Best of: The future of coastal erosion

0:00Hey everyone, it's your host Russ Altman from the Future of Everything. It's summertime, and for many of us that means a recreational trip to the beach or the coast. Worldwide, billions of people live year-round near a coastline, and these settings can be responsible for everything from buffering storms and preventing sea level rise, to fishing, flourishing tourism, and trade. For all of these reasons, the acceleration of coastal erosion is an important topic to understand. A couple of years ago, I sat down with Jane Willenbring, a geoscientist who says that by studying what coastlines looked like long ago, we can better understand where they are headed and how to protect them.

0:38No matter where you live, coast or not, I hope you'll tune in to better understand the forces behind coastal erosion.

0:45Jane Willenbring:Before we jump into this episode, a reminder to please rate and review the podcast. It'll help our audience grow and it'll help us improve.

0:56So we all know that sea level is rising, and we all know that one of the big consequences of that is loss of coastline. How does the coast even form, and then how does it degrade, and why does it matter? Well, the impacts on infrastructure and on human life and societal impact is quite non-trivial. And today we have Professor Jane Willenbring from Stanford University to tell us about it. She's a professor of Earth and Planetary Sciences and Earth Systems Science at Stanford University, and she's an expert on landscape and coastal erosion. So Jane, one of your interests, of course, is coastal erosion.

1:34And to start, what are the processes that lead to the buildup or the breakdown of coastal areas?

1:41Jane Willenbring:Yeah, so one of the really important things and one of the things that I really love about studying the coastal environment is that it's incredibly dynamic. And And so if we think about coastlines, we think about places that are changing all the time. And so in California in particular, some of the processes that are going on are obviously wave action. We also have pronounced wave action, especially when there are storms. And we also have things like water flow through coastal cliffs that can impact when cliffs fail on the coastline. Of course, we have buildup and loss of sand that happens seasonally, especially in some seasons when we have big storms.

2:33and so one of the we can think about it from a perspective of how the ocean is impacting the

2:42Jane Willenbring:cliffs but then also the nature of the cliffs themselves what they're made of how steep they are you know if there's been any kind of seismic activity like earthquakes or faults or any kind of jointing or anything like that in the cliffs themselves so when i've just living life and being at the, I grew up on the East Coast. I now live on the West Coast. I've watched coasts, you know, from a distance. And I don't see a lot. It always seems like things are kind of receding. But is it true that like the coasts everywhere are always receding? Or you made a brief mention of buildup. Like what leads to actually the addition of coast?

3:20Or is there anything that leads to the addition of coast?

3:23Jane Willenbring:Yeah, I mean, in places, especially by river mouths, we get the buildup of coastal material right now, like your observations were very astute because right now we're in a period of sea level rise. And so in periods of sea level rise, you know, on the East Coast, we have the drowning of estuaries or estuaries. And we have a lot of waves that are closer to the cliffs on the West Coast, where we have actively uplifting land surfaces. And so your perception is correct. It does seem like we're losing coasts in a lot of places. In other places, like the river mouths and deltas, for example, we also have buildup of land.

4:12Gotcha. Okay, good. And I haven't spent as much time by rivers, so that's interesting that I have a totally kind of biased sample. So I know that you're an engineer and one of the things you do is innovate in the area of measuring this erosion because as we always say, you can't intervene in anything if you can't measure it. So tell me a little bit about your measurement technologies and what are the challenges of understanding how things change? I don't even know if it's day-to-day, month-to-month or eon-to-eon and I suspect you're interested in all of the above. Yeah.

4:47Jane Willenbring:So I'm actually trained as a scientist. So my perspective is maybe a little longer term than the average coastal engineer. And so there are folks who are doing a lot of monitoring of coastal environments that use LIDAR, which is kind of like a laser level, if you are familiar with that carpenter tool. I think they're using them in self-driving cars as well. Yeah, exactly. Yes, exactly. And so you can use those, that technology that is actually from satellite data to understand over the period of monitoring how cliffs evolve and change. You can also go out there and just look. So those are things that happen over a short period of time.

5:38Jane Willenbring:So my role as a geomorphologist, who is someone who I like to say studies the science of scenery, is someone who will go out and kind of look over a longer term. So we can look at over hundreds of years, even before people were really monitoring and measuring the coastal environment or millennia to figure out how different the modern rates of retreat are from the past, like kind of natural baseline rates of retreat. Great. So tell me how you do that, because obviously we didn't have GPS 100 years ago, so you don't have any. And we don't we didn't even have photography 200 years ago, say. And so obviously you need to you have a problem of setting the baseline and then looking for the delta, the change.

6:28Delta. Good, good word. So tell me a little bit about how you can make such measurements over these time periods.

6:34Jane Willenbring:Yeah, so we use kind of what I like to think of as a bit of a fancy technique called cosmogenic isotopes. So isotopes are variants of different elements that have different amounts, different masses. And some of those isotopes that we can extract and measure are formed only through the interaction with cosmic radiation, which sounds sort of like a sci-fi novel or something out of Fantastic Four. It definitely does. Cosmic rays are going to help you measure the coast. Yes, that's right. So those cosmic rays produce certain isotopes that are only produced in that way. And then we can take a rock sample, for example, from a coastal platform, think like a tide pool, and we can figure out how long something has been exposed to cosmic radiation at the Earth surface.

7:28Jane Willenbring:And then we can calculate a rate. So if we have a sort of a long shore platform that extends into the ocean, you know, maybe 300 feet or so, we can take samples all along there and figure out how long those different parts have been exposed to these cosmic rays. And that gives us a rate. Does this also, could this involve going into an archaeological situation and kind of finding layers of rock that are not currently being exposed, but you see evidence that they were exposed. And then you can kind of say, okay, something must have happened to move this rock off the coast, you know, into the ground.

8:07Yeah.

8:08Jane Willenbring:So some places you have more of an archaeological record of settlements that have been there in the past and are now in a different place. People are usually setting up shop near water sources or near sources where they can launch a boat or something like that. And so it's really common to have a settlement that's near a coastline. And now that settlement was abandoned because that coastline is no longer in that particular place. And so that is one way that a lot of people measure such things. And And it's been a long history of like figuring out what people have done in the context of, you know, environmental change.

8:54Jane Willenbring:Because we've, as a species, we've really been very good at adapting to differences in, you know, the environment and the landscape around us. Right, right. Okay, great. So, okay, so I know, so, okay, that was very helpful because now we kind of see what you're measuring and that you can get these exposures. I had while you were describing this, it occurred to me that this must be extremely complex because, as you know better than I, it's not just the erosion that's happening. There are plate tectonics and there are earthquakes and there are things like that. So I'm guessing that you have to deconvolute lots of processes in order to isolate the impact of these things on the coast versus things moved because of an earthquake or because of other things.

9:38Is that true?

9:40Jane Willenbring:Yeah, that's exactly right. So in some places in the world, we have to kind of think about relative sea level. So sometimes sea level seems to actually be going down in certain places, even though globally sea level is rising. And that's because the land surface is being pushed up by tectonic forces. And that's one of the things that happens, especially along the California and West Coast of the United States and Alaska. Great, great. So I know that one of the things you're passionate about is studying the impacts. It's not just how the erosion happens and how fast it's happening, but also the impacts both on humans and on, as you said, you study the landscape.

10:23So let's get to humans second. But first, tell me about what are the impacts on the infrastructure and on the actual coast? Like, what are we seeing? And what catches your attention and makes you either concerned or excited or whatever the right verb would be?

10:40Jane Willenbring:Yeah, I mean, if you think if you kind of invoke sort of a coastal environment in your mind, you probably think of like a home perched on top of a cliff that looks like it's going to fall into the ocean. And so, of course, that's concerning because that person is going to lose their home. But then we also have things like, you know, lots of different kinds of infrastructure. We have roads and railroads. You know, the coaster line in Southern California goes right up alongside the beach. It's spectacular. Maybe a couple meters away. We have the Diablo Canyon nuclear power plant that is nestled right up in the mountains.

11:26I only laugh because I don't know what else to do.

11:29Jane Willenbring:I know. I know. It's really bizarre and maybe not a great idea. But we also have, you know, like water treatment plants and military installations and so airports. And so there are all kinds of different reasons to be concerned about this. And so that's one of the things that I think is really, really important and interesting is just like there are so many people who are stakeholders. And if you fix one thing in one place, which is kind of the engineer approach, you ruin something in another place. And so it really takes kind of a holistic view in order to figure out how to solve some of these problems from a policy perspective.

12:12So as a scientist who's pursuing knowledge about the fundamental processes that are leading to this, I can't imagine that you're not kind of sucked into the policy and the planning aspects of this. Do you have people from, say, California or from Florida calling you up saying, we need help? And if they are calling you, what are the questions that they're asking?

12:35Jane Willenbring:Yeah, so I think it intersects with policy in the sense that we can really tell how, you know, if we're thinking about erosion of landscapes, especially coastal landscapes, these happen very fast. And so people can see this happening, but then it doesn't happen in some ways fast enough from a policy perspective for, you know, someone in their term of office to actually make like really unpopular decisions. Because probably in four years, maybe not too much will happen, maybe something. And so we have these sort of episodic events where something will happen and then nothing for another five years and then something else will happen.

13:21Jane Willenbring:And so this is not ideal from a policy perspective. People want something that is going to happen for sure. And so the long term view, I think, is really important in that sense, because we can tell people this is the amount that the coastline is going to retreat over the next decade, two decades, 50 years, 100 years. And so if we have to invoke something like managed retreat, where people actually are moved away from the coastline, where railroads are moved away from the coastline, that is something where we can actually give people advance notice, which you'd think would be a good thing. Sometimes it's totally ignored, but in an ideal world, we could actually influence some future planning.

14:11Are you seeing policymakers and public leadership open to your projections or is it still an issue of even getting them to pay attention?

14:21Jane Willenbring:Yeah, I mean, there have been some wins. So recently in Southern California around Del Mar, that's where this coaster line, that's one of the busiest Amtrak lines in the country. they've actually invested$300 million to move it away from the coastline so it doesn't completely fall into the ocean. So that was a huge amount of money to be spent. Probably they wouldn't have had to spend so much if this had been decided upon years ago. Now it's kind of an emergency rush job because it was, every now and then it's closed down because of a bluff failure. And this also costs human lives. In 2019, three people died because of bluff erosion around Encinitas.

15:14So I'm interested. I know this is a little bit in the weeds, but is the solution not to build a bridge and to just leave the tracks where they are but support them in another way versus moving them? And it sounds like in this case, they're going to move them. Is building the bridge ever a good option or is that just delaying what's going to happen eventually, which is the water is simply too deep and you can't get structural stability?

15:41Jane Willenbring:I think it's problematic to build a bridge because a lot of times when you build a bridge, you're also kind of hardening the infrastructure around the bridge so the bridge doesn't collapse. And any time you do that to this dynamic environment, you're really going to affect some of the, you know, kind of up coast and down coast areas and how they accumulate sand. And so you can you can really make your neighbors angry by doing such a thing. Great. So in the last few seconds for this segment, before we take a break, I have to ask you in one of your papers, you refer to landscape unzipping. And I just needed to ask what that is.

16:21Jane Willenbring:Oh, so if you imagine a sort of like a plateau, sometimes streams are cutting through that plateau. And the way that they cut through it is they start at the bottom and then they create more of a valley as they move upstream. OK. And so that that is the unzipping of that landscape. I see. And you get multiple. I actually know this. I think I know this phenomenon from the west coast of California where you see these these. Yeah, these they look like rivers that are coming down from the hills, but they are creating all of these lines through the through the bluffs and through the through the cliffs.

17:03Jane Willenbring:Yeah, exactly. And that's another way like that's separate from the coastal erosion. But that's another thing, you know, that they can impact homes on some of these high plateaus. This is the Future of Everything with Russ Altman. More with Jane Willenbring next.

17:27Welcome back to the Future of Everything. This is Russ Altman and I'm speaking with Professor Jane Willenbring from Stanford University. In the last segment, Jane told us about coastal erosion, how she measures it and what we do about it. In this segment, she'll tell us about the different ways in which sea level rise is impacting the coast and also some of the human impacts. In this segment, Jane, I wanted to ask you about sea level rise. You made a couple of references to it before, but it's something that we're all seeing. We literally get updates in the news every week or month about how things are going.

17:59People are working very hard to try to stem sea level rise. What is the ways, what are the ways in which sea level rise is impacting our coasts?

18:08Jane Willenbring:Yeah, so sea level rise is problematic. And of course, you know, depending on where you are, the rate of sea level rise is going to be different depending on what the land surface is doing. But generally, it's about an eighth an inch a year these days. And one of the things people really worry about is that, you know, we're going to have some kind of episodic, kind of catastrophic loss of ice masses, which is going to increase that rate in a big way in lots of places around the world. And the kind of intuitive way that sea level rise impacts coastlines is that you can imagine that the water level, as it increases, you're going to flood a lot of the sandy areas, which actually protects coastlines.

18:57Jane Willenbring:And then you're going to have those waves that are closer to whatever coastal cliff is going to be around there. And so that's really problematic on the West Coast. On the East Coast, you are familiar probably with like submergence and how things are going to flood. And so that's really one way that we have the impact of sea level rise on the East Coast, where we don't have such dramatic topography right at the coastline. So in addition to the flooding, are there other patterns of damage that are perhaps not appreciated that we should be on the lookout for? I don't know if there's changes in the shape of the coast or the way in which the coast articulates with the ocean.

19:43I'm just wondering if flooding is number one and what's number two.

19:47Jane Willenbring:Yeah, so flooding of the coastlines is a big one. And then again, like anytime you have some of your water level higher, you're able to move offshore a lot of the sandy material that, again, protects those coastlines. So they found like the wider the beach, the lower the rate of erosion of the coastal cliffs on the West Coast. And so those beach environments are really some of the best defenses against coastal erosion. And so if you're eroding those beaches, not only do you not get a nice beach to go to, I'm sure you like to go to the beach. Yes, I do. I do. Yes, everyone does. So it's also a huge thing for a lot of local economies is just, you know, having that beach environment.