South Pole 4. Ice Shelf Melt
In this captivating episode of South Pole, host Clark Marchese engages with Dr. Elin Darelius, an esteemed physical oceanographer, to unravel the complex behaviors of Antarctica’s ice shelves. Together, they explore the vital interactions between the ice shelves and the Southern Ocean, illuminating their pivotal role in regulating the global climate and the serious implications of their melting.
Dr. Darelius sheds light on the distinctions between ice shelves and ice sheets, discussing how the melting of ice shelves, although already part of the ocean, can significantly influence sea level rise and transform the ocean's physical properties, with potential repercussions for marine life.
Additionally, the episode provides a fascinating glimpse into the techniques physical oceanographers employ to gather crucial data in the harsh Antarctic environment, enhancing our understanding of these critical processes.
Episode Guest: Dr. Elin Darelius
More information about Dr. Elin Darelius here.
Browse Dr. Elin Darelius’ publications on Google Scholar
Follow Dr. Elin Darelius’ blog
More information on the research group FRISP
Episode Transcript and more information on the Pine Forest Media Website
Follow Pine Forest Media on Instagram @pineforestmedia
Hosted, produced, written, and edited by Clark Marchese
Cover art and PFM logo by Laurel Wong.
Theme music by Nela Ruiz
Transcript:
[00:00:09.830] - Clark
Hello, and welcome to South Pole, the podcast that explores all things Antarctica. I am your host, Clark Marchese, and strap on your winter coat today because we are going to the ice. Ice sheets, ice shelves, sea ice. What's the difference? Well, you're going to find out right now. Antarctica has a lot of ice, and Antarctica is a continent, which means that there is land underneath it. So the ice that's on top of the land is the ice sheet. Think of it like a bedsheet. Antarctica is also surrounded by the Southern Ocean. The ice that is not free but still above the ocean is the ice shelf. Then sea ice is just hanging out down there in the sea floating around. I'm telling you this now because I got these mixed up in the interview and my guest had to correct me, but that's okay. Now, each of these ice things has its own unique properties, geological processes, different wildlife rely on them for different things, and they respond differently to a changing climate, which is why we're going to tackle one at a time. Today, it's the ice shelf, and we'll get to the others in good time.
[00:01:36.290] - Clark
To tell us all about ice shelves and their role in the Antarctica, I found a physical oceanographer named Elin Darelius. A physical oceanographer is a scientist that studies the ocean through the lens of physics. Easy enough to understand, but not the easiest work to do. Dr. Elin Darelius is a professor at the University of Bergen in Norway, and she studies how the Southern Ocean and the Antarctic ice shelves interact with each other and how these interactions are changing over time. We talked about how this work is done, what trends we see emerging in recent data, and the importance of ice shelves in our global climate system and the role they play in the polar region, and Without further ado, let's get started. Hello, Dr. Darelius. First of all, welcome. Thank you for coming on the show. The first question is if you could just introduce yourself and tell us a bit about your research.
[00:02:33.060] - Speaker 1
Of course. My name is Elin Darelius. I'm a professor in physical ocenography at the University of Bergen in Norway. I spent most of my career working in the Southern Ocean onto the continental shelves surrounding Antarctica on the water masses there and how they interact with the floating ice shelves
[00:02:52.800] - Clark
Okay. It sounds like you have a very cool job. I'm curious though, what made you want to study ice shelves in the first place?
[00:03:00.220] - Speaker 1
I'm not really studying the ice shelves, right? I'm studying the ocean and how that influences them. When I was a student along at I'm a call, I found it very fascinating that you can describe something as an understandable as the ocean with the math and physics. That's how I came into physical ocenography. The reason I choose to focus on polar ocenography is at least partly because I get terribly seasick. But if you're in the polar ocean, there are sea ice and so there are a little wave motion. So that's very good.
[00:03:36.840] - Clark
Okay. I'm glad you found a solution there. Well, it sounds like that might have even been the answer to my next question, but I like to ask everyone who I talk to, have you been to Antarctica? And then I'm wondering if you can tell us about some of the specific projects that took you down there.
[00:03:50.920] - Speaker 1
Yeah, I think I've been five or six times to Antarctica. All but one time, I've been on icebreakers or on large research vessels, so mostly in the Southern Weddell sea. My first cruise when was that 2004, so a long time ago. Up through the years, we've been deploying océanographic moorings, so instruments that we leave in the water between the sources that record the temperature and the salinity, the currents in the ocean. Then we come back a few years later and we can pick up the moorings and look at the data. That's most of the work I've been doing.
[00:04:30.070] - Clark
Okay, so a mooring in oceanography is a collection of instruments. They are attached to a wire that goes all the way down to the sea floor, and it is anchored there in a stationary place, so it doesn't move. And along the wire are buis and various measurement devices to track different variables, some of which were just mentioned. And it's used to collect data from a single location in the ocean along the water column.
[00:04:59.230] - Speaker 1
The last time I got the chance to join an expedition that's actually working on Antartican on one of these ice shelves, the Fimbul ice shelf in Drôning Mårdland. Then we drilled through the ice shelf to access the water, ocean cavity beneath and again, then install mooring instrumentation below the ice shelf or within the ice shelf cavity.
[00:05:22.550] - Clark
Okay, wow. What research questions are connected to data like that? What are you trying to find out by placing a mooring underneath an ice shelf?
[00:05:31.830] - Speaker 1
Yeah. One of the overarching question is the future of the Atlantic ice sheet. The ice sheet, which is the portion that's on land, it extends out into the ocean by these floating ice shelves. These are then in contact with the ocean to the ocean water below them. That water has heat that makes the ice shell melt from below. The The questions we're addressing is how much heat is the ocean bringing into the ice shell cavities that can be used to melt? What are the processes determining how much of this warm water that can reach the ice shelf?
[00:06:15.810] - Clark
Okay, that makes sense. We're going to get into why answering those questions is very important. But first, for clarity, because there are a lot of ice words when it comes to Antarctica. We've got ice shelves, ice sheets, icebergs. I've heard ice cores. An ice shelf is on top the land and an ice sheet is on top of the ocean?
[00:06:33.550] - Speaker 1
No, so the other way around. The ice sheet is on land. The ice shelves are the floating portions of floating part on the seaward side. Iceberg, then a piece of ice shelf that's broken off. Then you have sea ice. That's ice that's formed in the ocean when the air temperatures are low, just like ice forms on a lake. Those are very different kinds of ice. The sea ice would grow to thicknesses of a couple of meters, 2, 3 meters, typically in Antarctica. Whereas the ice shelves, where they are hundreds of meter thick. So when you're on top of them, you don't really know that you're actually on the ocean. It feels like you're on land.
[00:07:23.850] - Clark
Okay, thank you for clearing that up. Ice sheet covers the land, ice shelf hangs over the ocean. So you belong to a research group called Frisp, F-R-I-S-P, which concentrates on the processes controlling ice shelf behavior. So two questions there to unpack that. First, what kinds of behaviors do we see from ice shelves? Second, what processes control them? And also, maybe you can give us a few words about this research group.
[00:07:53.080] - Speaker 1
Yeah. So Frisp is an old group, and the original, originally the name, it was It's the same abbreviation, Frisp, but it was short for Frizzleranie Ice Shelf product. Filsha Rani is one of the largest or the largest ice shelf in Antarctica. You find it in this southwestern model sea. Initially, it was a group of researchers that worked together on a large project in that area. Then that project ended and they kept the aberration but shifted the meaning. Now it's, let's say, a group of researchers who all work with different aspects of ice shelf research, so glassologist, ocenographers, and everything around that. We have a workshop every year trying to bring people from different disciplines together and discuss their science and build a network and learn more.
[00:08:51.250] - Clark
Okay. The new meaning of Frisp is the Forum of Research into Ice Shelf Processes, which is part of SCAR, the Scientific Committee on the Antartic Research, research which has come up and will continue to come up on the show.
[00:09:04.760] - Speaker 1
The processes that would be referred to, that for example, things related to iceberg carving and related to ice shelf melt and what I talked about before, how the ice shelf melt from below and all the processes involved in that interaction with the ocean. What else are people working with? How the ice shelf is moving and how it's controlling the ice sheet upstream. The ice shelf is floating. I said in the beginning, I said that the overarching theme or motivation for our research is the future of the Atlantic ice shelf. That's because that's very important for the sea level. So if Antarctica melts, sea level rises, but the ice shelves, they are already floating. You may then think that it doesn't matter if they melt because that's just like we have ice cubes in your glass of Coke, and when they melt, that doesn't change the level of Coke in your glass. It's just the ice shelves disappearing or ice cubes.
[00:10:06.490] - Clark
Right. So massive amounts of ice melts and refreezes every year in both the North and the South Pole. And if it was already in the sea, then it's not a concern for sea level rise under stable climate conditions. Are there ways where ice shelf melting can influence sea level rise?
[00:10:25.130] - Speaker 1
The ice shelves are important to the sea level because they keep the ice sheet in place or they hold it back. We call that buttressing. That's the effect of how the ice shelves are stabilizing. If you want the ice sheet upstream and keep it from just moving out to the ocean. The question is related to that are processes that people are working with. Also, when you have fresh water entering the ocean from beneath the ice sheet, how is that affecting melt? How is that affecting the shape? Because the ice shelves ice in water, so it will melt differently depending on how the ocean is moving or circulating. Due to the temperature of the water, water will shape on the side of the ice. Processes related to that are also things that we're talking about.
[00:11:20.700] - Clark
Okay, so ice shelves prevent sea-level rise by keeping ice sheets in their place, and ice shelves melting could potentially inhibit their ability to do It seems like ice shelf melting can also have some other effects on the surrounding ocean. I'm curious, are we noticing any changes in data in the recent past in the way that these ice shelves are behaving?
[00:11:42.100] - Speaker 1
Oh, it's not changes that you can really see with your eye. Icebergs are breaking off. You see that, but that's the natural process. But I mean, people working with satellite data, for example, you can have a view of all over the continent and have long time series, there is evidence that the ice is thinning and accelerating in many areas.
[00:12:08.050] - Clark
What effect will this have on the surrounding environment or even the ecosystem, for example?
[00:12:13.320] - Speaker 1
If the ice shelves melt, that will have implications for sea level because the ice sheet behind will accelerate. So more ice will move from land and out into the ocean and then the sea level rise. So that's one thing. Another thing is that, of course, if you increase melt around a Tauke, then you will add all this fresh water to the ocean. If you add fresh water, then you change the density. That will affect how much sea ice is formed and lots of other things also. I'm not a biologist, but I would presume that it will also affect the conditions for the smaller life if you change the salinity. When you add all this fresh water, you will also, at least in the long run, you will affect the dense water formation that now occurs around Antarctica.
[00:13:09.380] - Clark
I'm not a biologist either, but what I do know is that all of the organisms in the sea have evolved to be best fit to survive in whatever current environmental conditions they have found themselves in. Continual changes in density, salinity, and certainly temperature will constitute an environmental pressure for sure. I did a bit of research and I found that a decrease in salinity will have an impact on krill, which we will find out in an upcoming episode are really the backbone of the Antarctica ecosystem. But their larvae rely on sea ice for a number of reasons, and decreased salinity can reduce levels of sea ice formation. In terms of density, water density affects nutrient cycling from lower depths to the surface, and plankton at the surface rely on this, so we can see an impact on plankton. Finally, temperature. We've seen evidence that warming of water can affect Antarctica silverfish by altering their breeding habits and even by making them more susceptible to disease. So a lot of biological impacts of this sea shelf melt.
[00:14:11.740] - Speaker 1
In the present climate on the continental shelves around Antarctica, especially in the Weddell Sea and the Ross Sea, you form during winter very dense water. Dense sea water, that's water that's cold and has a high salinity. This water then cascades down off the continental shelf and down into the deep ocean and form what we call the Antartic bottom water. This bottom water is then spreading through the world's ocean, northwise. You find it at the bottom of all over the world. There are observations showing that the production is reducing, that the dense water is less dense, it's warmer, and so on. That will also contribute to sea level because if the water is less dense, if it's warmer, it means that it takes more space, and so then the sea level will rise.
[00:15:04.610] - Clark
I'm going to quantify the impacts of sea level rise on humans in a couple of weeks when we talk about ice sheets. But this phenomenon definitely poses a host of risks to humans. I want to ask you another question. I've heard before that ice is important to regulating our climate and temperatures because it is white and therefore reflects the sun's energy back into space rather than absorbing it. How How concerned do we need to be about ice shelves' ability to perform this function on account of increased melting?
[00:15:36.340] - Speaker 1
This is what's called the albedo effect. You know, if you go out on a sunny day, it's a big difference in how warm you feel if you have a white shirt on or if you have a black one. If you melt ice on the ocean, then you effectively change its color from a quite bright white, if you have snow, to dark blue. The blue ocean will then much more effectively absorb solar heat than the white sea ice. But if you think of Antarctica, so if you reduce the ice thickness by a factor of two, it will still be white. So that effect is less... I mean, you can still have it partly if you form melt ponds on the surface and so on, but it's less dramatic than compared to in the Arctic. If you melt the sea ice in the Arctic, it will be replaced by dark blue ocean.
[00:16:32.630] - Clark
Other than general action to address climate change on the whole, is there any policy intervention you think could be addressed specifically to the ice shelves?
[00:16:43.740] - Speaker 1
No, not really. I mean, there is some talk about really large scale geo engineering where people are suggesting to build large underwater walls or curtains to stop or hinder warm water to enter the ice shelf committees. But I don't think we should go there. I think we should rather cut emissions and try to fix it in that end.
[00:17:12.170] - Clark
Yeah, I mean, those could be really cool ideas, but they're certainly not long-term solutions, and they're also not addressing the root cause. I guess we have to solve climate change, guys. Let's get to it. Now, on episodes where we talk about some of these anxiety-inducing major global problems like climate change, sea-level rise, for example, Now, towards the end, I'd like to ask if there's one piece of recent good news you can share that's come out in your field of research.
[00:17:37.000] - Speaker 1
Good news is that there are large technological advances and instrumentation making it possible for us to access and study regions that we haven't been before. I have a colleague at Gothenburg University, and she has this underwater AUV, so automatic underwater vehicle that they send in the eye shelves. It's swimming around mapping the other side of the eye shelf and the water and also the bottom and the amount of new data and insights that's coming out of that. I think that's just amazing to see There's so many things under there that we do not yet understand, but at least now we know what's there and that can hopefully bring us forward when we manage to understand what's actually happening there. That's maybe good news.
[00:18:30.210] - Clark
Yeah, I'd say that counts as good news.
[00:18:32.450] - Speaker 1
Unfortunately, that's another bad news. She lost it on her last cruises, but I think there will be a new version of it coming.
[00:18:41.530] - Clark
Oh, no. Okay, I'm glad to hear she's going to get another one. Next, I want to ask, what is your favorite thing about either Antarctica or the Southern Ocean environment?
[00:18:50.920] - Speaker 1
I think it's that there is so much we don't know. That's the motivation. It's a very fascinating environment. Very beautiful.
[00:19:02.590] - Clark
Oh, I wanted to ask you, too, do penguins come into the ice shelf equation at all?
[00:19:07.050] - Speaker 1
No, they don't really. They come onto the ice shelf occasionally, but Yeah. You wonder what they're doing there, but they don't affect the ice shelves. Not that I know of.
[00:19:22.400] - Clark
Okay. Then the last question I have is, is there anything that we missed today that you think is really important to mention when it comes to studying either the ice shelves or how oceans interact with them?
[00:19:32.390] - Speaker 1
There is so much to say. I only scratched on the surface. How much time do you have? I can talk for hours about ocean and the ice shelves interaction, but maybe we will save that for another time.
[0:19:49.000] - Clark
Okay. Well, then where can listeners find you and keep up with your work?
[00:19:52.850] - Speaker 1
I have a blog. I'm not very active right now, but I try to be so when I'm at sea or doing something exciting. It's elindarielius. No.
[00:20:06.260] - Clark
Okay. Well, listeners can find a link to that and much more in the episode description. This is the part where I say thank you so much for your time today. Thank you for teaching us about ice shelves and for your very important research.
[00:20:17.600] - Speaker 1
Thank you.
[00:20:27.690] - Clark
Okay. A major thank you to Dr. Elin Darelius. When I started this episode, I thought we'd be talking about ice melt and climate change, but it revealed again just how intricate the Antarctica ecosystem really is. We ended up mentioning ocean salinity, krill and plankton, density and nutrient cycling, and even underwater robots. Science is pretty cool, and so is this continent. As we close out the episode, and I know it's only the fourth one, and I already feel like a broken record, but this interview is just another example of how we are more connected to Antarctica than we probably realize. Last week, we talked about seabirds, and we learned how our human actions have an impact down south. And that's true with the ice shelves, too. But this is the first glimpse of how what happens down there may start to affect us up here. If you love this episode on ice shelves, I encourage you to follow the show so you don't miss an upcoming episode on ice sheets, because despite what you may assume, they are very different. Thank you to all of you who have made it this far, and we'll talk soon.
[00:21:41.830] - Clark
You've been listening to South Pole. You can find more information about this week's guest and links to their work in the episode description. Cover art for the show was done by Laurel Wong, and the music you're listening to was done by Nila Ruiz. I am your host, Clark Markezi, and this episode was produced, written, and engineered by me. So if you found it interesting, send it to someone you know. South Pole is part of a larger network of sciencey podcasts called Pine Forest Media. We've got one on plastic, one on drinking water, and a couple of new ones coming out soon. You can find more information about us in the episode description as well or on our website at pineforestpods. Com. We are also on Instagram and TikTok at Pineforest Media. If you love the show and want to support science communication like this, a five-star rating across platforms and a review on Apple podcast is one of the best things you can do to help us reach more people and for the entire network to grow. All right, thanks again to everyone who's made it this far, and we'll talk soon.
