Climate change, flooding and water management

Hello and welcome to Geography Matters. The podcast that looks at the role and the importance of geography in the modern world. In this episode, I'm delighted to welcome Hannah Clote, Regis Professor of Meteorology and Climate Science at the University of Reading, an old colleague of mine from King's College in London. Now, Hannah, your research speciality is hydrology and flooding. And today, we are going to discuss, I hope, some of the links between climate change and flooding. And we just have one of the hottest summers ever, maybe the hottest summer ever. So I wonder if you could just start by briefly summarizing some of the main issues regarding climate change at the moment. Well, that's a really easy question, isn't it? Because there are so many. And yes, here in the UK, we've had three heatwaves and possibly is pretty hot now in September when we're recording. So it's been a very unusually hot summer. And heatwaves are one of the clearest indications of our climate changing. The relationship between those higher temperatures, those longer periods, which are above a high threshold temperature, that is a very strong footprint of our changing climate. So then we can think about other things. So obviously, we've had wildfire in the UK that's been really quite a bad season. But elsewhere, it's been absolutely terrifying in Europe and elsewhere in the world this summer. We've had marine heatwaves that we're damaging the ecosystems in our oceans. And then, of course, we think about the drought. We've read a drought right now here in Reading at the end of September. People aren't behaving like it's a drought because it's been a little bit rainy and they haven't quite got it into the heads that were still in this place, but we don't have enough water in our reservoirs and in our groundwater. And then, you know, we're going to flip into winter. And there is a chance that we could have a very wet winter, this winter, and with, you know, it's quite severe flooding. So we need to prepare for that too. And we know that rainfall is getting heavier because of climate change. So whenever we do have floods, they are getting worse. And we've seen some terrible flash floods around the world as well, places like Fallensia in 2024, Germany in 2021, tropical cyclones as well, the rainfall getting heavier because of this underlying signal of climate. So it's affecting so much about our extreme weather. I'm glad you mentioned the flooding in 2021, and also the flooding in Britain, because to what extent do you think these are a consequence of climate change, the warming of the atmosphere, and the fact that the atmosphere for every one degree centigrade increase in sea temperature, the 7% increase in the amount of moisture taken up into the atmosphere. I mean, is that broadly correct? I was nearly correct. It's like the air temperature. So the physics of the atmosphere basically means I think warm as it can hold more water. And we know that because we can get clouds forming, for example, when you pass those boundaries in the atmosphere, and on a cold day the air can't hold much moisture and we might have missed and things like that. So the more that we warm the atmosphere, the more moisture it can hold, then the more it can rain down on us. And we've seen attribution studies come through which have shown that there is this link between those events being worse and changing climate. Now it's very difficult with floods to do that type of attribution, and we have to be very cautious about it, because once the rain has hit the ground, then it has to deal with the mess that's us humans have left on this planet by living in the wrong places, by concrete to go over our landscape, building drainage systems that don't have a big enough capacity. So because humans have modified the landscape and because we are moving around into the path of floods and live on the flood plain, we have to take that into account in terms of the severity of a disaster. So when we think about somewhere like Valencia, where we had extremely heavy rainfall, we know there's a climate change signal in there. We've got this underlying baseline warming causing heavier rainfall. But people were living on the flood plain and people chose to behave in a way, well, they probably didn't realize they were at risk, because they were not effective warnings out. They went into those underground car parks to try and rescue their cars, and many people died in that situation. So we do have this climate change signal, but we also have to really pay attention to human behavior and the way that we're planning, where we live, and how we adapt. So am I right in thinking that the floods in Valencia, the floods in Germany three or four years ago on the in the Elbe, etc., that these are not really one-off occurrences. So they're quite likely to become more frequent in the future as things warm up. Yeah, absolutely. We should be preparing for heavier rainfall and more of this type of surprise flash flood, which we unprecedented that we haven't seen before. I mean, the Germany one and the Valencia were on a quite interesting, because those areas have flooded before, actually quite badly. So some of it's about not remembering the past. Now, we also know that they're going to get worse because of climate change, but bad floods do happen, and you need this memory longer than human lifespan in order to be able to understand the risk of floods, which places are dangerous to live. So again, there's a little bit more going on that flooding is a bit more complicated to understand, we sometimes get flood-rich periods, and we've been talking about El Nino here today and the impact that has on these like slower timescales around the planet, which can cause certain places to flood in a whole series of years, and to be very dry in a different series of years. So the teleconnections between the atmosphere and the ocean and the influence on the land, you have to think about lots of timescales all at the same time. Now, many people are suggesting that El Nino at the moment is one of the most severe or one of the strongest that we've had for many years, do you think this is also consequence of climate change? Yeah, I mean, what we've got going on here is a very strong El Nino, and then underneath you've got the warming signal from climate change, so it's just layered on top, which is why people are calling it a super El Nino, because it is so very high. And if you just look at the kind of the raw temperatures of the ocean, I think today, here at the end of September, we've actually passed the record for the highest anomaly in an El Nino, but if you try to take away the climate change signal from that, then we haven't quite got there yet. So it's still quite a bad El Nino at the moment, but it hasn't quite got there. So we have to think about, again, those different timescales layered on top of each other. But of course, the atmosphere and the ocean don't really care what's caused it, they're going to behave in a particular way. So, you know, a hot ocean does and differences in the trade winds and differences in those circulations do mean that we do get changes to rainfall in Indonesia or East Africa, and we are going to see the impacts of these changes, floods and these drought periods on agriculture, on people's safety in the path of floods. Yeah, this is interesting, because once he's constantly on television, the flooding through York two or three years ago, the flooding in Lancashire, the big floods in Shrewsbury down on the 7, etc. I mean, do you think that really we're going to have to get used to much more flooding of low-lying areas in Britain and in other European countries? Absolutely, we need to prepare that, because we can see the future coming towards us, particularly at the coast, particularly where we've got estuaries, and we know we've got high SE level rise, so the basic level there is higher. So any flood that comes up, any storm surge that comes up, we will need to prepare for higher water levels. We know we're getting heavy rainfall, so when we have river flooding, then we know that those flood plains will be only with a larger amount of water. Now, places like Shrewsbury was very interesting, that this when the temporary flood barriers started wiggling around in a terrifying way, so our preparations there were not good enough for that flood coming towards us, and we've seen that before in places like Carlyle, where the newly built flood defenses were overtopped by a flood, you know, just after they'd been built, it weren't high enough. So we can't rely on barriers and building higher and higher walls, that is not the only solution. We need to really think about where people are living, and we've seen very recently in Wales, people being moved out of their homes, or the local council buying those properties and demolishing them and moving them away from floodplain. That is an absolutely unprecedented activity in this country. We see some of that in the US already, but those types of things are things we're going to have to think about, where is it, too dangerous for us to live? That's a very difficult conversation to have. So in addition to to increases in rainfall and in river flooding, what you're also pointing to is the impact of the rise in sea level, and the fact that we're likely, I'm thinking here, say New Orleans but many other cities, Shanghai, New York, London, etc. We're going to face the possibility of higher sea levels and we're really going to have to deal with that. Yeah, I mean, we're already seeing higher sea levels. There's some of this that we can already see. There's some of it that we're locked into and no matter what we choose to do about burning fossil fuels, we're locked into decades of change in higher sea levels and many of our world cities have built and places which will interact with these sea levels. I mean, London, for example, we need to think about a new term as barrier and that is a really big political decision. The old barrier is slowly wearing out and it takes a long time to get the little huge infrastructure project like that through and one of the reasons is because we're going to see higher sea levels so we need to make sure that London is protected from that. When we have something like a storm surge coming up from the ocean, at the same time, we often get very, very heavy rainfall and so it's actually as cities are kind of getting this kind of triple whammy from surface water flooding, from very heavy rainfall filling up the underground and the metro systems and our basements, flooding people's basements, particularly dangerous at night, people are sleeping downstairs. Our rivers flooding onto the flood plains and storm surge coming up from the ocean and then you know you're relying on these in the larger infrastructure projects to protect you and we saw in hurricane Katrina when that back can go wrong, right, when the levees break. So it's very important to think about what we need to do in our cities in order to minimise whatever we can do in all of those places for the storm surge, for the rivers, for the surface water flooding. Surface water flooding is actually very tricky and we've seen London inundated before, New York inundated. It can be very, very quick, very difficult to prepare for and drainage systems are wholly inadequate in places, you know, Victorian and not able to just not able to deal with the amounts of water that's falling. So there are lots of things you can do, so green roofs, you know, spaces, green blue spaces in your city are very good ideas and there are great examples from around the world in China and Indonesia where people have really, really gone to town on changing the way the city is with vegetation, with channels and temporary storage zones. So there are things we can do but it takes great political will. Yes, I have a strong personal interest really in storm surge just because in 1953 I lived in Mabelthorp on these coast. We lost our house in the floods and my father actually had to carry me as a small child on his back through the flood waters to the house next door, which was two stories and, you know, to safety. So then go back and get my sister, my mother, et cetera. So I remember this rather vividly but the North Sea flood aside, I mean we're seeing I think an increase in typhoons in the Pacific, big storms sweeping across Indonesia, China, et cetera. So you would anticipate really that there are many areas of the world that are going to have to be dealing with this kind of phenomenon in future. Yeah, and of course many of those places that we have very vulnerable populations already. So and who can't deal with a major disaster in the sense they don't have the resources and people are living in a lot of people living in poverty, lots of displaced, temporary displaced people. So when you then have a hurricane, a typhoon that is stronger and is dumping more rainfall and perhaps is more stationary. So some of the simulations show that they slow down or they rapidly intensify really, really quickly and then divert track or something like that. So when you've got those types of problems, then it, you know, we really we really do need to up our game in adapting to those types of things. What do you think of the geographical implications of coastal flooding? I mean, I remember vividly in the early ages my first visit to Bangladesh and I was absolutely astonished there by the scale of the the low lying area of much of the country and the exposure of so many of the people to storms coming up into the into the Bay of Bengal, et cetera. So it strikes me that places like Bangladesh are really, really at risk. Yeah, they absolutely are. You know, a lot of the country is basically a floodplain and that there's, you know, there's so much to do in that space. I mean, one of the, so one of the things I work on is flood forecasting at early morning and that is really, really important and we've been working with Bangladesh and the most important thing that we have found is the timing of the planting of agricultural crops. So if you have some indication that a big flood is coming, or the monsoon, it pulses are going to be slightly different this year and you can see that ahead of time, you can delay planting and then you can save the crop for for that season. And so it's very simple things like that, you know, just actually changing your planting day on in response to a forecast can make a massive difference to livelihoods. So we know we can we can do that kind of thing. We know that we can improve our mangroves at the coast to like to buffer some of the surge. But you know, we are locked into increased melting, increased sea levels, increased rainfall from the monsoon pulses. So there are going to be more vulnerable people in the way of floods. Now, at this point you're making Hannah about being locked into more, more melting, more flooding. I think it's a really important one because we're both aware of the astonishing flood that we just saw in Nepal with the with the glacial collapse and the the loss of maybe five, six thousand lives. But we've also seen similar events in in Switzerland. I think last year the the birch glaze here, a big chunk of that collapse down in to a bladder in the Lossental Valley. And the the picture I'm picking up is that the Himalaya in general and also big chunks of the Alps are really a quite severe risk of of increasing flooding. Yeah, I mean that that's absolutely right. But the problem is once those floods have passed, then that water is not available for people to drink or for agriculture. So you've got the worst of both worlds. You've got the heightened risk of flash very fast flooding. Very difficult to get people out of the way. And then you have not enough water for the rest of the year. And that that's the reality. So I think there's going to be have to be a lot of decisions, particularly where you have people downstream of a glacier, huge communities downstream at risk. Then I think some very strong conversations about where people are allowed to live, you know, and where is too dangerous. But again, very, very difficult to do. But it causes a lot of tension internationally. Of course, water security across borders is really difficult. But there's a limited amount of snow and ice up in the glaciers that are feeding more than one catchment. And if you get water, that's always, you know, transboundary rivers are always a problem of a transboundary kind of snow and ice storage as well. So actually, what you're saying here is that in addition to the problem of flooding, there's actually likely to be in the future, a problem of water shortage. Because as the glacier is melt, the regular source of water which many people depend on is going to is going to really to shrink quite dramatically. Is that right? Yeah, that's right. And we shouldn't really restrict ourselves to thinking about places like Himalayas. We can also see the same thing going on in the UK. So right now, you know, we're in a drought. And some of the reason is because we do not treat water as precious. We do not try and hang onto it when it's flooding. We let it run straight through the drains down the rivers and just get trying to get rid of it as fast as possible. And we really need to rethink how precious that water is. And in those places that are really water insecure in the world already, they treat water with respect and they look after it. And they do not, you know, leave their their taps running or wash their cars, you know, in such a kind of kind of terrible way. We see people in the middle of a drought doing in this country. So it's a real shift in the way that we think about this really precious resource. None of us can live without. So this is this is quite interesting because what you're suggesting is that it's not really just issues of higher rainfall, more flooding, a glacial melt, etc. There's actually a long term issue of water insecurity. If that's the the correct phrase and that we're going to have to be much more aware in the future of of water as a scarce resource. Yes, so we definitely are facing water insecurity and it's not something we should be thinking about in the future because it's right now and and we need to be moving very fast on this. It's very difficult to put in new water infrastructure to change the way we're operating our industry and the way we're building our homes. So actually we do really need to think about more regulation in this area and that's not a very popular one thing to think about but it's absolutely necessary. I'm We're going to store our problems for the future. So there's obviously different countries are going to need to address this in different ways. One of the issues I think we have certainly in southern England is that there have been no new water reservoirs built for the last 30 or 35 years. So presumably we should be trying to store water much more. We don't necessarily have to do it with the reservoirs, all that's not the only solution. So sometimes that is going to be the solution because we have a lot of people who require that water. But actually the more that we can use our own homes to store the water we need. So things like underground storage tanks, so you collect the rain in the falls, you use it in your home, perhaps you can recycle it as well in the home, so if we change the way we're building the way we're using things, then that would be a much better thing to do. But also in just agricultural land, so soil, if we look after our soils, it can hold the water for us. It's a slight wire. And then it goes down into the rocks in those places in the country where we do have groundwater stores. So actually that's a reservoir that is just operating for us, if we let the water drain in and don't let it just rush off. So lots of natural flood management techniques can really help also with water security, with drought, with preparing for hotter summers. Now moving away from Britain, I'd like really to go back to the Himalayas, if I may. People often talk about them as being the third pole, and this area of Tibet holding a very large amount of ice. And when you look at the river pattern coming off the Himalayas, you've got obviously you've got the Ganges, the Brahma Putra, the Meekong, the Yang Sea. And really you've got a very large chunk of the world, which is dependent on the water flow from the Tibetan plateau. And I wonder what do you think the implications of climate change for that area? I mean, to be honest, I'm a little bit terrifying because you know that there are going to cause problems where there's not going to be enough water. And you know that can lead to conflict, particularly when you've already got tensions in place. So water management is going to be very tricky indeed and it's going to get worse. And again, of course, you're going to have to deal with floods and other problems to you and it will affect agriculture and it will affect people in their homes. So yeah, it's just a very, very big problem to solve. And what about the fact that a number of countries are also trying to develop hydropower and to actually dam these rivers? I mean, we're seeing this obviously in Africa, but China's also damned a very large number of rivers. But I think there's a now even a proposal for Ethiopia to put a dam in on the upper reaches of the mile, which Egypt is less than happy with. I mean, is this likely to be the sort of situation we're going to be dealing with in the future where countries are really much more in conflict with one another, over water as a resource? Yeah, although to be honest, countries have always been in conflict with each other over water. And one of those things that can cause a war, and we've seen in, you know, from ancient history, that that is one of the biggest problems is who gets the water downstream. And we've seen big dams built before and causing a lot of problems. I mean, dams are a solution to being able to get water to your population and they are a solution to provide power. And so there is a real ethical balance there between, you know, being able to get power and water to people so that they can grow food and so they can live their lives and sharing that in an equitable way with other people who are relying on that water. And as it might get drier in some periods of the year in some places, that's going to become even more of a problem. And I think there is a role, though, here for kind of innovation and thinking about other ways of dealing with water, and water, you know, low water use crops, and if we add at the ocean, I'm sure, you know, there is going to be an increasing role for desalionization plants as well. But in those parts of the world that are just going to get drier and drier and then that water sharing is going to be a problem. What you're suggesting, if I understand this correctly, is that we're going to have to really change the way in which we think about water and the way in which we use water. We're going to have to be much more careful, is this right, in the way we use water in the future? Yeah. And so things like, you know, growing crops within a low water environment, industrial processes that are, you know, water, they don't use a lot of water. And of course we're talking about data centers and how much we require, which is a big problem at the moment, even from those data centers that say they have a kind of a closed loop. You know, there's still quite a large requirement for water there. So these all conversations happening at the same time as our world is changing. I think definitely there is a role for recycling water, so the more that we can recycle water the better. And so when we have wastewater or whatever quality that we treat it as precious and then we treat it and we filter it and then we can reuse it. So I think water reuse is one of the, you know, the biggest thing that we can aim at in improving those technologies so that they can be used by the people who really don't have enough water. Yeah. One of the interesting, I think, things which has emerged, Hannah, in the, in the current Middle East conflict between the USA and Iran is that Iran has struck a number of the desalination plans of countries adjacent, I'd not really quite realized how dependent some of those countries are on desalinated water as a, as their major source of water. Yeah. And I think actually there are a lot of countries who are now doing this very well and have some, some really good infrastructure. I mean, there are environmental consequences of these, of these plants as well, you know, the waste that comes out of them, the, the brain that comes out of them and, you know, and, and damaging the coastline and lots of things like that. So it's not, it's not a magic wand, but in those places where they just don't have enough water, then, you know, that's, that's the technology that works. And we've been, you know, dabbling with this in the UK as well, but it's a very expensive technology. So it own, it's only a value where there aren't any other options, you know, there aren't any cheaper options and often it's only used for drinking water enough for, you know, irrigation. So you still needed some water from somewhere else at the moment because of the expense of the technology. But yes, if we're reliant on only one source, we've seen that with most of our infrastructure as well. And luckily, here in Redding, we've got more than one train line to Red, to London. So sometimes when one train line goes down, you can still use the other one. But if you're reliant on one thing and it goes down, then you don't have the resilience you need. And there's been a lot of chatter this week from the government talking about preparing householders, preparing and being resilient and having things in place. In case there was a cyber attack from the electricity goes off, or there's a flood or a heat wave, you know, how do you keep yourself safe in your own home and what, what is the role of the government in trying to provide that resilience to our large systems? Like, I had traffic control systems, for example. So are you doing more work these days on the, if you like, the issues, the problems of policy, of how to become more resilient, of the sort of strategies and policies that governments and local governments should be adopting in order to deal with some of the problems we discussed? Absolutely. I mean, I'm absolutely passionate about people being able to imagine what is coming towards us. And when I'm talking about imagination, I'm talking about people in their own homes, thinking about whether they're at flood risk, what that flood is actually going to be like and then what they need to do to prepare for that. And also, governments thinking about, you know, are we resilient to flooding? Is our housing policy joined up, you know, with our environmental policy in the answer? No, it's not. It should be better. And so what can we do about that? How do we make those changes in and rapidly shifting political environment? One of the things, given that I've had a long term interest in housing, one of the things which, as always, really rather astonished me, is the way in which it's been possible to develop quite large-scale housing on river flood plains. And then people turn around when the, whether it's heavy rainfall and say, oh gosh, we never really anticipated this, but it seems to me very, very predictable and I'm really rather astonished that successive local authorities have allowed this development to take place. Yeah, we just didn't have the policies in place. And so lots of properties have been, we have a lot of legacy housing on the flood plain, which is complete madness from somebody who understands flood risk. But when there was no, you know, very little regulation, and that was allowed. you know, now it's too late. Those people who are living in those properties, you know, didn't understand the risk of flooding when they bought them. And there's not a lot we can do about it. But we did go to pick up those houses and just move them away. You know, that's an impossibility. So we left with this problem. People not able to get insurance. And so we have a, we have flood re now in the UK, which is underwriting, or that's probably the wrong word, but you know, providing those kind of reinsurance provisions for people like risk of flooding, but only properties before 2009, I think. So the, and that is going to end, I think in 2039 or something like that. And so we can have to think about what we're doing with those people who, who are in that situation, who are still struggling to get insurance and got changing floods because of climate change as well. So you've got other stuff going on at the same time. So it is a bit of a mess. And it's really, really hard to see people living on the flood plane, whose homes get flooded, who just didn't really understand that they were going to be in that situation. And of course, there's lots of things you can do to adapt your home, but they're very expensive. Can I ask you quickly if you could just perhaps what are the key things you think that we as a country should be trying to address them. So to, to be able to make ourselves more resilient in the future. Well, we should be really, really racking up our renewable energies and making sure that we, you know, are all generating our own electricity and we are not contributing more to burning fossil fuels, which will make climate change worse in the future. We need to absolutely really nail that down because that is, can you imagine the lives of my children and their children, you know, we do not want to put them in that position that the extreme weather is just going to keep getting worse. I think that's probably a very good moment to wrap up. And I'd like to thank you very much, Hannah, for taking part in this discussion and for contributing your range of really expert, extensive knowledge. So thank you very much. I hope that you have enjoyed it and look forward to you listening next time. Goodbye.