57. Rising sea levels – more data for better modelling
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CORDIScovery podcast- Episode #57 - Rising sea levels – more data for better modelling.
This is an AI transcription.
00:00:20:21 - 00:00:38:11
Abigail Acton
The best way to understand what’s coming is to look at what happened in a similar context, in the past. So, what can prehistoric ice tell us about sea-level rise, one of the most damaging impacts of climate change? Threatening the economy, the ecology, and the existence of coastal regions worldwide,
00:00:38:12 - 00:01:03:13
Abigail Acton
global-mean sea level has risen by around 8 cm since 1992. Land ice loss and ocean thermal expansion contribute equally: the future of sea level rise is set to become dominated by the highly uncertain behaviour of the Antarctic and Greenland Ice Sheets. The potential for the rapid collapse of these ice sheets, which may already be underway, is making us aware of humanity’s vulnerability to ice-sheet change.
00:01:03:13 - 00:01:32:09
Abigail Acton
So, knowing how they are reacting to global warming is central to getting a clearer idea of what lies ahead. Our three guests, all of whom have received support from EU research and innovation funding, have been working on improving our understanding of these interactions. Here to share their work with us today are: Eric Wolff, an Honorary Fellow at the British Antarctic Survey, who studies past climate and environment, mainly from polar (Antarctic and Greenland) ice cores.
00:01:32:10 - 00:01:39:15
Abigail Acton
He is a Royal Society Research Professor in the Department of Earth Sciences at Cambridge University. Hello, Eric.
00:01:39:16 - 00:01:40:18
Eric Wolff
Hello there.
00:01:40:20 - 00:01:56:19
Abigail Acton
Alessio Rovere, a professor at the Department of Environmental Sciences, Informatics and Statistics, at Ca’Foscari, the University of Venice, is interested in paleo climate & sea level changes and how geological processes have changed coastlines over deep time. Hello, Alessio.
00:01:56:20 - 00:01:57:24
Alessio Rovere
Good morning everyone.
00:01:58:00 - 00:02:20:18
Abigail Acton
Good morning. A Director of Research at the French National Centre for Scientific Research (CNRS), Gaël Durand specialises in the modelling of polar ice sheets and the dynamics of coastal glaciers, with a focus on their impact on sea-level rise. He is particularly interested in understanding the stability of ice sheets, and their potential responses to climate change. Hello, Gaël.
00:02:20:22 - 00:02:22:16
Gaël Durand
Hello. Thank you.
00:02:22:18 - 00:02:36:08
Abigail Acton
Eric, I'm going to turn to you first. The WACSWAIN project aimed to understand what happened to the West Antarctic Ice Sheet during the last interglacial period. Eric, when was the last interglacial period, and why is understanding that important for us now?
00:02:36:09 - 00:03:00:23
Eric Wolff
So the last interglacial period is a few thousand years, around 125,000 years ago. And it's a period when we know that the polar regions were a little bit warmer than today. And there's evidence from, particularly from corals suggesting that sea level was higher than it is today. So that suggested that the Antarctic Ice Sheet must have been partly lost during the last integration.
00:03:00:23 - 00:03:18:13
Eric Wolff
And we're particularly interested in West Antarctica, which is considered the most vulnerable part and as glaciologist, it was kind of shocking to me that we didn't actually know. We didn't actually have any direct evidence as to whether the West Antarctic Ice Sheet was there or was completely missing at this crucial time in the past.
00:03:18:14 - 00:03:20:21
Abigail Acton
Gosh, yes, that's quite a gap in the knowledge, isn't it?
00:03:20:22 - 00:03:37:16
Eric Wolff
It is. So we tried to think of ways to find this out. And the approach that I took, because it's my specialty, is to drill an ice core in an area very near to the West Antarctic Ice Sheet. But there would be sensitive to the presence or absence of that ice.
00:03:37:17 - 00:03:47:23
Abigail Acton
Right, okay. So that must have presented enormous challenges. Can you tell us a little bit more about how you go about actually extracting ice cores that are that old? I mean, there must be vast, great big long cores?
00:03:48:01 - 00:04:16:08
Eric Wolff
Yes. So this ice core was 650m long. But I don't want people to think that somewhere we've got 650m in one piece, it comes up in 1 or 2 meter sections and is stored in a deep freeze somewhere around Cambridge. So to do that, we had to go to the Antarctic. Well, firstly, we had to find the right place where we thought we would get this ice that was particularly sensitive to the to the ice sheet presence, and that was accessible to us.
00:04:16:08 - 00:04:45:18
Eric Wolff
But it's a pretty inaccessible place. We did this in one field season. So a field season means about three months between November and January in the southern hemisphere summer. So we went in November 2018. We're a team of eight people, basically spent a lot of time digging, eventually drilling, cutting up ice with a band saw and putting it in polystyrene boxes in order to send them back to the United Kingdom for analysis.
00:04:45:19 - 00:04:47:24
Abigail Acton
Very carefully labeled polystyrene boxes.
00:04:48:00 - 00:04:55:16
Eric Wolff
All carefully labeled in every core. Actually, that's the one important thing. Every core has an arrow on it pointing up because it's a shame to turn 100 years upside down.
00:04:55:21 - 00:05:07:00
Abigail Acton
Yes, that's true. I don't even thought of that sort of the labeling, but hadn't thought of being up or down. Absolutely, indeed. And were you satisfied with the amount of samples that you managed to get? Did you feel that you were in the right place and that you got what you needed?
00:05:07:01 - 00:05:25:07
Eric Wolff
Yes. So the crucial thing is we got to the bottom without losing the drill, which is always an important thing. So we've got 650m of core. And it turned out subsequently when we did the analysis that it does indeed go back to this period we were interested in, 125,000 years ago. So after a lot of cold feet and cold hands, we had what we were after.
00:05:25:08 - 00:05:33:10
Abigail Acton
Okay, great. And how did by looking at it? What characteristics were you looking for that would indicate how old it was and that it was inappropriate sample?
00:05:33:12 - 00:05:51:09
Eric Wolff
Well, there are lots of ways to find out how old the ice is. We can actually match up with previous calls in other parts of Antarctica that have gone back to the same period, and certain things like the concentration of greenhouse gases, for example, should be the same in every ice core you drill in Antarctica. So we can match up the pattern.
00:05:51:10 - 00:06:04:01
Eric Wolff
We also sent some samples off to a laboratory that can measure a radioactive element that's krypton-81. That's sensitive to the age of the ice. So we did some checks near the bottom to make sure we really did have ice the age that we thought we had.
00:06:04:02 - 00:06:07:03
Abigail Acton
Great. Okay. And what do the samples tell us?
00:06:07:05 - 00:06:27:23
Eric Wolff
So the most important two things that samples told us. Firstly, it turned out that the ice is a little warmer than one would expect for that period, which actually implies that the ice sheet is a bit thinner than it used to be, which implies that there was less ice in the past. So the West Antarctic Ice Sheet did partly disappear at that time.
00:06:28:00 - 00:06:47:23
Eric Wolff
But then also it sits next to what we call an ice shelf, which is hundreds of kilometers of floating ice that have come off the ice sheet and sit over the ocean. And many ice sheet models suggest that under a warming situation that ice shelf would disappear. We can tell whether that happened, because we can measure sea salt in the ice.
00:06:47:23 - 00:07:09:09
Eric Wolff
And sea salt, of course, comes from the edge of the ice, from the ocean water on the edge of the ice. So currently the seawater is 600km away from where we were drilling. If the ice shelf had disappeared, it would be 50km away. So we would see it would be a seaside resort. We'd be able to smell the salt in the air effectively, and we'd certainly be able to measure it in our ice core, but we actually found that it didn't change.
00:07:09:09 - 00:07:27:12
Eric Wolff
And that implies that the ice shelf didn't retreat. So it's kind of good news and bad news. The bad news is that the ice sheet was smaller in the last interglacial. But the good news is we didn't lose that ice shelf, which is crucial for holding back the inland ice. So it means it's not quite as bad as some people have suggested it could have been.
00:07:27:13 - 00:07:32:20
Abigail Acton
Right. So that ice shelf facts almost as a barrier to stop the ice sheet from from slipping into the water.
00:07:32:21 - 00:07:40:19
Eric Wolff
Exactly that. It acts as a restraint. We actually talk about it as restraining. You think of it as a hand pushing back against the ice and stopping it.
00:07:40:19 - 00:07:42:01
Abigail Acton
Holding it in place.
00:07:42:02 - 00:07:42:13
Eric Wolff
Yeah.
00:07:42:19 - 00:07:51:11
Abigail Acton
Okay. Very interesting. Okay. Super. Thank you very much, Eric, for explaining that to us. Does anyone have any observations or comments to make to Eric? Yes, Gaël, what's your question?
00:07:51:17 - 00:07:58:12
Gaël Durand
Were you able to reconstruct the volume that was lost at that time from West Antarctica?
00:07:58:14 - 00:08:15:15
Eric Wolff
I would probably not claim that we were that precise. I mean, we could make an estimate for how much the ice where we are thinned, and we can look at ice models that have been run for the last interglacial and see whether they're consistent with what we said, but we can't actually estimated ourselves, I think is the answer.
00:08:15:15 - 00:08:26:09
Eric Wolff
So the main benefit of this is that it it enabled us to rule out certain versions of ice sheet models that either suggest the ice shelves disappeared or that suggest that nothing at all happened.
00:08:26:10 - 00:08:29:00
Abigail Acton
It gives you a more accurate picture of what was happening at that time.
00:08:29:01 - 00:08:34:11
Eric Wolff
Yes, but we need people to run more models in order to have more chances to understand what happened.
00:08:34:12 - 00:08:40:22
Abigail Acton
Well, we're going to come to that in a second, I suspect. Excellent. Perfect. It's a wonderful segue. Alessio, would you like to ask something?
00:08:40:24 - 00:08:55:09
Alessio Rovere
Yeah. I have a question for you, Eric. The last interglacial was long, like 15,000 years more or less, do you have any clue for when the melting happened (early? late?) in this long period?
00:08:55:13 - 00:09:15:08
Eric Wolff
Well, I'm pretty sure, although we actually are missing a very small amount of ice right at the beginning of the interglacial, but it's pretty clear that it was at its minimum at the beginning of the interglacial towards the beginning of the interglacial. Okay. So I think that's probably not surprising to us based on other things that we knew, but that turns out to be the case.
00:09:15:09 - 00:09:16:07
Abigail Acton
Confirmation.
00:09:16:08 - 00:09:16:18
Eric Wolff
Yeah.
00:09:16:19 - 00:09:39:16
Abigail Acton
Okay, Alessio, I'm going to turn to you now. Actually, WARMCOASTS offers insights into sea level and storm scenarios that can help us to assess the extent to which global temperature increase will impact our coastal areas. Eric's walked us through what ice core samples can tell us about the ice sheets in the last interglacial, but can you tell us why that period can help us with simulations for the future?
00:09:39:17 - 00:10:03:19
Alessio Rovere
Well, yes of course. Well, first of all, , WARMCOASTS was born because I don't like to go on the ice as Eric and his colleagues do. I like to be more on tropical settings. And so this is where we are. We are looking for proxies of what happened in Antarctica. , how can it affect the coastlines even far away from Antarctica?
00:10:03:20 - 00:10:06:03
Abigail Acton
So Alessio, can I ask you to explain what is a proxy?
00:10:06:04 - 00:10:33:18
Alessio Rovere
Oh, yeah. A proxy is basically something that we can read in the geological record that gives us a clue about a property of what happened on our planet. We have proxies for sea level, for example, a coral which was growing back in time in a in a old reef. Or we have proxies for storms like sands deposited on top of a coastline that were deposited in a certain way that remind us of storms.
00:10:33:19 - 00:10:34:22
Abigail Acton
So it's like evidence.
00:10:34:23 - 00:10:36:21
Alessio Rovere
Yes, it's paleo evidence.
00:10:36:22 - 00:10:38:04
Abigail Acton
Paleo evidence. That's great. Wonderful.
00:10:38:04 - 00:10:40:03
Alessio Rovere
Paleo evidence for...
00:10:40:05 - 00:10:41:06
Abigail Acton
...for past events.
00:10:41:07 - 00:10:41:15
Abigail Acton
Yeah.
00:10:41:16 - 00:10:47:12
Abigail Acton
Super. Okay, so tell us a little bit more. Tell me about why the Last Interglacial is so significant on this level.
00:10:47:13 - 00:11:14:17
Alessio Rovere
Well, the Last Interglacial is very significant because this is the last time the Earth was, let's say I don't want to say as warm as today, but slightly warmer than today. So we speak about, there are many different estimates, but we speak about a couple of degrees Celsius higher than pre-industrial globally. And the poles we think five eight slash,
00:11:14:18 - 00:11:37:13
Eric Wolff
somebody says a little bit more, degrees warmer at the poles. So we are speaking about a world that is very similar to the one where we are, , towards where we are going. So that's something interesting to see if this happened in the past for different reasons than today, how can we try to project the future?
00:11:37:13 - 00:11:45:05
Alessio Rovere
How can we try to understand better the future by using the past, which is basically the foundation of geology, I would say.
00:11:45:06 - 00:11:51:13
Abigail Acton
Right. Super. So what did the WARMCOASTS project actually do? And then please tell me what you found. So what did you do?
00:11:51:14 - 00:12:24:12
Alessio Rovere
So what we did was basically going in different sites along the Atlantic. So we started from Patagonia in Argentina, and we drove our way up all the way to Brazil, then to the Caribbean coastlines. Then we went into the East Coast of the United States looking for these proxies. So looking for ancient corals, ancient beach deposits deposited in the last interglacial, which could give us clues about what happened in terms of sea level and storms during this past period.
00:12:24:12 - 00:13:00:15
Alessio Rovere
So we wanted to have a picture of the Atlantic during this past period of time by looking at, , paleo coral, fossil corals, fossil shells and cemented beach deposits in slightly above modern sea level. So this is what we did and what we, , what we used was basically lots of techniques such as, other than normal field geology, we would have ground penetrating radar to look under the surface to see how the beach was responding to pass climates under the surface.
00:13:00:15 - 00:13:16:02
Alessio Rovere
And we use many different dating techniques because whenever you find something like a shell or a coral which can be dated, you can use different geochemical methods to basically assign to it an age. We don't know how old the shell is just by looking at it. We need to bring it in the lab.
00:13:16:02 - 00:13:27:02
Abigail Acton
Sure, it sounds like you get together quite a lot of various disciplines here because it sounds like a broad range of specializations that permit you to have these insights. Is that the case?
00:13:27:03 - 00:13:47:15
Alessio Rovere
Yes, quite a lot. Actually, I'm a field geologist, so I was the one basically doing the measuring and collecting in the field. But then, , lots of colleagues come together, lots of different labs come together to actually adopt the different geochemical methods that you want to use to date a shell, for example, or a coral.
00:13:47:15 - 00:13:52:11
Alessio Rovere
And so you need to have lots of good collaborators scattered around the world and work with them.
00:13:52:12 - 00:14:06:01
Abigail Acton
It also sounds like you managed to generate a huge amount of data. You were looking at so many different things. That was such a large geographical area. So how can people have a look at your data? Is it just for other scientists or can anybody interested have a look? Tell us a little bit about how that is accessible.
00:14:06:01 - 00:14:39:10
Alessio Rovere
Well actually that's interesting because it's absolutely available to everybody. We have a website where we collected not only what we did, what we found around the world, but what people like us found from 1930s up to today. So we have about one century of research summarized in a big database, which is called the World Atlas of Last Interglacial Shorelines, where basically anybody can go and look and see if they have maybe a paleo shoreline, , on their backyard.
00:14:39:11 - 00:14:40:17
Abigail Acton
Yeah, fascinating.
00:14:40:19 - 00:14:46:02
Alessio Rovere
Which is often the case because there are several thousands of these places scattered around the globe.
00:14:46:03 - 00:14:49:18
Abigail Acton
Yeah. You might find yourself near one. And what's the website, please?
00:14:49:19 - 00:14:56:18
Alessio Rovere
It's warmcoasts.eu. And then you navigate to WALIS.
00:14:56:20 - 00:15:10:09
Abigail Acton
Wonderful. Navigate to WALIS, That's what we should all be doing. Well I'm not far away from Brighton coast and the white cliffs of Dover in that area. So maybe there's something there. There's lots of interesting fossils on the beaches around there. So maybe there's some other stuff there.
00:15:10:10 - 00:15:15:09
Alessio Rovere
They'd be older. But you might find something there from the last interglacial.
00:15:15:11 - 00:15:34:02
Abigail Acton
Yeah that's true. It is older. I've just remembered my little tiny bit of geological knowledge nonetheless. Have a look and see if your area actually has some information for you. So finally, is there something that you want us to remember from your project? Is there something that you think is of particular interest, maybe to anybody charged with making policy or any takeaways?
00:15:34:03 - 00:15:58:02
Alessio Rovere
Well, , starting also from Eric's research. So we know that Antarctica is probably going to be one of the issues that we have to face in the future, right. And we are probably already half facing it. And what we found was that compared to what was done previously, it was thought that sea level during this period, during the last interglacial was, say, 5 to 10m above present.
00:15:58:02 - 00:16:30:08
Alessio Rovere
But, also thanks to our research, we start to think that it was about maybe a bit lower than that, like 2 or 3m, four meters maximum as a peak during the last interglacial. Now different ice sheets could have contributed in different ways or with different timings. Hence my question to Eric before. But it's actually very important to remember if in a warmer period, similar to where we are going like two degrees Celsius global, is in the talks, right?
00:16:30:09 - 00:16:54:12
Alessio Rovere
Is in what we are talking about in terms of policy. So if this is what was produced during a warmer period, let's say a couple of meters of sea level rise, then think about our coastlines and even a meter of sea level rise. It's quite a big problem for us. So we need to think about it. And I live in Venice so I know.
00:16:54:14 - 00:16:56:10
Abigail Acton
Yeah. Some places more vulnerable than others.
00:16:56:11 - 00:16:57:10
Alessio Rovere
Yeah.
00:16:57:11 - 00:17:02:07
Abigail Acton
Thank you so much. Alessio. Does anyone have any observations or questions for Alessio? Gaël, yes, please.
00:17:02:08 - 00:17:07:20
Gaël Durand
And what about the storms? this change anything with time during that period?
00:17:07:22 - 00:17:32:01
Alessio Rovere
Well, I can tell you that finding the proxies for the storms was incredibly difficult. We tried hard, like, super hard. So I can't give you an answer because we found some evidence of past storms, but we could get to the point where we refined the models that we borrowed from coastal engineering, basically, to understand more about the storms.
00:17:32:01 - 00:17:56:17
Alessio Rovere
So this is a question we are leaving for the future generations of scientists. There are, I think, places where you can see, like in the Bahamas, in some places you can see that storms were possibly a bit stronger than today. And one of the things I am more convinced about from some proxies is that probably there was a change in direction of the storm, not as much in intensity, but in direction.
00:17:56:20 - 00:18:19:20
Alessio Rovere
I mean, if you think about the fact that today everything we built on the coastline is based on intensity and direction of a storm, like a harbor, construction is based on intensity and direction, changing direction, even just a few degrees. It's actually something very dangerous, if it happens. And in some places we think it may have happened in Argentina, for example.
00:18:19:20 - 00:18:22:07
Alessio Rovere
So there is something to be aware of.
00:18:22:07 - 00:18:24:06
Abigail Acton
Something else to add to the picture.
00:18:24:07 - 00:18:24:19
Alessio Rovere
Yeah
00:18:24:20 - 00:18:38:17
Abigail Acton
Yeah. Thanks for that question, Gaël. And I'm going to turn to you now. We need a better understanding of the interactions between the atmosphere, the ocean and the ice sheets, which is where the PROTECT project comes in. So Gaël, can you tell me why did this field of research attract you?
00:18:38:19 - 00:19:10:12
Gaël Durand
Actually, I started my research by studying a path climate. And actually, during my PhD, I worked together with Eric on the EPICA project, on the DOME C ICE CORE in Antarctica, which turned to reveal the story of climate for the last 800,000 years. And it was some 20 years ago. And at that time, new satellite observations started to reveal that the ice sheets were losing mass and contributing to the rise at a rate higher to what we were expecting.
00:19:10:12 - 00:19:40:05
Gaël Durand
So that was typically for a young researcher and exciting topic. And also still, a rise is not simply a scientific topic. It is a fundamental issue for the long term organization of human societies. So we already know that sea level rising. We know this process will continue for centuries, but at which rate? This remains a key question even after two decades of efforts by the research community.
00:19:40:05 - 00:19:54:03
Gaël Durand
So having a modest word in such a big societal question was really appealing to me. So, from a scientific perspective, what I personally find fascinating is the highly non-linear behavior of issues.
00:19:54:04 - 00:20:02:06
Abigail Acton
So the highly nonlinear behavior. So what do you mean by that? When you say nonlinear, you mean it's not predictable. Just because something happens at one point doesn't mean it will repeat.
00:20:02:07 - 00:20:19:10
Gaël Durand
I'm not saying that it's not predictable. I'm saying that the response is not only gradual in a simple and predictable in simple way. There are thresholds that may exist and be on which part of Ontario region of the Ice Sheet I could undergo a self-sustaining retreat.
00:20:19:13 - 00:20:24:01
Abigail Acton
Okay, yes, I see what you mean. You mean that there are triggers that can make things happen in stops and starts?
00:20:24:02 - 00:20:24:21
Gaël Durand
Exactly.
00:20:24:22 - 00:20:42:20
Abigail Acton
Yeah. Okay. Can you tell me... PROTECT brought together these various parameters that the atmosphere, the ocean and the ice sheet. So, we've talked a bit about the ice and what that can reveal. And also, what's studying the coasts now can tell us about the past. You kind of brought all three of these things together.
00:20:42:20 - 00:20:45:21
Abigail Acton
So can you tell me a little bit about what project actually did?
00:20:45:22 - 00:21:10:20
Gaël Durand
So, the largest uncertainty in the coming see level rise for the coming centuries, clearly attached to the evolution of both Ice Sheets and the only available tool to investigate the future similarly to weather forecast actually it's numerical models. So PROTECT aims at contributing to improve ice sheet and climate models and hopefully better constraint in certainty in future sea level rise.
00:21:10:22 - 00:21:37:08
Gaël Durand
And there are various ways to do so. First we need to better understand some critical processes and their representation in the numerical models. So for example, the water from the ocean could flow below the Ice Sheet, lubricate the bedrock, and enhance the sliding of the glacier, increasing its flow toward the sea and then its contribution to sea level.
00:21:37:10 - 00:22:04:20
Gaël Durand
Even if ice sheets are far away from us, they are not isolated from the rest of the climate system. They respond to the forcing of the ocean, of the atmosphere, even the Earth's crust and mantle. So better representing this interaction in the models is key. It's basically a reminder of an artifact of the past. Today, Scandinavia is rising up because from 20,000 years ago there was a huge ice sheet.
00:22:04:20 - 00:22:23:12
Gaël Durand
So due to the load of the ice sheet, the Earth's crust sank and now there is no more ice sheet. So it's going up. And it's also the case in Greenland and Antarctica because the ice sheet were bigger before. And if we continue losing mass this rise will change. So we have to take into account is changing this.
00:22:23:17 - 00:22:26:19
Abigail Acton
So the notion is there that the land might rise slightly.
00:22:26:21 - 00:22:27:17
Gaël Durand
Exactly.
00:22:27:18 - 00:22:41:23
Abigail Acton
Oh okay. So that's an intriguing one. Okay. So we might bob up a little bit more like a cork above the rising levels. So movements in the ice and the dissolving of the sea ice raising the level of the oceans, but also perhaps causing landmasses to rise slightly.
00:22:42:00 - 00:22:51:23
Gaël Durand
Yes. Typically in Scandinavia today, the sea level is not rising, it's dropping. And actually the sea level is not dropping. It's like locally the earth is rising it.
00:22:52:03 - 00:22:58:20
Abigail Acton
It's fascinating. Thank you. Any other kind of examples of things that you have to take into account when you're doing a modeling characteristics.
00:22:58:22 - 00:23:21:17
Gaël Durand
Yes. Typically Antarctica is extremely cold and the melt at the surface of the earth is extremely limited. But depending on the climate evolution, it might really change in the future. And we know from Greenland observation that some melt leads to more melt. It's what we call the positive feedback loop. And it's important to take into account.
00:23:21:19 - 00:23:45:17
Gaël Durand
Also we know that in Antarctica the change we are observing are due to intrusion of warm water from the ocean below the ice shelf that fragilises this ice shelf and lead the granite ice sheet to flow faster. So we also need to better understand this connection between the ocean and the ice sheet.
00:23:45:21 - 00:23:57:11
Abigail Acton
After all this work on modeling and these complex modeling systems that you've managed to create. Can you tell us anything from the project that really stands out in your mind as memorable, or something that we should already take note of?
00:23:57:13 - 00:24:34:10
Gaël Durand
I think there are two major things that are emerging. The first one is that we often hear that I sheet models are disagreeing. I think they are agreeing much more than what we think for the coming decades, and that the amplitude of the sea level rise for the coming decades can be narrowed down. The other point, and I think this is really important, is that because of this threshold we have, and because the ice sheet and glacier are relatively slow elements of the climate system, we have what we call committed sea level rise.
00:24:34:10 - 00:24:54:14
Gaël Durand
So today we have already launched a given amount of sea level rise. Typically, if we look at the glaciers, whatever we do, even if we follow the Paris Agreement, we likely on the long term have lost 30% of the glaciers. But depending on what we will do in the future, we will commit even more on the long term.
00:24:54:19 - 00:25:06:01
Abigail Acton
Right. So it's a long term projection. And we're committed, as you say already to a certain amount. Thank you. That's very interesting. Thank you very much. Does anyone have any questions or observations to make? Yeah, Eric.
00:25:06:02 - 00:25:15:10
Eric Wolff
Gaël, you're obviously looking at both the Greenland and Antarctica sheet where I think you are at one, what can you tell us about which of them we should be most worried about?
00:25:15:11 - 00:25:51:06
Gaël Durand
I would say that it's Antarctica for two reasons. It's first, because it's absolutely huge. It's a 60 meter, approximately 58m of sea level that is over the continent of Antarctica when Greenland, it's about seven meters. So in terms of potential, there is much more ice that can be mobilized to go towards the ocean. And also it might be much faster in the contribution to see level rise if we have this instability starting popping up and rising up in the in the coming decades and centuries.
00:25:51:06 - 00:26:00:09
Gaël Durand
So I would fear more on Antarctica, but I'm biased. That's the ice sheet I have in my heart.
00:26:00:11 - 00:26:10:12
Abigail Acton
It is a very compelling area. I remember reading a book many years ago and always being totally caught up with the notion of Antarctica. Now it's a... have you been Gaël, have you visited it?
00:26:10:13 - 00:26:20:21
Gaël Durand
Yes, I was in Dome C in Concordia some 20, almost 25, years ago. That was great. And you realise how big it is.
00:26:20:23 - 00:26:26:18
Abigail Acton
Like a completely different alien environment. Yeah. Fascinating. Any other comments at all or observations to make?
00:26:26:19 - 00:26:40:05
Eric Wolff
Well, I was also going to ask Gaël because he's much nearer to sort of application and policy than probably than Alessio and I are. So do you feel that people are listening when you warn them about sea level rise?
00:26:40:07 - 00:27:14:19
Gaël Durand
This is a very hard question. I would say yes, they are frightened, but they don't listen that much in the sense that we, sea level practitioners, are most interested in the coming decades. When I think that the issue is on a longer timescale in our global organization, and I think this is hard to explain, that yes, what we are doing now is impacting generations of people and that we should act now.
00:27:14:21 - 00:27:28:09
Abigail Acton
Well, that's a strong way to end the episode. Thank you very much. Excellent. Okay. Thank you for your important work, guys. And at least it's reaching a slightly wider audience now. Hopefully people listening will take it on board. Thanks for your time.
00:27:28:10 - 00:27:29:02
Alessio Rovere
Thank you.
00:27:29:03 - 00:27:29:12
Eric Wolff
Bye.
00:27:29:13 - 00:27:30:17
Gaël Durand
Thanks a lot. Bye.
00:27:30:18 - 00:27:31:14
Alessio Rovere
Bye bye.
00:27:31:15 - 00:28:04:15
Abigail Acton
Goodbye. Thanks for coming. If you've enjoyed this podcast, follow us on Spotify or Apple and check out the podcast homepage on the Cordis website. Subscribe to make sure the hottest results in EU funded research and innovation aren't passing you by. And if you're enjoying listening, why not spread the word? We talked about how robots can help small wine producers stay in business, innovative ways of identifying the chemical agents used in possible terrorist attacks, and how the gut microbiome might impact the way patients respond to chemotherapy.
00:28:04:17 - 00:28:23:24
Abigail Acton
Maybe you're involved in a project or would like to apply for funding. Take a look at the CORDIS website and see what others are doing in your domain. So come and check out the research that's revealing what makes our world tick. We're always happy to hear from you. Drop us a line editorial@cordis.europa.eu. Until next time.
This is an AI transcription.
00:00:20:21 - 00:00:38:11
Abigail Acton
The best way to understand what’s coming is to look at what happened in a similar context, in the past. So, what can prehistoric ice tell us about sea-level rise, one of the most damaging impacts of climate change? Threatening the economy, the ecology, and the existence of coastal regions worldwide,
00:00:38:12 - 00:01:03:13
Abigail Acton
global-mean sea level has risen by around 8 cm since 1992. Land ice loss and ocean thermal expansion contribute equally: the future of sea level rise is set to become dominated by the highly uncertain behaviour of the Antarctic and Greenland Ice Sheets. The potential for the rapid collapse of these ice sheets, which may already be underway, is making us aware of humanity’s vulnerability to ice-sheet change.
00:01:03:13 - 00:01:32:09
Abigail Acton
So, knowing how they are reacting to global warming is central to getting a clearer idea of what lies ahead. Our three guests, all of whom have received support from EU research and innovation funding, have been working on improving our understanding of these interactions. Here to share their work with us today are: Eric Wolff, an Honorary Fellow at the British Antarctic Survey, who studies past climate and environment, mainly from polar (Antarctic and Greenland) ice cores.
00:01:32:10 - 00:01:39:15
Abigail Acton
He is a Royal Society Research Professor in the Department of Earth Sciences at Cambridge University. Hello, Eric.
00:01:39:16 - 00:01:40:18
Eric Wolff
Hello there.
00:01:40:20 - 00:01:56:19
Abigail Acton
Alessio Rovere, a professor at the Department of Environmental Sciences, Informatics and Statistics, at Ca’Foscari, the University of Venice, is interested in paleo climate & sea level changes and how geological processes have changed coastlines over deep time. Hello, Alessio.
00:01:56:20 - 00:01:57:24
Alessio Rovere
Good morning everyone.
00:01:58:00 - 00:02:20:18
Abigail Acton
Good morning. A Director of Research at the French National Centre for Scientific Research (CNRS), Gaël Durand specialises in the modelling of polar ice sheets and the dynamics of coastal glaciers, with a focus on their impact on sea-level rise. He is particularly interested in understanding the stability of ice sheets, and their potential responses to climate change. Hello, Gaël.
00:02:20:22 - 00:02:22:16
Gaël Durand
Hello. Thank you.
00:02:22:18 - 00:02:36:08
Abigail Acton
Eric, I'm going to turn to you first. The WACSWAIN project aimed to understand what happened to the West Antarctic Ice Sheet during the last interglacial period. Eric, when was the last interglacial period, and why is understanding that important for us now?
00:02:36:09 - 00:03:00:23
Eric Wolff
So the last interglacial period is a few thousand years, around 125,000 years ago. And it's a period when we know that the polar regions were a little bit warmer than today. And there's evidence from, particularly from corals suggesting that sea level was higher than it is today. So that suggested that the Antarctic Ice Sheet must have been partly lost during the last integration.
00:03:00:23 - 00:03:18:13
Eric Wolff
And we're particularly interested in West Antarctica, which is considered the most vulnerable part and as glaciologist, it was kind of shocking to me that we didn't actually know. We didn't actually have any direct evidence as to whether the West Antarctic Ice Sheet was there or was completely missing at this crucial time in the past.
00:03:18:14 - 00:03:20:21
Abigail Acton
Gosh, yes, that's quite a gap in the knowledge, isn't it?
00:03:20:22 - 00:03:37:16
Eric Wolff
It is. So we tried to think of ways to find this out. And the approach that I took, because it's my specialty, is to drill an ice core in an area very near to the West Antarctic Ice Sheet. But there would be sensitive to the presence or absence of that ice.
00:03:37:17 - 00:03:47:23
Abigail Acton
Right, okay. So that must have presented enormous challenges. Can you tell us a little bit more about how you go about actually extracting ice cores that are that old? I mean, there must be vast, great big long cores?
00:03:48:01 - 00:04:16:08
Eric Wolff
Yes. So this ice core was 650m long. But I don't want people to think that somewhere we've got 650m in one piece, it comes up in 1 or 2 meter sections and is stored in a deep freeze somewhere around Cambridge. So to do that, we had to go to the Antarctic. Well, firstly, we had to find the right place where we thought we would get this ice that was particularly sensitive to the to the ice sheet presence, and that was accessible to us.
00:04:16:08 - 00:04:45:18
Eric Wolff
But it's a pretty inaccessible place. We did this in one field season. So a field season means about three months between November and January in the southern hemisphere summer. So we went in November 2018. We're a team of eight people, basically spent a lot of time digging, eventually drilling, cutting up ice with a band saw and putting it in polystyrene boxes in order to send them back to the United Kingdom for analysis.
00:04:45:19 - 00:04:47:24
Abigail Acton
Very carefully labeled polystyrene boxes.
00:04:48:00 - 00:04:55:16
Eric Wolff
All carefully labeled in every core. Actually, that's the one important thing. Every core has an arrow on it pointing up because it's a shame to turn 100 years upside down.
00:04:55:21 - 00:05:07:00
Abigail Acton
Yes, that's true. I don't even thought of that sort of the labeling, but hadn't thought of being up or down. Absolutely, indeed. And were you satisfied with the amount of samples that you managed to get? Did you feel that you were in the right place and that you got what you needed?
00:05:07:01 - 00:05:25:07
Eric Wolff
Yes. So the crucial thing is we got to the bottom without losing the drill, which is always an important thing. So we've got 650m of core. And it turned out subsequently when we did the analysis that it does indeed go back to this period we were interested in, 125,000 years ago. So after a lot of cold feet and cold hands, we had what we were after.
00:05:25:08 - 00:05:33:10
Abigail Acton
Okay, great. And how did by looking at it? What characteristics were you looking for that would indicate how old it was and that it was inappropriate sample?
00:05:33:12 - 00:05:51:09
Eric Wolff
Well, there are lots of ways to find out how old the ice is. We can actually match up with previous calls in other parts of Antarctica that have gone back to the same period, and certain things like the concentration of greenhouse gases, for example, should be the same in every ice core you drill in Antarctica. So we can match up the pattern.
00:05:51:10 - 00:06:04:01
Eric Wolff
We also sent some samples off to a laboratory that can measure a radioactive element that's krypton-81. That's sensitive to the age of the ice. So we did some checks near the bottom to make sure we really did have ice the age that we thought we had.
00:06:04:02 - 00:06:07:03
Abigail Acton
Great. Okay. And what do the samples tell us?
00:06:07:05 - 00:06:27:23
Eric Wolff
So the most important two things that samples told us. Firstly, it turned out that the ice is a little warmer than one would expect for that period, which actually implies that the ice sheet is a bit thinner than it used to be, which implies that there was less ice in the past. So the West Antarctic Ice Sheet did partly disappear at that time.
00:06:28:00 - 00:06:47:23
Eric Wolff
But then also it sits next to what we call an ice shelf, which is hundreds of kilometers of floating ice that have come off the ice sheet and sit over the ocean. And many ice sheet models suggest that under a warming situation that ice shelf would disappear. We can tell whether that happened, because we can measure sea salt in the ice.
00:06:47:23 - 00:07:09:09
Eric Wolff
And sea salt, of course, comes from the edge of the ice, from the ocean water on the edge of the ice. So currently the seawater is 600km away from where we were drilling. If the ice shelf had disappeared, it would be 50km away. So we would see it would be a seaside resort. We'd be able to smell the salt in the air effectively, and we'd certainly be able to measure it in our ice core, but we actually found that it didn't change.
00:07:09:09 - 00:07:27:12
Eric Wolff
And that implies that the ice shelf didn't retreat. So it's kind of good news and bad news. The bad news is that the ice sheet was smaller in the last interglacial. But the good news is we didn't lose that ice shelf, which is crucial for holding back the inland ice. So it means it's not quite as bad as some people have suggested it could have been.
00:07:27:13 - 00:07:32:20
Abigail Acton
Right. So that ice shelf facts almost as a barrier to stop the ice sheet from from slipping into the water.
00:07:32:21 - 00:07:40:19
Eric Wolff
Exactly that. It acts as a restraint. We actually talk about it as restraining. You think of it as a hand pushing back against the ice and stopping it.
00:07:40:19 - 00:07:42:01
Abigail Acton
Holding it in place.
00:07:42:02 - 00:07:42:13
Eric Wolff
Yeah.
00:07:42:19 - 00:07:51:11
Abigail Acton
Okay. Very interesting. Okay. Super. Thank you very much, Eric, for explaining that to us. Does anyone have any observations or comments to make to Eric? Yes, Gaël, what's your question?
00:07:51:17 - 00:07:58:12
Gaël Durand
Were you able to reconstruct the volume that was lost at that time from West Antarctica?
00:07:58:14 - 00:08:15:15
Eric Wolff
I would probably not claim that we were that precise. I mean, we could make an estimate for how much the ice where we are thinned, and we can look at ice models that have been run for the last interglacial and see whether they're consistent with what we said, but we can't actually estimated ourselves, I think is the answer.
00:08:15:15 - 00:08:26:09
Eric Wolff
So the main benefit of this is that it it enabled us to rule out certain versions of ice sheet models that either suggest the ice shelves disappeared or that suggest that nothing at all happened.
00:08:26:10 - 00:08:29:00
Abigail Acton
It gives you a more accurate picture of what was happening at that time.
00:08:29:01 - 00:08:34:11
Eric Wolff
Yes, but we need people to run more models in order to have more chances to understand what happened.
00:08:34:12 - 00:08:40:22
Abigail Acton
Well, we're going to come to that in a second, I suspect. Excellent. Perfect. It's a wonderful segue. Alessio, would you like to ask something?
00:08:40:24 - 00:08:55:09
Alessio Rovere
Yeah. I have a question for you, Eric. The last interglacial was long, like 15,000 years more or less, do you have any clue for when the melting happened (early? late?) in this long period?
00:08:55:13 - 00:09:15:08
Eric Wolff
Well, I'm pretty sure, although we actually are missing a very small amount of ice right at the beginning of the interglacial, but it's pretty clear that it was at its minimum at the beginning of the interglacial towards the beginning of the interglacial. Okay. So I think that's probably not surprising to us based on other things that we knew, but that turns out to be the case.
00:09:15:09 - 00:09:16:07
Abigail Acton
Confirmation.
00:09:16:08 - 00:09:16:18
Eric Wolff
Yeah.
00:09:16:19 - 00:09:39:16
Abigail Acton
Okay, Alessio, I'm going to turn to you now. Actually, WARMCOASTS offers insights into sea level and storm scenarios that can help us to assess the extent to which global temperature increase will impact our coastal areas. Eric's walked us through what ice core samples can tell us about the ice sheets in the last interglacial, but can you tell us why that period can help us with simulations for the future?
00:09:39:17 - 00:10:03:19
Alessio Rovere
Well, yes of course. Well, first of all, , WARMCOASTS was born because I don't like to go on the ice as Eric and his colleagues do. I like to be more on tropical settings. And so this is where we are. We are looking for proxies of what happened in Antarctica. , how can it affect the coastlines even far away from Antarctica?
00:10:03:20 - 00:10:06:03
Abigail Acton
So Alessio, can I ask you to explain what is a proxy?
00:10:06:04 - 00:10:33:18
Alessio Rovere
Oh, yeah. A proxy is basically something that we can read in the geological record that gives us a clue about a property of what happened on our planet. We have proxies for sea level, for example, a coral which was growing back in time in a in a old reef. Or we have proxies for storms like sands deposited on top of a coastline that were deposited in a certain way that remind us of storms.
00:10:33:19 - 00:10:34:22
Abigail Acton
So it's like evidence.
00:10:34:23 - 00:10:36:21
Alessio Rovere
Yes, it's paleo evidence.
00:10:36:22 - 00:10:38:04
Abigail Acton
Paleo evidence. That's great. Wonderful.
00:10:38:04 - 00:10:40:03
Alessio Rovere
Paleo evidence for...
00:10:40:05 - 00:10:41:06
Abigail Acton
...for past events.
00:10:41:07 - 00:10:41:15
Abigail Acton
Yeah.
00:10:41:16 - 00:10:47:12
Abigail Acton
Super. Okay, so tell us a little bit more. Tell me about why the Last Interglacial is so significant on this level.
00:10:47:13 - 00:11:14:17
Alessio Rovere
Well, the Last Interglacial is very significant because this is the last time the Earth was, let's say I don't want to say as warm as today, but slightly warmer than today. So we speak about, there are many different estimates, but we speak about a couple of degrees Celsius higher than pre-industrial globally. And the poles we think five eight slash,
00:11:14:18 - 00:11:37:13
Eric Wolff
somebody says a little bit more, degrees warmer at the poles. So we are speaking about a world that is very similar to the one where we are, , towards where we are going. So that's something interesting to see if this happened in the past for different reasons than today, how can we try to project the future?
00:11:37:13 - 00:11:45:05
Alessio Rovere
How can we try to understand better the future by using the past, which is basically the foundation of geology, I would say.
00:11:45:06 - 00:11:51:13
Abigail Acton
Right. Super. So what did the WARMCOASTS project actually do? And then please tell me what you found. So what did you do?
00:11:51:14 - 00:12:24:12
Alessio Rovere
So what we did was basically going in different sites along the Atlantic. So we started from Patagonia in Argentina, and we drove our way up all the way to Brazil, then to the Caribbean coastlines. Then we went into the East Coast of the United States looking for these proxies. So looking for ancient corals, ancient beach deposits deposited in the last interglacial, which could give us clues about what happened in terms of sea level and storms during this past period.
00:12:24:12 - 00:13:00:15
Alessio Rovere
So we wanted to have a picture of the Atlantic during this past period of time by looking at, , paleo coral, fossil corals, fossil shells and cemented beach deposits in slightly above modern sea level. So this is what we did and what we, , what we used was basically lots of techniques such as, other than normal field geology, we would have ground penetrating radar to look under the surface to see how the beach was responding to pass climates under the surface.
00:13:00:15 - 00:13:16:02
Alessio Rovere
And we use many different dating techniques because whenever you find something like a shell or a coral which can be dated, you can use different geochemical methods to basically assign to it an age. We don't know how old the shell is just by looking at it. We need to bring it in the lab.
00:13:16:02 - 00:13:27:02
Abigail Acton
Sure, it sounds like you get together quite a lot of various disciplines here because it sounds like a broad range of specializations that permit you to have these insights. Is that the case?
00:13:27:03 - 00:13:47:15
Alessio Rovere
Yes, quite a lot. Actually, I'm a field geologist, so I was the one basically doing the measuring and collecting in the field. But then, , lots of colleagues come together, lots of different labs come together to actually adopt the different geochemical methods that you want to use to date a shell, for example, or a coral.
00:13:47:15 - 00:13:52:11
Alessio Rovere
And so you need to have lots of good collaborators scattered around the world and work with them.
00:13:52:12 - 00:14:06:01
Abigail Acton
It also sounds like you managed to generate a huge amount of data. You were looking at so many different things. That was such a large geographical area. So how can people have a look at your data? Is it just for other scientists or can anybody interested have a look? Tell us a little bit about how that is accessible.
00:14:06:01 - 00:14:39:10
Alessio Rovere
Well actually that's interesting because it's absolutely available to everybody. We have a website where we collected not only what we did, what we found around the world, but what people like us found from 1930s up to today. So we have about one century of research summarized in a big database, which is called the World Atlas of Last Interglacial Shorelines, where basically anybody can go and look and see if they have maybe a paleo shoreline, , on their backyard.
00:14:39:11 - 00:14:40:17
Abigail Acton
Yeah, fascinating.
00:14:40:19 - 00:14:46:02
Alessio Rovere
Which is often the case because there are several thousands of these places scattered around the globe.
00:14:46:03 - 00:14:49:18
Abigail Acton
Yeah. You might find yourself near one. And what's the website, please?
00:14:49:19 - 00:14:56:18
Alessio Rovere
It's warmcoasts.eu. And then you navigate to WALIS.
00:14:56:20 - 00:15:10:09
Abigail Acton
Wonderful. Navigate to WALIS, That's what we should all be doing. Well I'm not far away from Brighton coast and the white cliffs of Dover in that area. So maybe there's something there. There's lots of interesting fossils on the beaches around there. So maybe there's some other stuff there.
00:15:10:10 - 00:15:15:09
Alessio Rovere
They'd be older. But you might find something there from the last interglacial.
00:15:15:11 - 00:15:34:02
Abigail Acton
Yeah that's true. It is older. I've just remembered my little tiny bit of geological knowledge nonetheless. Have a look and see if your area actually has some information for you. So finally, is there something that you want us to remember from your project? Is there something that you think is of particular interest, maybe to anybody charged with making policy or any takeaways?
00:15:34:03 - 00:15:58:02
Alessio Rovere
Well, , starting also from Eric's research. So we know that Antarctica is probably going to be one of the issues that we have to face in the future, right. And we are probably already half facing it. And what we found was that compared to what was done previously, it was thought that sea level during this period, during the last interglacial was, say, 5 to 10m above present.
00:15:58:02 - 00:16:30:08
Alessio Rovere
But, also thanks to our research, we start to think that it was about maybe a bit lower than that, like 2 or 3m, four meters maximum as a peak during the last interglacial. Now different ice sheets could have contributed in different ways or with different timings. Hence my question to Eric before. But it's actually very important to remember if in a warmer period, similar to where we are going like two degrees Celsius global, is in the talks, right?
00:16:30:09 - 00:16:54:12
Alessio Rovere
Is in what we are talking about in terms of policy. So if this is what was produced during a warmer period, let's say a couple of meters of sea level rise, then think about our coastlines and even a meter of sea level rise. It's quite a big problem for us. So we need to think about it. And I live in Venice so I know.
00:16:54:14 - 00:16:56:10
Abigail Acton
Yeah. Some places more vulnerable than others.
00:16:56:11 - 00:16:57:10
Alessio Rovere
Yeah.
00:16:57:11 - 00:17:02:07
Abigail Acton
Thank you so much. Alessio. Does anyone have any observations or questions for Alessio? Gaël, yes, please.
00:17:02:08 - 00:17:07:20
Gaël Durand
And what about the storms? this change anything with time during that period?
00:17:07:22 - 00:17:32:01
Alessio Rovere
Well, I can tell you that finding the proxies for the storms was incredibly difficult. We tried hard, like, super hard. So I can't give you an answer because we found some evidence of past storms, but we could get to the point where we refined the models that we borrowed from coastal engineering, basically, to understand more about the storms.
00:17:32:01 - 00:17:56:17
Alessio Rovere
So this is a question we are leaving for the future generations of scientists. There are, I think, places where you can see, like in the Bahamas, in some places you can see that storms were possibly a bit stronger than today. And one of the things I am more convinced about from some proxies is that probably there was a change in direction of the storm, not as much in intensity, but in direction.
00:17:56:20 - 00:18:19:20
Alessio Rovere
I mean, if you think about the fact that today everything we built on the coastline is based on intensity and direction of a storm, like a harbor, construction is based on intensity and direction, changing direction, even just a few degrees. It's actually something very dangerous, if it happens. And in some places we think it may have happened in Argentina, for example.
00:18:19:20 - 00:18:22:07
Alessio Rovere
So there is something to be aware of.
00:18:22:07 - 00:18:24:06
Abigail Acton
Something else to add to the picture.
00:18:24:07 - 00:18:24:19
Alessio Rovere
Yeah
00:18:24:20 - 00:18:38:17
Abigail Acton
Yeah. Thanks for that question, Gaël. And I'm going to turn to you now. We need a better understanding of the interactions between the atmosphere, the ocean and the ice sheets, which is where the PROTECT project comes in. So Gaël, can you tell me why did this field of research attract you?
00:18:38:19 - 00:19:10:12
Gaël Durand
Actually, I started my research by studying a path climate. And actually, during my PhD, I worked together with Eric on the EPICA project, on the DOME C ICE CORE in Antarctica, which turned to reveal the story of climate for the last 800,000 years. And it was some 20 years ago. And at that time, new satellite observations started to reveal that the ice sheets were losing mass and contributing to the rise at a rate higher to what we were expecting.
00:19:10:12 - 00:19:40:05
Gaël Durand
So that was typically for a young researcher and exciting topic. And also still, a rise is not simply a scientific topic. It is a fundamental issue for the long term organization of human societies. So we already know that sea level rising. We know this process will continue for centuries, but at which rate? This remains a key question even after two decades of efforts by the research community.
00:19:40:05 - 00:19:54:03
Gaël Durand
So having a modest word in such a big societal question was really appealing to me. So, from a scientific perspective, what I personally find fascinating is the highly non-linear behavior of issues.
00:19:54:04 - 00:20:02:06
Abigail Acton
So the highly nonlinear behavior. So what do you mean by that? When you say nonlinear, you mean it's not predictable. Just because something happens at one point doesn't mean it will repeat.
00:20:02:07 - 00:20:19:10
Gaël Durand
I'm not saying that it's not predictable. I'm saying that the response is not only gradual in a simple and predictable in simple way. There are thresholds that may exist and be on which part of Ontario region of the Ice Sheet I could undergo a self-sustaining retreat.
00:20:19:13 - 00:20:24:01
Abigail Acton
Okay, yes, I see what you mean. You mean that there are triggers that can make things happen in stops and starts?
00:20:24:02 - 00:20:24:21
Gaël Durand
Exactly.
00:20:24:22 - 00:20:42:20
Abigail Acton
Yeah. Okay. Can you tell me... PROTECT brought together these various parameters that the atmosphere, the ocean and the ice sheet. So, we've talked a bit about the ice and what that can reveal. And also, what's studying the coasts now can tell us about the past. You kind of brought all three of these things together.
00:20:42:20 - 00:20:45:21
Abigail Acton
So can you tell me a little bit about what project actually did?
00:20:45:22 - 00:21:10:20
Gaël Durand
So, the largest uncertainty in the coming see level rise for the coming centuries, clearly attached to the evolution of both Ice Sheets and the only available tool to investigate the future similarly to weather forecast actually it's numerical models. So PROTECT aims at contributing to improve ice sheet and climate models and hopefully better constraint in certainty in future sea level rise.
00:21:10:22 - 00:21:37:08
Gaël Durand
And there are various ways to do so. First we need to better understand some critical processes and their representation in the numerical models. So for example, the water from the ocean could flow below the Ice Sheet, lubricate the bedrock, and enhance the sliding of the glacier, increasing its flow toward the sea and then its contribution to sea level.
00:21:37:10 - 00:22:04:20
Gaël Durand
Even if ice sheets are far away from us, they are not isolated from the rest of the climate system. They respond to the forcing of the ocean, of the atmosphere, even the Earth's crust and mantle. So better representing this interaction in the models is key. It's basically a reminder of an artifact of the past. Today, Scandinavia is rising up because from 20,000 years ago there was a huge ice sheet.
00:22:04:20 - 00:22:23:12
Gaël Durand
So due to the load of the ice sheet, the Earth's crust sank and now there is no more ice sheet. So it's going up. And it's also the case in Greenland and Antarctica because the ice sheet were bigger before. And if we continue losing mass this rise will change. So we have to take into account is changing this.
00:22:23:17 - 00:22:26:19
Abigail Acton
So the notion is there that the land might rise slightly.
00:22:26:21 - 00:22:27:17
Gaël Durand
Exactly.
00:22:27:18 - 00:22:41:23
Abigail Acton
Oh okay. So that's an intriguing one. Okay. So we might bob up a little bit more like a cork above the rising levels. So movements in the ice and the dissolving of the sea ice raising the level of the oceans, but also perhaps causing landmasses to rise slightly.
00:22:42:00 - 00:22:51:23
Gaël Durand
Yes. Typically in Scandinavia today, the sea level is not rising, it's dropping. And actually the sea level is not dropping. It's like locally the earth is rising it.
00:22:52:03 - 00:22:58:20
Abigail Acton
It's fascinating. Thank you. Any other kind of examples of things that you have to take into account when you're doing a modeling characteristics.
00:22:58:22 - 00:23:21:17
Gaël Durand
Yes. Typically Antarctica is extremely cold and the melt at the surface of the earth is extremely limited. But depending on the climate evolution, it might really change in the future. And we know from Greenland observation that some melt leads to more melt. It's what we call the positive feedback loop. And it's important to take into account.
00:23:21:19 - 00:23:45:17
Gaël Durand
Also we know that in Antarctica the change we are observing are due to intrusion of warm water from the ocean below the ice shelf that fragilises this ice shelf and lead the granite ice sheet to flow faster. So we also need to better understand this connection between the ocean and the ice sheet.
00:23:45:21 - 00:23:57:11
Abigail Acton
After all this work on modeling and these complex modeling systems that you've managed to create. Can you tell us anything from the project that really stands out in your mind as memorable, or something that we should already take note of?
00:23:57:13 - 00:24:34:10
Gaël Durand
I think there are two major things that are emerging. The first one is that we often hear that I sheet models are disagreeing. I think they are agreeing much more than what we think for the coming decades, and that the amplitude of the sea level rise for the coming decades can be narrowed down. The other point, and I think this is really important, is that because of this threshold we have, and because the ice sheet and glacier are relatively slow elements of the climate system, we have what we call committed sea level rise.
00:24:34:10 - 00:24:54:14
Gaël Durand
So today we have already launched a given amount of sea level rise. Typically, if we look at the glaciers, whatever we do, even if we follow the Paris Agreement, we likely on the long term have lost 30% of the glaciers. But depending on what we will do in the future, we will commit even more on the long term.
00:24:54:19 - 00:25:06:01
Abigail Acton
Right. So it's a long term projection. And we're committed, as you say already to a certain amount. Thank you. That's very interesting. Thank you very much. Does anyone have any questions or observations to make? Yeah, Eric.
00:25:06:02 - 00:25:15:10
Eric Wolff
Gaël, you're obviously looking at both the Greenland and Antarctica sheet where I think you are at one, what can you tell us about which of them we should be most worried about?
00:25:15:11 - 00:25:51:06
Gaël Durand
I would say that it's Antarctica for two reasons. It's first, because it's absolutely huge. It's a 60 meter, approximately 58m of sea level that is over the continent of Antarctica when Greenland, it's about seven meters. So in terms of potential, there is much more ice that can be mobilized to go towards the ocean. And also it might be much faster in the contribution to see level rise if we have this instability starting popping up and rising up in the in the coming decades and centuries.
00:25:51:06 - 00:26:00:09
Gaël Durand
So I would fear more on Antarctica, but I'm biased. That's the ice sheet I have in my heart.
00:26:00:11 - 00:26:10:12
Abigail Acton
It is a very compelling area. I remember reading a book many years ago and always being totally caught up with the notion of Antarctica. Now it's a... have you been Gaël, have you visited it?
00:26:10:13 - 00:26:20:21
Gaël Durand
Yes, I was in Dome C in Concordia some 20, almost 25, years ago. That was great. And you realise how big it is.
00:26:20:23 - 00:26:26:18
Abigail Acton
Like a completely different alien environment. Yeah. Fascinating. Any other comments at all or observations to make?
00:26:26:19 - 00:26:40:05
Eric Wolff
Well, I was also going to ask Gaël because he's much nearer to sort of application and policy than probably than Alessio and I are. So do you feel that people are listening when you warn them about sea level rise?
00:26:40:07 - 00:27:14:19
Gaël Durand
This is a very hard question. I would say yes, they are frightened, but they don't listen that much in the sense that we, sea level practitioners, are most interested in the coming decades. When I think that the issue is on a longer timescale in our global organization, and I think this is hard to explain, that yes, what we are doing now is impacting generations of people and that we should act now.
00:27:14:21 - 00:27:28:09
Abigail Acton
Well, that's a strong way to end the episode. Thank you very much. Excellent. Okay. Thank you for your important work, guys. And at least it's reaching a slightly wider audience now. Hopefully people listening will take it on board. Thanks for your time.
00:27:28:10 - 00:27:29:02
Alessio Rovere
Thank you.
00:27:29:03 - 00:27:29:12
Eric Wolff
Bye.
00:27:29:13 - 00:27:30:17
Gaël Durand
Thanks a lot. Bye.
00:27:30:18 - 00:27:31:14
Alessio Rovere
Bye bye.
00:27:31:15 - 00:28:04:15
Abigail Acton
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00:28:04:17 - 00:28:23:24
Abigail Acton
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Fine-tuning modelling of future sea levels by considering the last interglacial period
Threatening the economy, the ecology and the existence of coastal regions worldwide, global mean sea level has risen by around 8 cm since 1992. Land ice loss and ocean thermal expansion contribute equally: the future of sea level rise is set to become dominated by the highly uncertain behaviour of the Antarctic and Greenland ice sheets. The potential for the rapid collapse of these ice sheets, which may already be under way, is making us aware of humanity’s vulnerability to ice sheet change. So, knowing how they are reacting to global warming is central to getting a clearer idea of what lies ahead. Our three guests, all of whom have received support from EU research and innovation funding, have been working on improving our understanding of these interactions. Here to share their work with us today are: Eric Wolff(opens in new window), an honorary fellow at the British Antarctic Survey(opens in new window), who studies past climate and environment, mainly from Antarctic and Greenland ice cores. He is a Royal Society research professor in the Department of Earth Sciences(opens in new window) at the University of Cambridge and coordinated the WACSWAIN project. Alessio Rovere(opens in new window), a professor in the Department of Environmental Sciences, Informatics and Statistics(opens in new window) at Ca’Foscari University of Venice, is interested in palaeo climate and sea level changes and how geological processes have changed coastlines over deep time, a subject he explored through the WARMCOASTS project. A director of research at the French National Centre for Scientific Research(opens in new window) (CNRS), Gaël Durand(opens in new window) specialises in the modelling of polar ice sheets and the dynamics of coastal glaciers, with a focus on their impact on sea level rise. Through the PROTECT project, he improved our understanding of the stability of ice sheets, and their potential responses to climate change.
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