海面上昇による賃料上昇：気候変動がどのようにコミュニティを移転させるのか

気候変動は、台風や洪水を増加させるため、沿岸地域の居住者は、内陸部への移転を余儀なくされています。それにより賃料が上昇し、その地域の現在の居住者が立ち退きを余儀なくされています。ミリマンは先頃、この問題を調査しており、コミュニティのレジリエンスを高める支援をする非営利組織Rebuild by Designと「ニューヨーク市における気候をきっかけとする転居：近隣に空地を設ける（Climate Displacement in New York City: Making Space for Our Neighbors ）」という論文を共同発表しています。クリティカルポイントの今回のエピソードでは、本研究の著者2名が、最もリスクにさらされているグループ、マンハッタンを香港のようにデザインすること、そして積極的な都市計画をしないとニューヨーカーの40%が移転を余儀なくされる可能性があることについて論じます。

As climate change causes more storms and floods, residents of coastal areas are being forced to move inland—driving up rents and displacing current residents of those regions. Milliman recently studied this issue in a paper called “Climate Displacement in New York City: Making Space for Our Neighbors,” published with Rebuild by Design, a nonprofit that helps communities build resilience. On this episode of Critical Point, two of the study authors discuss the groups most at risk, designing Manhattan to be more like Hong Kong, and how 40% of New Yorkers may be displaced without proactive city planning.

Transcript

Announcer: This podcast is intended solely for educational purposes and presents information of a general nature. It is not intended to guide or determine any specific individual situation, and persons should consult qualified professionals before taking specific action. The views expressed in this podcast are those of the speakers and not those of Milliman.

Rebecca Driskill: Hello and welcome to Critical Point, brought to you by Milliman. I'm Rebecca Driskill and I'll be your host today. In this episode of Critical Point, we're going to be talking about climate displacement—that is, the ways that climate change and natural disasters will cause people to relocate and the impact that may have on communities and local economies.

In particular, rising sea levels will increase flooding along the coasts. Milliman recently worked with a not-for-profit organization called Rebuild by Design to study this issue in New York, looking at how the population there might shift as a result of climate change.

I have two of the report's authors here with me today. Amy Chester, good morning.

Amy Chester: Good morning. Thanks for having me.

Rebecca Driskill: Amy is Rebuild by Design’s managing director, and she's joined by Molly Barth, who is a geographic information systems, or GIS, consultant here with Milliman. Morning, Molly.

Molly Barth: Hi. Thanks for hosting.

Rebecca Driskill: So, thank you both for joining. Let’s jump right in. I just want to start with a brief overview. Amy, can you give listeners a quick summary of the research? What did you guys set out to investigate and why?

Amy Chester: Sure, Rebecca. And I'm sorry if my audio is a little choppy. As we all know, working from home can be a little bit challenging.

Rebecca Driskill: No worries.

Amy Chester: So, Rebuild by Design started after Hurricane Sandy. And we were originally an initiative of the U.S. Department of Housing and Urban Development (HUD). HUD set aside a billion dollars of the disaster recovery funds to bring experts from around the world to work with communities and local governments on the ground to rethink our climate infrastructure.

Since then, we've not only worked in the Sandy region but worked in over a dozen cities around the world. And what we've realized is that even though it's been 10 years since Hurricane Sandy, cities around the world are not yet comprehensively thinking about what's going to happen with climate change. We already know that climate change is here. We recently put out a report that was able to show that 90% of U.S. counties had had disasters between 2011 and 2021. And what that means is that Americans are already suffering. However, our governance structures and our policy making have not yet caught up. So the impetus of this report was to show what would happen if we don't act now because we don't yet have a comprehensive approach to climate change.

How a 2050 flood could displace New Yorkers

Rebecca Driskill: OK. And so can you, Molly or Amy, could you both tell me what did the report look at? You know, what were you investigating in terms of New York?

Molly Barth: Sure, I can hop in here. So we were looking at which coastal areas could be impacted by a severe flooding event in the year 2050 and then who lives in those coastal areas. And then we took a look inland to figure out where could those people, forced to move from coastal areas as a result of increasing flooding risk, where could they go? Are there neighborhoods in the city where these coastal residents might retreat to?

Rebecca Driskill: Yeah. And actually I think it's important here to just pause and define briefly what is climate displacement versus climate migration? What are we talking about with climate displacement, and socioeconomics and communities? Maybe Amy, do you want to talk about that?

Amy Chester: Sure. Already, in places like New York, there is a huge housing strain, and it's becoming more and more unaffordable for the people who are the lowest income. Climate change is likely going to force some communities to move away from the coast. And when they do, they're going to move to another area. However, people already live in that other area. So unless we're making room for our neighbors, one of the things that could happen is that the existing residents might not be able to stay in that area because the change in the migration patterns would cause the housing market to increase. So all of a sudden an apartment that may have been affordable to a family may no longer be affordable when there's more demand for that same apartment.

Residents most vulnerable to climate change

Rebecca Driskill: Tell me briefly who you guys looked at or how you delineated the data when you were looking at climate displacement.

Molly Barth: Great question. So we set out to segregate the city into four different, what we call in the report, “displacement quadrants.” So each quadrant represents an income level and a flood risk level. And we have separated the city into high flood risk, higher income; high flood risk, lower income; lower flood risk, high income; and lower flood risk, lower income. And so that allowed us to just take a kind of a big picture take on the different socioeconomic groups throughout the city and how they could be affected by future coastal flooding.

Rebecca Driskill: Amy, do you want to add anything to that in terms of the community perspective?

Amy Chester: It was important for us to know exactly who lived in the flood zone, and what resources they may need in the future because I don't think anybody's really thought through this. There's going to be people in the flood zone who are going to have their own financial means that will be able to leave when it's comfortable for them. Maybe it would be after a storm, but hopefully it would be before they have suffered.

Then there's a big group of residents in the flood zone who won't be able to leave on their own, some of whom live in public housing or government-subsidized housing, and other folks who live in regular housing, maybe they’re in rental apartments, but they're not going to be able to leave.

In a disaster, the people who are the most vulnerable fare the worst, kind of regardless of whether they're vulnerable by age, they're vulnerable by socioeconomic income, they're vulnerable by race. So we as policy makers and as advocates need to make sure that we're always thinking and centering the people who are the most vulnerable first in our policies. In this case, it's going to end up being the people who aren't going to be able to move without a lot of government assistance.

Surprise findings about climate displacement

Rebecca Driskill: Got it. So was there anything that surprised you both about the findings?

Molly Barth: For me, I grew up in San Francisco and have actually never been to New York City. So not knowing much about the city, I really didn't know what to expect when we ran the analysis. And what was really surprising for me was how many low-income renters live along the coast and how risky those buildings are for both current and future flood risk. When I think of coastal areas in New York, I think wealthy people, luxury apartments, but that's not always the case. And I was, yeah, really blown away with the number of public housing units along the coast and risky areas and the concentration of these units across the city.

Amy Chester: A few years ago, we wanted to really understand exactly who lives in these areas because they’ve never been reported before. So we did a very simple demographic analysis and we found that currently there are 1.3 million New York City residents that live within or directly adjacent to the floodplain. And by 2100, that number could rise to 2.2 million. That's a lot of people. It's about 20% of our city. Fifty-six percent of the residents within or directly adjacent to the floodplain identify as nonwhite. And more than half are considered low-income for New York City for a family of three by our federal government.

New York City is going to be experiencing a lot of diversity in climate change. We're going to get hotter. We're going to get wetter. And our storms are going to be more severe. We're also going to experience somewhere between three to six feet of sea level rise, which isn't going to happen overnight. It's actually going to be a slow burn.

So little by little, the people who are the most vulnerable population are going to become more and more vulnerable to these events. And what we've seen from a lot of studies is that low-income communities experience greater challenges evacuating during a storm, putting them at more risk for injury or death. And that years after a storm, there's a larger decline in credit scores for people who live in communities of color, instead of people who are white. So these are major long-term issues for the people who are most vulnerable.

Data shows your climate-displacement risk

Rebecca Driskill: The report has a lot of really great maps and statistics in it, so I encourage anybody to check it out because I think that you can get a closer look at some of the potential impact here based on what you guys have modeled.

I'm curious, Molly, actually, in terms of the data, if you could talk about, were there any challenges you faced in finding the right data to put the report together? Or in terms of having open data available, any challenges there?

Molly Barth: Yeah, absolutely. And honestly, surprisingly so. There is so much data out there with respect to future flooding and future catastrophes. But I had an exceptionally hard time finding anything with respect to where future coastal flooding could happen based on, you know, the scientific community's current forecast of climate change.

When Amy and I first started talking about this work, we wanted to do several cities and look at several coastal cities, including San Francisco and Charleston and others. And it was just too hard to find the data to do that. So luckily, the New York City Panel on Climate Change produces these really excellent reports, I believe every few years. And along with the reports, they release maps of future coastal flooding for various decades in the future, for example, 2050 and 2100 and different sea level rise scenarios. And they were willing to supply the data, and they actually host the data online for the public to view, so you can actually go to their flood hazard mapper, zoom in to your neighborhood, zoom in really close and see if you are in the projected future floodplain.

And I think that this data is so essential, not only for just everyday people to be able to access, to know like if they're living in risky areas, but also for people like myself interested in researching these topics. Having free access to this type of data would just really expand the questions that we can ask and answer with geospatial analysis. And I think it's really important to have the data readily available to those who are interested. And so, really thankful that the New York City Panel on Climate Change does this work and publicly hosts their data so that others can access it.

Amy Chester: I'd like to add that this report is only focused on coastal migration. We did not overlay the New York City areas that are likely to have rain, or likely to be most impacted by heat, which are other climate hazards that are very real and can also cause migration. I think that would be a step two.

When we started putting together the scope of this analysis, we were realizing that mixing all of those data points together can get more and more complicated. And what we wanted to tell was a very simple story.

And what we were able to show with the data that we had is that, just with the coastal data, over 40% of New Yorkers will be at risk for displacement without some type of proactive government planning. Forty percent of New Yorkers. Either they're at risk because they themselves are going to have to move inland. Or because, when they move inland, the people who already live there could potentially be displaced and then move to another area in New York. And I think that that's what's really unique about this study is we're not just looking at what's going to happen or what could happen in the flood zone. We actually created a kind of predictive model to say OK, where are these people going to go? And what's going to happen next?

Climate adaptation must start now

Rebecca Driskill: Yeah, it's interesting. I personally spent 15 years in New York City and four of those about a block from the Gowanus Canal and very clearly remember it flooding more than once in my time there. You know, we were just up the hill, but you can clearly see how this can impact folks.

You know, Amy, from your point of view, I'm curious: What's the message to community planners and governments in New York City, but then also more broadly? Because, obviously, this is an issue that goes beyond just New York.

Amy Chester: Well first, I want to just let listeners know that the Gowanus Canal is a superfund site. So when it floods, all of the contaminated water gets backed up into people's homes and the streets and yards that children may play in afterwards. It is a very serious issue when a superfund site floods.

And this is a good example of why we should care, and why we need to pay attention today. It is going to take us probably a generation to plan and to build the infrastructure we're going to need to meet climate change, which means we need to start now. We are already seeing the effects of climate change. What we need to do is think about how can we make space for the people who are most at risk? And where can they go to make sure that people actually stay and that our city continues to be just as vibrant?

Rebecca Driskill: And from a risk perspective, Molly, do you have any thoughts in terms of insurance or risk management? Or even, you know, I mean, you spoke about data, maybe the question for scientists and modelers and actuaries is about continuing to ask the questions and trying to study them. I'm curious to get your take on what you would like to see happen.

Molly Barth: Yeah, absolutely. I think the research that, for example, that the New York City Panel on Climate Change has done locally for New York should continue. I mean it's just such a rich resource. And I know that they're, you know, continually working on new reports. So I hope that that can continue to be a resource for those looking at these issues.

It’s very important that everyone living in New York City really understand their risk. And that can be really hard to do from a lack of data, or a lack of data access, or a lack of education. And so, you know, as all these changes are happening, as flooding is worsening along the coast, and our, you know, municipalities and governments are struggling to make policies and adapt to these changes, it's important to keep the residents informed. And that can be educating them about the risk and educating them about what they can do to mitigate that risk while they're there. Not everyone's going to be able to move right away. And so helping people know their options is going to be one strategy that we can take now to help people avoid suffering when events do happen.

Amy Chester: And I'd like to add that we at Rebuild by Design are not asking anybody to move or telling anybody to move or want anybody to move. What we want is comprehensive climate action from our elected officials and our policy leaders so we know where are the areas we will be able to fortify, and where are the areas where we'll be able to retreat, or where we'll have to retreat well in advance of us being in a crisis situation.

Climate displacement lessons from Hurricane Sandy

Rebecca Driskill: So Molly, I was living in New York during Hurricane Sandy, and I'm really curious: When you guys are talking about future flooding, sea level rise, potential disaster events in 2050, how does that compare to what New York City has experienced during a storm like Sandy? I mean, I remember Battery Tunnel was flooded, like that was pretty bad. How does this compare?

Molly Barth: Yeah. So in the report we have a comparison map that shows the estimated inundation. So the flood inundation extent of Hurricane Sandy compared to the future 2050 floodplain, which is—you know, it's also an estimation. These things cannot be delineated perfectly. But as you'll see in the report, the future floodplain extends much further inland than the Hurricane Sandy inundation extent. So we know—like just as you're saying, Hurricane Sandy was this catastrophic event. So many people died. So many buildings and housing units were destroyed. And so many people were forced to relocate.

Looking at the future 2050 floodplain for an event such as Hurricane Sandy, it could be so much worse. So many more people could be affected. And the water depths could be so much deeper in some areas. We always think of Hurricane Sandy as a benchmark for a very terrible event in New York City. Based on the current predictions it is likely that an event like that could happen again if we don't plan ahead to help mitigate the effects of the flooding on communities.

Amy Chester: And I'd like to add that an event like that will happen again. We know that there’ll be hurricanes that are going to be equally as bad if not worse than Sandy. What we don't want to happen, again, is the amount of suffering that happened after Sandy. So if we invest in climate infrastructure and we invest in making smart decisions about our policies and our budgets, we can basically assure ourselves that we will be able to bounce back faster after the storm. The point I want to make is that we're all going to suffer, but we can suffer a lot less if we make smart decisions now.

How cities can plan for climate change

Rebecca Driskill: When you talk about making space for our neighbors, what does that mean in terms of practical next steps?

Amy Chester: It means actually making physical space. That we need more places where we can build housing, and housing that is affordable to the people who need it at any level income. So, you know, around the world, around the country, but also in New York, there's something called NIMBYism, where people do not want to site additional development in their backyard. But hey, we need to do it for our own neighbors. And we need to do it right away because it's going to take a while. So if we need to build tens of thousands of new units just to catch up with where we are today in the housing market, then we need to start right away.

Molly Barth: And Amy, I think, when we were writing the paper there was some question that’s like, OK, what does that mean? And you talked about kind of building up like other countries have really different ways of accommodating dense populations that we're not used to seeing. Can you explain that a little bit more?

Amy Chester: Yeah. I mean, have you ever visited Hong Kong? It's very interesting because it's not that different from Manhattan in the sense that it's an island, and Manhattan is an island. And Hong Kong has—it's very, very, very dense, meaning that there are more buildings that are closer together and that they are taller. So it definitely feels a little bit different than Manhattan. However, it's still a very vibrant and livable city.

And we don't need to put these 40-story buildings everywhere, but we do need to maybe put a 10- or 20-story building where you might have a parking lot today. Or on top of a maybe something—a low-density housing unit or a supermarket, there's another space on top to build more housing. We need to be a lot more creative.

And in that we should never be thinking about it as just housing because that would be really hard and might even kind of suffocate our neighborhoods. But also thinking about, how can we be more creative with park space? What are the parks that can do double duty? So not only do we need to be building parks, we need to be building parks that will be able to absorb from rain events. Not only do we need to be building parks that will absorb from rain events, but we need to be building the parks that will absorb from rain events and also cool our communities in heat waves.

So it's really this kind of like chain reaction of knowing all the different climate hazards that we will be faced with, some of which we’re already faced with, and then thinking about how could we reimagine our communities in ways that make it places we still want to live and use the new infrastructure to address climate change.

Rebecca Driskill: Great. I think that that is a great way of wrapping up today's episode. I want to thank you, Amy and Molly, for joining me. You can learn more about this report at rebuildbydesign.org and at milliman.com.

In the meantime, you've been listening to Critical Point presented by Milliman. If you enjoyed this episode, please rate us five stars on Apple podcasts, or share the episode with your colleagues and friends. We'll see you next time.