1 00:00:00,240 --> 00:00:10,850 [Music] 2 00:00:18,089 --> 00:00:13,890 hi I'm Julia Horne 3 00:00:20,220 --> 00:00:18,099 I'm here as a graduate student from the 4 00:00:23,070 --> 00:00:20,230 school of Earth and shine earth and 5 00:00:25,710 --> 00:00:23,080 ocean sciences in the University of 6 00:00:27,769 --> 00:00:25,720 Victoria in Canada I'm here to talk to 7 00:00:29,700 --> 00:00:27,779 you about our Keon biogeochemistry 8 00:00:31,230 --> 00:00:29,710 investigating environmental controls on 9 00:00:33,240 --> 00:00:31,240 Archaean earth's habitability which is 10 00:00:35,280 --> 00:00:33,250 different than the program has listed 11 00:00:39,000 --> 00:00:35,290 because I changed the title because I 12 00:00:41,370 --> 00:00:39,010 can and my supervisor at University of 13 00:00:43,830 --> 00:00:41,380 Victoria is Colin Goldblatt and he is 14 00:00:47,280 --> 00:00:43,840 actually an alumnus of the a Brad 15 00:00:48,990 --> 00:00:47,290 conventions or conch meetings so he was 16 00:00:51,630 --> 00:00:49,000 very excited that I could come and visit 17 00:00:56,779 --> 00:00:51,640 you and he wanted to highlight but he 18 00:01:01,650 --> 00:00:56,789 has an AB grad Khan oh nine shirt so 19 00:01:03,990 --> 00:01:01,660 yeah so thank you amber for explaining 20 00:01:06,870 --> 00:01:04,000 the faint young Sun paradox so I do not 21 00:01:10,020 --> 00:01:06,880 have to it is kind of central to my 22 00:01:13,429 --> 00:01:10,030 interest in Archaean earth and the earth 23 00:01:16,140 --> 00:01:13,439 Earth's development of habitability so 24 00:01:20,070 --> 00:01:16,150 it's a little bit complex to look at 25 00:01:22,830 --> 00:01:20,080 this figure on the left but what I want 26 00:01:24,690 --> 00:01:22,840 you to take a note of is that the major 27 00:01:25,230 --> 00:01:24,700 outgoing radiation from the Earth's 28 00:01:29,789 --> 00:01:25,240 surface 29 00:01:32,580 --> 00:01:29,799 Thermal IR is in the attend well 8 to 13 30 00:01:34,770 --> 00:01:32,590 micron vapor window where neither carbon 31 00:01:38,910 --> 00:01:34,780 dioxide nor water vapor necessarily 32 00:01:40,770 --> 00:01:38,920 absorb that much radiation so this is 33 00:01:43,710 --> 00:01:40,780 where most of the heat is lost from the 34 00:01:46,649 --> 00:01:43,720 planet and basically the faint young Sun 35 00:01:48,719 --> 00:01:46,659 paradox since it requires at least 30 to 36 00:01:50,399 --> 00:01:48,729 15 watts per meter squared of additional 37 00:01:54,330 --> 00:01:50,409 radiative forcing to keep the planet 38 00:01:56,420 --> 00:01:54,340 habitable in the Archaean it needs a 39 00:01:59,969 --> 00:01:56,430 greenhouse gas to plug this hole so 40 00:02:03,120 --> 00:01:59,979 there are many greenhouse gases as you 41 00:02:06,569 --> 00:02:03,130 probably know one of our favorites is in 42 00:02:10,109 --> 00:02:06,579 the modern day is co2 ch4 has also been 43 00:02:15,790 --> 00:02:10,119 proposed to fill in this gap but nh3 44 00:02:19,000 --> 00:02:15,800 ammonia is uniquely good for this kind 45 00:02:22,720 --> 00:02:19,010 of greenhouse gas forcing because it 46 00:02:27,120 --> 00:02:22,730 fills almost exactly the 8 to 13 micron 47 00:02:30,190 --> 00:02:27,130 vapor window it is theoretically 48 00:02:32,320 --> 00:02:30,200 proposed to be abundant or at least way 49 00:02:34,390 --> 00:02:32,330 more abundant than a modern-day in a 50 00:02:37,270 --> 00:02:34,400 reducing or subtly reducing atmosphere 51 00:02:39,790 --> 00:02:37,280 which is what the Archaean earth should 52 00:02:42,880 --> 00:02:39,800 have been it's a very low oxygen in the 53 00:02:45,790 --> 00:02:42,890 atmosphere when they say reducing and it 54 00:02:48,340 --> 00:02:45,800 has a few cons some some detractions it 55 00:02:50,200 --> 00:02:48,350 is soluble in water so theoretically it 56 00:02:53,410 --> 00:02:50,210 can get rained out but if you have a 57 00:02:56,260 --> 00:02:53,420 constant supply of ammonia from you know 58 00:02:58,360 --> 00:02:56,270 biological or geologic systems you can 59 00:03:00,970 --> 00:02:58,370 kind of perpetuate its atmospheric 60 00:03:02,860 --> 00:03:00,980 partial pressure it is also photolytic 61 00:03:05,350 --> 00:03:02,870 li destroyed irreversibly in the 62 00:03:07,330 --> 00:03:05,360 atmosphere so incoming radiation breaks 63 00:03:13,300 --> 00:03:07,340 it apart hydrogen escapes you left to 64 00:03:15,070 --> 00:03:13,310 die nitrogen yay kind of so anyway I'll 65 00:03:17,650 --> 00:03:15,080 get a little bit more into the model 66 00:03:20,230 --> 00:03:17,660 details later but a background model was 67 00:03:23,920 --> 00:03:20,240 developed by a previous undergrad 68 00:03:26,380 --> 00:03:23,930 student who found that just working with 69 00:03:27,970 --> 00:03:26,390 nitrogen only biogeochemical systems you 70 00:03:29,680 --> 00:03:27,980 can get at least three watts per meter 71 00:03:31,750 --> 00:03:29,690 squared which is about a tenth of what 72 00:03:33,850 --> 00:03:31,760 we need as a baseline but it's not 73 00:03:35,860 --> 00:03:33,860 insignificant so this is still very 74 00:03:38,790 --> 00:03:35,870 promising and I decided to take the 75 00:03:41,970 --> 00:03:38,800 project on and move forward with it so 76 00:03:44,500 --> 00:03:41,980 most of you probably don't use 77 00:03:47,020 --> 00:03:44,510 biogeochemical models so I'll explain 78 00:03:48,250 --> 00:03:47,030 them a little bit to you so you can kind 79 00:03:51,010 --> 00:03:48,260 of understand where I'm coming from 80 00:03:52,990 --> 00:03:51,020 so they model development just like 81 00:03:54,640 --> 00:03:53,000 everything just starts when you have a 82 00:03:55,990 --> 00:03:54,650 question and you're defining what kind 83 00:03:58,240 --> 00:03:56,000 of species or systems you're 84 00:04:01,090 --> 00:03:58,250 investigating so for me it was not only 85 00:04:03,940 --> 00:04:01,100 the nitrogen biogeochemical species but 86 00:04:05,500 --> 00:04:03,950 also carbon can i biogeochemical species 87 00:04:07,750 --> 00:04:05,510 because I want to understand what other 88 00:04:10,240 --> 00:04:07,760 greenhouse gases may interact in order 89 00:04:11,860 --> 00:04:10,250 to promote habitability so once you 90 00:04:14,860 --> 00:04:11,870 identify those species you have to 91 00:04:16,690 --> 00:04:14,870 quantify fluxes and build OD ease or 92 00:04:18,699 --> 00:04:16,700 ordinary differential equations so 93 00:04:20,710 --> 00:04:18,709 fluxes are just mass movement from one 94 00:04:22,570 --> 00:04:20,720 reservoir to the other reservoirs can be 95 00:04:25,200 --> 00:04:22,580 anything from the atmosphere to the 96 00:04:28,860 --> 00:04:25,210 surface ocean to sediments and the deep 97 00:04:30,210 --> 00:04:28,870 ocean and Oh des are these ordinary 98 00:04:32,850 --> 00:04:30,220 differential equations are just 99 00:04:34,800 --> 00:04:32,860 describing how these reservoirs and the 100 00:04:37,290 --> 00:04:34,810 species within them change over time 101 00:04:39,150 --> 00:04:37,300 simple enough you set that up you run 102 00:04:41,550 --> 00:04:39,160 your model over a geologically relevant 103 00:04:43,140 --> 00:04:41,560 amount of time so anywhere from a 104 00:04:46,740 --> 00:04:43,150 hundred million to a billion years 105 00:04:50,879 --> 00:04:46,750 basically what I run not in real time 106 00:04:53,779 --> 00:04:50,889 obviously and you have to validate your 107 00:04:55,110 --> 00:04:53,789 model so what happens is that I have two 108 00:04:58,080 --> 00:04:55,120 parameterizations and this 109 00:05:00,719 --> 00:04:58,090 parameterization is based on key 110 00:05:02,760 --> 00:05:00,729 insights into our difference the 111 00:05:04,200 --> 00:05:02,770 difference between the modern planet the 112 00:05:07,080 --> 00:05:04,210 modern earth I should say and the 113 00:05:09,180 --> 00:05:07,090 Archaean earth which is oxygenation so 114 00:05:14,820 --> 00:05:09,190 the PD acity of oxygen partial pressure 115 00:05:16,710 --> 00:05:14,830 of co2 the amount of continental erosion 116 00:05:20,149 --> 00:05:16,720 per year would have been lower 117 00:05:22,800 --> 00:05:20,159 without oxidative erosion etc etc so 118 00:05:25,170 --> 00:05:22,810 parameterizing it at modern-day running 119 00:05:28,170 --> 00:05:25,180 that model I should get modern outputs 120 00:05:29,939 --> 00:05:28,180 for reservoir and flux estimates so if I 121 00:05:31,950 --> 00:05:29,949 do I just seen my fluxes because you can 122 00:05:33,810 --> 00:05:31,960 always improve and then I can run the 123 00:05:36,890 --> 00:05:33,820 tests on my Archaean parameterization 124 00:05:40,290 --> 00:05:36,900 because essentially my fluxes are valid 125 00:05:41,969 --> 00:05:40,300 of course if they don't agree you have 126 00:05:43,770 --> 00:05:41,979 to recalculate your fluxes modify your 127 00:05:45,570 --> 00:05:43,780 OD ease you might have to add more boxes 128 00:05:47,610 --> 00:05:45,580 which you definitely do usually you have 129 00:05:49,890 --> 00:05:47,620 to rerun the model you go into this loop 130 00:05:53,399 --> 00:05:49,900 of sadness from which it appears you 131 00:05:56,610 --> 00:05:53,409 will never return but you do kind of 132 00:05:59,010 --> 00:05:56,620 usually in the end you end up with 133 00:06:01,110 --> 00:05:59,020 something that can be represented in a 134 00:06:03,089 --> 00:06:01,120 schematic like this where all of the 135 00:06:05,459 --> 00:06:03,099 arrows are fluxes that I calculate all 136 00:06:07,219 --> 00:06:05,469 of the species are tracked in the model 137 00:06:09,749 --> 00:06:07,229 I don't want you to get overwhelmed by 138 00:06:11,279 --> 00:06:09,759 the details in it and obviously there 139 00:06:13,920 --> 00:06:11,289 are a lot more fluxes and species that I 140 00:06:15,120 --> 00:06:13,930 could include format more accuracy but I 141 00:06:19,080 --> 00:06:15,130 don't want to be in that loop of sadness 142 00:06:21,810 --> 00:06:19,090 anymore I want to move on so just note 143 00:06:23,570 --> 00:06:21,820 that like there's a lot going on there 144 00:06:25,620 --> 00:06:23,580 are a lot of interplaying 145 00:06:28,200 --> 00:06:25,630 reactions between the carbon and 146 00:06:29,490 --> 00:06:28,210 nitrogen system and I include phosphate 147 00:06:32,010 --> 00:06:29,500 because it's going to be the key 148 00:06:35,070 --> 00:06:32,020 nutrient for my biological systems in 149 00:06:36,530 --> 00:06:35,080 the Archaean yes there's oxygen in here 150 00:06:37,970 --> 00:06:36,540 the oxygen is 151 00:06:40,100 --> 00:06:37,980 they kept at a low level for the 152 00:06:42,830 --> 00:06:40,110 Archaean parameterization and it's it's 153 00:06:45,530 --> 00:06:42,840 included in like nitrate and phosphate 154 00:06:46,910 --> 00:06:45,540 species because I need to compare with 155 00:06:50,390 --> 00:06:46,920 modern-day and if I don't include them 156 00:06:52,160 --> 00:06:50,400 that doesn't work so once I run the 157 00:06:54,380 --> 00:06:52,170 model at my two different 158 00:06:57,230 --> 00:06:54,390 parameterizations again this figure is 159 00:07:00,050 --> 00:06:57,240 kind of hard to look at I know because I 160 00:07:02,330 --> 00:07:00,060 look at it a lot the black dots are the 161 00:07:04,340 --> 00:07:02,340 model output for my modern 162 00:07:07,220 --> 00:07:04,350 parameterization so I'm comparing that 163 00:07:09,440 --> 00:07:07,230 to these green blue and red symbols that 164 00:07:11,870 --> 00:07:09,450 are literature compiled literature 165 00:07:14,420 --> 00:07:11,880 estimates from different researchers for 166 00:07:15,980 --> 00:07:14,430 reservoirs in the modern day so I want 167 00:07:19,880 --> 00:07:15,990 to see how those black dots fit in with 168 00:07:21,470 --> 00:07:19,890 those circle symbols and the gray dots 169 00:07:23,900 --> 00:07:21,480 which you may or may not be able to see 170 00:07:25,730 --> 00:07:23,910 are simply just the plots of my Archaean 171 00:07:29,120 --> 00:07:25,740 parameterization results for my 172 00:07:31,340 --> 00:07:29,130 reservoir sizes so suffice to say that 173 00:07:33,410 --> 00:07:31,350 there the parameterization certainly 174 00:07:35,300 --> 00:07:33,420 does matter and you'll get very 175 00:07:38,300 --> 00:07:35,310 different reservoir outputs depending on 176 00:07:39,740 --> 00:07:38,310 your parameterization and the privation 177 00:07:42,530 --> 00:07:39,750 of the Archaean system is basically 178 00:07:44,390 --> 00:07:42,540 included over here I won't go over it 179 00:07:46,340 --> 00:07:44,400 too much because you guys probably have 180 00:07:48,020 --> 00:07:46,350 a little bit of an idea how different 181 00:07:51,940 --> 00:07:48,030 the Archaean earth would have been from 182 00:07:53,930 --> 00:07:51,950 the present earth a very important 183 00:07:56,320 --> 00:07:53,940 parameterization is this extended 184 00:07:59,090 --> 00:07:56,330 ammonia atmospheric lifetime so 185 00:08:02,780 --> 00:07:59,100 atmospheric ammonia is photolytic li 186 00:08:05,150 --> 00:08:02,790 destroyed today at a rate about it lasts 187 00:08:07,820 --> 00:08:05,160 for maybe five days in the atmosphere so 188 00:08:09,890 --> 00:08:07,830 in the are can we assume that lasts for 189 00:08:11,960 --> 00:08:09,900 at least 10 years some people would say 190 00:08:13,640 --> 00:08:11,970 that's too high some people would say 191 00:08:16,360 --> 00:08:13,650 that's way too low so it's a happy 192 00:08:20,180 --> 00:08:16,370 medium for me to make that assumption 193 00:08:22,760 --> 00:08:20,190 and as I said that schematic before 194 00:08:24,830 --> 00:08:22,770 there are a lot of interacting reactions 195 00:08:27,590 --> 00:08:24,840 between the two systems nitrogen and 196 00:08:29,180 --> 00:08:27,600 carbon and you have to before you run 197 00:08:30,890 --> 00:08:29,190 any tests on this model you have to 198 00:08:32,690 --> 00:08:30,900 consider those reactions you know what 199 00:08:34,670 --> 00:08:32,700 to perturb in order for it to be Geo 200 00:08:38,240 --> 00:08:34,680 physically relevant or biologically 201 00:08:39,560 --> 00:08:38,250 relevant this is a feedback diagram I'm 202 00:08:43,159 --> 00:08:39,570 going to highlight some freeze you don't 203 00:08:45,440 --> 00:08:43,169 have to look at it too long so what 204 00:08:47,000 --> 00:08:45,450 we're trying to get at is increasing the 205 00:08:47,990 --> 00:08:47,010 global temperature through partial 206 00:08:50,150 --> 00:08:48,000 pressure of 207 00:08:51,830 --> 00:08:50,160 house gasses so if you increase the 208 00:08:54,650 --> 00:08:51,840 global temperature increase continental 209 00:08:56,090 --> 00:08:54,660 erosion kind of continental erosion will 210 00:08:58,750 --> 00:08:56,100 increase the flux of alkalinity 211 00:09:02,120 --> 00:08:58,760 bicarbonate to the ocean that will 212 00:09:04,360 --> 00:09:02,130 increase the pH and it was said in a 213 00:09:08,480 --> 00:09:04,370 talk yesterday I forget by who sorry 214 00:09:12,380 --> 00:09:08,490 that there's this reaction in 215 00:09:15,200 --> 00:09:12,390 equilibrium at around 9 pH between 216 00:09:18,200 --> 00:09:15,210 ammonia and ammonium it's protonated 217 00:09:21,950 --> 00:09:18,210 sister species and if so if you increase 218 00:09:25,100 --> 00:09:21,960 that ocean pH you decrease the amount of 219 00:09:26,770 --> 00:09:25,110 hydrogen atoms that are in the water so 220 00:09:29,360 --> 00:09:26,780 you're actually going to force this 221 00:09:31,370 --> 00:09:29,370 speciation more towards ammonia which 222 00:09:33,620 --> 00:09:31,380 increases your partial pressure and your 223 00:09:36,500 --> 00:09:33,630 radiative forcing for ammonia and that's 224 00:09:38,210 --> 00:09:36,510 a positive feedback however if you do 225 00:09:40,010 --> 00:09:38,220 the same thing you increase Continental 226 00:09:41,510 --> 00:09:40,020 erosion you also increase nutrient 227 00:09:43,700 --> 00:09:41,520 transport which in this case is 228 00:09:45,320 --> 00:09:43,710 phosphate and if you do that you 229 00:09:48,170 --> 00:09:45,330 increase primary productivity and 230 00:09:50,180 --> 00:09:48,180 atmospheric co2 drawdown so if you do 231 00:09:52,910 --> 00:09:50,190 that it becomes a negative feedback or 232 00:09:56,090 --> 00:09:52,920 the global temperature so this begs the 233 00:09:58,370 --> 00:09:56,100 question do the co2 and ammonia green 234 00:10:01,520 --> 00:09:58,380 houses potentially negate one another in 235 00:10:02,540 --> 00:10:01,530 the Archaean earth so I gotta have two 236 00:10:04,730 --> 00:10:02,550 questions at this point 237 00:10:07,010 --> 00:10:04,740 one can I get high enough partial 238 00:10:09,140 --> 00:10:07,020 pressure of ammonia to kind of resolve 239 00:10:11,990 --> 00:10:09,150 the faint young Sun paradox cross my 240 00:10:15,140 --> 00:10:12,000 fingers second one is this gonna be a 241 00:10:16,760 --> 00:10:15,150 problem I have the I kind of explained 242 00:10:19,130 --> 00:10:16,770 it to you but if this is a breakdown of 243 00:10:21,590 --> 00:10:19,140 the feedback loop that may or may not be 244 00:10:23,990 --> 00:10:21,600 destructive for the atmospheric 245 00:10:26,650 --> 00:10:24,000 radiative forcing the Archaean 246 00:10:28,760 --> 00:10:26,660 how do I determine which one of these 247 00:10:30,470 --> 00:10:28,770 feedback loops is going to be most 248 00:10:33,970 --> 00:10:30,480 important how do I determine which 249 00:10:37,160 --> 00:10:33,980 parameter values are going to control 250 00:10:39,980 --> 00:10:37,170 basically how much radiative forcing I 251 00:10:41,780 --> 00:10:39,990 can get out of the Archaean earth well 252 00:10:44,150 --> 00:10:41,790 what I do is I take my parameter 253 00:10:47,180 --> 00:10:44,160 assumptions which for the Archaean are 254 00:10:51,370 --> 00:10:47,190 not well constrained at all their way 255 00:10:53,420 --> 00:10:51,380 assumptions and I take basically a 256 00:10:56,570 --> 00:10:53,430 magnitude of values 257 00:10:58,820 --> 00:10:56,580 I choose each one I put them into the 258 00:11:01,400 --> 00:10:58,830 model its kind 259 00:11:04,850 --> 00:11:01,410 to explain because it's you know it's 260 00:11:06,230 --> 00:11:04,860 code but basically I evaluate a bunch of 261 00:11:08,420 --> 00:11:06,240 different values for all of my 262 00:11:12,380 --> 00:11:08,430 assumptions so I assume at least like 263 00:11:15,680 --> 00:11:12,390 three to the eight years of you know for 264 00:11:17,920 --> 00:11:15,690 continental erosion but I go from 10 to 265 00:11:21,080 --> 00:11:17,930 the 8 to 10 to the 9 years in order to 266 00:11:22,670 --> 00:11:21,090 kind of test this area and then I 267 00:11:26,060 --> 00:11:22,680 produce something like this where I show 268 00:11:28,220 --> 00:11:26,070 you my assumption in this black Asterix 269 00:11:30,470 --> 00:11:28,230 if you can see it and it gives me a 270 00:11:32,960 --> 00:11:30,480 contour graph of which of these two 271 00:11:34,880 --> 00:11:32,970 parameters is kind of forcing more 272 00:11:36,800 --> 00:11:34,890 change in the radiative forcing and 273 00:11:39,440 --> 00:11:36,810 personal pressure so these two that's 274 00:11:41,270 --> 00:11:39,450 ammonius partial pressure in log units 275 00:11:44,210 --> 00:11:41,280 can't really read it but and this is co 276 00:11:46,070 --> 00:11:44,220 2 and log units ppm and then these are 277 00:11:47,450 --> 00:11:46,080 their radiative forcings respectively 278 00:11:49,730 --> 00:11:47,460 and this is the combined radiative 279 00:11:53,080 --> 00:11:49,740 forcing what I want you to note is that 280 00:11:55,610 --> 00:11:53,090 if I increase on the x axis here is 281 00:11:59,840 --> 00:11:55,620 ammonia's lifetime in the atmosphere if 282 00:12:01,730 --> 00:11:59,850 I increase that and I well subtly 283 00:12:03,500 --> 00:12:01,740 increase or decrease excuse me the 284 00:12:05,750 --> 00:12:03,510 erosion timescale so if the continents 285 00:12:08,240 --> 00:12:05,760 last longer there's less erosion of the 286 00:12:10,160 --> 00:12:08,250 continents then I can get potentially 20 287 00:12:13,310 --> 00:12:10,170 watts per meter squared out of ammonia I 288 00:12:15,950 --> 00:12:13,320 can get potentially 55 watts per meter 289 00:12:18,290 --> 00:12:15,960 squared of co2 for a total of over 70 290 00:12:23,210 --> 00:12:18,300 watts per meter squared so a reminder I 291 00:12:24,950 --> 00:12:23,220 needed 30 to 50 and so we but of course 292 00:12:27,590 --> 00:12:24,960 this means I can potentially do it I 293 00:12:30,350 --> 00:12:27,600 don't know if these are G or physically 294 00:12:31,820 --> 00:12:30,360 relevant numbers but still and applies 295 00:12:35,540 --> 00:12:31,830 an ammonia solution faint young Sun 296 00:12:38,600 --> 00:12:35,550 paradox so I feel pretty good but I saw 297 00:12:40,640 --> 00:12:38,610 another question don't I but what about 298 00:12:42,650 --> 00:12:40,650 this interaction because I can 299 00:12:46,280 --> 00:12:42,660 parameterize my model this way with 300 00:12:48,560 --> 00:12:46,290 these high high atmospheric ammonia a 301 00:12:51,920 --> 00:12:48,570 lifetime low Continental erosion but 302 00:12:53,330 --> 00:12:51,930 will it actually yield a high partial 303 00:12:55,010 --> 00:12:53,340 pressure of both of those greenhouse 304 00:12:57,890 --> 00:12:55,020 gases enough to solve the faint young 305 00:13:01,430 --> 00:12:57,900 Sun paradox in the model because I don't 306 00:13:03,230 --> 00:13:01,440 know so what I do is I take my model as 307 00:13:06,200 --> 00:13:03,240 its fluxes have evolved to steady state 308 00:13:09,269 --> 00:13:06,210 I perturb them and what I want you to 309 00:13:12,210 --> 00:13:09,279 focus on in this is that these then the 310 00:13:15,119 --> 00:13:12,220 top graph I have the dashed line is the 311 00:13:18,509 --> 00:13:15,129 reference value study state for red is 312 00:13:22,290 --> 00:13:18,519 ammonia and you can't see atmospheric 313 00:13:24,030 --> 00:13:22,300 co2 because it's just so much I made it 314 00:13:26,579 --> 00:13:24,040 so much bigger both of them were 315 00:13:29,400 --> 00:13:26,589 perturbed by 150% and what's important 316 00:13:32,189 --> 00:13:29,410 to note is that co2 and this blue line 317 00:13:34,650 --> 00:13:32,199 does not get drawn down it remains on 318 00:13:36,329 --> 00:13:34,660 it's high perturbed value way above what 319 00:13:38,730 --> 00:13:36,339 we assume partial pressure of co2 would 320 00:13:40,559 --> 00:13:38,740 have been in the air can however even 321 00:13:42,869 --> 00:13:40,569 though I perturb demonium basically as 322 00:13:44,160 --> 00:13:42,879 soon as like 10 to the negative one 323 00:13:46,980 --> 00:13:44,170 years so as soon as my biological 324 00:13:49,350 --> 00:13:46,990 systems kick in ammonia is drawn down 325 00:13:52,189 --> 00:13:49,360 into the ocean and it's partial pressure 326 00:13:55,110 --> 00:13:52,199 has reduced back down to basically its 327 00:13:56,759 --> 00:13:55,120 original steady state value so that 328 00:13:58,679 --> 00:13:56,769 implies that yes 329 00:14:00,660 --> 00:13:58,689 elevated P co2 in the Archaean should 330 00:14:03,269 --> 00:14:00,670 control the amount of partial pressure 331 00:14:04,860 --> 00:14:03,279 of ammonia in the atmosphere so it 332 00:14:06,540 --> 00:14:04,870 couldn't potentially be an issue for 333 00:14:10,559 --> 00:14:06,550 this faint young Sun solution that I 334 00:14:14,569 --> 00:14:10,569 have proposed however I want to move on 335 00:14:16,829 --> 00:14:14,579 so what happens is that this becomes 336 00:14:19,679 --> 00:14:16,839 basically a stepping stone to a larger 337 00:14:22,170 --> 00:14:19,689 geochemical model so I have a summary of 338 00:14:23,790 --> 00:14:22,180 basically what I've found in this 339 00:14:25,590 --> 00:14:23,800 current work that Archaean 340 00:14:27,360 --> 00:14:25,600 biogeochemical feedbacks are capable of 341 00:14:30,360 --> 00:14:27,370 maintaining modern surface temperatures 342 00:14:31,980 --> 00:14:30,370 so I feel good about that but I want to 343 00:14:33,449 --> 00:14:31,990 understand more about the development of 344 00:14:36,269 --> 00:14:33,459 the Earth's system beyond this faint 345 00:14:38,819 --> 00:14:36,279 young Sun paradox kind of question so 346 00:14:42,329 --> 00:14:38,829 adding oxygen to a biogeochemical model 347 00:14:45,809 --> 00:14:42,339 and the oxygenation events therein would 348 00:14:47,910 --> 00:14:45,819 help a lot with its precision and you 349 00:14:51,150 --> 00:14:47,920 know biogeochemical relevance I want to 350 00:14:53,129 --> 00:14:51,160 include more of a mantel box so I can 351 00:14:55,590 --> 00:14:53,139 get fractionation both biological and 352 00:14:57,419 --> 00:14:55,600 geochemical and I want to trace those 353 00:15:00,569 --> 00:14:57,429 biological and geochemical isotopic 354 00:15:05,340 --> 00:15:00,579 fractionation in nitrogen 1514 and 355 00:15:09,900 --> 00:15:05,350 carbon 1213 and basically tracing them 356 00:15:12,540 --> 00:15:09,910 in in in association with noble gases 357 00:15:15,179 --> 00:15:12,550 which are not fractionated usually with 358 00:15:18,689 --> 00:15:15,189 the geochemical or by biological cycling 359 00:15:20,259 --> 00:15:18,699 can I constrain the evolution of Earth's 360 00:15:23,379 --> 00:15:20,269 major volatiles and not 361 00:15:26,019 --> 00:15:23,389 the evolution of the atmosphere from the 362 00:15:27,460 --> 00:15:26,029 Archaean state to the present so with 363 00:15:29,769 --> 00:15:27,470 that I want to thank you and everybody 364 00:15:45,780 --> 00:15:29,779 at the University of Victoria has helped 365 00:15:53,230 --> 00:15:48,759 is the original source of ammonium in 366 00:15:55,299 --> 00:15:53,240 your oceans nitrogen fixation a source 367 00:15:59,679 --> 00:15:55,309 of ammonium yes it's continental erosion 368 00:16:03,670 --> 00:15:59,689 continental yeah so I I'm gonna take 369 00:16:05,920 --> 00:16:03,680 back you your back to my schematic so I 370 00:16:09,160 --> 00:16:05,930 have a River input of calcium carbonate 371 00:16:11,230 --> 00:16:09,170 phosphate ammonium and organic carbon so 372 00:16:14,009 --> 00:16:11,240 it's sorting that and then I can have 373 00:16:17,049 --> 00:16:14,019 nitrification speciation and 374 00:16:19,119 --> 00:16:17,059 remineralization of ammonium but yeah 375 00:16:21,189 --> 00:16:19,129 its geologically sourced right so then 376 00:16:33,850 --> 00:16:21,199 this would apply more towards like paleo 377 00:16:37,509 --> 00:16:33,860 archaea yes I just had a question about 378 00:16:39,579 --> 00:16:37,519 the increased life time for the ammonia 379 00:16:41,619 --> 00:16:39,589 enemy atmosphere is that just due to 380 00:16:44,129 --> 00:16:41,629 decreased flux or are you also taking 381 00:16:48,400 --> 00:16:44,139 into account like wavelength shifts so 382 00:16:51,220 --> 00:16:48,410 it's kind of a it's an assumption that 383 00:16:52,689 --> 00:16:51,230 we have to make in order for this kind 384 00:16:55,179 --> 00:16:52,699 of system to work that it had a longer 385 00:16:57,429 --> 00:16:55,189 lifetime it's certainly the reduced 386 00:17:00,179 --> 00:16:57,439 solar flux at the time would have 387 00:17:02,590 --> 00:17:00,189 extended its you know just on its face 388 00:17:04,049 --> 00:17:02,600 I'm having a reducing atmosphere also 389 00:17:05,319 --> 00:17:04,059 just would have extended its lifetime 390 00:17:10,600 --> 00:17:05,329 you know 391 00:17:14,679 --> 00:17:10,610 baseline but we don't know whether there 392 00:17:16,809 --> 00:17:14,689 would be like other you know photolytic 393 00:17:19,269 --> 00:17:16,819 reactions that we're not thinking of in 394 00:17:22,510 --> 00:17:19,279 the reducing atmosphere or if wavelength 395 00:17:24,250 --> 00:17:22,520 would kind of come into play I don't 396 00:17:27,490 --> 00:17:24,260 know enough about atmospheric chemistry 397 00:17:28,930 --> 00:17:27,500 in order to really study that but it is 398 00:17:32,169 --> 00:17:28,940 yeah it's a prevailing assumption that 399 00:17:33,909 --> 00:17:32,179 it just had a longer life time and you 400 00:17:36,940 --> 00:17:33,919 know it's possible if we had some sort 401 00:17:39,430 --> 00:17:36,950 of like stratospheric or look you know 402 00:17:41,560 --> 00:17:39,440 upper tropospheric haze or something of 403 00:17:43,299 --> 00:17:41,570 you know reduced organic molecules that 404 00:17:45,430 --> 00:17:43,309 that that would be even more valid that 405 00:17:47,680 --> 00:17:45,440 I could put in even a longer lifetime 406 00:17:56,460 --> 00:17:47,690 for ammonia but I just don't know it 407 00:18:01,540 --> 00:17:59,470 yeah actually a really sweet work um how 408 00:18:03,790 --> 00:18:01,550 do you like estimate biological activity 409 00:18:06,820 --> 00:18:03,800 like how do you know how much life is 410 00:18:10,240 --> 00:18:06,830 around and how hungry it was yeah so 411 00:18:12,850 --> 00:18:10,250 okay yeah so the biological assumptions 412 00:18:15,010 --> 00:18:12,860 are totally based on modern day so we're 413 00:18:18,120 --> 00:18:15,020 saying that they're photosynthesizers in 414 00:18:21,070 --> 00:18:18,130 the ocean if I can get their biological 415 00:18:22,900 --> 00:18:21,080 you know productivity fluxes and then 416 00:18:25,030 --> 00:18:22,910 death fluxes to meet the modern-day 417 00:18:28,450 --> 00:18:25,040 estimate I just say okay it's higher 418 00:18:31,000 --> 00:18:28,460 pco2 it's lower oxygen try to live you 419 00:18:33,040 --> 00:18:31,010 know so it is it's totally theoretical 420 00:18:37,180 --> 00:18:33,050 but it is based off of the fact that I 421 00:18:41,200 --> 00:18:37,190 can model these fluxes and you know at 422 00:18:42,760 --> 00:18:41,210 modern-day so as any good modelers 423 00:18:42,760 --> 00:18:43,690 should tell you everything in this is 424 00:18:56,770 --> 00:18:48,700 but also kind of cool so you know take 425 00:19:01,480 --> 00:18:56,780 it with like a whole lake or thistle any 426 00:19:04,250 --> 00:19:01,490 other questions all right if not let's