 Any of the local urbanizers here, so we're going to start session now. It's already 10 minutes past so this is the session on coastal risk, thank you all for being here and The first talk is from Amy Slangen who's joining us online from the Netherlands so welcome Amy and You can take it from here. Thanks Yes, let me unmute. So do you hear and see everything? Okay? Yes, we can hear you Amy. Okay, great. And you see the right presentation? Yeah, I think so, right? Okay Yeah, so Thank you for having me speak at this at this workshop today and I will be the first of this block on on sea level related Risks and impacts and I will be introducing how we model the sea level Change projections in AR6 So I was part of the working group one chapter nine report where we focus on the observed and modeled changes in in sea level change Yeah, let me see. Okay. So You probably all have an idea of sea level change So there's a lot of processes that come together in something as simple as the level of Of the ocean basically So you can see in this figure There is the the ice sheets when they melt they contribute to sea level rise but also if needs of course is a very important Contributor because warming water expands so therefore the sea level rises But there's also groundwater extraction meltwater runoff mountain glaciers and of course all of that Leads to changes in how the sea level extremes Behave so the this these processes are melting melting melting ice warming ocean They influence how the mean sea level changes But that in turn affects how the extremes on a beach or on the coast will be felt When you get a surge or a high tide or such So you can imagine if you want to model this there's a lot of processes that you need to take into account and unfortunately We don't have one model that we can use to do this It would be great if we did but instead we have this spaghetti of different contributions different Models that we need to piece together in order to get to sea level projections So I'm not gonna go through all the details of this plot but basically in the In the yellow blocks you can see all the different contributors So this is vertical land movement from the top to the bottom vertical land movement terrestrial water storage ice sheet contribution glacier contribution thermal expansion and dynamic sea level and you need to Individually model each of these processes in order to get to the global mean sea level contribute Change projected into the future And to the relative sea level change and the relative sea level changes then how sea level changes Spatially because sea level doesn't just changed at the same rate everywhere. There's large regional variations So you really need to take into account how it varies from place to place So we used in the in the IPC report for the first time now we used emulators For for instance the ice sheet contribution and the glacier contributions And emulators are basically simple climate models So we have these huge climate we have these climate models, but they take a very long time to run So you can't run them for every possible scenario every possible Thing you can think of because it just takes months to run a climate model So what we do with these emulators is you have a set of climate model runs and you sort of compare or you use Methods linear statistical methods to link these complicated methods to a more simpler approach And then to to get a PDF to get a normal distribution of how this for instance in this case The ice sheets would contribute to sea level rise Now all of these different components To to to bring those together so to bring those yellow blocks together into the red block basically We developed a framework called facts the framework for analyzing changes to sea level And this is a framework where you have a module It's a modularized framework So for every contribution for instance for the ice sheet Antarctic ice sheet Greenland ice sheet thermal expansion You have a module and and you can also change those modules So if you have a new ice sheet model, you can use that you can replace the current module and and build a new module for it And this was set up mainly by Greg Garner and Bob Cop in the US And and it's also published. It's freely available on github. Everyone can download it It's still we're still working on making it more user friendly And and we also welcome Uses feedback from that as well And there's a paper currently in review for Q scientific model development presenting this facts framework as well But this is facts framework where we so we combine these modules And then to make the the sea level projections Another thing that we did in this ar6 report is that we made the sea level projections consistent with the assessed equilibrium climate sensitivity and surface temperature now what is equilibrium climate sensitivity That is when you double in a model you double the cu2 amount and you see how long it takes or when when the surface temperature Stabilizes again And and this is a measure that we use to to evaluate climate models as well um And and what we saw was that in the newer set of climate models the most recent set of climate models, so The c-map six climate models This equilibrium climate sensitivity range was larger than it was before in the c-map five climate models And also in what we knew to be the best Well, what was what was thought to be the best range the best estimate of this equilibrium climate sensitivity um, so the ar6 c-reports Assessed the equilibrium climate sensitivity came up with a range and what we did is we use these emulators to sort of trim the the The the distribution so that this equilibrium climate sensitivity is The most correct or closest to the assessed equilibrium climate sensitivity um Yeah, so this was used for the projections to the 2100 And then for the projections to 2300 we used a literature assessment So that was really looking into the literature and and seeing What are the different values that are around the different model estimates? And how do these compare to each other? Well for 2100 we we ran this fact framework To make new projections based So what do you need to make projections? Well, you need scenarios of how The climate might develop and how do we do that in in the physical climate world? We use Scenarios of carbon dioxide So in this graph on the left you can see in the for instance in the bottom line, which is the light blue line There's a scenario called ssp 119 um, which Has goes back really quickly to about zero Cu2 emissions by the year 2050 for us on the other end We have a dark red line which doubles the currency or two emissions by the year 2050 So by by making these scenarios you can make an envelope of of the different types of How how the climate might develop so we can ask the question if Everyone if if this Cu2 emissions would go down really quickly what would happen to the climate and what would happen to the sea level? So on the right you can see what this what the output then is from the climate models If you use this, um, this light blue You get to about one and a half degrees by the year 2100 if you use the dark red You would get closer towards the four and a half five degrees of warming by the year 2100 Now if the Paris agreement that's the closest to this lower light blue scenario So that's the one that we're aiming for as a world basically Um, of course the question is what does this mean for um for sea level? So here, um, I show what the sea level how how this global mean sea level looks for the different contributions So we have for instance, uh in this black line the thermal expansion in the light blue the glacier contribution The gray is the green and ice sheet contribution Her brown the Antarctic and then dark blue is the land water storage So you can see that each of these contributions has um has its own Um sea level contribution. Yeah, so there's difference and then of course we're going to add them together into global mean sea level projections total global mean Um, and those are the color lines you see in this graph So you can see for the Paris agreement scenario, you would end up just uh around well So this is with regards to the 1900 by the way, so it would be about half a meter compared to the 1900 um Or a higher scenario that is closer to a meter uh of sea level rise These are the so-called medium confidence scenarios and these medium confidence scenarios They they include the contributions that we're fairly sure of that We have a relatively good idea of what that they're gonna happen and how they will respond We can model them. We have faith in in how we model them. Um, so that's thermal expansion ocean dynamics greenland Antarctica um sort of the Surface mass balance processes on those glaciers Groundwater and dams and vertical land movement. Of course, there's still significant uncertainties with each of these So we still have medium confidence and not high confidence Um, but this is already so this is sort of the the average set of sea level projections And then we have this famous already famous dash line up here um Which is uh a low confidence scenario And what's what we did in this scenario? There's a couple of of um literature Some literature available that is pointing to much higher contributions from Mainly the Antarctic ice sheet. So um these projections they either modeled or they they were Asking experts about what they think that might happen to Antarctica and how fast it might happen um, so there's but they're like a couple of single Um publications about this Antarctic contribution um, and then if you would add those contributions So those greenland and Antarctic dynamic contributions to the to the medium confidence projections You get this really high line and this is so this is the 83rd uh The 83rd percentile. So it's really the upper range and it's used to inform Extremely risk averse policy makers and it's to say okay We we have more confidence in these in these medium confidence projections But we cannot rule out that a much much higher contribution From the ice sheets might occur and if it did it might end up giving values around up to this dashed line. So you you get really an extremely high um, um sea level Scenario, but need to keep in mind we have low confidence in this because there's not that much proof In the scientific literature yet. So there's not that much agreement in the scientific literature yet so I basically already said this so so we included destructed expert judgments. So that's basically asking experts And a model that is modeling mickey marine ice cliff instability And if you add those you get to this dashed line But yeah, keep in mind. This is deep uncertainty. We really don't know Very well, what will happen? How fast it will happen? And how to model it What you could do there's some Current situations that we could already look at And you could for instance the thwaites glacier and Antarctica is already Showing some signs that it might be Experiencing this mickey process this marine ice cliff instability And if that happens you might get a bit of a runaway effect or a very big runaway effect We're not sure And that might lead to these accelerated contributions from Greenland So if for instance in the next few decades, we can see this thwaites glacier Experiencing these runaway effects That might be an early warning for in the further future that this indeed we are moving towards this dash line rather than to the regular Medium confidence projections Yeah, I'm gonna sorry skip this for time. Okay, so How do we then get from these global to the regional projections? It's all done in the same in the same go, but it is it requires an extra step And that's mainly because of the self-gravitational effect um, so If you look at all Mars on earth, it attracts each other So if we have this giant amount of ice sitting on Antarctica, it's pulling on the ocean The ocean is also pulling on the ice, but that has a bit less of an effect obviously Because the ocean can move easier so Normally you would think okay. I'm gonna Melt some ice This will go into the ocean and the ocean will rise at the same rate everywhere But instead because you have less ice now sitting on Antarctica. It's pulling less hard on The sea on the ocean So because of this loss of gravitational attraction actually close to the ice sheet The sea level will fall whereas further away sea level will rise And of course, it's still this amount of water needs to be distributed around the ocean So the further away you get actually the more sea level rise you get So for instance for us in in um in europe for me in europe Antarctica is the one to watch because we are further away from Antarctica than we are from greenland But if you're living in uh in south africa actually closer to Antarctica So the one to watch dan is greenland because that's on the other side of the ocean So instead, um if greenland loses mass you will get an above average sea level rise in southern Africa Um, and here you can see the effect. Uh, this has on um The spatial distribution So here again in the top if you melt Miles in Antarctica, then you can see that towards the northern hemisphere The the sea level rises faster where and the opposite happens for greenland So if you melt miles on greenland actually towards the southern hemisphere this amount of sea level rise increases Now you can do this for all of the different contributions and he again see them for the two for two scenarios So the lower um ssp one one six one two six scenario and the upper five eight five scenario, I think And then comparing you can see very clearly this gravitational patterns in the glaciers in the ice sheets in greenland And in the land water storage Then for ocean dynamics and thermal expansion that is mainly derived from climate modeling And you can see a lot of variability. Um, this is also driven by wind It's driven by density variations of temperature salinity Um, so changes in the flow of the ocean will come across in this ocean dynamics component And then we have a vertical land motion component that is um Not a scenario dependent. So it's mainly dependent on The loss of ice masses after the last glacial maximum, but it can also be tectonics volcanic eruptions Um local subsidence due to groundwater extraction or oil extraction So vertical land motion is really a very complicated factor Because there's a large human component in it. So if a certain city is really Extracting more and more groundwater it might lead to that city actually sinking And therefore if your city sinks it means you will experience more sea level rise If you add this all together Here, I show the uh on the left the paris agreement scenario on the right is more the scenario that we're currently Heading for if you think about three three and a half degrees of warming And and from this uh, so this adds up all the different patterns So you can see close to the ice sheets that there's a sea level fall But you can also see the large spatial differences coming from this Ocean dynamics component. So it's important to realize that everywhere around the coast like at every coastal point basically you will Experience a sea level rise that is not the same as the global mean But approximately two-thirds of the global coastline does have a value that is within about 20 percent of the global mean So the global mean is a nice good first aim direction If you will but it's important to go and dig into what is causing the sea level rise at every location To figure out what might happen to sea level rise at your particular coast um Now if we go towards the longer term because so far I've mainly talked about until the year 2100 We know that sea level rise will continue for some quite some time to come. Um, and that's because The ice sheets are currently still not in equilibrium with the current climate So they they don't even know that the sea that the temperature has risen that much already The deep ocean doesn't even know. So that's still coming But there's also something we can do so by Reducing the greenhouse gas emissions as fast as we can we can reduce the speed of this sea level rise Um Also in the on the longer term And that's really important So because the speed of sea level rise will also determine how fast how much time you have to adapt to a rising sea level So if you really look into this far right plot We see that under a low emission scenario the ranges are enormous The uncertainty is enormous. Of course, if you go towards these longer time scales Um, both because of the modeling but also mainly because we don't really know what people are going to do So that makes um the year 2300 a quite difficult projection horizon But if you look at the lower emission scenario you could see somewhere between half and three meter of sea level rise Whereas for a very high emissions scenario It could be two to seven or much more if these accelerations processes on Antarctica really start kicking in So the question really is not if we will reach say half or one or one and a half or maybe even two meters of sea level rise But the question is when And you can uh look at it therefore from a different sort of you can flip the framework And look at when will we see half a meter of sea level rise? When will we see one meter of sea level rise? And then if you look at this plot on the right you can see that for a very low emission scenario The first opportunity to see this half meter is already before the year 2100 Um, and and for the highest scenarios, it's it's moving There's there's more and more probability that we will see this half meter before the year 2100 Um, and if you go and look at the top then this two meter might first occur around the year 2100 But it could also be quite a lot later But in in most of these scenarios actually before the year 2300 we would have Cross this two meter threshold um So yeah, this is really important if you're looking at at how to adapt to sea level rise How to protect a coastline The faster this sea level rises The less time you have to plan to think ahead to to to build something or to come up with plans to to adapt to this sea level rise Now what we did in this ipc report is There's a lot more focus on regional information. Um, so we have these regional fact sheets We have the interactive atlas and for sea level specifically we built this sea level tool together with the nasa Which is showing the ipc sea sea level projections um, what you can do is um, you can enter this uh, this tool everyone should be able to enter using this address on the top um, and then You can select which process you want to show. Do you want to see total sea level? What decade do you want to see it for and what scenario and then click on update the map? Um, I don't know if I can what and then you see these blue dots all over those are tight gauge measurements. Um And you can see traditionally there's there's a higher concentration of tight gauge measurements in the in the northern hemisphere Um, and a lower in the southern hemisphere generally Um, but actually that doesn't matter much for the sea level projections because you can click on any point Oops, um on any point in this map and get a sea level projection for that point So you're not dependent on on the on the past observations basically You can click on any, uh, desired point across your coastline and see it will then give you line graphs for the sea level the mean sea level projections along your coast So to wrap up, I think I've almost talked for about 20 minutes. Um, so we know that sea level is Going to continue to rise throughout the 21st century and beyond Um, but but the rate of this rise is really strongly determined by how much greenhouse gases we emit as a world So, um, we will get sea level rise, but how fast and how long it will continue Um really depends for a lot on on Um on the policies that are made Um, but it's good to keep in mind that even on the strong emission reductions The sea level rise will continue and it could still amount to about one to three meters by the year 2300 And with that, I think I'll take any short questions, but I'll leave it up to rush to organize Further from there. Thank you. Thank you, Amy. Um, do we ask some questions now or we'll later, Erica Maybe one burning question Anybody who has a burning question to ask