WEBVTT - From the Vault: The Sunken Lands, Part 4 0:00:06.360 --> 0:00:09.560 Hello, and welcome to Stuff to Blow your Mind. My 0:00:09.680 --> 0:00:12.200 name is Joe McCormick. Today we're going to finish out 0:00:12.200 --> 0:00:14.760 the Vault series that we've been running this week. This 0:00:14.840 --> 0:00:18.520 is part four of our series called The Sunken Lands. 0:00:18.640 --> 0:00:23.239 This originally published on December seventh, twenty twenty three. Hope 0:00:23.280 --> 0:00:28.640 you enjoy. 0:00:27.480 --> 0:00:31.320 Welcome to Stuff to Blow your Mind, the production of iHeartRadio. 0:00:37.400 --> 0:00:39.360 Hey you welcome to Stuff to Blow your Mind. My 0:00:39.440 --> 0:00:40.599 name is Robert Lamb. 0:00:40.960 --> 0:00:43.879 And I am Joe McCormick. And we are back with 0:00:44.000 --> 0:00:47.120 the fourth and final part in our series called the 0:00:47.159 --> 0:00:51.600 Sunken Lands, about places on Earth that relatively recently used 0:00:51.640 --> 0:00:55.160 to be dry land but are now covered by water now. 0:00:55.200 --> 0:00:58.000 In previous parts of the series we talked about, of course, 0:00:58.080 --> 0:01:01.880 legendary lands of this sort Atlantis and other fictional or 0:01:01.920 --> 0:01:05.280 mythical sunken civilizations. And sorry to be a bummer to 0:01:05.319 --> 0:01:08.080 the many Atlantis hunters out there, but yes, it does 0:01:08.120 --> 0:01:10.520 seem like the experts on the original sources that this 0:01:10.600 --> 0:01:13.560 story comes from, namely a couple of dialogues of Plato, 0:01:13.959 --> 0:01:16.720 think that it probably is a fictional invention and not 0:01:16.800 --> 0:01:19.520 a reference to a real place that existed but that 0:01:19.600 --> 0:01:22.920 doesn't mean that there are not lands that have been 0:01:23.520 --> 0:01:28.000 within the history of the human species submerged by water. 0:01:28.080 --> 0:01:30.520 In fact, we know of some examples of places that 0:01:30.560 --> 0:01:33.800 were both inhabited by humans and sunk under the water, 0:01:33.959 --> 0:01:36.919 not really anything like was described in the Atlantis story, 0:01:37.240 --> 0:01:40.039 but there are examples of the sunken land masses of 0:01:40.120 --> 0:01:44.600 Beringia and dogger Land, which during and briefly after the 0:01:44.720 --> 0:01:48.480 Last Ice Age formed land bridges between North America and Asia, 0:01:48.840 --> 0:01:52.480 and Great Britain and continental Europe perspectively. We also talked 0:01:52.480 --> 0:01:56.520 about vanished islands in the Pacific. Some of these supposedly 0:01:56.640 --> 0:01:59.440 vanished islands are probably a result of errors in their 0:01:59.480 --> 0:02:04.360 original reporting, but others are places that probably actually did 0:02:04.480 --> 0:02:08.560 vanish or sink beneath the water due to cataclysmic seismic activity. 0:02:09.000 --> 0:02:12.760 We also talked about atolls, how they're formed, and where 0:02:12.800 --> 0:02:16.680 their central islands went. There was a hypothesis that Darwin 0:02:16.760 --> 0:02:18.400 had about this going all the way back to his 0:02:18.520 --> 0:02:22.240 voyage on the Beagle. There are new ideas related to 0:02:22.360 --> 0:02:27.600 karcification and the dissolution of carbonate rock or limestone when 0:02:27.639 --> 0:02:30.560 it's exposed over the surface of the sea. Dissolution by 0:02:30.639 --> 0:02:34.240 rain water. And then also finally, in the last episode, 0:02:34.280 --> 0:02:38.960 we talked about places that have been flooded by damming, 0:02:39.000 --> 0:02:43.200 the damming of freshwater resources, damming rivers and streams to 0:02:43.440 --> 0:02:46.720 end up submerging areas that used to be exposed land 0:02:46.880 --> 0:02:47.960 now under lakes. 0:02:49.280 --> 0:02:51.320 Now. A quick note on just the idea of sunken 0:02:51.360 --> 0:02:54.200 islands and sunken lands. We had a listener ask about 0:02:54.240 --> 0:02:56.200 this and discord, so I want to just briefly point 0:02:56.200 --> 0:02:59.239 out that, especially in our discussion of atolls in the 0:02:59.320 --> 0:03:03.200 last episode, the terms sunk in or to sink may 0:03:03.280 --> 0:03:06.160 ultimately be too simplistic for these discussions because they're all 0:03:06.280 --> 0:03:09.600 very based on the human perspective of what's going on. 0:03:10.120 --> 0:03:12.760 And in any case, we're talking about situations that may 0:03:12.919 --> 0:03:15.800 entail both rising and lowering sea levels, as well as 0:03:15.880 --> 0:03:19.760 land that is pushed up and or created by volcanic, organic, 0:03:19.840 --> 0:03:23.760 or seismic forces, and land that lowers sometimes beneath water 0:03:23.880 --> 0:03:29.160 level due to erosion, seismic forces, etc. So just in 0:03:29.200 --> 0:03:31.440 all cases, just keep in mind that, yeah, sunk in 0:03:31.680 --> 0:03:35.840 sinking maybe doesn't fully capture the picture of what's going on. 0:03:36.400 --> 0:03:39.080 Well. Actually, as luck would have it, I do want 0:03:39.120 --> 0:03:43.520 to get to one example of actual sinking of lands 0:03:44.320 --> 0:03:47.880 in just a bit here. So in the background of 0:03:48.080 --> 0:03:52.320 discussing these historical cases of landscapes covered by rising seas, 0:03:53.000 --> 0:03:55.400 there is the knowledge that most of us have now 0:03:55.600 --> 0:03:59.800 that relatively rapid increases in sea level are happening right 0:03:59.840 --> 0:04:03.440 now and will continue in the coming decades due to 0:04:03.760 --> 0:04:06.560 climate change, due to the warming of the seas, the 0:04:06.600 --> 0:04:10.880 melting of glaciers. Sea level changes have happened on Earth before. 0:04:10.920 --> 0:04:13.960 But one thing that's different now is how much of 0:04:14.000 --> 0:04:19.080 the physical infrastructure and culture of modern human civilization was 0:04:19.160 --> 0:04:21.960 designed on the assumption of current sea levels staying where 0:04:21.960 --> 0:04:25.640 they are. Whole cities, whole countries even are threatened by 0:04:25.720 --> 0:04:29.520 rising waters because they have been built without those rising 0:04:29.560 --> 0:04:30.520 waters in mind. 0:04:31.000 --> 0:04:33.039 Yeah, some of the very places we've discussed, at least 0:04:33.040 --> 0:04:37.000 in passing in these episodes, like the Maldives, are greatly 0:04:37.040 --> 0:04:39.040 threatened by these rising sea waters. 0:04:39.680 --> 0:04:42.719 Yes, absolutely, But of course this applies to coastal settlements 0:04:42.800 --> 0:04:46.039 all over the world, on every continent on Earth, though 0:04:46.560 --> 0:04:50.000 though in different ways. Not every coastal settlement will be 0:04:50.000 --> 0:04:51.520 affected the same, And I want to get to some 0:04:51.560 --> 0:04:54.800 of that variance in just a bit here. But as 0:04:54.839 --> 0:04:58.159 a baseline, I thought we should look at how much 0:04:58.400 --> 0:05:01.520 are sea levels expected to rise in the next century 0:05:01.640 --> 0:05:04.760 or so. That depends on a number of variables, but 0:05:05.120 --> 0:05:08.200 I was looking at the most recent IPCC report, which 0:05:08.240 --> 0:05:11.400 had put together a series of estimates. First of all, 0:05:11.480 --> 0:05:13.560 they look at the question of what is happening to 0:05:13.720 --> 0:05:17.160 global mean sea level right now, what has already happened 0:05:17.240 --> 0:05:21.640 in the traceable recent past, whatever happens in the future. 0:05:21.680 --> 0:05:23.880 One thing we know for certain is that the sea 0:05:23.960 --> 0:05:27.480 level is already rising and has already risen, and the 0:05:27.600 --> 0:05:31.680 rate at which it rises will very likely accelerate in 0:05:31.720 --> 0:05:35.320 the future. Based on our best measurements averaged over different 0:05:35.320 --> 0:05:37.960 time periods, we can see that sea levels have risen 0:05:38.200 --> 0:05:43.400 over the past century, and basically the more recent the 0:05:43.480 --> 0:05:46.440 chunk of time you look at is the faster they're rising. 0:05:46.839 --> 0:05:50.200 So the IPCC report points out that sea levels rose 0:05:50.240 --> 0:05:53.480 about one point four millimeters per year if you look 0:05:53.480 --> 0:05:56.200 at the time period nineteen oh one to nineteen ninety 0:05:57.040 --> 0:05:59.480 If you shift more recently and look at nineteen seventy 0:05:59.520 --> 0:06:03.120 to twenty five fifteen, it's two point one millimeters per year. 0:06:03.360 --> 0:06:06.400 If you just look at nineteen ninety three, to twenty fifteen, 0:06:06.760 --> 0:06:09.640 it's three point two millimeters per year. If you just 0:06:09.680 --> 0:06:12.440 look at two thousand and six to twenty fifteen, it's 0:06:12.480 --> 0:06:16.000 three point six millimeters per year. So the later the 0:06:16.000 --> 0:06:18.280 period of the last century you look at, the more 0:06:18.320 --> 0:06:22.080 it is rising per year. Now you might reasonably wonder, 0:06:22.360 --> 0:06:25.200 how do you actually measure sea level down to the millimeter? 0:06:25.480 --> 0:06:27.920 Like the top of the water is always moving, So 0:06:28.120 --> 0:06:31.240 that's a reasonable question. What methods do you have to 0:06:31.400 --> 0:06:34.039 know that the average level of the sea is rising. 0:06:34.800 --> 0:06:37.800 There are a couple of major metrics here cited, and 0:06:37.839 --> 0:06:40.760 I didn't fully know how these worked beforehand, so I 0:06:40.760 --> 0:06:45.160 thought this was interesting. One method used is tide gauges. 0:06:45.920 --> 0:06:49.919 These systems have been used in some form to record 0:06:50.000 --> 0:06:52.160 sea levels for hundreds of years, or at least going 0:06:52.200 --> 0:06:54.680 back I think to the early eighteen hundreds, though now 0:06:54.680 --> 0:06:58.440 they've changed form to incorporate different types of sensors and 0:06:58.520 --> 0:07:03.680 computers other modern components, but they still have some things 0:07:03.720 --> 0:07:06.680 in common. So the old method here was that they 0:07:06.680 --> 0:07:09.800 would use a device called a stilling well, and this 0:07:09.960 --> 0:07:13.200 was basically a pipe about a foot wide that would 0:07:13.200 --> 0:07:16.640 be plunged down into the water from a place called 0:07:16.680 --> 0:07:19.960 a tide station essentially a house built out on a dock, 0:07:20.480 --> 0:07:24.240 and this pipe would still the water around a floating device. 0:07:24.760 --> 0:07:27.520 The float would be suspended down into the well by 0:07:27.560 --> 0:07:30.400 a wire, and then that wire would be attached at 0:07:30.440 --> 0:07:33.080 the other end to a recording device, which might be 0:07:33.120 --> 0:07:36.360 something like a pin that would mark the water level 0:07:36.480 --> 0:07:40.440 automatically on a paper strip. So the float floats on 0:07:40.440 --> 0:07:42.720 the top of the water. As the water rises, the 0:07:42.760 --> 0:07:45.640 pin moves and marks that level on the paper strip. 0:07:45.840 --> 0:07:48.520 As the water goes down, the pin moves again, and 0:07:48.560 --> 0:07:51.600 then these marks were analyzed and averaged together to form 0:07:51.640 --> 0:07:54.960 a picture of the tidal variance and the average sea 0:07:55.120 --> 0:07:58.400 level over time. This method changed so that the data 0:07:58.440 --> 0:08:02.360 could be fed directly into computers, and these tide stations 0:08:02.360 --> 0:08:05.000 also they had measuring staffs as well. You've probably seen 0:08:05.040 --> 0:08:08.280 things like this somewhere around the coast before, where it's 0:08:08.320 --> 0:08:10.040 just like a stick poking out of the water. Is 0:08:10.120 --> 0:08:12.560 basically a ruler, you know, it's got height markings on them, 0:08:12.920 --> 0:08:16.240 and then the operators could visually observe the staff and 0:08:16.320 --> 0:08:20.520 compare that to the mechanical readings from the float device. Now, 0:08:20.560 --> 0:08:23.240 tide gauges still exist, and they still make readings, but 0:08:23.240 --> 0:08:26.720 they've got new systems, new types of sensors today to 0:08:27.000 --> 0:08:30.240 get their readings from. Modern tide gauges tend to use 0:08:30.400 --> 0:08:35.520 acoustic sounding tubes instead of a float and distilling well. 0:08:35.880 --> 0:08:39.160 So the acoustic sounding tube will admit, will emit a 0:08:39.200 --> 0:08:41.960 sound wave from a fixed height and then wait for 0:08:42.040 --> 0:08:45.040 it to bounce off of the water's surface and come back. 0:08:45.520 --> 0:08:47.880 And the time to return of the signal allows you 0:08:47.960 --> 0:08:51.199 to calculate the height of the water across the tidal variants. 0:08:51.440 --> 0:08:54.040 So you can put in place these tide gauges in 0:08:55.080 --> 0:08:58.600 coastal environments all around the world and average them out 0:08:58.679 --> 0:09:01.679 to try to get some information about what the global 0:09:02.040 --> 0:09:05.560 sea levels are doing all around the world. And if 0:09:05.640 --> 0:09:08.240 you look at that information, it shows yes, indeed the 0:09:08.240 --> 0:09:10.880 sea levels have been rising. They've been rising over the 0:09:10.960 --> 0:09:14.839 last century along the lines of the measurements I mentioned 0:09:14.880 --> 0:09:17.400 a minute ago. But if you're able, you'd also want 0:09:17.400 --> 0:09:20.160 to compare that data to other sources of information to 0:09:20.160 --> 0:09:23.200 make sure you're getting the most accurate possible average. So 0:09:23.320 --> 0:09:26.960 there is another method that is used, and that is altimetry. 0:09:27.760 --> 0:09:31.360 This is the use of satellite based tools called radar 0:09:31.440 --> 0:09:35.040 altimeters to measure the height of the sea. Basically, you 0:09:35.080 --> 0:09:37.520 can know the altitude of a satellite with a high 0:09:37.520 --> 0:09:40.240 degree of precision. You can track that with instruments like 0:09:40.760 --> 0:09:45.400 laser range rangefinders, like you bounce a laser off the satellite, 0:09:45.440 --> 0:09:47.840 so you can tell pretty much exactly how high it is. 0:09:48.400 --> 0:09:52.040 And then with that information in mind, you can use 0:09:52.120 --> 0:09:56.000 a satellite to send out a microwave pulse toward the Earth. 0:09:56.920 --> 0:09:59.600 That pulse bounces off of the surface of the ocean 0:09:59.640 --> 0:10:02.760 and then ounces back to the satellite and hits a 0:10:02.760 --> 0:10:06.360 return sensor, and then the satellite measures the time of 0:10:06.440 --> 0:10:10.600 the round trip between the emitter and the surface of 0:10:10.600 --> 0:10:13.560 the ocean to get a very precise measurement of the 0:10:13.600 --> 0:10:16.560 distance between the satellite and the water, which, again in 0:10:16.600 --> 0:10:20.319 combination with the precisely known altitude of the satellite, can 0:10:20.360 --> 0:10:22.600 be used to measure the level of the sea. And 0:10:22.679 --> 0:10:25.600 of course radar altimetry can be used to measure average 0:10:25.600 --> 0:10:28.679 sea level changes over time and get global averages and stuff. 0:10:28.720 --> 0:10:31.040 But it can be also used. I thought this was 0:10:31.080 --> 0:10:35.920 interesting to measure variations in the height of the water 0:10:36.160 --> 0:10:39.560 around the world at the same time, so a kind 0:10:39.600 --> 0:10:42.440 of crazy thing about the ocean is that it is 0:10:42.559 --> 0:10:46.080 not at the same height everywhere on Earth all the time. 0:10:46.200 --> 0:10:49.640 That seems counterintuitive because you think of water in a 0:10:49.679 --> 0:10:52.560 container like a bowl or something eventually finding you know, 0:10:52.640 --> 0:10:55.200 finding its own level. It kind of levels out. But 0:10:55.480 --> 0:10:59.400 across the world's oceans, there are peaks and valleys that 0:10:59.440 --> 0:11:02.880 arise in certain places at certain times, and so one 0:11:02.920 --> 0:11:05.800 example we're all familiar with is the tide. You know, 0:11:05.840 --> 0:11:08.720 the tide is caused mainly by gravity, by the gravitational 0:11:08.760 --> 0:11:11.920 influence of the Moon, but also the Sun, but there 0:11:11.920 --> 0:11:15.480 are other factors that can cause local and sometimes temporary 0:11:15.600 --> 0:11:18.440 high and low altitudes of seawater as well. I was 0:11:18.480 --> 0:11:22.360 reading a report from NASA Earth Observatory about this and 0:11:22.480 --> 0:11:25.640 it mentioned friction caused by wind on the surface of 0:11:25.679 --> 0:11:28.079 the water. So like wind sort of dragging the water 0:11:28.200 --> 0:11:31.400 around and piling it up in certain places. I guess 0:11:31.400 --> 0:11:33.760 that's a crude way of describing it, but that is 0:11:33.800 --> 0:11:37.680 sort of what happens. There are also Coriolis effects and 0:11:37.760 --> 0:11:42.160 ocean currents, and there are also effects of variations in 0:11:42.200 --> 0:11:46.200 atmospheric pressure, so you know, the atmosphere pushing the surface 0:11:46.200 --> 0:11:48.640 of the water down in regions where the pressure is 0:11:48.720 --> 0:11:51.839 high and so forth, and we can measure these altitude 0:11:51.880 --> 0:11:55.600 variations across the ocean with the help of satellite based 0:11:55.720 --> 0:11:59.640 radar altimetry. As just one example of the variance in 0:11:59.640 --> 0:12:03.559 the high of the oceans around the world. According to NASA, 0:12:04.040 --> 0:12:07.800 the sea level in the Pacific Ocean is generally higher 0:12:07.840 --> 0:12:11.200 than the Atlantic Ocean, roughly twenty centimeters or about eight 0:12:11.240 --> 0:12:15.240 inches higher. How is that possible, Well, the volume of 0:12:15.280 --> 0:12:19.520 seawater is not static. Changes in the temperature and salinity 0:12:19.600 --> 0:12:25.000 of seawater affect its density, so warmer water generally is 0:12:25.160 --> 0:12:29.319 less dense it takes up more space per unit of mass. 0:12:29.679 --> 0:12:33.600 The Pacific is on average warmer, so its volume is greater, 0:12:33.800 --> 0:12:37.240 and thus Pacific sea levels are higher and other factors 0:12:37.280 --> 0:12:40.840 contribute like this as well. This kind of variation is 0:12:40.880 --> 0:12:44.640 actually acknowledged in the IPCC report where they say quote 0:12:44.720 --> 0:12:48.880 sea level rise is not globally uniform and varies regionally. 0:12:49.120 --> 0:12:53.480 Thermal expansion, ocean dynamics, and land ice loss contributions will 0:12:53.480 --> 0:12:57.760 generate regional departures of about plus or minus thirty percent 0:12:58.000 --> 0:13:02.720 around the global means sea level rise, and those regional 0:13:02.840 --> 0:13:05.480 variations in changes in sea level I want to come 0:13:05.520 --> 0:13:08.240 back to that in a minute. Now, of course, we 0:13:08.320 --> 0:13:11.120 all know the main cause of the current warming that 0:13:11.240 --> 0:13:14.600 is driving sea level rise is of course what the 0:13:14.720 --> 0:13:20.440 IPCC report calls anthropogenic forcing. This means results of human activity, 0:13:20.760 --> 0:13:24.600 primarily the changing of the composition of the atmosphere causing 0:13:24.640 --> 0:13:27.720 it to trap more heat. This is the famous greenhouse effect. 0:13:27.760 --> 0:13:32.640 Putting more things like carbon methane into the atmosphere increases 0:13:32.679 --> 0:13:36.600 the heat trapping potency of the atmosphere. It traps more 0:13:36.640 --> 0:13:49.800 heat the earth worms. So we know sea levels have 0:13:50.000 --> 0:13:53.959 been rising and they will continue to rise, but how 0:13:54.280 --> 0:13:58.280 much and how fast they rise is highly variable from 0:13:58.320 --> 0:14:01.800 our current point of view. So there are some estimates 0:14:01.880 --> 0:14:06.479 based on current data. According to the IPCC predictions relative 0:14:06.600 --> 0:14:09.520 to the mean sea level in the period from nineteen 0:14:09.559 --> 0:14:12.160 eighty six to two thousand and five, they predict that 0:14:12.360 --> 0:14:16.280 the global mean sea level will rise probably somewhere between 0:14:16.440 --> 0:14:18.920 zero point four to three meters or about one point 0:14:18.920 --> 0:14:22.400 four feet to zero point eight four meters, which is 0:14:22.400 --> 0:14:25.680 about two point eight feet, by the year twenty one hundred, 0:14:26.040 --> 0:14:28.480 and then due to a cascade of factors, sea levels 0:14:28.520 --> 0:14:31.160 will continue to rise for centuries after that, and will 0:14:31.160 --> 0:14:35.600 probably stay higher for thousands of years. Now. I wouldn't 0:14:36.000 --> 0:14:39.760 hang on those exact numbers too much because those are estimates. 0:14:39.760 --> 0:14:43.240 They are also averages of estimates, and I've seen other 0:14:43.280 --> 0:14:45.960 reports with different estimates, especially at the high end of 0:14:46.040 --> 0:14:48.280 like how bad could it possibly get if we just 0:14:48.360 --> 0:14:52.480 keep increasing more and more greenhouse gas emissions? But the 0:14:52.520 --> 0:14:55.040 important thing to note is that the high and low 0:14:55.160 --> 0:14:59.200 end projections here are dependent on the variable of human activity. 0:15:00.040 --> 0:15:03.040 If we continue increasing the concentration of greenhouse gases in 0:15:03.080 --> 0:15:06.360 the atmosphere, we're somewhat closer to the top end of 0:15:06.400 --> 0:15:09.880 that range, and the low end is feasible if we 0:15:10.000 --> 0:15:13.600 drastically reduce greenhouse gas output and factor in some kind 0:15:13.640 --> 0:15:17.200 of negative emissions as well, such as massive natural or 0:15:17.280 --> 0:15:21.960 artificial carbon sequestration. And natural carbon sequestration would be I think, 0:15:22.040 --> 0:15:25.000 you know, trapping carbon in things like plants and forests. 0:15:26.120 --> 0:15:28.720 Yeah, so as is I've heard a lot of experts 0:15:28.720 --> 0:15:33.000 say it's not that there isn't room for optimism in 0:15:33.040 --> 0:15:38.560 all of this, but the optimism does not come without action, right, 0:15:39.000 --> 0:15:43.400 there are definite steps that need to be taken. We 0:15:43.480 --> 0:15:45.640 can't just be like, ah, it might be, it might 0:15:45.680 --> 0:15:47.280 be okay, maybe it's just gonna be the lower We'll 0:15:47.280 --> 0:15:48.840 just we'll roll the dice and see, like, that's not 0:15:49.240 --> 0:15:50.320 how it's going to work out. 0:15:50.880 --> 0:15:54.000 Yeah, that's exactly right. The lower end of the prediction 0:15:54.200 --> 0:15:57.320 range there is based on an assumption of action if 0:15:57.400 --> 0:16:02.280 humanity does something to massively reduce the contribution to global 0:16:02.280 --> 0:16:06.680 warming through greenhouse gases. So in that case, yes, we 0:16:06.720 --> 0:16:09.360 could limit it to the lower levels of sea level rise. 0:16:09.400 --> 0:16:12.560 But to be clear, some amount of sea level rise 0:16:12.600 --> 0:16:16.760 at this point has already happened and is basically locked in. 0:16:17.080 --> 0:16:20.760 The question is how much worse will it get, and 0:16:20.880 --> 0:16:23.560 that outcome is clearly dependent to a large extent on 0:16:23.640 --> 0:16:27.120 what we do, But in most plausible scenarios we can 0:16:27.200 --> 0:16:31.760 expect somewhere between something like one and three feet of 0:16:31.920 --> 0:16:35.280 global sea level rise by the end of this century. 0:16:36.120 --> 0:16:38.200 Now I mentioned there are other estimates I've come across. 0:16:38.200 --> 0:16:41.760 Some of these are specifically focused on like certain countries 0:16:41.920 --> 0:16:46.560 or regions, or might be drawing on some emphasizing different 0:16:46.600 --> 0:16:49.320 data sources or something. But another estimate I came across 0:16:49.440 --> 0:16:53.120 was a twenty twenty two joint report by NASA, the NOAA, 0:16:53.160 --> 0:16:56.320 and several other federal agencies of the US government called 0:16:56.320 --> 0:16:59.920 Global and Regional Sea Level Rise Scenarios for the United States. 0:17:00.400 --> 0:17:03.360 This was an update to a previous report from twenty seventeen, 0:17:04.080 --> 0:17:07.400 and this report quote concludes that sea level along US 0:17:07.520 --> 0:17:11.080 coast lines will rise ten to twelve inches or twenty 0:17:11.119 --> 0:17:14.880 five to thirty centimeters on average above today's levels by 0:17:14.960 --> 0:17:18.480 twenty fifty. So that's predicting, you know, roughly a foot 0:17:18.480 --> 0:17:21.480 of increase by the middle of the century. Also on 0:17:21.560 --> 0:17:25.719 the more dire end, this one was predicting much higher 0:17:25.800 --> 0:17:28.639 levels of sea level rise at the you know, basically 0:17:28.680 --> 0:17:31.480 at the letter rip scenario. It's just like do nothing 0:17:31.560 --> 0:17:34.280 scenario by the end of this century. If you want 0:17:34.280 --> 0:17:36.840 to experiment with the findings of this report, it actually 0:17:36.880 --> 0:17:39.600 has an online mapping tool you can look up you 0:17:39.600 --> 0:17:42.960 and mess around with yourself, called the Interagency Sea Level 0:17:43.080 --> 0:17:46.399 Rise Scenario Tool. You can google that and mess with 0:17:46.400 --> 0:17:49.440 it yourself if you want. Now, there are a couple 0:17:49.520 --> 0:17:53.200 of major contributors to the actual physical causes of sea 0:17:53.280 --> 0:17:55.760 level rise due to a warming climate. One of them 0:17:55.920 --> 0:18:00.480 is melting ice melting glaciers and ice sheets. Already talked 0:18:00.480 --> 0:18:03.000 about the roll of melting ice in the sea level 0:18:03.040 --> 0:18:06.120 increases at the end of the Pleistocene, which were responsible 0:18:06.160 --> 0:18:10.480 for inundating Doggerland and Boringia. But there's still a lot 0:18:10.480 --> 0:18:14.080 of ice on Earth left to melt. Another important cause 0:18:14.240 --> 0:18:17.280 of sea level rise is the thermal expansion of water. 0:18:17.600 --> 0:18:19.359 Remember what I was talking about a minute ago with 0:18:19.440 --> 0:18:21.800 the difference in the height of the Pacific Ocean versus 0:18:21.880 --> 0:18:25.200 the Atlantic Ocean. One factor there being that the Pacific 0:18:25.240 --> 0:18:29.240 Ocean waters on average are warmer. This stacks on top 0:18:29.280 --> 0:18:31.840 of the melting, but as water heats up, it becomes 0:18:31.960 --> 0:18:35.280 less dense and takes up more space. Warmer water takes 0:18:35.359 --> 0:18:38.640 up more space pre unit of mass, so warmer oceans 0:18:38.680 --> 0:18:43.040 will be taller. And the thermal expansion of water plays 0:18:43.040 --> 0:18:47.000 a role already in a number of different phenomena that 0:18:47.040 --> 0:18:49.760 happened within the ocean, for example in the in the 0:18:49.800 --> 0:18:53.440 creation of ocean currents and in stratification of water levels 0:18:53.480 --> 0:18:56.439 within the ocean. Like warmer water floats on top of 0:18:56.480 --> 0:19:01.240 colder water, but anyway, as the earth worms, the water 0:19:01.480 --> 0:19:04.720 thermally expands also, so that contributes to the sea level 0:19:04.760 --> 0:19:08.080 being higher. Now, what does this actually mean for the 0:19:08.119 --> 0:19:11.920 everyday life of people living in low lying coastal areas 0:19:12.080 --> 0:19:16.080 of planet Earth. I think one thing people sometimes like, 0:19:16.080 --> 0:19:18.040 if you haven't read much about this, you might have 0:19:18.080 --> 0:19:22.200 trouble imagining the form exactly this will take. Like you're 0:19:22.200 --> 0:19:25.480 just imagining the sea rising in a kind of static way, 0:19:25.600 --> 0:19:28.320 Like you know, it's either dry land or it's underwater, 0:19:28.440 --> 0:19:31.840 what's in between. There actually is something in between, which 0:19:31.880 --> 0:19:37.240 is frequent flooding. The way many people will probably experience 0:19:37.440 --> 0:19:41.080 sea level rise at first is an increase in the 0:19:41.119 --> 0:19:45.480 frequency and destructiveness of extreme weather events that are dependent 0:19:45.520 --> 0:19:48.159 on sea level for the amount of damage they cause. 0:19:48.720 --> 0:19:51.000 So a person who lives in a low lying coastal 0:19:51.040 --> 0:19:55.320 city will start dealing with storm related floods on a 0:19:55.400 --> 0:19:57.960 more and more frequent basis. What used to be a 0:19:58.000 --> 0:20:01.639 once in a century flood will become a regular occurrence, 0:20:01.800 --> 0:20:04.720 until at some point the flooding becomes so common that 0:20:04.760 --> 0:20:08.879 people may start to simply consider a place uninhabitable. And 0:20:09.040 --> 0:20:12.840 this happens before that place is more or less permanently underwater, 0:20:13.160 --> 0:20:16.159 But that eventually happens too. Of course, this kind of 0:20:16.160 --> 0:20:20.119 flooding and water encroachment, it comes with all kinds of 0:20:20.119 --> 0:20:25.080 consequences of massive economic damage, destruction of property, destruction, of livelihoods, 0:20:25.440 --> 0:20:28.520 displacement of people, and all of the downstream effects of that. 0:20:29.680 --> 0:20:32.680 But another factor people might not think about are the 0:20:32.720 --> 0:20:37.520 effects of the ingress of salt water into places with 0:20:37.600 --> 0:20:41.359 freshwater resources, like into river deltas and so forth. Of course, 0:20:41.400 --> 0:20:44.280 this kind have negative effects on habitats and wildlife, but 0:20:44.320 --> 0:20:47.480 also on agriculture and groundwater and all that. You don't 0:20:47.520 --> 0:20:50.080 want to salt your earth. But to come back to 0:20:50.119 --> 0:20:54.639 an issue I raised earlier, an interesting factor contributing to 0:20:54.720 --> 0:20:58.480 the coming inundation of coastal areas and especially coastal cities 0:20:59.040 --> 0:21:02.800 is that not only are sea levels definitely rising around 0:21:02.840 --> 0:21:06.560 the globe and differently in different places, in some places 0:21:06.800 --> 0:21:10.879 the ground is literally sinking. The lands are not just 0:21:11.000 --> 0:21:14.080 metaphorically sunken because the water covers them, they are quite 0:21:14.080 --> 0:21:18.040 literally directly sunken. The land is going down. So you 0:21:18.119 --> 0:21:20.560 might have a coastal city that is experiencing more and 0:21:20.640 --> 0:21:24.240 more frequent flooding during storm surges as the sea grows taller, 0:21:24.320 --> 0:21:27.679 but also the ground level of the city is several 0:21:27.800 --> 0:21:31.680 millimeters lower every year, which makes the relative sea level 0:21:31.760 --> 0:21:36.239 rise even worse. Now, how is that possible? Well, there 0:21:36.240 --> 0:21:38.800 are multiple causes but I was reading about this in 0:21:38.840 --> 0:21:41.919 a major One of the causes seems to be the 0:21:42.080 --> 0:21:48.119 extraction of ground water from underlying aquifers, especially you're extracting 0:21:48.119 --> 0:21:51.679 it faster than those aquifers are replenished, and as the 0:21:51.720 --> 0:21:56.879 water is extracted, it creates these voids underground. These voids grow, 0:21:57.040 --> 0:22:00.280 the soil gets compressed, especially if you're putting a bunch 0:22:00.280 --> 0:22:02.800 of heavy stuff on the soil, such as a city 0:22:03.000 --> 0:22:06.000 like building on top of it, and then that compressing 0:22:06.040 --> 0:22:09.400 of the ground and the compressing into the voids below 0:22:09.880 --> 0:22:14.040 essentially means the city literally starts to sink. And this 0:22:14.080 --> 0:22:16.040 is happening to cities all around the world. I was 0:22:16.080 --> 0:22:21.000 reading a really interesting article that addresses this issue. It's 0:22:21.040 --> 0:22:24.520 in Wired by Matt Simon called sea level rise will 0:22:24.560 --> 0:22:29.560 be catastrophic and unequal. So this article is emphasizing again 0:22:29.640 --> 0:22:32.880 that the global means sea level rise estimates are averages. 0:22:33.000 --> 0:22:36.520 In specific places, the problem could be not as bad 0:22:36.800 --> 0:22:42.240 or much much worse. Simon writes, quote, Galveston, Texas, where 0:22:42.240 --> 0:22:45.399 the land is slumping, could see almost two feet of 0:22:45.520 --> 0:22:49.440 rise by the year twenty fifty. Meanwhile, Anchorage, Alaska could 0:22:49.440 --> 0:22:52.719 see eight inches of sea level drop thanks to the 0:22:52.720 --> 0:22:56.600 fact that its land is actually rising following the departure 0:22:56.680 --> 0:23:01.920 of long gone glaciers. So why is Galveston, Texas sinking 0:23:02.040 --> 0:23:05.800 relative to the sea level? He says, mainly there are 0:23:05.800 --> 0:23:09.320 two causes here, and they're both related to the extraction 0:23:09.520 --> 0:23:13.080 of liquids from underground reservoirs. One is the extraction of 0:23:13.160 --> 0:23:17.040 water and the other is oil extraction of oil. And 0:23:17.119 --> 0:23:19.520 this is true in many places as a result of 0:23:19.560 --> 0:23:23.360 the combination of global sea level rise and land subsidence. 0:23:23.880 --> 0:23:25.680 Some of the areas of the world that are going 0:23:25.720 --> 0:23:29.000 to be the hardest hit by the greatest relative local 0:23:29.000 --> 0:23:31.679 sea level rise are on the Gulf Coast of the 0:23:31.760 --> 0:23:34.600 United States, the Gulf Coast, because they're suffering both of 0:23:34.640 --> 0:23:36.680 these at the same time. The land is going down 0:23:36.680 --> 0:23:39.720 and the sea is coming up. Simon in this article 0:23:39.800 --> 0:23:42.600