you two to look at these your critique 173 00:07:20,569 --> 00:07:23,750 these are but this is basically what we 174 00:07:22,580 --> 00:07:25,609 do we write down what the boundary 175 00:07:23,750 --> 00:07:28,520 conditions are we use calculus we use 176 00:07:25,610 --> 00:07:31,390 basic conservation of energy that's 177 00:07:28,520 --> 00:07:34,849 that's a big deal and for each of those 178 00:07:31,390 --> 00:07:37,680 different things we then take some code 179 00:07:34,849 --> 00:07:39,110 and you get lots and lots of lines of 180 00:07:37,690 --> 00:07:42,500 code there are some comments now that 181 00:07:39,110 --> 00:07:45,349 that's pleasing arm mr. the last bit 182 00:07:42,500 --> 00:07:49,400 that there's some melting and we make 183 00:07:45,349 --> 00:07:51,650 that one piece into like a component and 184 00:07:49,400 --> 00:07:52,940 so okay well when we do see ice that's 185 00:07:51,650 --> 00:07:56,628 the piece of code that we're going to 186 00:07:52,940 --> 00:07:58,789 use and we can add in lots of different 187 00:07:56,629 --> 00:08:01,159 processes so that was the sea-ice 188 00:07:58,789 --> 00:08:04,219 process now there's one other processes 189 00:08:01,159 --> 00:08:08,930 associated with clouds there's a process 190 00:08:04,219 --> 00:08:10,460 associated with radiation and the solar 191 00:08:08,930 --> 00:08:12,319 radiation coming through the atmosphere 192 00:08:10,460 --> 00:08:14,568 and being absorbed at the different 193 00:08:12,319 --> 00:08:19,639 layers of the atmosphere that's one more 194 00:08:14,569 --> 00:08:23,120 piece there are other pieces the winds 195 00:08:19,639 --> 00:08:25,699 and the way use and other pieces the 196 00:08:23,120 --> 00:08:27,560 flow of water through plants the flow of 197 00:08:25,699 --> 00:08:31,189 water and rivers back down to the ocean 198 00:08:27,560 --> 00:08:35,240 so the point is that each of those bits 199 00:08:31,189 --> 00:08:37,849 makes up part of the picture of the 200 00:08:35,240 --> 00:08:40,700 climate system now I've left and pieces 201 00:08:37,849 --> 00:08:42,799 out because our picture of the timing 202 00:08:40,700 --> 00:08:46,430 system is not complete right we don't 203 00:08:42,799 --> 00:08:51,109 know everything about the system and yet 204 00:08:46,430 --> 00:08:53,479 when we put it all together we end up 205 00:08:51,110 --> 00:08:56,870 with a simulation 206 00:08:53,480 --> 00:09:00,139 that has all of the emergent properties 207 00:08:56,870 --> 00:09:03,790 that we can see in the real world right 208 00:09:00,139 --> 00:09:05,720 so these storm systems in the Southern 209 00:09:03,790 --> 00:09:07,279 Ocean you can anybody has been to the 210 00:09:05,720 --> 00:09:09,440 Southern Ocean knows exactly what they 211 00:09:07,279 --> 00:09:11,600 look like or storms in the North 212 00:09:09,440 --> 00:09:16,100 Atlantic Kevin can tell you about those 213 00:09:11,600 --> 00:09:19,790 tropical cyclones in in the Pacific the 214 00:09:16,100 --> 00:09:21,380 convective bands in in the was a couple 215 00:09:19,790 --> 00:09:23,839 of tropical cyclones are going to cycle 216 00:09:21,380 --> 00:09:29,600 around each other kind of meat 217 00:09:23,839 --> 00:09:32,329 yeah now within the code there was no 218 00:09:29,600 --> 00:09:35,149 code that says hey do an atmospheric 219 00:09:32,329 --> 00:09:37,910 River that hits Oregon there's no code 220 00:09:35,149 --> 00:09:40,160 that says do tropical cyclones and make 221 00:09:37,910 --> 00:09:42,260 them dance around each other right 222 00:09:40,160 --> 00:09:45,230 all of these things are emergent 223 00:09:42,260 --> 00:09:47,360 properties that just arise from the fact 224 00:09:45,230 --> 00:09:50,290 that the system that you're modeling is 225 00:09:47,360 --> 00:09:51,589 chaotic is dynamic and all of the 226 00:09:50,290 --> 00:09:54,949 different processes that we put together 227 00:09:51,589 --> 00:10:04,579 intersect and interact in ways that you 228 00:09:54,949 --> 00:10:09,439 can't predict a priori now just having 229 00:10:04,579 --> 00:10:12,800 done that i think is a intellectual 230 00:10:09,440 --> 00:10:14,810 endeavor worthy of of of Cato 231 00:10:12,800 --> 00:10:16,939 and-and-and Chomsky right trying to 232 00:10:14,810 --> 00:10:18,589 understand exactly what's going on in 233 00:10:16,940 --> 00:10:21,620 such a complex system and being 234 00:10:18,589 --> 00:10:24,500 successful at doing so is an enormous 235 00:10:21,620 --> 00:10:28,399 challenge and i think one we can rightly 236 00:10:24,500 --> 00:10:31,519 be proud of but we're not just doing it 237 00:10:28,399 --> 00:10:35,149 to understand the system we're doing it 238 00:10:31,519 --> 00:10:37,610 because that system can be kicked in 239 00:10:35,149 --> 00:10:40,310 many many different ways and right now 240 00:10:37,610 --> 00:10:43,190 humans are kicking this system in a very 241 00:10:40,310 --> 00:10:44,930 particular way so let's look at some 242 00:10:43,190 --> 00:10:47,000 ways in which the system can be kept 243 00:10:44,930 --> 00:10:49,880 right so there are waffles in the 244 00:10:47,000 --> 00:10:51,860 Earth's orbit these bubbles kind of make 245 00:10:49,880 --> 00:10:54,529 a difference on ten thousand two hundred 246 00:10:51,860 --> 00:10:57,740 thousand year time scales and a big 247 00:10:54,529 --> 00:10:59,660 driver of the of the of the Ice Age 248 00:10:57,740 --> 00:11:04,690 cycle that we've been seeing for the 249 00:10:59,660 --> 00:11:05,569 past 2.5 million years right so Iceland 250 00:11:04,690 --> 00:11:06,979 used to have a lot more ice 251 00:11:05,569 --> 00:11:10,130 it's not quite as I see 252 00:11:06,980 --> 00:11:14,209 as it used to be and and and it will get 253 00:11:10,130 --> 00:11:15,470 messy as well with 10,000 years ago 254 00:11:14,209 --> 00:11:16,849 20,000 years ago 255 00:11:15,470 --> 00:11:20,360 Iceland was almost completely emaciated 256 00:11:16,850 --> 00:11:21,860 right all right yeah and that's due to 257 00:11:20,360 --> 00:11:24,589 these bubbles so that's that's a very 258 00:11:21,860 --> 00:11:26,300 powerful kick to the system right that's 259 00:11:24,589 --> 00:11:29,660 everything changed 260 00:11:26,300 --> 00:11:32,389 you know can we understand that ok there 261 00:11:29,660 --> 00:11:35,290 are changes because of the Sun the Sun 262 00:11:32,389 --> 00:11:37,190 has cycles that has activity and it's 263 00:11:35,290 --> 00:11:40,459 over its lifetime of the lifetime of the 264 00:11:37,190 --> 00:11:42,470 earth has expanded and become more 265 00:11:40,459 --> 00:11:44,599 active by about thirty percent over the 266 00:11:42,470 --> 00:11:46,880 last four billion years that has an 267 00:11:44,600 --> 00:11:50,890 impact on the climate the set the solar 268 00:11:46,880 --> 00:11:52,220 cycles an 11-year cycle have an impact 269 00:11:50,890 --> 00:11:58,400 on the climate we need to understand 270 00:11:52,220 --> 00:12:00,800 those things volcanoes as have also well 271 00:11:58,400 --> 00:12:02,689 aware have an impact on the climate not 272 00:12:00,800 --> 00:12:06,229 just locally but they can have a global 273 00:12:02,690 --> 00:12:07,820 impact on the climate by the injection 274 00:12:06,230 --> 00:12:10,130 of sulfates into the stratosphere 275 00:12:07,820 --> 00:12:11,420 changing the albedo of the palette 276 00:12:10,130 --> 00:12:14,180 changing the amount of energy coming 277 00:12:11,420 --> 00:12:16,399 into the system right so you're getting 278 00:12:14,180 --> 00:12:20,779 the idea there are lots of different 279 00:12:16,399 --> 00:12:23,600 ways in which we can change the climate 280 00:12:20,779 --> 00:12:25,430 right or the system itself can be 281 00:12:23,600 --> 00:12:28,100 changed whether its biomass burning 282 00:12:25,430 --> 00:12:31,579 ozone depletion land-use change 283 00:12:28,100 --> 00:12:35,449 contrails or of course greenhouse gases 284 00:12:31,579 --> 00:12:37,579 all of these change the balances and the 285 00:12:35,449 --> 00:12:39,380 flows of energy in the system and when 286 00:12:37,579 --> 00:12:40,969 you change the balances and flows of 287 00:12:39,380 --> 00:12:49,100 energy in the system you change the 288 00:12:40,970 --> 00:12:51,190 climate so what we need to understand is 289 00:12:49,100 --> 00:12:53,600 whether the simulations that i discussed 290 00:12:51,190 --> 00:12:56,180 before where the weather models are the 291 00:12:53,600 --> 00:12:57,768 climate models whether they have skill I 292 00:12:56,180 --> 00:12:59,719 want to be very clear about this 293 00:12:57,769 --> 00:13:02,510 these models are not complete right 294 00:12:59,720 --> 00:13:04,250 there were holes in the jigsaw there's 295 00:13:02,510 --> 00:13:07,610 whole bunches of things that we have to 296 00:13:04,250 --> 00:13:10,519 and empirically fill-in write the word 297 00:13:07,610 --> 00:13:12,680 that we can't predict from a priori 298 00:13:10,519 --> 00:13:16,339 considerations 299 00:13:12,680 --> 00:13:17,300 so why do we think that these things are 300 00:13:16,339 --> 00:13:19,310 useful 301 00:13:17,300 --> 00:13:20,258 we think that they're useful because 302 00:13:19,310 --> 00:13:24,608 they have 303 00:13:20,259 --> 00:13:26,979 demonstrated skill skill is I model 304 00:13:24,609 --> 00:13:28,689 results skillful if it's better than 305 00:13:26,979 --> 00:13:31,569 what you would have had otherwise 306 00:13:28,689 --> 00:13:34,540 that's not to say it's perfect it's not 307 00:13:31,569 --> 00:13:36,219 to say that there are uncertainties but 308 00:13:34,540 --> 00:13:38,858 it's something that's better than what 309 00:13:36,220 --> 00:13:41,889 you had before with the weather forecast 310 00:13:38,859 --> 00:13:43,720 you could stick your finger in the air 311 00:13:41,889 --> 00:13:46,539 and predict what the weather is going to 312 00:13:43,720 --> 00:13:48,549 be tomorrow based on just persistence of 313 00:13:46,539 --> 00:13:50,559 the weather today that probably doesn't 314 00:13:48,549 --> 00:13:54,390 work very well here but it works quite 315 00:13:50,559 --> 00:13:56,319 well in New York but we can do better 316 00:13:54,390 --> 00:13:58,779 than that with models right weather 317 00:13:56,319 --> 00:14:00,189 models a skillful despite the fact that 318 00:13:58,779 --> 00:14:03,189 there was that whole range of things 319 00:14:00,189 --> 00:14:05,919 that we had to empirically include and 320 00:14:03,189 --> 00:14:09,399 so we need to demonstrate that climate 321 00:14:05,919 --> 00:14:11,649 models are skillful at estimating the 322 00:14:09,399 --> 00:14:13,720 changes to the climate when you kick 323 00:14:11,649 --> 00:14:15,789 that system in all of the different 324 00:14:13,720 --> 00:14:16,600 myriad ways that that system can be 325 00:14:15,789 --> 00:14:19,239 kicked 326 00:14:16,600 --> 00:14:22,290 okay so is that true is there are the 327 00:14:19,239 --> 00:14:24,999 models skillful so well they know 328 00:14:22,290 --> 00:14:27,759 volcanoes are a current topic of 329 00:14:24,999 --> 00:14:29,289 interest in in Iceland I said well 330 00:14:27,759 --> 00:14:31,660 actually not not anymore right we're 331 00:14:29,289 --> 00:14:33,850 done with the volcanoes right so that's 332 00:14:31,660 --> 00:14:36,999 it for the next week right 333 00:14:33,850 --> 00:14:40,590 remember no more volcanoes ok 334 00:14:36,999 --> 00:14:42,519 all models skillful with respect to big 335 00:14:40,590 --> 00:14:45,129 volcanic forces so the large big volcano 336 00:14:42,519 --> 00:14:47,190 that we had that had a global impact was 337 00:14:45,129 --> 00:14:51,369 magnitude but went off in june nineteen 338 00:14:47,190 --> 00:14:54,399 ninety one arm and this is a graph of 339 00:14:51,369 --> 00:14:56,889 how much stuff basically there was in 340 00:14:54,399 --> 00:14:59,169 the stratosphere are from the main 341 00:14:56,889 --> 00:15:01,359 eruption and then it took like three or 342 00:14:59,169 --> 00:15:02,980 four years for all that stuff to kind of 343 00:15:01,359 --> 00:15:05,289 fall out of the atmosphere 344 00:15:02,980 --> 00:15:07,749 ok so this is actually quite a large 345 00:15:05,289 --> 00:15:09,669 amount of stuff right on the amount of 346 00:15:07,749 --> 00:15:13,329 stuff that that is there that's the 347 00:15:09,669 --> 00:15:17,100 technical term stuff and got some people 348 00:15:13,329 --> 00:15:21,209 pay attention okay 349 00:15:17,100 --> 00:15:24,450 the amount of stuff that was there cause 350 00:15:21,210 --> 00:15:26,640 the radiation to be from the Sun to be 351 00:15:24,450 --> 00:15:28,530 significantly less than it was right 352 00:15:26,640 --> 00:15:31,710 because each of those little particles 353 00:15:28,530 --> 00:15:33,360 is white and so when the Sun shines on a 354 00:15:31,710 --> 00:15:35,910 white particle it reflects back to space 355 00:15:33,360 --> 00:15:37,560 and that reduces the total amount of 356 00:15:35,910 --> 00:15:39,569 energy coming in the amount of energy 357 00:15:37,560 --> 00:15:41,459 going out was pretty much the same and 358 00:15:39,570 --> 00:15:43,650 so you have less energy coming into the 359 00:15:41,460 --> 00:15:46,620 system right so basic conservation of 360 00:15:43,650 --> 00:15:48,660 energy suggest that that would lead to a 361 00:15:46,620 --> 00:15:51,930 cooling of the planet but by how much 362 00:15:48,660 --> 00:15:53,819 how much should the planet call with a 3 363 00:15:51,930 --> 00:15:57,239 watt per meter squared energy imbalance 364 00:15:53,820 --> 00:15:59,160 over a few years you have to do the 365 00:15:57,240 --> 00:16:02,100 calculation and the climate models allow 366 00:15:59,160 --> 00:16:04,410 you to do that calculation so what do 367 00:16:02,100 --> 00:16:06,990 they suggest well what they suggested 368 00:16:04,410 --> 00:16:09,300 are the the little thin lines that you 369 00:16:06,990 --> 00:16:10,350 can see there's a bit of noise because 370 00:16:09,300 --> 00:16:13,140 of the different weather and each of 371 00:16:10,350 --> 00:16:14,670 those models and then the red line there 372 00:16:13,140 --> 00:16:17,850 is what actually happened 373 00:16:14,670 --> 00:16:21,270 so the models were able to estimate 374 00:16:17,850 --> 00:16:23,160 quite precisely the rate at which this 375 00:16:21,270 --> 00:16:26,760 the climate called because of this 376 00:16:23,160 --> 00:16:28,949 forcing and we know that is better than 377 00:16:26,760 --> 00:16:30,180 what we could just worked out by doing a 378 00:16:28,950 --> 00:16:32,430 calculation on the back of the envelope 379 00:16:30,180 --> 00:16:35,280 and in fact the first time that we did 380 00:16:32,430 --> 00:16:39,510 that calculation we did it in October 381 00:16:35,280 --> 00:16:41,970 1991 and made this prediction before any 382 00:16:39,510 --> 00:16:45,300 of those changes had actually occurred 383 00:16:41,970 --> 00:16:47,370 the model was skillful and it wasn't 384 00:16:45,300 --> 00:16:49,589 just fearful estimating the global 385 00:16:47,370 --> 00:16:51,330 cooling which you know kind of my energy 386 00:16:49,590 --> 00:16:54,540 balance arguments you might argue was 387 00:16:51,330 --> 00:16:58,350 the easy part but it was also skillful 388 00:16:54,540 --> 00:17:01,500 at predicting that in the wintertime you 389 00:16:58,350 --> 00:17:03,570 got a strange pattern in Europe where 390 00:17:01,500 --> 00:17:06,210 you actually get winter warming after a 391 00:17:03,570 --> 00:17:08,970 big volcano and that turns out to be a 392 00:17:06,210 --> 00:17:10,770 dynamic response changes in the winds 393 00:17:08,970 --> 00:17:13,800 that are affected by the temperature 394 00:17:10,770 --> 00:17:17,670 changes our loft that actually push more 395 00:17:13,800 --> 00:17:19,680 warm water over more warm air over over 396 00:17:17,670 --> 00:17:21,450 Europe during the wintertime and that is 397 00:17:19,680 --> 00:17:24,000 also captured by the model and the 398 00:17:21,450 --> 00:17:26,099 models are skillful even with the 399 00:17:24,000 --> 00:17:29,280 dynamics and the radiation and the 400 00:17:26,099 --> 00:17:30,169 temperature there are lots of other 401 00:17:29,280 --> 00:17:32,299 example 402 00:17:30,169 --> 00:17:34,159 solar cycles you know we can measure and 403 00:17:32,299 --> 00:17:36,200 calculate the change in ozone in the 404 00:17:34,159 --> 00:17:38,419 stratosphere because of this change in 405 00:17:36,200 --> 00:17:41,840 the sun with models are skillful because 406 00:17:38,419 --> 00:17:44,179 of that in overall changes those wobbles 407 00:17:41,840 --> 00:17:46,369 in the Earth's orbit like even 6,000 408 00:17:44,179 --> 00:17:48,139 years ago they were relatively important 409 00:17:46,369 --> 00:17:50,629 and we can look at that difference and 410 00:17:48,139 --> 00:17:52,908 the models are skillful estimating how 411 00:17:50,629 --> 00:17:55,129 the northern hemisphere temperatures got 412 00:17:52,909 --> 00:17:58,399 better because our change because of 413 00:17:55,129 --> 00:18:01,700 that ok 414 00:17:58,399 --> 00:18:03,139 the response to the ice sheets 20,000 415 00:18:01,700 --> 00:18:04,129 years ago the models are successful are 416 00:18:03,139 --> 00:18:06,289 getting that right 417 00:18:04,129 --> 00:18:07,908 the 20th century multi-decade all trends 418 00:18:06,289 --> 00:18:10,940 were successful getting that right 419 00:18:07,909 --> 00:18:12,109 models are skillful even bizarre things 420 00:18:10,940 --> 00:18:14,629 that have happened to the climate about 421 00:18:12,109 --> 00:18:17,590 8,000 years ago there was a huge great 422 00:18:14,629 --> 00:18:18,590 lake that covered most of Manitoba and 423 00:18:17,590 --> 00:18:20,749 Ontario much larger than all of the 424 00:18:18,590 --> 00:18:25,369 great lakes that exists right now and it 425 00:18:20,749 --> 00:18:27,980 was kept in place by the remnant by the 426 00:18:25,369 --> 00:18:30,350 remnant ice sheet that was kind of 427 00:18:27,980 --> 00:18:32,929 standing over hudson bay about 8,000 428 00:18:30,350 --> 00:18:34,519 years ago that I sheet finally broke and 429 00:18:32,929 --> 00:18:37,900 all of that water that was kept in that 430 00:18:34,519 --> 00:18:38,629 Lake rushed into hudson bay and into the 431 00:18:37,900 --> 00:18:41,659 labrador sea and into the North Atlantic 432 00:18:38,629 --> 00:18:43,730 around here and at that same time there 433 00:18:41,659 --> 00:18:46,190 is evidence of a cooling event that 434 00:18:43,730 --> 00:18:48,350 happened in the Greenland ice cause in 435 00:18:46,190 --> 00:18:49,850 Europe and in Newfoundland and all 436 00:18:48,350 --> 00:18:52,189 around here and I'm sure that they would 437 00:18:49,850 --> 00:18:55,340 a nice and have been affected as well 438 00:18:52,190 --> 00:18:57,799 the models are skillful at responding to 439 00:18:55,340 --> 00:19:00,619 that water going in by changing the 440 00:18:57,799 --> 00:19:01,908 circulation in the in the ocean and by 441 00:19:00,619 --> 00:19:03,379 changing the temperatures in the 442 00:19:01,909 --> 00:19:05,600 rainfall patterns associated with that 443 00:19:03,379 --> 00:19:08,209 the models are skillful across a whole 444 00:19:05,600 --> 00:19:09,320 range of different ways that we can kick 445 00:19:08,210 --> 00:19:14,130 that system 446 00:19:09,320 --> 00:19:17,610 ok 447 00:19:14,130 --> 00:19:20,910 and that system is complicated and 448 00:19:17,610 --> 00:19:23,969 global right this is a simulation again 449 00:19:20,910 --> 00:19:25,110 of tiny little atmospheric particles and 450 00:19:23,970 --> 00:19:28,590 all the different kinds of particles 451 00:19:25,110 --> 00:19:31,500 that you can have these orange swirls 452 00:19:28,590 --> 00:19:33,300 are dust coming from the Sahara Desert 453 00:19:31,500 --> 00:19:35,909 and you can see them affecting the 454 00:19:33,300 --> 00:19:37,770 climate and affecting a deposition of 455 00:19:35,910 --> 00:19:41,430 stuff all the way across the Atlantic 456 00:19:37,770 --> 00:19:43,320 the white wispy parts over over Europe 457 00:19:41,430 --> 00:19:45,270 you can see that's atmospheric pollution 458 00:19:43,320 --> 00:19:47,220 sulfates right and you can see that 459 00:19:45,270 --> 00:19:50,760 what's happens in Europe does not stay 460 00:19:47,220 --> 00:19:53,250 in Europe the green and the Reds 461 00:19:50,760 --> 00:19:54,780 indicate where there is our where there 462 00:19:53,250 --> 00:19:57,000 are fires and whether its biomass 463 00:19:54,780 --> 00:19:58,470 burning and where is organic carbon and 464 00:19:57,000 --> 00:20:01,170 black carbon being put into the 465 00:19:58,470 --> 00:20:02,940 atmosphere and again these things don't 466 00:20:01,170 --> 00:20:04,950 just stay where they are stuck there 467 00:20:02,940 --> 00:20:08,190 they started you can see the pollution 468 00:20:04,950 --> 00:20:12,480 over China that again does not just stay 469 00:20:08,190 --> 00:20:15,300 in China the blue dots associated with 470 00:20:12,480 --> 00:20:17,850 the big tropical storms are associated 471 00:20:15,300 --> 00:20:20,610 with sea salt particles so as the winds 472 00:20:17,850 --> 00:20:23,280 whip up the waves small particles of sea 473 00:20:20,610 --> 00:20:26,370 salt which are a key element in the 474 00:20:23,280 --> 00:20:28,440 production of low-level clouds you can 475 00:20:26,370 --> 00:20:32,159 see them again in the in the Southern 476 00:20:28,440 --> 00:20:35,610 Ocean all of these things are connected 477 00:20:32,160 --> 00:20:38,250 and important and we can answer now with 478 00:20:35,610 --> 00:20:40,500 the click with the with the computer 479 00:20:38,250 --> 00:20:42,300 models that we have we can answer 480 00:20:40,500 --> 00:20:43,860 questions that associate that are 481 00:20:42,300 --> 00:20:47,700 associated with all of those things 482 00:20:43,860 --> 00:20:52,979 how does pollution change climate and 483 00:20:47,700 --> 00:20:55,530 air quality all at the same time I love 484 00:20:52,980 --> 00:20:57,240 this but this this animation that they 485 00:20:55,530 --> 00:20:59,970 they did a really nice job here this is 486 00:20:57,240 --> 00:21:01,470 my colleagues at NASA Goddard Space 487 00:20:59,970 --> 00:21:03,510 Flight Center and now there's another 488 00:21:01,470 --> 00:21:06,450 volcano in Madagascar that just went off 489 00:21:03,510 --> 00:21:08,400 and so you can include all thoughts of 490 00:21:06,450 --> 00:21:10,560 things in these models and answer all 491 00:21:08,400 --> 00:21:15,460 sorts of actually quite subtle and 492 00:21:10,560 --> 00:21:19,990 interesting nuance questions 493 00:21:15,460 --> 00:21:22,570 how things work over the 20th century 494 00:21:19,990 --> 00:21:25,590 when we've seen an amount of global 495 00:21:22,570 --> 00:21:28,590 warming right so is this is a model 496 00:21:25,590 --> 00:21:30,789 simulation this is the observations you 497 00:21:28,590 --> 00:21:32,620 can see the patterns of whether you know 498 00:21:30,789 --> 00:21:35,649 they're not correlated the weather isn't 499 00:21:32,620 --> 00:21:38,490 predictable 50 years in advance but the 500 00:21:35,649 --> 00:21:40,239 emerging patterns have changed that you 501 00:21:38,490 --> 00:21:41,950 see towards the end of the 20th century 502 00:21:40,240 --> 00:21:45,399 and that we end up where we are today 503 00:21:41,950 --> 00:21:47,559 those patterns are predictable they are 504 00:21:45,399 --> 00:21:49,959 predicted by the models the models are 505 00:21:47,559 --> 00:21:51,970 skillful at getting these patterns right 506 00:21:49,960 --> 00:21:53,799 this warming in the Arctic compared to 507 00:21:51,970 --> 00:21:55,270 the Antarctic the warming over land 508 00:21:53,799 --> 00:21:57,549 compared to the ocean the warming in the 509 00:21:55,270 --> 00:22:04,210 North versus the woman in the south 510 00:21:57,549 --> 00:22:06,700 these are skillful models but then let's 511 00:22:04,210 --> 00:22:09,100 think about the real reason why we need 512 00:22:06,700 --> 00:22:12,668 models right and then this this comes 513 00:22:09,100 --> 00:22:14,620 from a rebuttal that the two scientists 514 00:22:12,669 --> 00:22:17,799 wrote when somebody you know they talked 515 00:22:14,620 --> 00:22:20,200 about modeling of of future tropical 516 00:22:17,799 --> 00:22:21,580 cyclones and somebody wrote a response 517 00:22:20,200 --> 00:22:24,100 to them they say well why are you 518 00:22:21,580 --> 00:22:28,149 looking observations and they responded 519 00:22:24,100 --> 00:22:30,340 i think quite finally what if we had 520 00:22:28,149 --> 00:22:32,590 observations of the future we obviously 521 00:22:30,340 --> 00:22:36,610 would trust them more than models but 522 00:22:32,590 --> 00:22:40,449 unfortunately observations of the future 523 00:22:36,610 --> 00:22:43,360 and not available at this time and 524 00:22:40,450 --> 00:22:45,429 that's funny but it's actually the real 525 00:22:43,360 --> 00:22:49,000 reason why we build models we want to 526 00:22:45,429 --> 00:22:51,130 have predictive capability of situations 527 00:22:49,000 --> 00:22:53,649 where we don't yet have any observations 528 00:22:51,130 --> 00:22:55,720 so that we can make plans accordingly 529 00:22:53,649 --> 00:22:57,610 whether it's a weather forecast whether 530 00:22:55,720 --> 00:22:59,830 it's a climate forecasts whether it's an 531 00:22:57,610 --> 00:23:03,908 economic projection which we could get 532 00:22:59,830 --> 00:23:06,939 into is as well but Sir what we want our 533 00:23:03,909 --> 00:23:10,270 is an ability to make informed decisions 534 00:23:06,940 --> 00:23:12,460 about the future right so predictable 535 00:23:10,270 --> 00:23:15,668 lity and predicting the future is the 536 00:23:12,460 --> 00:23:16,929 absolute fundamental reason why we're 537 00:23:15,669 --> 00:23:18,309 looking at models right that's what 538 00:23:16,929 --> 00:23:21,159 science is all about making predictions 539 00:23:18,309 --> 00:23:22,570 testing your theories adapting them 540 00:23:21,159 --> 00:23:26,799 making them better making them more 541 00:23:22,570 --> 00:23:27,679 predictive so what does the future hold 542 00:23:26,799 --> 00:23:31,430 what we have 543 00:23:27,680 --> 00:23:34,700 in the future of course our choices and 544 00:23:31,430 --> 00:23:37,580 we don't have to fall down one 545 00:23:34,700 --> 00:23:40,220 particular line the economic an economy 546 00:23:37,580 --> 00:23:42,350 technology how we structure societies 547 00:23:40,220 --> 00:23:44,810 these things are not written in stone 548 00:23:42,350 --> 00:23:50,510 we have choices society has choices you 549 00:23:44,810 --> 00:23:52,700 individuals have choices and these 550 00:23:50,510 --> 00:23:55,850 aren't you know completely accurate 551 00:23:52,700 --> 00:23:58,400 labels we don't know really what will 552 00:23:55,850 --> 00:24:02,000 happen if we just continue as we go 553 00:23:58,400 --> 00:24:03,830 along this is an estimate of that we 554 00:24:02,000 --> 00:24:06,170 have a pretty good idea of what it would 555 00:24:03,830 --> 00:24:09,230 take to bring everything kind of back 556 00:24:06,170 --> 00:24:12,650 down to the level that it was you know 557 00:24:09,230 --> 00:24:16,550 at the beginning of this century this 558 00:24:12,650 --> 00:24:18,350 aggressive mitigation i am kevin will 559 00:24:16,550 --> 00:24:21,860 tell you this is not going to happen 560 00:24:18,350 --> 00:24:25,340 this is the under two-degree world that 561 00:24:21,860 --> 00:24:26,270 people talk about sometimes business as 562 00:24:25,340 --> 00:24:29,720 usual 563 00:24:26,270 --> 00:24:31,160 that's a 56 degree world that's a 564 00:24:29,720 --> 00:24:33,140 totally different planet 565 00:24:31,160 --> 00:24:34,580 remember how different the ice age was 566 00:24:33,140 --> 00:24:36,950 to today 567 00:24:34,580 --> 00:24:39,439 well that is just as different but in 568 00:24:36,950 --> 00:24:42,140 the opposite direction the ice age was a 569 00:24:39,440 --> 00:24:44,510 different planet different organization 570 00:24:42,140 --> 00:24:47,510 of ecosystems where people lived where 571 00:24:44,510 --> 00:24:50,480 things live where things grew the same 572 00:24:47,510 --> 00:24:53,870 will be true for the business-as-usual 573 00:24:50,480 --> 00:24:58,490 planet where were more likely to end up 574 00:24:53,870 --> 00:25:00,649 in my opinion is some effort serious 575 00:24:58,490 --> 00:25:02,840 mitigation not today not tomorrow maybe 576 00:25:00,650 --> 00:25:05,450 in the next 10 years 20 years 30 is 577 00:25:02,840 --> 00:25:08,990 armed and now I'll still be a planet 578 00:25:05,450 --> 00:25:11,390 that has significantly warmer 579 00:25:08,990 --> 00:25:13,700 temperatures particularly on land 580 00:25:11,390 --> 00:25:16,760 particularly in the North particularly 581 00:25:13,700 --> 00:25:19,520 in the Arctic this will be a radically 582 00:25:16,760 --> 00:25:22,640 different planet as well but exactly how 583 00:25:19,520 --> 00:25:26,210 different is still to be determined but 584 00:25:22,640 --> 00:25:31,430 the choices are really ours to make 585 00:25:26,210 --> 00:25:33,740 now I'm a scientist and and I spend my 586 00:25:31,430 --> 00:25:35,750 time working on those small scale 587 00:25:33,740 --> 00:25:37,400 processes and the encapsulation of all 588 00:25:35,750 --> 00:25:39,299 of that physics that you store in those 589 00:25:37,400 --> 00:25:42,360 animations 590 00:25:39,299 --> 00:25:47,999 and these projections these predictions 591 00:25:42,360 --> 00:25:50,758 put us in a very odd position and it was 592 00:25:47,999 --> 00:25:56,639 very clearly encapsulated by showed 593 00:25:50,759 --> 00:25:59,820 Rowland who are was the one of the the 594 00:25:56,639 --> 00:26:01,738 chemists who discovered the reactions 595 00:25:59,820 --> 00:26:03,960 that led to ozone depletion and some of 596 00:26:01,739 --> 00:26:06,389 you here will remember spray cans and 597 00:26:03,960 --> 00:26:09,480 freon and the Montreal Protocol and how 598 00:26:06,389 --> 00:26:12,748 that was negotiated and how that changed 599 00:26:09,480 --> 00:26:15,600 so sure Roland understood quite clearly 600 00:26:12,749 --> 00:26:17,730 the consequences of having made 601 00:26:15,600 --> 00:26:22,259 scientific discoveries that have 602 00:26:17,730 --> 00:26:25,409 real-world implications and he said in 603 00:26:22,259 --> 00:26:27,389 an interview what's the use of having 604 00:26:25,409 --> 00:26:30,989 developed a science well enough to make 605 00:26:27,389 --> 00:26:33,269 predictions if in the end all willing to 606 00:26:30,989 --> 00:26:37,109 do is stand around and wait for them to 607 00:26:33,269 --> 00:26:41,279 come true and that's really the dilemma 608 00:26:37,109 --> 00:26:44,699 that people like me fais do we just 609 00:26:41,279 --> 00:26:46,649 continue to make predictions or do we go 610 00:26:44,700 --> 00:26:49,649 out and tell people about what these 611 00:26:46,649 --> 00:26:51,779 predictions mean do we go and help 612 00:26:49,649 --> 00:26:53,998 people work out what they should do 613 00:26:51,779 --> 00:26:57,119 about the energy system i'm not an 614 00:26:53,999 --> 00:26:58,679 expert in energy systems you know should 615 00:26:57,119 --> 00:27:00,590 we use nuclear power should be used 616 00:26:58,679 --> 00:27:01,109 geothermal power should we do this 617 00:27:00,590 --> 00:27:04,408 should we do that 618 00:27:01,109 --> 00:27:08,399 those are decisions that are not up to 619 00:27:04,409 --> 00:27:11,609 me though I would like to think that the 620 00:27:08,399 --> 00:27:14,639 information that we produce informs the 621 00:27:11,609 --> 00:27:16,918 decisions that you make individually and 622 00:27:14,639 --> 00:27:22,529 that you make as a city or as a country 623 00:27:16,919 --> 00:27:28,590 and as the world and I don't know what 624 00:27:22,529 --> 00:27:34,440 our future will hold arm but i'm i'm 625 00:27:28,590 --> 00:27:37,289 hopeful that whatever future we choose 626 00:27:34,440 --> 00:27:42,529 it's an informed future so thank you 627 00:27:37,289 --> 00:27:42,529 very much