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In this episode, we discuss how long-term climate change and short-term weather variability may influence migration patterns and how country context is important in determining where to invest in public infrastructure.
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Transcript:
Roumeen Islam: This is the World Bank’s Infrastructure Podcast. In today’s episode, we discuss how we should think about Infrastructure Investments in the face of climate-induced migration. Remember to listen to the key messages of the episode at the end.
More than 4,000 years ago in the Indus river valley, there were sophisticated cities with their own infrastructure, such as well-planned streets and drainage. Yet, the Harrapans had moved away from there by 18000 BCE, abandoning it all to settle at the Himalayan foothills. A recent study found that the drying up of the summer monsoon rains had reduced agricultural productivity over time and the people were increasingly abandoning what they built. The fall of the Accadian empire in Mesopotamia is also believed to have some climate roots. The abrupt onset of drought and falling agricultural productivity also led to mass migrations. Investments made in the infrastructure of these civilizations were left behind and lost their value. While those in new areas, where they moved to, gained in value. While these changes occur over a long expansive time and a long time ago, the questions they raise are relevant for us today. Let’s find out how.
Roumeen Islam: Good morning and welcome. I am Roumeen Islam, host of Tell me How. My guest today is Michael Oppenheimer, Professor at Princeton School of Public and International Affairs. Welcome, Michael.
Michael Oppenheimer: Thank you for having me.
Roumeen Islam: We’re very lucky to have you with us today. Climate-induced migration has been getting a lot of attention in recent years, and I wanted to begin today’s discussion by asking you to explain what this is and why this is something that we should pay attention to.
Michael Oppenheimer: First of all, and not just weather disturbances, but long-term changes in climate patterns that have always occurred naturally.
What’s new today is that climate change caused by the buildup of the human-made greenhouse gases, primarily by the combustion of coal, oil, and natural gas to fuel our industrial society, has begun to cause changes in those patterns, which themselves we believe are capable of causing large-scale movements of populations.
Now, here, I’m not talking about, globally, everybody getting up at once and moving somewhere. I’m talking about populations at many places across the globe, moving in ways they would not have otherwise. After all, mobility is a human phenomenon, where only we are used to it, but we do it anyway for lots of constructive purposes, not necessarily to flee bad political situations or bad climate situations.
What we do see, however, is the likelihood that climate change will impose alterations in those patterns. So, we’ll get more people moving from some places to other places, and we’ll get roots of migration probably, which are quite different than what we’ve seen in the past. So that’s why it’s come to our attention.
And if you layer on top of that the fact that several recent extreme climate conditions, for instance, in the U.S. Hurricane Katrina caused the evacuation and non-return, in fact, of a large fraction of the population of New Orleans, there has been an argument that the large migration out of Syria, and other parts of the Middle East into Europe, which caused some significant degree of political turmoil that still reverberates today had the long-term drying in that region, as severe drought, as a contributory, if not, an initially causative factor.
We’re seeing things in front of us which make us concerned that if these sorts of situations are not handled with forethought and with great care by governments in the future, they’ll spin out of control and lead to the kind of political dislocation as we had seen in Europe over the past five years or so.
Roumeen Islam: Yes. And having forethought and being able to design appropriate policy, you can do those better when you have some idea of where the migration is going to be and anticipating large movements, but that’s not an easy thing to do. Predicting migration patterns, the timing, the direction, the magnitude of the changes, those are not simple things to do.
And there are a number of top-down or macro-level models and some micro-level models that look at the individual or household behavior that try to understand migration patterns. So, I’d like you to speak about these models that are commonly used. How do they do this?
Michael Oppenheimer: So that everybody understands, a model is supposed to be a replica of reality. And because you can do experiments on the model that you can’t do in the real world, you can use these models. If they contain the proper sort of laws of how things occur in reality, you can use them to project what will happen in the future under conditions that are similar to today, for instance. Or, if they’re good enough models, and the situation we will be dealing with can be generalized enough, you can project what will happen under vastly different conditions.
This is certainly true in the physical science arena, where we know the basic laws of physics. But the difficulty in dealing with…and that’s, by the way, why we’re able to project the climate changes we’ve seen with some fair degree of accuracy. When you get to the question of how humans will respond to those climate changes, you’re talking about quite a different kettle of fish. You’re talking about laws of human behavior, and our understanding of human behavior, our ability to cite particular laws is nowhere near the way it is in physics.
So, , and we can’t do it to any degree of accuracy now.
I wouldn’t take the numbers that come out of today’s models very seriously, but they do illustrate tendencies, and at least that much is something that policymakers need to be aware of.
Roumeen Islam: Of course, these tendencies will depend very much not just on the physical world, but they will depend on the policy, on the societies, the infrastructure, the economics of where people live.
And we’re going to get into that a bit more, but could you speak a bit, broadly speaking, about what these models show.
Michael Oppenheimer: The empirical or econometric models show a tendency to move when things get too hot or too dry. Now, whether people in their movement are responding only to the information they have about what’s going on around them, and how well and carefully they think about what the conditions are in the place they are going it’s not yet clear, and that’s being explored now with what is called network models.
Models which ask the question, “if someone migrated from your village A to village B, 200 miles away, and you maintain contact, do you use that information?” That would be the effect on the network, and that would sharpen the ability of an individual to be able to move. They’d have better information. We don’t have good answers at this point about how much that network information matters, but network models are starting to penetrate, and we’re starting to get that information.
So, there’s another sort of area, which is the area of information, and there’s a lot of uncertainty on what kind of information people have and how much they act upon it. Or whether they’re anchored in various places by a tendency to want to just stay no matter what the information is. We don’t have thorough answers, and it depends on the context.
An entirely different type of model is one that’s very commonly used in climate change. It’s called an integrated assessment model. This is basically a model of the global economy and how that economy responds to climate change. So, it’s not looking at, say, migration from Mexican villages to Mexican cities or migration from Mexican villages across the U.S. border. It’s looking at a bigger picture, which is how whole regions of the world respond to climate change.
Migration is starting to be put in a usable way into those models. And they show some very interesting results. Like people get stuck in certain areas because it looks like the impacts of climate change rob the local economies in a way that causes people to not have enough money to be able to move.
So,
Roumeen Islam: Michael, how does the quality of infrastructure affect how people move from where they are to where they go.
Michael Oppenheimer: So, .
Let me give you a few examples. If movement is going to happen, and there are certain destinations that people are going to move to preferentially, for instance, places with better climate conditions than what they came from. And if the infrastructure isn’t prepared to absorb those people and allow the region to economically benefit essentially from more people coming in, whether it’s highways or whether it’s railroads or airports, no matter what it is. If you put a lot of people in a new area and the area isn’t set up to receive them, then not only do you have a reduced capability to take advantage of people with new skills and interest in working hard moving in, but you basically may have economic chaos, because you’ve got overloaded systems, which all of a sudden can’t handle the influx.
Roumeen Islam: But don’t you think people might also want to migrate to places where there is good quality infrastructure, and that is also one of the incentives for them to move there. It could work either way, right?
Michael Oppenheimer: Yes, the basic, long-standing economic theory is that people primarily move because of wage differences. They can earn more in one place, and they can earn in another place, but it’s not that simple.
And I don’t know of any study that’s looked specifically at infrastructure as a key to determining where people move, but it’s without a doubt that a lot of people in the modern world after all move by air transit, so you at least have to have some sort of facilities to take air traffic in the place that you head for.
On the other hand, don’t forget most migration isn’t international. And of course, urbanization being successful both for the migrant than for the urban area, it depends on there being adequate infrastructure.
So, . But there’s a flip side to that too. Areas that people move out of frequently essentially get drained of skills and talent and enough population so that the current infrastructure is even sustainable.
And governments are already in a position of making decisions about how long they can maintain infrastructure in certain areas, which are, for instance, being abandoned due to flooding -which is becoming more and more common- when they can’t afford to spend every penny everywhere. And all of a sudden there’s half the number of people or a third the number of people that used to live in a particular place. So,
Roumeen Islam: So, can we move on to the micro agent-based models that you mentioned and think specifically of some cases you may have studied because you’ve done studies on specific communities and localities that are facing changes in climate or seeing a lot of weather variability. So, would you speak a bit about some of these?
Michael Oppenheimer: Yeah. So, one of the things we did is…First of all, let me explain an agent-based model looks not at the overall statistical situation, and it doesn’t look at the economic equilibrium situation. What it does is it looks at the decision-making that occurs at the household level and tries to figure out how households which have a certain number of members, certain age structure, certain economic capabilities, certain income, how they will make decisions to move or not to move as the climate changes.
And there’s a lot of important detail that goes into this. For instance,. They may send out members in anticipation of bad climate conditions to other places or other countries to earn income and send them back through remittances.
So,
Roumeen Islam: Yes, that’s a good point.
Michael Oppenheimer: And so, what we did is we looked at households in Bangladesh and tried to understand how the threat of increased flooding, particularly near the coast, would affect people’s decision to move or to stay or to find some other way to earn income in the same area.
And what it turns out, despite the sort of delivered wisdom that as sea level rises, the coast is going to flood in Bangladesh, it’s going to become harder and harder to defend the coast, basically, it’s going to become depopulated eventually, at least for most of this century, even under relatively high greenhouse gas emissions and therefore the higher warming scenarios, we don’t see that.
It’s because the growth in economic opportunity in Bangladesh occurs near the coast, we anticipate people staying and taking advantage of those job opportunities. So, you may see a shift from rural to more urban lifestyle as people look to work in urban areas, but we don’t think we are going to see a great depopulation.
And that, in turn, has a big, important implication for infrastructure planning. It means that the government there has to think about it. Do they really want to start abandoning areas, or if people are going to want to move there, that’s where the economic opportunities are? Do they want to take advantage of that and instead protect areas, building as much coastal defense as selectively possible? Because it’s not possible economically, I don’t think, to defend the whole Bangladesh coast, but create defended enclaves, essentially because people seem to want to stay in the coastal area and because that’s where the greater wage opportunities are.
Or the government might decide that this is still not smart and that eventually, the ocean is going to win, you might say. And the government might decide it wants to invest elsewhere. In any event, the information about what’s likely to happen allows the government to have a basis for planning infrastructure, whether its coastal defense infrastructure and continued enhancement of transportation capability around the coastal area, or whether it’s “well, we’re really going to have to abandon parts of this place eventually, that is the coastal zone, and encourage the development of infrastructure more inland.”
Roumeen Islam: I seem to recall that you have actually done some work estimating the infrastructure losses in some of these cases that you looked at, due to climate change. Were they large relative to other losses?
Michael Oppenheimer: If you go to a place that’s really taken a big hit from climate remembering that some climate effects are now also climate change effects, that is they would not have happened without the buildup of the greenhouse gases, the example that has been worked out the best is actually for New York City which took a beating in Hurricane Sandy in 2012.
And it turns out that 10% of the flood damage approximately was caused by incremental flooding due to climate change. And that caused expenses. The whole damaging effect of the hurricane in New York City, for instance, was about $20 billion. And about 10% of that is $2 billion; it’s quite a lot of money.
And most of that, I think, was devoted to rebuilding infrastructure, like the mass transit subway system in the area that was shut down for three or four days flooded, and sections of it were devastated, and they’re still repairing the system from something that happened nine years ago. So, one thing you need to remember…
Roumeen Islam: That’s a very long time!
Michael Oppenheimer: It’s a very long time, but you cannot recover when the resources aren’t there to do everything overnight.
Roumeen Islam: So, imagine if this is New York City, what happens in poor countries.
Michael Oppenheimer: Well, you can see what happens in poor countries. You can see what happens in poor parts of the United States after all.
And even in places where literally hundreds of billions of dollars have been poured in, for instance, Southern Louisiana, around New Orleans, they’re still recovering from Hurricane Katrina, which was 16 years ago. So, what we do when we think about risk is we think about the distance in time between two bad events. And you think about: “is there any chance of recovering?”
And the threat with climate change is that time between severe events shrinks. So, then an event that used to be a 100-year flood over the last century becomes a 20-year flood, a 10-year flood, a 5-year flood, and then an annual flood at many coastal locations by 2050, in fact!
So, we’re seeing a development around the world where a lot of coastal locations are going to have the threat of essentially never being able to fully recover.
Roumeen Islam: So, this is because the frequency of extreme events is increasing quite fast, right?
Michael Oppenheimer: Correct.
Roumeen Islam: Now, this, of course, makes me think that then any new investment in infrastructure needs to factor in resilience.
If you’re going to be seeing very frequent, extreme events, then the way you think about rebuilding really has to take into account how resilient your infrastructure will be to this increased onslaught.
Michael Oppenheimer: That’s a very important point. If we take the world as it is presented to us today, there’s no way we could effectively deal with the current hundred-year flood in a major city happening every year, but that’s where we’re headed.
And so, you have to think, “okay, how could we build cities so they could deal with it?” One way to do it is to build floodable infrastructure. Cities are hard to move, especially with all that value right along the coast, say, or next to some river, which is, flooding is also increasing. So, what you want to do is think about how in the future you can make the existing infrastructure floodable by retrofitting and in some way. Or building new infrastructure going right down, for instance, to the sidewalks, which are floodable, which can drain easily, which could be flooded one day, let the flood water recede, and they’re usable, as soon as the water goes, rather than having to spend five years rebuilding.
There are examples of this in the Netherlands; there are examples of this in Denmark. In other countries, there has been some resistance to thinking about building floodable infrastructure, but in a lot of places, that’s the only way to avoid this squeeze caused by extreme events coming so frequently. You just don’t have the time to rebuild everything, and then the next one is on you already.
Roumeen Islam: Yes. I wanted to think a bit more about your agent-based models and what they say about human behavior. Because I was wondering, do people react differently depending on whether they think that whatever’s happening in the weather is a temporary phenomenon, as opposed to whether they think it’s a permanent phenomenon? I presume they do.
Michael Oppenheimer: Yes, they do. For instance, the events that move people quickly in enlarged numbers are extreme events, climate, or non-climate. Non-climate events, like a volcano, climate events, like an extreme flood. Those cause people to move right away, but they don’t move far in general, and they return, except in really extreme situations as again, happened in New Orleans with Hurricane Katrina, where about a third of the population didn’t come back, and a lot of those people are eventually going to be replaced by people who didn’t come from New Orleans. If you look, however, on the long-term and think about people experiencing a trend in warming or a trend in drying, their view appears to be somewhat different.
There the reaction is more, “what are we going to do in the long term?” And in the long term, they’re not going to come back because the conditions were only getting worse where they are. So they want to move away, and if they’re going to move away and not come back, they’re going to move farther.
And more international migration is a response to this kind of thinking about long-term trends. Now, a lot of what I’ve just said is inferred from the observation that people who respond to extreme events tend not to go too far and tend to come back, and people who are responding to long-term trends tend to stay away. We don’t have a good picture of how that thinking develops and how they make those decisions, and that’s why people are starting to develop agent-based models because it helps us get at the decision process and look at the individual factors that households decide upon.
Roumeen Islam: So, before we end, is there anything that you would like to add.
Michael Oppenheimer: Yeah. I’d like to add that the whole purpose of thinking about why people move, the whole purpose of trying to model this behavior is to provide a basis for sensible policy. And your particular interest here is in infrastructure. Infrastructure involves a lot of investment. It involves hopefully thinking ahead.
And so, I think at this point, And also, to have a base for making some hard decisions about where you’re going to build new infrastructure and where you’re going to let things shrivel a little bit because the climate changes that are coming are just too much to deal with.
There is no one answer. It all depends on the local context. It all depends on local proclivities and what individuals and individuals’ countries want. But when you put it all together, it’s a kind of decision about the future that governments make all the time. And now they better fold in this question of enhanced mobility the desire, the necessity of people to move, so that they have a good livelihood for themselves and their families. Or to stay if the governments can make it easier for them to stay.
Roumeen Islam: Thank you very much. That was very interesting, and I learned a lot. Thank you, Michael.
Michael Oppenheimer: Thank you for having me.
Roumeen Islam: Well listeners, here are some things we learned today. Firstly, Large macro models that aim to predict physical changes to habitats all the way to micro models that focus on individual or household behavior and their incentives to move. They all provide information about likely scenarios, and this is important for planning. Secondly, For example, investing in flood-proof transport infrastructure will allow more people to stay in areas affected by water levels increases or they can choose to invest in areas that are less likely to be affected by significant climate events. Thirdly,
Thank you, and bye for now.