The Excerpt podcast: America's East Coast is sinking. How can coastal cities adapt?

On a special episode of The Excerpt podcast: As the eastern seaboard slowly drops lower each year, it is compounding the impacts of climate change in the U.S. Rising sea levels and severe weather events mean coastal cities will have to adapt or perhaps even be abandoned. How bad is it? Who is most at risk here, and most importantly, what can we do about it? Kenneth Miller, professor of earth and planetary sciences at Rutgers University, joins The Excerpt to dig into how sinking land mass could mean disaster for some parts of the world.

Hit play on the player below to hear the podcast and follow along with the transcript beneath it. This transcript was automatically generated, and then edited for clarity in its current form. There may be some differences between the audio and the text.

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Dana Taylor:

Hello and welcome to The Excerpt. I'm Dana Taylor. Today is Thursday, March 14th, 2024, and this is a special episode of The Excerpt.

The East Coast is quite literally sinking. Slowly to be sure, but it is compounding the impacts of climate change as sea levels rise and severe weather events become more frequent. How bad is it? Who is most at risk here? And most importantly, what can we do about it?

Joining me to dig into these topics in more detail is Kenneth Miller, Professor of Earth and Planetary Sciences at Rutgers University.

Kenneth, thanks for joining me.

Kenneth Miller:

Great to be here. Thank you.

Dana Taylor:

Let's talk about the fact that the East Coast is sinking. What are the causes and why should we be concerned?

Kenneth Miller:

I think many people understand the idea of compaction, that if you walk across the beach, the sediments compact underneath your feet. If you take a bucket of sand by the ocean and you walk across the beach with it, it's not as filled when you get to the edge of the beach as it was when you, because the sand is compacted and water's been driven off. That's a natural process that can be made worse by humans. If we pump groundwater or if we pump oil or gas out of a place, we've taken out the fluid, the grains move closer together and compact. So that's one process.

The other process has got a really fancy name, glacial isostatic adjustment. It's a seesaw effect, and that's the best way to think about it. And while compaction mostly works locally, this effect works throughout the region, let's say the East Coast, the northeast part of the United States.

So if we go back 20,000 years ago, there was a huge ice sheet in Central Canada that extended all the way down to New Jersey and New York City. New York City would've been covered by it. The Empire State Building would've been covered by ice. So we know that that ice has mass, weight, and it pushes down on the earth. When that ice sheet disappeared, the earth naturally rebounds is the word we prefer. One of my students said yesterday, "It bounces up," which is not a bad way to say it, but we like to use the word rebound.

And so that effect means that because Canada is going up, something goes up, something has to go down, and New York, New Jersey, Delaware, Maryland, Virginia, even into the Carolinas are subsiding or sinking, as you said.

So those are the two main effects, compaction of the sediments themselves and this seesaw effect.

Dana Taylor:

Why should we be concerned? What are the implications for infrastructure?

Kenneth Miller:

It gets added on to the anthropogenically driven or human driven sea level rise that's occurring due to warming of temperatures and melting of ice on land. Those are two very large effects. And just to give you a scale, every decade, a little bit more than an inch, about 1.3 inches, sea level rises because of those effects.

Now, if you add that on to, it's a smaller effect, it's about a third due to this seesaw, it just gets added together. And then that sea level rise gets added on to storm surge, and that's really when we see the greatest effects.

Dana Taylor:

Let's go back to groundwater. Of course, we need to pump it for drinking and other essential uses. Are you suggesting that we not pump groundwater?

Kenneth Miller:

No, but you have to be aware that the effects will happen, that we are ... So Atlantic City pumps their groundwater from what's called the 800-foot sand, which is, as you might suspect, 800 feet below Atlantic City. And even as a geologist, I was surprised to observe that that groundwater pumping, even at that depth has resulted in a measurable sinking about again, we generally talk in millimeters per year, or that'd be equivalent to centimeters per decade. One centimeter per decade is about a third of an inch. So it's not a lot, but it's quite measurable. And if you have a dock in Atlantic City, you can observe that effect in addition to the global rise in sea level.

I always like to say sea level is like politics. It's all local. It starts at the global level like politics does, in this case global sea level. It goes to the regional level, which again is the seesaw effect. But ultimately what you really care about is at the local level, whether or not you be at LaGuardia Airport or whether you're at Sandy Hook or whether or not you're sitting in the Battery of New York, you're going to have slightly different responses. And that's what the planners need to know.

Dana Taylor:

Regarding sea level rise and talk about who's most at risk here, what areas of the world and the United States are most vulnerable and why?

Kenneth Miller:

Well, the two poster children that we like to show, one would be in the Gulf Coast and basically New Orleans environments, particularly in the southern part of Louisiana, the so-called Plaquemines Delta where the Mississippi is going in. And another one would be Bangladesh.

So in those regions you have large rivers bringing in tons of sediment, mega tons of sediment, really. And that sediment is compacting. And it's that compaction. So in the same relative units, if I said the three for global and maybe two more for Atlantic City, New Orleans is seeing 13.

Dana Taylor:

Let's talk about storm surge. Hurricane Katrina, New Orleans and Hurricane Sandy up in New York and New Jersey as you mentioned, two big storms that hit in the US. I'd like to talk about how we might protect areas like these in the future. Are there realistic solutions out there? Has any other city or country figured this out?

Kenneth Miller:

Well, the Dutch have, obviously. They've lived in areas that have been sinking and eventually have gone below sea level by building dikes, and they are ready for they quote 10,000 year storm. We have a funny way of describing storms. Sandy was a hundred-year storm, which means it had a hundred-year recurrence interval, which meant that there was a one in 100 chance of Sandy occurring.

So the way we actually figure out what the recurrence interval truly is needs to be improved. But the Dutch have engineered against the so-called 10,000-year storm. In other words, they made their engineering standards so high, they are more resistant. They still will experience flooding. There still will be storms that are going to severely impact them, and there will have extensive flooding, but they've done the best that they can.

And so in New York City, obviously we're girding ourselves against the next Sandy, and the next Sandy will eventually come. But the real concern is the big ice sheets existing, particularly in Antarctica and in Greenland. And those store a tremendous amount of water. And in fact, if you melted Greenland, you'd get 23 feet of rise of sea level. If you melted West Antarctica, you'd get a similar number, a little bit less. If you melted the ice sheet in East Antarctica, you would get 170 feet of rise.

So even small variations and melting rates there will accelerate our rate of sea level rise. And that's what we're concerned with as we move into the later part of the 21st century and into the 22nd century, that we will see increasing contributions from those. We're already seeing them.

Dana Taylor:

What happens if global warming, the rising of sea levels and the sinking of land aren't addressed?

Kenneth Miller:

There's an old Danish proverb that prediction is difficult if it involves the future. We can say we know that if we double CO2 in the atmosphere, carbon dioxide in the atmosphere, and it seems very likely we will in this century, that the temperature will rise about three degrees Celsius, which is about five degrees Fahrenheit. And we say that with a reasonable degree of certainty. And that means by the way, with a three degree rise of sea level, we can guarantee you that the temperature effect is going to give you basically a foot rise.

We know the mountain glaciers will be largely disappearing. We're seeing that happen now. One of the ones in Iceland has disappeared. We're seeing heavy loss there. So by the end of the century, we will get a foot of sea level rise from the melting of those glaciers.

But we know the large ice sheets are going to continue to melt. And that's where we don't have a firm handle on just maybe they could be much more catastrophic in their loss than we think. So the best estimate is maybe a foot from those ice sheets, but that is potentially a low estimate. And so that's why there's great concern is studying places like Greenland and West Antarctica, trying to understand how those ice sheets are responding to ocean warming. And actually, there's been a lot of surprises in recent years to suggest that in fact, we may be underestimating the amount of rise.

Dana Taylor:

And finally, what gives you hope Kenneth? Can you leave us with a note of optimism?

Kenneth Miller:

I am optimistic that we can adapt to rising sea level. The question will be whether or not we are going to allow it to go beyond three feet by the end of this century. We can adapt to it. People are concerned that the global warming will kill the planet. The planet's going to be fine. It's our human systems that have been narrowly adapted to a very stable climate of the past 10,000 years and stable sea level of the past 10,000 years.

But as our climate's warm, we're concerned about obviously sea level, but perhaps more concerned about extreme weather events. So again, I think my optimism will be, look what happened after Sandy. Unfortunately, over a hundred souls lost their lives, but we came back stronger. I mean, the classic Jersey's thing. We're Jersey strong. We came back from Sandy. Right? And I think that that would be my optimistic message.

But at the same time, we have to do something to control our emissions and to try to limit the effects that we're seeing of rising sea levels and extreme weather events.

Dana Taylor:

Kenneth, thank you for being on The Excerpt.

Kenneth Miller:

Thank you. It was great to be here. It was a lot of fun.

Dana Taylor:

Thanks to our senior producer, Shannon Rae Green and Bradley Glanzrock for their production assistance. Our executive producer is Laura Beatty. Let us know what you think of this episode by sending a note to podcast@usatoday.com. Thanks for listening. I'm Dana Taylor. Taylor Wilson will be back tomorrow morning with another episode of The Excerpt.

This article originally appeared on USA TODAY: The Excerpt podcast: America's East Coast is sinking