The Past, Present, and Future of Antarctic Ice Sheets

At this very moment, the ice sheets covering and surrounding Antarctica are dynamic, moving and receding in response to temperature and other factors. Some of the changes are abrupt and quite apparent, like calving events where large chunks of ice break off of glaciers and plunge into the ocean. Others are more subtle because the movement of the ice is occurring slowly, like it has done for over thousands of years. Dr. Phil Bart, LSU College of Science Geology & Geophysics professor, invites us to learn about the evolution of Antarctic ice sheets and how he investigates the movement of ice sheets and ice rises over geologic time to aid in predicting their future behavior. (Transcript below.)

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Additional Resources

LSU Experimental is a podcast series that shares the research and the “behind the scenes” stories of LSU faculty, student, and alumni investigators across the disciplines. Listen and learn about the exciting topics of study and the individuals posing the questions. Each episode is recorded and produced in CxC Studio 151 on the campus of Louisiana State University, and is supported by LSU Communication across the Curriculum and LSU College of Science. LSU Experimental is hosted by Dr. Becky Carmichael and is produced by Dez Stovall and Kyle Sirovy.


Transcript

Becky Carmichael  

[0:01] This is LSU Experimental, where we explore exciting research occurring at the Louisiana State University and learn about the individuals posing the questions. I'm Becky Carmichael, at this very moment, the ice sheets covering and surrounding Antarctica are dynamic, moving and receding and response to temperature and other factors. Some of the changes are abrupt and quite apparent, like calving events when large chunks of ice break off of glaciers and plunge into the ocean. Others are more subtle, because the movement of ice is occurring slowly, like it has done for thousands of years. Dr. Phil Bart, LSU College of Science Geology and Geophysics Professor, invites us to learn about the evolution of Antarctic ice sheets and how he investigates the movement of ice sheets and ice rises over geologic time to aid in predicting their future behavior.


Phil Bart  

[0:58] Hi, I'm Phil Bart. I'm a faculty in the LSU College of Science Department of Geology and Geophysics. Thanks for tuning in. I'm going to talk with you about a new project here at LSU that began earlier this month. The idea for this project got started some time ago. In 2015, I read an interesting paper by Kenichi Mazzuca et al. It was published in the Earth Science Reviews. Their papers showed the existence of several 10s of features that are called ice rises and ice rumples. These features are closely associated with the grounded and floating margins of the Antarctic ice sheet. These ice rises and rumples are evidently places where the floating ice margins are thick enough to be in contact with an underlying seafloor bank. The contact between the floating ice shelf and the underlying seafloor bank significantly slows the offshore discharge of ice volume, and hence stabilizes the extent and the volume of the Antarctic ice sheet. Being stable is a good thing. Because the ice sheets, all three of them, have enough volume that were it to melt, global sea level would rise significantly. Indeed in those places where pinning points between the ice shelves and the seafloor banks are absent, ice volume discharge is extremely rapid. This observation of rapid unbuttress flow strongly suggests that if modern day ice shelves lose contact with the underlying seafloor banks, then ice volume discharge would increase. An increase discharge of ice volume could eventually lead to ice sheet contraction and global sea level rise. But how can we be sure of what might happen if I shelves decouple from sea floor banks? Here is where geological analyses of past events can provide context and insight. Data from ice free areas of the Antarctic continental shelves show the existence of offshore sea floor banks that must have formerly been ice rises and rumples of a larger than present Antarctic ice sheet. One of the seafloor banks is located approximately 200 kilometers seaward of the Ross ice shelf edge. The Ross ice shelf is the largest ice shelf in the world, roughly the same areas the entire state of Texas and it buttresses flow from about 30% of the Antarctic ice sheet. The location of this bank suggests that it was the site of an ice rise until very recently. As such, our new NSF project represents an opportunity for LSU scientists to generate a database understanding of how and when and a recent underpinning event occurred, as well as an understanding of how ice sheet flow, subsequently reorganized. Thanks for listening.


Becky Carmichael  

[4:20] Phil, Bart, thank you so much for joining us today. Really excited to talk to you about your recent... This is a recent research piece that you've just received, correct?


Phil Bart  

[4:33] Yes. Thank you for the invitation to come chat with you. Delighted to be here. And it's a very recent grant. And it actually started officially this month.


Becky Carmichael  

[4:42] Oh, my goodness. Well, I'm glad we've got right here on the forefront or the beginning of this. Well, I always like to start the episode with a little bit of an introduction of you. So would you tell our listeners a little bit about yourself and your background? What drew you to this field and if you had an inspiration, who was it?


Phil Bart  

[5:01] Well, um, so let's see. I started doing Antarctic research in, I think it was 1989. When I started the graduate program with dr. John Anderson who just newly retired last year. And John's been a fantastic mentor. He's a guy who always brought a ton of his students to the Antarctic with him. And so when I first started graduate school, he offered me the opportunity to join on the cruise. There was an open spot, so I got to go to Ross Sea. And I got to see the continent. And it's been a kind of a passion of mine ever since to kind of go there and try to understand this important part of the climate system. So it's kind of a strange place for a guy like myself to go because I'm from here in the south. I'm from New Orleans. And I never thought I would be going to the Antarctic. And the other thing is, I never thought I would be on a boat because I get motion sickness very, very easily. I love fishing. I did a lot of fishing with my dad when I was growing up. But I'm the first one to get seasick. And so now I'm a researcher, a marine geologist researcher, and I go spend, you know, a month to two months time on a very large ship. So, but But yeah, it's an amazing career for me.


Becky Carmichael  

[6:25] So this really leads us into some of what I was interested in learning some of the logistics of travel. So first and foremost, you've got motion sickness. That's your friend, or not so much a friend that you have to deal with. But I would imagine you've also... because you said you spend a month or two at sea?


Phil Bart  

[6:45] At least a month and sometimes we are partnered with another research team. And so we typically request 30 days of ship time, and they prefer not to have the ship lose some of the very short field season going to and from port to drop off research teams. So they have enough berths on the ship that they can put two and sometimes three research groups on board. And we have to assist each other and, you know, share the ship.


Becky Carmichael  

[7:17] Well how many people are approximately on the ship?


Phil Bart  

[7:19] Well, let's see, there a probably... I think on the order of 50 when you kind of count in all of the folks who are responsible for keeping the engines running, folks who are actually guiding the ship, and those who are doing the science and those who are supporting the science. So it's a good number of folks.


Becky Carmichael  

[7:40] Wow. Um, I would also imagine just because you already are in R1 University here at LSU, what is it like in terms of the forms you have to fill out and things that you have supplies you have to gather to do 30 days on a boat?


Phil Bart  

[7:54] Well, that's one of the really great things about the Antarctic program. So there's an enormous equipment pool that's available to the researchers, whether it's geologists like myself or biologists or any other field. And so we very heavily rely on that equipment pool. And we request all of the equipment that we need. So, for example, there's a lot of coring devices that are available in the pool. I have, you know, colleagues in my department that kind of maintain the same kind of coring equipment to go out on their expeditions, but in the Antarctic, it's all supplied and all of its kind of transported there for us. And so we're lucky in that regard. So it's kind of like, you know, available for us to just request what we need. 


Becky Carmichael  

[8:42] So you've got, you've got kind of the setup. So really, you have to kind of consider what are you personally needing when you're going on these trips, right? And then maybe some of the specific equipment you need for the questions you're asking. So once you get there, where do you stay?


Phil Bart  

[9:01] Well, we, we travel from here, we usually go west coast, and then through New Zealand and in New Zealand we go to a facility where they give us all of our cold weather gear. And we're usually there for a few days waiting for a good weather window to fly from New Zealand to Antarctica. And that's usually... Well not usually. It's always on a military vessel, a C 130. And we take a like an eight hour long flight. It's not like the standard airline flight, but we're in the cargo bin up this huge airplane and we fly down and  we land on the Ross ice shelf actually, which is floating ice. And from there we take a very large tractor with all of our cold weather gear and any equipment we bring along with us to the US station which is McMurdo. It's on Ross Island and we usually stay there for at least a few days until the ship arrives so since the ship time is so expensive we make sure that we're there in advance of the ship so that the ship is not losing time waiting for us. So at the US station McMurdo, we're put into bunk house. They call it the Hotel California. And it's just a very, you know, basic kind of facility. Nothing fancy. Bunk beds for everyone and a big mess hall and when the ship arrives, then we transfer everything to the ship.


Becky Carmichael  

[10:48] So we're not talking about some comfy accommodations. This isn't a vacation kind of style. 


Phil Bart  

[10:53] Not at all. Not at all. 


Becky Carmichael  

[10:54] Particularly if you're talking about flying on a military like cargo plane.


Phil Bart  

[10:57] Right. Yeah. 


Becky Carmichael  

[10:58] Oh my goodness. There's no in-flight kind of thing. 


Phil Bart  

[11:01] No in-flight service. None whatsoever.


Becky Carmichael  

[11:04] So, most of us we've never set foot on Antarctica. How would you describe it? 


Phil Bart  

[11:11] Well, it's certainly is a kind of, I would say, a funny place. It's just so desolate, you know? If you have allergies, great place to go. There's nothing green. 


Becky Carmichael  

[11:26] Nothing green? 


Phil Bart  

[11:26] Nothing green. So you won't have any problems with allergies or anything like that. So that's the first thing that kind of strikes you. I think one of my earliest memories I have about going to the Antarctic was the first flight over way back in 89, and we're high, high, high above the, you know, the continent. And I can see that there's land there, ice covered snow everywhere. And I look out into the ocean because we're kind of passing by the Transantarctic Mountains but I could see the ocean. Oh my God. That must be icebergs guys can see these white things and there's a lot of them. But then I learned that it wasn't actually icebergs. These were, you know, breaking waves. So there was a lot of heavy, heavy seas. So it's a very, very windy place. It's a very cold place. Average coastal temperatures like -10 degrees Celsius. You know, some of the Northernmost extensions of the continent get a little bit warmer in the summer, but very, very, very cold. Very white, obviously, ice everywhere, ice covers more than way more than 90% of the continent. So much so that you know, pretty much all but the highest and tallest mountains are covered. And the ice actually expanded from land into many of the marine areas. So, there is ice everywhere, ice everywhere. And, and then you know, you see some life. There is, you know, you see the penguins, of course, you see seals, lots of birds. But that's about it. Yeah, but it is it's an amazing place. It's very, very different than anything I had ever seen.


So are there any kind of like threats or issues that you have to keep your guard up for?


Well, and I mentioned to you that we go through New Zealand and when we're there we're required to watch some videos. We're required to get all our cold weather gear. So very, very serious about everything safety. And so you do have to be very careful even to say if you're just walking about. We go into the Austral summer, so January, February is the best time for us. And your cautioned to make sure you put on plenty of sunscreen. So there's not much in the way of protection against the sun at that latitude. So you want to make sure you're protected that way. And then it's just a question of being out in this kind of a cold. It is really, really very cold. They they give us this thing they call Bunny boots. And they're, you know, they're very, very large. They actually have a valve that controls how much air you have inside the shoe as an insulation barrier. And I remember the first time I went, I was walking around with the moccasins I brought with me. And even after a few minutes, my feet felt like they were just completely frozen. So you do have to take some precautions. And they do take that very seriously. When we're there prior to the ship's arrival we're allowed to go around and explore a little bit around but they they are they're very strict about when you leave the base, you have to make sure that someone knows where you're going. You have to check out and check back in. So safety is a very, very big concern. Once we get on the ship, it's the same thing. The captain of the ship is responsible for everything safety, and myself as a chief scientist, I'd be responsible for my crew's safety. So we're required to when we're operating to wear the proper gear, hard hats if we're lifting anything on the back deck, and you know, just general paying attention to everything that's going on around us.


Becky Carmichael  

[15:11] So as the chief... You're the chief scientist on the boat. How many people are with you? What's the size of your particular crew? And are they all from LSU or are you bringing in collaborators from other universities when you go?


Phil Bart  

[15:25] Well, the last time I went was in 2015. And we had with me... I brought three undergraduate and three graduate students who were working and all of them are in our department. And so that was a pretty small crew. It just so happened that particular field season, we were sharing ship time with a group from another university, and they had a similar size team. And between all of us, we kind of helped each other with the data acquisition. We were getting similar kinds of data. So that was plenty enough folks for the type of data that we're acquiring. And so that's typically the case. Usually my group is all LSU graduate students and undergraduates. I've in the past had some faculty from LSU join me. This year I have... I've got open slots. I haven't recruited my team yet. So that's what I'm going to be doing in the next year before we hit down.


Becky Carmichael  

[16:25] Nice. Well, that's exciting that you have the opportunity for undergraduates to participate as well as your graduate students to go on this experience.


Phil Bart  

[16:33] Yeah, it's, it's a great opportunity for the students to see if they like this kind of research and get a chance to see a really interesting part of our planet.


Becky Carmichael  

[16:45] So I would like to take our listeners into what exactly you are studying in Antarctica. And I know we in your monologue, you mentioned some different terms. But if you can give us again, a brief overview and then let's get into some of the nitty gritty of what this is. 


Phil Bart  

[17:04] Okay. Yeah, I think... Well, I would call what I do as a geologist kind of as ice sheet reconstruction. So it's paleoclimatic research. And the thing that I focused on the last several years concerns, the pattern and timing with which the grounded and floating parts of the ice sheet have retreated since an interval of time that's called the last Glacial Maximum, LGM, last Glacial Maximum. And that last Glacial Maximum, lasted may be from about 26,000 years ago to about 16,000 years ago, and at that time, the climate, global climate was much colder. As a consequence of that cold ice sheets in both the South and the northern hemispheres expanded greatly. And sea level as a consequence fell. And in the time since then, Earth's climate has shifted towards a warmer phase. And as a consequence of that, the ice sheets have contracted. So most of the work I've been doing, since I've been here at LSU, concerns this contraction and expansion cycles. Most recently, we're looking at details of the contraction history. And so in my monologue, I talked a little bit about the new project that we're going to be beginning now. And that one concerns these features that are called ice rises and ice rumples. And so those are things we've known about for a long time. But it looks like there's a growing appreciation of the importance of those features for the stability of the ice sheet and when I say stability, basically keeping it like it is right now without it changing. So changes is part of what happens. And it does go through natural cycles. And like I mentioned in the LGM, it was much, much larger. It was much larger. And it's contracted quite a bit since then. Even with that contraction, most of the continent is still covered with ice. So it's still a very, very large ice sheet. But in places the magnitude of contraction has really been phenomenal. It's been more than 1000 kilometers of retreat, of grounded ice and parts of raw sea. So significant contractions that have occurred and right now where its current configuration, its extent is partly controlled by these Penny points. These places where the margins of the ice sheet are basically stuck, if you will, on some obstacles. Places where the seafloor sticks up very, very high and the floating edge kind of stuck on there. Just kind of get stuck, the friction kind of is holding it in its place. It's still flowing. But it's kind of... Its extent is partly controlled by these things that are called ice rises, these places where the ice sheet is stuck to an underlying seafloor bank.


Becky Carmichael  

[20:19] And am I correct and understanding that ice and ice sheets are two different things. And an ice sheet is... Is it like a... I'm thinking of this as a frozen plate that's just kind of... that can be of a certain depth and size, but it is a mass of frozen... Would I say frozen material?


Phil Bart  

[20:44] Well, yeah, it's ice. Very, very thick ice. And what makes it a glacier is that it's flowing under the influence of its own weight. So it's thick enough that it flows. And the distinction between what we say is an ice sheet and an ice shelf concerns whether or not the ice is actually in contact with the underlying surface. So that surface could be land that's above sea level. And in that case, we call it a land base ice sheet. The land could be below sea level. And if the ice is thick enough that it's grounded below sea level to the sea floor, we'd call that a marine base ice sheet. And in those places, where as you get towards the, the terminus of the ice, where it's in the Marine realm, and it floats off the seafloor, the floating part forms what we call an ice shelf. So it's just the fringes of the areas that are grounded, so grounded ice sheet, floating ice shelf. And the line that separates those two zones is called the grounding line. It's actually a zone, a broad zone maybe 10s of kilometers wide, where ice is kind of loosely coupled to the sea floor. So those are the two areas


Becky Carmichael  

[22:16] And those couplings, because we've talked to... You'd mentioned that Antarctica is composed of three ice sheets?


Phil Bart  

[22:25] Right? Mhm.


Becky Carmichael  

[22:26] Is it where they're joined. Is that kind of those... That zone area?


Phil Bart  

[22:32] No, that's... So the three ice sheets are on the East Antarctic ice sheet, the West Antarctic ice sheet and the Antarctic Peninsula ice sheet. So it's a bit geographical, but the other thing about it that's interesting is that most of the East Antarctic ice sheet is on East Antarctica. But most of that land of East Antarctica is above sea level. Not all of it, but most of it is above sea level. The West Antarctic ice sheet is on land that is mostly below sea level. So they're really different ice sheets. Very, very different volume. It's very different elevation, and very different way that it interacts with the global climate. And then the third one is the Antarctic Peninsula ice sheet. And that's a very mountainous terrain. It's a very thin peninsula. It's a former volcanic arcs system, just south of South America across the Drake Passage, and very, very small ice volume, but it's mostly like a mountainous region that has, you know, ice covered that flows down toward the coast.


Becky Carmichael  

[23:39] So when you're there, you're on your ship and you've got these different regions that you're exploring. What's the type of sampling that you are you are doing? 


Phil Bart  

[23:49] We get both geophysical and geological data. And so the geological data includes core, physical core. So we lower devices that can make subsurface samples of either you know, the near surface samples or as many as three, four or five meters into the subsurface. And we retrieve those cores and box them up and take them back here for analysis. Sometimes we do on board analyses, but that's the primary geological data that we acquire. In you know, everything from the marine realm. I work exclusively offshore. And the geophysical data includes several different types. One type is called multi beam swath bathymetry and it's basically a high resolution image of the sea floor in not just the single transect, but it gives us a wide swath. So we can kind of like... if you can imagine mowing your lawn back and forth, back and forth to cover the whole thing. We do the same thing with the ship we go back and forth in a rectangular grid, and we get a large scale image of the seafloor and the changes in topography. And those images are really, really important to what we do because when the grounded ice sheet retreats, it leaves an important record of erosion and deposits of where the ice sheet used to be. And so from those kind of images, we can restrict that the ice sheet used to be exactly here, not there. But this data shows it was exactly here in the path.


Becky Carmichael  

[25:30] So I'd imagine you're also being able to see that there was like uplifting potentially where the sheet was stuck as well. Right? 


Phil Bart  

[25:38] Right.


Becky Carmichael  

[25:38] Interesting. So the cores you're taking too, are those... I'm familiar with taking cores on land and it's like a mud substrate or it's soil. The cores you're taking, are you getting both ice cores as well as other material.


Phil Bart  

[25:56] We only do sediment samples. There are lots of groups that do study the ice core. But we strictly work in the Marine realm. And we just take the cores of the sediment. And the nice thing about what we've been able to do over the years, is, you know, get these larger and larger swath bathymetry images and know exactly where the ice used to be. And so we can kind of pinpoint from where we want to acquire a core. And that's really important, because if we want to know when the ice sheet was there, well we better get samples that were deposited when the ice sheet was at that particular location. And so yeah, we recover those core. And we look for things, you know, in (inaudible) carbonate fossils in those settlements. Things like forams or whatnot that we could radiocarbon date to give us an age estimate of when the ice sheet used to be at a location and when it was that the ice vacated that location.


Becky Carmichael  

[26:59] That gives you that fuller picture then.


Phil Bart  

[27:02] Right. Yeah.


Becky Carmichael  

[27:03] Interesting. Um, so what I would imagine like any, you just given this is an example, knowing where to do the core is a challenge. Is there any other challenges that you experience in that space?


Phil Bart  

[27:19] Where do I start? So, you know, the biggest challenge is the actual conditions in the field themselves. And so the field season is very short. And I guess probably I should back up and say the biggest challenge is to get ship time. So the field season is short. And so you have a limited amount of time that you have the ship to get data in the area where you want to be, and then you have to be a little bit lucky. Because there's always sea ice sprawl. There's always iceberg. There's always times when the sea state is not good for acquiring marine data. So a little bit earlier, we were chatting about signal to noise ratio and whatnot. So when the wind is blowing really hard for lots of days, the sea state is really churned up. And that creates a lot of challenges for us getting good quality, high signal to noise ratio records. So there's so much choppiness in the sea state that it interferes with our ability to get good quality data. And it's sometimes we can't get data, the captain won't let us because the sea state is too high, it's too dangerous to operate the winches that we need to lower the devices off of the back of the ship to collect data. So the conditions can be quite, quite challenging. And, you know, when you get a good field season, there's still some challenges because it's... the area is so large, and, you know, we're trying to make detailed reconstruction of an ice sheet that is, you know, a continental scale. And so it's a lot of area. But we can't cover a lot of area, we have to pick our spots and choose well, to try to get a good record of something that might be representative of the larger ice sheet's changes.


Becky Carmichael  

[29:20] So this leads me to one of my favorite questions to ask all my guests. You're already explaining that you have to be pretty flexible. You have to deal with a lot of different elements and changes that can occur in that expected window of time that you are on the ship. Can you share with us any moment or moments where you've had to improvise or MacGyver your way to achieve sampling or a goal?


Phil Bart  

[29:50] Well, yeah, there's... I think anybody that's been on a ship knows that there's always going to be stuff that goes wrong. You know, I remember there was one moment when we were having exceptionally good conditions. The wind was flat, calm. The sea state was perfect. There was no sea ice. There were no icebergs around. And the data looked horrible, horrible. And everybody on board was... we were scratching our heads that the techs who help us acquire the data were puzzled. And so this went on for a good little stretch. And one of the techs had the idea actually, not me, but to to check the actual cable and it has a battery that needs to be in a good state. Well, we pulled out the cable where that has the hydrophones that records the sound signals that we generate when we're collecting seismic data and it turns out the nine volt battery was out. 


Becky Carmichael  

[31:03] Oh, no. 


Phil Bart  

[31:04] So we had to swap out the nine volt battery, you know, for $1.50. And our data miraculously started looking much, much better. So anyway, yeah, there's always something that goes wrong. I tell you what, there was another moment. it's not a MacGyver moment so much, but it was one of these things that happened while we were acquiring seismic data again. And in this case, there's a particular type of seismic source we're using, it's called an air gun. And it basically gets compressed air from a generator in the engine room. And that hose goes out to the back deck to this device that's deployed off of the back of the ship. It sends 200 pounds per square inch of pressure to that air gun and periodically we released that and it creates a sound source. So everything's working fine. But the hose actually broke. Thankfully nobody was was hurt. Nobody was in the area where the hose broke, but we had to stop. And we started to acquire some other types of data while we did the repairs on that. So our crew did their MacGyver thing and got the hose repaired. But it took a little while. And in the meantime, we were acquiring multi beam swath bathymetry data which we really like. Because it's always a lot of fun. It's beautiful images of the sea floor. And we saw these very interesting features that we still haven't figured out what they are on the seafloor, but that's forming the basis of a Master's project, a current masters project. So it was one of these serendipity cases that, you know, something going wrong, got it repaired, thankfully, but in the process we happened upon a very interesting set of our observations that I think are going to be quite important. 


Becky Carmichael  

[33:02] Oh, that's exciting. 


Phil Bart  

[33:03] Yeah.


Becky Carmichael  

[33:03] Because then I can admit, I can only imagine the frustration that happens when any piece of equipment breaks. But then having that added, we are so far away. How are we going to get this repaired? We didn't have something great happen from it. That's going to be interesting.


Phil Bart  

[33:19] Yeah, you know, it's gotten to the point, I think, where you kind of expect things to go wrong. And, you know, you just chart the best course you can, because something always goes wrong.


Becky Carmichael  

[33:32] Oh, yeah. The in-the-field modifications to the methodology is something to always have with you.


Phil Bart  

[33:38] Yeah, you know, I think even there's an understanding. I won't speak for NSF, of course, but I think the National Science Foundation realizes that there are these difficult field conditions. So we rarely get exactly the data we intended to get. We have to stay in the same geographic area and same objective scientifically, but we never get, you know, we have to provide a detailed map of this is where I'm going to be, I'm going to get this much data of this type, and so on and so forth. But I've never, in the seven times that I've gone, actually gotten exactly the data set I intended to get.


Becky Carmichael  

[34:17] And that's nice to have the flexibility. So I'm glad that you brought up NSF. So this current project is funded through NSF, is that correct? 


Phil Bart  

[34:25] Yes. 


Becky Carmichael  

[34:27] And you've also mentioned the ship that you're on. Would you tell us a little bit? Would you want to tell us a little bit about the importance of that funding to being able to go on this shift?


Phil Bart  

[34:45] Yeah, I'm very happy to. And so then the NSF, the National Science Foundation funds, all of the US participation in anything Antarctic science whether it's, you know, geologists like myself, a glaciologist who works on land, a biologist like Mike Polito in our department here, Peter Doran, who also works in land in my department. And so they they provide all the funding through various different units of the Office of Polar programs. And that funding for myself gives me time on the ship. And the ship is the Nathaniel B. Palmer. There's a second ship that's for other types of operations. So actually, the ship was built by Edison Chouest, which is here from Louisiana. It's a Louisiana shipbuilder and so if you're down on the coast at any time, and you see the orange and yellow ships, that's Edison Chouest, and their two icebreakers that they built are also the same colors. And so that's the Lanny and the Palmer, so I sail on the Palmer, and they have a very Louisiana crew. And you know, we have very good food, of course.


Becky Carmichael  

[36:09] So it makes you feel like you're at home. 


Phil Bart  

[36:11] It makes you feel... Yeah, for somebody like myself who grew up in New Orleans. So that's kind of fun. But yeah, that's a tremendous investment that the National Science Foundation makes in things Antarctic research. There, I think, are several investigators in the physics department that also do studies there at the South Pole is a very good place to do types of experiments that atmospheric physicists do. So, but the commitment actually involves what they give us to do our individual projects, but they also supply the vessel. So they lease the Palmer and the Lanny from Chouest, and the day rate is in the 10s of thousands of dollars per day. So it's a really enormous commitment of funds to make sure that we can get some data based understanding of what's happened to the ice sheet in the past. And from a geologic perspective that insight of what happened in the past. And you know, what types of shifts have occurred to the grounded and floating ice and when and over what durations. That's really important information to kind of understand going forward. Okay, how might the sheet respond? What might it do? Why'd it expand? Might it contract? If it does, by how much? For what cause? That kind of thing. So those are the kinds of things that the NSF funds at least in terms of the marine G&G, geology and geophysics side of things.


Becky Carmichael  

[37:47] So I'd like to take... kind of go now toward the significance of this, of your work. And one of the things when I think about Antarctica I envision all of these these multiple ice sheets, or just great big, solid pieces of ice surrounding the continent like a jigsaw puzzle. You've talked a little bit about what we already know about the ice sheets, but how dynamic are the Antarctic ice sheets relative to geologic time?


Phil Bart  

[38:26] Yeah, that's a very interesting question. So I think this is one of the things that a lot of geologists, I know myself included, struggle with this idea of things, geologic time. And relating it to things human timescale. So that's a big challenge. So we have to operate under the constraints that, you know, we have these records that record processes in the past. So products are the result of you know, geologic products, the sediment, the landforms are the products of processes, the ice sheet processes. So we have to make a connection there, and then we have to date them. So we have the challenge of getting the physical records and dating it in a way that is meaningful for things that that happened on a human lifetime scale. So I'll tell you, and I hope this story kind of gets to the challenge. I had a paper that we published in 2018. And we talk about this interval of time when the ice was in a stationary position in terms of its extent, for a good long time being 3000-ish years, okay. And it held that position and because it was there for so long, the ice is always flowing, it carried a lot of debris that it piled up at its Terminus, and that's why we know it was at this position. So that's if you ever took some geology, you might have heard that term moraine. It's basically a Delta associated with fast flowing ice. And and it marks the former extent of the fast flowing ice. So we can see that and then we can see from that other data that we acquired that there was an event that happened and it caused the ice floe to accelerate. So there was an ice shelf that broke apart, and when it broke apart, the ice floe accelerated very, very rapidly, but it maintained that position for a while. Eventually the ice retreated. It took 800 years, in terms of the data we acquired, for the ice shelf between the time that the ice shelf broke up and the ice experienced a major retreat. So geologically we'd say that this was instantaneous retreat. Very, very rapid retreat. But 800 years, that's a lot of lifetime. That's a lot of generations.


Becky Carmichael  

[41:20] Yeah absolutely.


Phil Bart  

[41:21] But, you know, the breakup of the ice shelf is, from what our data tells us, is what triggered the big retreat, you know, nearly a millennium later. So, there's a definite cause and effect that this data demonstrates. It's not, you know, geologically rapid, lifetime not rapid, but certainly, it's a cause and effect. Yeah. So it's, it's really difficult to try to connect the things sometimes with geologic time scales and... but you know, getting back to I guess what you started out asking about the changes. There are places where modern observations show that there's a lot of rapid change. And one of the things that the Antarctic community is is most concerned about concerns the what's called the Pine Island and the weights glaciers. The National Science Foundation and NERC funding agency in the UK actually teamed up to study both of those systems because they're deflating, losing a lot of ice volume very rapidly on the order of 100 Giga tons of ice per year. So lots of ice volume loss that's happening for these two glacial systems. And so, in that particular case, the rapid loss of volume is partly related to the intrusion of warm ocean that's it contact with the marine terminations of those two glaciers system. So there's really, really high rates of melting. And we know that because we have ships that kind of go in, but also we have satellites that do repeat measurements and see that the ice sheet surface is deflating as well. So very, very, very rapid changes are occurring. And of course, you may have heard about the Larson ice shelf. In 2002 a very large part of that broke up in the course of a few months. So very, very rapid. And then the other thing I came across when I attended conferences summer in Vienna, the EGU meeting, European Geophysical Union, and a colleague presented a study where he synthesized a lot of satellite measurements that showed there were 10s of thousands of meltwater lakes that formed over the summer season on the surface of the ice sheet. So there are lots of changes both from underside melt from surface melt that are occurring and it's impacting the ice sheet today.


Becky Carmichael  

[44:07] And so I can imagine when you say these melt lakes, these are things you can... this would be something you would see on the surface, and potentially, in maybe those little areas where it's pooling water.


Phil Bart  

[44:18] Yeah, it's actually it's what their data showed. I think this was... If I remember his name, Chris Stoke showed it that it's showing up on satellite data. You can see it on the satellite data. And so over the summer the temperatures are becoming warm enough that there's a lot of surface melting that's occurring. Yeah.


Becky Carmichael  

[44:40] So because they're ice sheets, how much water is potentially trapped in the ice sheets, and how much does this vary over years and then change the sea levels? 


Phil Bart  

[44:54] Well at present the I sheets combined contain on the order of about 65 meters of sea level equivalent. So a tremendous volume. Most of that's in the East Antarctic ice sheet. So that's the land-based one, but a smaller amount of that is contained in the West Antarctic ice sheet. That's the one that's a marine-base, it's grounded on land that's below sea level. So all of its Terminus is in contact with the global ocean, which makes it susceptible to melting from a warm ocean, but also from from atmospheric warming because its surface is lower than that of the larger East Antarctic ice sheet. So that one... it's even, you know, a three-four meter sea level equivalent for a smaller ice sheet is highly significant in terms of, you know, the capacity for it to raise sea level, if it were to melt.


Becky Carmichael  

[45:57] So we have the record that provides us evidence that sea levels have fluctuated over time. So you ever look at how much sea level is expected in the near future? And is any of your work, also helping kind of estimate what might happen?


Phil Bart 

[46:20] Yeah, so the current estimates of global sea level rise, I think it's on the order of three millimeters per year as a global estimate. There are places where it's higher and places where actually the land surface is rebounding and from places where it was formerly covered by ice up in the High Arctic regions, but the global average estimate is on the order of three millimeters. So my work doesn't deal directly with providing estimates for what that sea level magnitude would be on with the rate might be. So we mostly look at trying to do reconstructions of the past. And hopefully, what we kind of demonstrate, well this is the past behavior of the ice sheet will provide some context for, Okay, here's the scale of things. Here's the sort of timing in terms of causal mechanisms. This is what else was happening. So these might have been the triggering mechanisms. And I guess in terms of the most recent project, I'm hopeful that we're able to make some contributions along those lines, because what we have right now in terms of data we've analyzed from archives suggest that this was a relatively recent climatic change that we're investigating. And that I talked about a little bit in the monologue and hopefully we can try to narrow down the timing and then start asking some questions about well, what might have been its impact on sea level?


Becky Carmichael  

[48:07] I think that that part is particularly interesting to me because you could... since you're doing this reconstruction, there's, at least in my mind, there's some things that have obviously changed now, and matching that up. But I think it would be interesting even to understand what potentially is triggering those changes and how that matches up.


Phil Bart  

[48:30] Stay tuned. So hopefully... We're not going to acquire new data until 2021. That'll be our first scheduled ship time. But actually next month, in maybe just a week or so from now, I'm traveling to Oregon, which is in Corvallis, Oregon is where they keep all of the sediment samples that have been acquired over the years in Antarctica. And so there are several 10s that are relevant for project we're going to conduct so myself and my two graduate students and my undergraduate student are going to travel there to do some visual core descriptions and some sampling to kind of start this new project. So hopefully we'll find some meaningful data on this, this first get go before we go out and acquire our own data.


Becky Carmichael  

[49:22] I'm sure that will kind of inform maybe some of the other questions that you're asking. I have another one of the fun questions I like to ask is what's the coolest, craziest, weirdest or most dangerous thing you've done in the name of your work? 


Phil Bart  

[49:41] Hmmm. Let's see. Oh, coolest, craziest. I'm afraid, you know, in terms of dangerous, we usually don't go anywhere near there. And so it's just the stakes are too high. So we play it really, really safe.


Becky Carmichael  

[50:05] I'm glad to hear that. Because since you are so... Well not that I'm advocating anybody does anything dangerous. And sometimes those dangerous moments happen and you got to work. 


Phil Bart  

[50:13] Right. Right.


Becky Carmichael  

[50:14] But I'm glad to hear you're not doing that.


Phil Bart  

[50:16] Yeah, I know what you meant. But I think, yeah, we've been kind of lucky that we've kind of not had trouble. I guess... I'm not... Nothing's coming to mind. But I'll tell you there's one story of a recent thing I just saw online. And I'm not even sure who it was, but you can probably find it on YouTube. There was the Palmer, the antarctic vessel, was relatively close to the calving front of one of the ice shelves, and in the process of acquiring data and parts of the ice shelf just as it always does just kind of calved and fell into the ocean. So that was caught on some folks who were actually on the back deck, and then the event kind of continued for a little bit longer than folks might have expected. And a big chunk of the shelf fell into the ocean. And then you could see it rise back up and it created like a mini tsunami, not really what you would call a tsunami, but a very sizable wave. And, and so anyway, during the video, then you can see the ship captain who's always monitoring what's going on and the back deck motors away from there as this wave kind of approaches. 


Becky Carmichael  

[51:32] Wow. 


Phil Bart  

[51:33] So that was the most dangerous thing I've seen. But unfortunately, you do hear about some accidents happen. And because it is a dangerous place and the weather conditions can be quite, you know, tricky to navigate through. And I mean, you know, I think everything that we kind of observed there is falls into the really cool category. There's always some observations that we make were unexpected. I'll tell you on my most recent cruise, it was the first time I deployed a what's called the yo yo camera. And you know you've probably played with a yo yo when you were growing up.


Becky Carmichael  

[52:15] Yeah.


Phil Bart  

[52:15] And the yo yo camera is a video and still picture camera that's mounted in a cage that's maybe two meters by two meters square. And we lower that to the sea floor. At the bottom of that camera, there's a line, a lanyard with a lead weight. And when the lead weight hits the sea floor before the camera cage does. 


Becky Carmichael  

[52:43] Yeah.


Phil Bart  

[52:44] There's a live feed back up to the ship. It triggers a flash and the camera takes a photo of the bottom. And then we use this camera system while we're underway at about the speed of one knot. So moving very, very slowly, and the winch operator is taking line in and letting line out. So that that lead weight periodically hits the sea floor and causes it to take a picture. Exactly. And so we actually took several hundred of those kind of photo sites where we collected core. Were just amazed to see the abundance of of life at the sea floor. 


Becky Carmichael  

[53:31] Oh yeah?


Phil Bart  

[53:32] Lots of life. Tons of sponges, tons of (inaudible), echinoderms. We saw, you know, tons of brittle starfish, all kinds of things. Lots of sea cucumber, soft body animals. We even saw coral. We saw horn coral. We actually took a core which has a special kind of core. It's called (inaudible) core and we took a core and at the top of the core there was a rock about maybe the size of your your palm and attached to it was a horn coral. A dead one. But anyway, we were like, Oh my god, this is so amazing. We got a horn coral, what are the chances? Well, apparently the chances are pretty good because we looked at the photographs. There are lots of live horn corals living in this particular sector of the Ross Sea where we acquired data. So that was a very surprising thing because myself as a geologist, I'm not a biologist, but we concern ourselves with what happens in or what's recorded in the near surface settlements. And to know that there's an abundance of benthic life is important because there's the possibility that it disturbs the near surface sediments. Where we try to reconstruct what were the paleo climatic changes? 


Yeah. And to hear that there's that much... There's that much life, I wasn't expecting to know that that was occurring in those depths and those temperatures.


Yeah, it was a total shock. It was a total shock. It really made me wonder how well we could make detailed reconstruction for those areas where there is. I'm not... I don't think I could say that for certain there's that much benthic life everywhere, but in the places we surveyed, there was abundant benthic life. There was another funny story because one time we let out the line and with the camera, and when we get on station, we it takes a long time to load the camera into 400 meters of water depth. And with that much cable out there's some stretching that occurs. So the camera you can see that it's bouncing, you know, not bouncing off the bottom but it's hovering closer to the sea floor further from the seafloor as the cable is stretching. So you wait for that to stop. So, the whole time there's a live feed with the video. So we're looking at the lead weight, it's probably not made out of lead. But all of a sudden a fish appears in the view. And it's down there at 400 meters water depth. So, you know, other than our lamp, there's not much in the way of light, right? And so the fish is staring at that lead weight. And he rams into it. Bang, bang, bang, and we couldn't believe it. And then it goes away.


Becky Carmichael  

[56:43] He was probably excited thinking this is some food here.


Phil Bart  

[56:48] That was the first thing I think he ever saw in his life.


Becky Carmichael  

[56:52] Wow. This is something that I didn't ask you earlier, when you're taking these cores and when you're doing the samples, how much time you have to dedicate to just get one sample.


Phil Bart  

[57:03] Well, the... We usually give ourselves like at least three to four hours to be on station to get a core sample. So the bigger prep time involves the setup of the core. And so we try to plan it out that we give the science tech support group enough heads up that they can prepare everything. It takes them three, four hours to set up the core to get it prepared on the back that so once we get on station, there's a process of hoisting it up off of the back deck, putting it vertically over the side of the ship, lowering it down very, very slowly. And then the last little bit we let it free fall. And so it's all gravity driven coring, that we do. And then you come up again, very slowly again, at some prescribed, you know, rate and then we get it on board. So we can't get a whole bunch of those in one day. But we get... We can get plenty, plenty enough to keep us busy for, you know, a year or two. I'm still working on data that I acquired in 2015 to give you an idea. It's kind of a slow, deliberate process of generating data. 


Becky Carmichael  

[58:19] Wow. But still, I mean, that goes back to how valuable the ship time is, and how much you're trying to get done. But then once you can get that accomplished, yeah, the amount of things that you then have... the samples that you have


Phil Bart  

[58:33] I think most scientists have appreciation for this, you know, that the data is obviously of utmost importance, but it's also making the observation in the right place. So you have to make good choices. You can't just go out and get data, wherever. So that's what I was mentioning about the multi beam swap bathymetry. You get a really good high resolution, and then you can start to try to core particular geo morphologic features that have some more significance than other features.


Becky Carmichael  

[59:02] If you have a picture of that, I would love to have a peek. If it's not like... If it's not sensitive and you can't


Phil Bart  

[59:09] I think there's one on the Department of geology webpage. It may not be on there, but it was up for most of last semester. It may still be there.


Becky Carmichael  

[59:18] I think that maybe the listeners would probably like to see this too. So a couple of final questions for you. When you are not sampling, what is your favorite thing to do while you're on this ship? Do they have karaoke? Do they have lounges? I know you've said that the accommodations are not resort type.


Phil Bart  

[59:37] No, no, but we do have some options. And you know, one of the things we do is we have a ping pong tournament. Ping Pong. 


Becky Carmichael  

[59:47] Oh nice.


Phil Bart  

[59:48] So I do love ping pong. When I was in high school. I think I played every day with my next door neighbor for two hours every day. So we have a tournament and you know, lots of pickup games when people were not on watch. We do operate 24 seven, you know, always acquiring data. But when you're not on watch, you can do whatever you like. And so ping pong is one. Cornhole. 


Becky Carmichael  

[1:00:11] Cornhole?! 


Phil Bart  

[1:00:12] We play cornhole.


Becky Carmichael  

[1:00:13] Oh that's awesome.


Phil Bart  

[1:00:14] On board and see other than that, so we usually have at least one person who is musically inclined who brings a guitar. Once I was sailing with one who had a... A colleague brought up an accordion.


Becky Carmichael  

[1:00:29] Oh, yeah? Those are heavy.


Phil Bart  

[1:00:31] This was a tiny one. It wasn't a big one. It's more like a Squeezebox. 


Becky Carmichael  

[1:00:35] Ah, nice.


Phil Bart  

[1:00:36] So we have that. They sometimes do... I don't really like these, but they do these crossing ceremonies. When you cross into the, you know, the Arctic, Antarctic, I should say, circle. The newbies are, you know, christened so there's always some silliness about that. It's not exactly hazing, but sometimes it's approaching that. So I don't, I don't really care for that too much. But you know, and then of course everybody brings music. So when we're not needing to be really focused on something someone will supply some music for us to listen to while we're underway collecting data.


Becky Carmichael  

[1:01:22] Phil, do you have any final thoughts on the impact of your work, your research and what's coming next you'd like to share?


Phil Bart  

[1:01:29] Well, thanks, Becky, for inviting me to come thanks for that opportunity, and Kyle as well. So I think you know, in terms of impact, I'm really excited about this current project. I'm really excited about it. I think it it has the potential to provide really a lot of data, we got 2 field seasons. And that's nice because we'll have the chance to look at some of the data and then go back out and hopefully have learned something from the first round of data acquisition. But you know, so as I said in the monologue, we're trying to understand how the Ross Ice Shelf, really enormous ice shelf, unpinned from, what's called Ross bank. On top of that it's in Ross Sea. So Ross keeps showing up. But the Ross ice shelf is an enormous... largest ice shelf on earth. And up until what we think was recently, it must have been larger, and it must have been pinned about 200 or so kilometers further than where it is now. So we have the opportunity to understand that unpinning history, but more importantly, is what were the consequences. When it unpinned, what happened? How long did it take to unpin? How rapidly did these changes occur? The thing that's super neat is that a lot of those changes any reorganization in the flow of ice from the east and west Antarctic ice into the Ross ice shelf could be recorded by the fabric of fractures that are in the ice shelf. And so there have been lots of investigators who have looked at the fabric of the ice shelf and made deductions about what type of flow changes that might have caused this particular pattern to exist. But nobody's been able to connect it to a causal mechanism. So I think we can... if we can get the timing well, we can can provide a really interesting data set that could be tied back to that. The other bit of data that's actually an active research project concerns coring through the ice shelf at the one other ice rise that currently exists on the Ross ice shelf. That's at Roosevelt Island. And (inaudible) and her colleagues in New Zealand have drilled an ice core through that ice rise. And they're looking at changes in precipitation that might have occurred at that site, which also ties in really directly with things that we might be able to observe because the precipitation at that site is controlled by the extent of the ice. Once the ice contracted back, you have open water that's closer to that site, it should have caused a spike in the accumulation at that site. So I think there's tons of possibilities for us to really gain a much fuller understanding of this part of the climate system in a way that couldn't be revealed from a study of the shelf itself, or couldn't be revealed strictly from a study of ice core at Roosevelt or for that matter by our study from data on the Ross bank, so I think we got an opportunity to really get a full understanding and it's connected to things that you know, global scale things to about what might have been happening with sea level at time.


Becky Carmichael  

[1:05:12] Phil I'm really excited to see and hear more about what happens with this particular study. Thank you again for sitting down with us. This has been a pleasure. And I'm... Again, I'm looking forward to hearing about this next adventure in 2021, right?


Phil Bart  

[1:05:29] 2021 and 2022. And thanks again for the chance it's been a pleasure for me as well.


Becky Carmichael  

[1:05:37] This episode of LSU Experimental was recorded and produced in the CxC Studio 151 here on the campus of Louisiana State University, and is supported by LSU's Communication Across the Curriculum and the College of Science. Today's interview was conducted by me Becky Carmichael, and it was produced by Dez Stovall and Kyle Sirovy. Our theme music is "Brambi at Full Gallop" by PC3. To learn more about today's episode, ask questions and recommend future investigators visit cxc.lsu.edu/experimental. And while you're there, subscribe to the podcast. We're available on SoundCloud, Stitcher, Google Play and Apple podcasts.