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Sea level rise is already happening and affecting people right now. We invited Prof. James Renwick back to TILclimate to talk about the near future: what will sea level rise look like for coastal areas in the next 20 or 30 years, and what can we do about it?
Professor James Renwick is a weather and climate researcher. He is a Professor of Physical Geography at Victoria University of Wellington, specializing in large-scale climate variability and change across the Southern Hemisphere and Antarctica. He was a lead author for the 4th and 5th Intergovernmental Panel on Climate Change (IPCC) Assessment Reports.
For more episodes of TILclimate by the MIT Environmental Solutions Initiative, visit tilclimate.mit.edu.
LHF: [00:00:00] Hello, and welcome to Today I Learned: Climate, I’m your host Laur Hesse Fisher -- in our last episode, we talked with Prof. James Renwick from Victoria University of Wellington in New Zealand about the science of climate change and sea level rise, and we heard about what will likely unlikely unfold over the next hundred years… But Prof. Renwick also told us this: .
JR: [00:00:27] If you're in one of these regions where you're more exposed to faster sea level rise, then even in the next 20 or 30 years, it will be a problem.
LHF: [00:00:37] But what kinds of problems can we expect and what can we do about it? This is what we’ll cover in today’s episode.
Let’s jump in.
First off, as we mentioned in our last episode, the U.S. is home to some of the cities and regions that are seeing among the fastest rates of sea level rise on Earth. We’re talking the Gulf of Mexico, mostly the coasts of Louisiana and Texas -- and all up and down the east coast but especially the mid-Atlantic -- including New York, New Jersey, Delaware, Maryland, Virginia, North Carolina… And these are really heavily populated areas.
JR: [00:01:21] All coastal regions are at risk eventually, but the Eastern U.S. is more at risk sooner, and there's a lot of people live very close to sea level from Florida northwards, certainly in the Carolinas, and in a city like New York, a lot of the heavily urbanized parts of New York—Manhattan island, for instance, are pretty close to sea level.
LHF: [00:01:34] All in all, about 3 in 10 Americans live in coastal counties that will see some amount of sea level rise in the coming decades. It matters a lot to us to understand what we’re in for. So… what are we in for?
JR: [00:02:02] So it's like everything to do with climate change. There’s an effect of things, just changing gradually, and there's an effect from extreme events. And that's very true with sea level rise.
Florida, especially Miami beach and a lot of the low lying areas that have been developed as population centers over the last half century or longer, they're already having trouble with what's called sunny day flooding. That is just a high tide. And when the tide comes in, it’s a bit higher, you know, maybe best part of a foot higher than it used to be a hundred years ago. And that's enough when there's a high tide to push the water onto the roads, if you're very close to sea level.
LHF: [00:02:47] Yeah, this surprised me, like, the first thing that happens in certain areas isn’t that the beach disappears and the sea is lapping up against houses. It can also look like new, high tide flooding through sewers, roads and backyards.
JR: [00:03:05] The sort of everyday gradual encroachments of the water, you know, you can put in pumps and divert water away. And I think people can get by that way for quite a long time if the sea level is just gradually creeping up. I suppose the gold star example is the Netherlands.. A lot of the country is below sea level and they've got this amazingly sophisticated system of seawalls, dikes and pumping stations and so on, and areas that can be flooded when it's necessary and then drained again, all sorts of things.
LHF: [00:03:40] But, unfortunately, this gradual rise in high tides isn’t the only thing we need to worry about when it comes to sea level rise.
JR: [00:03:49] It's really the storm events that cause the damage. Beaches are pretty flat places. And when you get a storm, even with a little bit of sea level rise, that makes it so much easier for the storm waves, to come inland and, and do damage.
LHF: [00:04:05] There are engineers that specialize in coastal areas and try to prepare for these kinds of situations.
JR: [00:04:12] Coastal engineers have this amazing rule of thumb, which I’ve seen verified. I didn't believe it at first. But I know it's right now. It’s four inches of sea level rise roughly triples the occurrence of a given coastal inundation event. So the one in a hundred year coastal flooding event would become the one in 33 year coastal flooding event. And that's just because those four inches adds to the waves, um, peaking and running up onto the beach.
LHF: [00:04:44] Because we’ve already had a foot to a foot and a half of sea level rise on parts of the east coast of the U.S., that means a flood that a hundred years ago would only happen once in 100 years, today, it can be more like one every twelve or even one every four years.
This is key for trying to prepare for all this. Our coastal roads and bridges and homes weren’t built for big floods to happen that often.
JR: [00:05:10] So if you have your home insured and it's damaged in a coastal storm, then probably you can get a payment to rebuild or repair, but insurance companies will start pulling out of coastal areas. And this is already happening in some places. And I think that's what's going to drive people away from their coastal neighborhoods. Just the economic costs of, you know, loss of property value and the cost of repair, if it becomes too frequent or too damaging,
LHF: [00:05:45] There’s a lot at stake here. Which is why some regions are enacting or looking at enacting some big changes to stop flooding, but also to live with it.
Here are a few examples from the U.S.:
After Hurricane Katrina hit in 2005, New Orleans built a massive system of walls, and pumps and drains -- at a cost of over $14 billion. Texas is looking at doing the same to protect the Houston area from flooding, at a likely cost of over $20 billion.
In towns along the Jersey shore -- including one near Atlantic City, that I’ve been going to since I was kid -- homeowners are starting to raise up their houses in order to cope with more frequent flooding.
In the same town, they’ve reintroduced dunes, which are these long, big mounds of sand that help protect from big waves and erosion.
And there are other ways we can work with nature: lots of coastal habitats, like wetlands and mangrove forests, do a great job of acting like a big sponge, absorbing waves in big storms.
So maybe more parts of the U.S. and the world will start to look like these places, with pumps and seawalls, revitalized dunes and wetlands.
So, can we... adjust to what’s coming?
JR: [00:07:09] Is there a way to, yeah, build your way out on sea level rise? Well, it really depends on how much sea level rise we're talking about. If greenhouse gas emissions can reduce to zero soon, you know, in the next 20 or 30 years, we may see only, only a meter of sea level rise, which would be hard enough to deal with, but not impossible. But if we get into a situation where, um, parts of the West Antarctic ice sheet, parts of the Greenland ice sheet, really start melting irreversibly, it would be really hard to build your way out of that level of sea-level rise.
LHF: [00:07:48] And this also depends on exactly where you live. Because in some places, even the best-case scenario—maybe two or three feet of sea level rise—could be really hard to adapt to.
JR: [00:08:03] If you're reasonably close to the shoreline now, uh, you’re really in the firing line, even with a little bit of sea level rise. And you can build a seawall or whatever, but in the end that’ll get eaten away by the waves.
LHF: [00:08:17] At this point in the interview, our producer Dave Lishansky had a question.
DL: [00:08:21] Say you have a young couple, they're looking to buy property in a low-lying coastal place. Say Miami, Miami gets picked on a lot, but I'm going to pick on them again. What would you tell them to expect?
JR: [00:08:36] If they wanted to ask me, then I would tell them to think very carefully. You know, it varies depending where you are, but certainly if you're in Florida or some of the Southeastern States of the U.S. along the coast...Yeah. Be very careful. Because you might be able to live successfully in a home like that for 20 or 30 years—maybe raise a family, who knows— but beyond that, I think all bets are off. If the home you're looking at is close to the beach, like really close to the beach, you can be pretty sure it won't be there, uh, by the end of the century, because either it will have been washed away or it will have been picked up, put on a truck and moved away.
LHF: [00:09:15] And in some parts of the world, we’re not just talking about neighborhoods or even cities -- we’re talking about entire countries.
JR: [00:09:25] Some of the island nations in the Pacific are built on very low-lying coral atolls. And so the highest point might only be a meter or two above sea level. So of course, those places are already in trouble. That's a terrible tragedy. we're talking hundreds of thousands of people who might move to New Zealand or Australia. For a country, say like Vietnam or Bangladesh, and even parts of China, we're talking millions of people, maybe tens of millions of people being displaced by sea-level rise. And so a country like Bangladesh, I think the statistic is something like 30 million people live within a meter of sea level at present and with a meter of sea level rise, I think something like half the country would go underwater in a storm. And so we're talking about massive displacement of people.
It’s something that will develop over time. It's not as though next week we’ll suddenly see 50 million migrants on our shores. Um, but it's not going to take all that long either. Um, over the next 30 or 40 years, we might see another foot of sea-level rise, and that's going to start causing problems for quite a lot of people.
the kind of political tensions and, national security issues that might come with some of this are what’s really worrying. It's one of the best arguments for taking action as soon as we can, because if we get to more than two degrees C of warming, a lot of the coastal cities and all the infrastructure that's there now would have to be abandoned or go under water. We're going to see people looking to be re-homed on a scale that just hasn't been seen before. Personally, I think, you know, we all have a moral responsibility to help others, so I’d be up for it, but I don't run the world. The more we talk about it, the sooner, and the more planning is done around this, to have it all happen in a sort of compassionate, humane way, the better.
LHF: [00:11:37] If you want to learn more about sea level rise and its impact on Americans and people around the world, check out our Twitter page to find a links to our show notes—or ask us a question, on Twitter @tilclimate or by email at firstname.lastname@example.org. Until next time, thank you to our guest Prof. Renwick, and thank you for listening.
- For more about Professor James Renwick and his work, visit: https://people.wgtn.ac.nz/james.renwick
- Visit the National Oceanic and Atmospheric Administration’s (NOAA’s) Sea Level Rise Viewer and Coastal Flood Exposure Mapper to assess coastal hazard risks and vulnerabilities within your communities.
- Miami, a city we highlighted in this episode, is already facing the impacts of sea level rise. This short video from The New Yorker explains how sea level rise is impacting South Florida and how residents of this region are adapting to rising seas.
- Professor Renwick mentioned the “sophisticated system of seawalls, dikes and pumping stations” that the Netherlands has to offset flooding. This article from the New York Times further explains how the low-lying Netherlands is adapting to sea level rise.
- Coastal storms have severely impacted the North Atlantic Coast of the United States, including the New York-New Jersey Harbor region. The US Army Corps of Engineers completed the North Atlantic Coast Comprehensive Study to better understand how sea level rise will impact this region in the future.
- In this episode, Professor Renwick said, “Insurance companies will start pulling out of coastal areas, and that’s what’s already happening in some areas.” This article from Grist explains why insurance companies are reluctant to insure homes in areas vulnerable to climate change.
- We mentioned massive coastal barriers in New Orleans, Louisiana (the Greater New Orleans Hurricane and Storm Damage Risk Reduction System - constructed) and near Houston, Texas (called the Ike Dike - proposed) to protect these cities from sea level rise and storm damage. The bill for these projects comes to tens of billions of dollars.
- To learn more about what causes sea level rise, how sea level rise affects us, and how we can prepare for the impacts of sea level rise, read our sea level rise explainer.
- For an overview of climate change, check out our climate primer: Climate Science and Climate Risk (by Prof. Kerry Emanuel and the MIT Environmental Solutions Initiative). There, you can read the chapter on the science of sea level rise.
- For more episodes of TILclimate by the MIT Environmental Solutions Initiative, visit tilclimate.mit.edu.
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Sea level rise is already happening and affecting people right now. Following up on the demonstrations in Today I Learned About Sea Level Rise, Part 1, these student activities explore data related to the impacts of thermal expansion, land ice melt, storm surge, and high-tide flooding.