Nature Quest: How High Will Sea Levels Rise?

How high will the ocean rise under climate change? By 2050, scientists have a pretty good idea. But why does it matter where you live? And what can humans do to slow it down? This episode is part of Nature Quest, our monthly segment that brings you a question from a Short Waver who is noticing a change in the world around them. Our question comes from Peter Lansdale in Santa Cruz, Calif. To see what future sea levels will look like where you live, check out NOAA’s Sea Level Rise Viewer here https://coast.noaa.gov/slr/#. Noticed any changes in *your* local environment that you want us to investigate? Send a voice memo to [email protected] mailto:[email protected] telling us your name, your location, and the change you’ve noticed – it could be our next Nature Quest episode! Listen to every episode of Short Wave sponsor-free and support our work at NPR by signing up for Short Wave+ at plus.npr.org/shortwave http://plus.npr.org/shortwave. See pcm.adswizz.com https://pcm.adswizz.com for information about our collection and use of personal data for sponsorship and to manage your podcast sponsorship preferences. NPR Privacy Policy https://www.npr.org/about-npr/179878450/privacy-policy

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• 0:00Speaker 00

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• 0:16Emily Kwong?

  You're listening to Short Wave from NPR.

• 0:24Emily Kwong?

  Hey, Shortwavers. Emily Kwong here with NPR climate reporter Rebecca Hersher.

• 0:28Speaker 02

  Hi.

• 0:29Emily Kwong?

  Who is bringing us this month's listener question for Nature Quest. OK, Becky, what do you got?

• 0:34Speaker 02

  All right. This month's question comes from a listener in Santa Cruz, California.

• 0:39Emily Kwong?

  I love how we are automatically game show hosts right now. Welcoming onto the stage. Santa Cruz, it's on the coast, right? It's an area a little bit south of San Francisco.

• 0:48Speaker 02

  Yeah, I've actually never been there, but I've heard it's very gorgeous. I've seen pictures. There are cliffs, there are beaches. This listener, though, his name is Peter Lansdale, is kind of worried about what's going to happen to that landscape in the future.

• 1:01Speaker 03

  Hey, Short Wave. This is Peter from Santa Cruz, California. I am wondering what the projections are for sea level rise in the next couple of decades. We've seen a lot of damage recently on our coast, and to some extent, that's normal because we're built on sandstone and everything is always changing here. But it would certainly accelerate if the sea was any higher than it already is. So I'm wondering if there's consensus on how many feet we're looking at.

• 1:34Emily Kwong?

  All right. What do you think, Becky?

• 1:36Speaker 02

  I love this question. I do. It's such a simple and important one. Yeah. Basically, is there scientific consensus about how much sea levels will rise and how quickly it'll happen? And since we don't all live in beautiful Santa Cruz, we'll also answer a different question, which is, you know, is the amount of sea level rise that's happening different in California versus, say, Louisiana or Virginia?

• 2:01Emily Kwong?

  So for this month's Nature Quest, we are tackling sea level rise, how fast it's happening, what humans could do to slow it down, and how to find out what the future looks like where you live. You're listening to Short Wave, the science podcast from NPR.

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• 3:33Emily Kwong?

  It is Nature Quest Day. This is my favorite segment. It's our monthly segment that brings you a question from a short waiver who's noticing a change in the world around them. And we've brought on one of the best, Rebecca Herscher, climate reporter at NPR. Okay, Becky, let's start with the first bit of Peter's question about sea level rise. Is there scientific consensus about how high the water will get?

• 3:55Speaker 02

  An excellent question and a fun one to answer because the answer is yes.

• 4:00Emily Kwong?

  Well, I guess that's it then. That's the episode. Okay, you've been listening to Short Wave from NPR.

• 4:06Speaker 02

  Can you imagine? We just ended the episode.

• 4:07Emily Kwong?

  Get out of here.

• 4:09Speaker 02

  Uh, yeah, if only if we're that simple. So basically, the answer is yes. Scientists have a really good idea of how much sea levels will rise in the next three decades or so. And I'm going to give you some concrete numbers because just from listening to Peter, I kind of get the feeling that that is what he's yearning for.

• 4:28Emily Kwong?

  Me too, yeah.

• 4:30Speaker 02

  Okay, so let's start really big picture. Globally, the oceans are about nine inches higher today than they were in the 1880s. So that's the worldwide average for all the oceans everywhere. And sea level rise is accelerating. So by 2050, sea levels are projected to be about 15 inches higher than they were in the 1880s. Again, that's the global average, the whole planet.

• 4:54Emily Kwong?

  How sure are scientists about those numbers?

• 4:56Speaker 02

  They're really sure. So 2050 is actually pretty soon in scientific terms. And it takes time for the planet to react to the extra heat that humans have trapped in the atmosphere. So even if humans totally stopped burning oil and gas and coal today, there would be a lag while all that extra heat dissipated and the glaciers stopped melting. And that lag would take decades.

• 5:19Emily Kwong?

  So this is all happening for sure, the next 25 years?

• 5:23Speaker 02

  Yeah, there's just, there's not a lot of scientific uncertainty about what's happening in the couple of decades between now and 2050.

• 5:30Emily Kwong?

  Which means, I guess, scientists can be more confident?

• 5:32Speaker 02

  Indeed.

• 5:33Emily Kwong?

  So I'm hearing an average of about 15 inches of sea level rise globally by 2050. It's good for planning, imagining the future of different shorelines. But what about specifically in Santa Cruz, where Peter lives?

• 5:45Speaker 02

  Right, yes. So let's zoom in. Scientists expect about one foot of sea level rise in that area by 2050 compared to the year 2000. So that's a little less than the global average.

• 5:56Emily Kwong?

  Why less? Is it something about how Santa Cruz is situated that makes it that way?

• 6:00Speaker 02

  Not particularly. It's just sort of how the math maths when you look at Santa Cruz in the context of the whole planet.

• 6:06Emily Kwong?

  Gotcha.

• 6:07Speaker 02

  So again, there's not a lot of uncertainty about that number, though. Like, with any prediction about the future, there's going to be a range. So we don't know exactly how much planet warming pollution people are going to emit in the next couple of decades. But there's not a huge range. So for the sea level rise in Santa Cruz going out to 2050, the low end of that range is a little less than a half a foot. The high end is just over a foot. So it's really quite small. And so when we say there's a lot of certainty, that's what we're talking about. You know, Peter can feel confident that sea levels will rise in that area about a foot by 2050, plus or minus a few inches.

• 6:41Emily Kwong?

  Honestly, it's really nice to hear about something where there's not a lot of uncertainty. You know, there's so many science stories out there about what we don't know yet, the mysteries, but this sounds altogether not that mysterious.

• 6:52Speaker 02

  Yeah, it's really not that mysterious. We know a lot about this, at least about sea level rise in the short term. It's very well understood.

• 6:58Emily Kwong?

  OK, well, let's talk about the second piece of Peter's question because not everyone lives in Santa Cruz, California. So are sea levels rising faster in other parts of the US?

• 7:08Speaker 02

  Yeah, there is variation. So here are some more numbers. You ready? So remember, in Santa Cruz, there will be about a foot of sea level rise by 2050. In Seattle, it's less than a foot in that same time period. In Annapolis, Maryland, it's about a foot and a half.

• 7:28Emily Kwong?

  Oh, close to where I live.

• 7:29Speaker 02

  Yeah.

• 7:32Speaker 02

  In Galveston, Texas, upwards of two feet. And in New Orleans, it's almost two and a half feet. So it really varies depending on where you live in the US.

• 7:47Emily Kwong?

  Again, like, why? It just doesn't make sense to me intuitively. Like glaciers are melting. That should put extra water in the ocean. So why wouldn't the water just rise the same amount everywhere?

• 7:58Speaker 02

  So first of all, just one thing to note here. It's not just glaciers and ice caps that are melting that drives sea level rise. It's that the ocean water is absorbing most of the extra heat that's trapped by carbon dioxide and other greenhouse gases. And when water absorbs heat, it expands. It gets bigger, actually takes up more space. Yeah, we've talked about this before on Short Wave, and that's also a big driver of sea level rise around the world. So anyway, I just had to mention that before we go any further. But going back to your question, why do different places have such different amounts of sea level rise? Because I don't think I've fixed that problem.

• 8:31Emily Kwong?

  Well, just because melting ice and expanding water both seem like they'd affect every part of the planet somewhat equally.

• 8:37Speaker 02

  Yes, exactly. So I called up one of the top sea level rise scientists to talk about this.

• 8:43Speaker 07

  My name is Ben Hamilton. I am a research scientist at the NASA Jet Propulsion Laboratory. I'm also team lead of the NASA Sea Level Change Team.

• 8:50Emily Kwong?

  Oh, cool.

• 8:51Speaker 07

  And I study pretty much everything to do with sea level science and coastal impact.

• 8:55Speaker 02

  So the first thing Ben pointed out is that the ocean is not static. It's not like a bucket of water. It has currents moving through it.

• 9:04Speaker 07

  It's definitely not a bathtub. So it's not like it's just going up and down as though you're filling up a bathtub with a faucet.

• 9:09Speaker 02

  So depending on where you are relative to ocean currents, you might see more rapid or less rapid sea level rise. And actually, if you live very close to an ice sheet, like in Greenland, for example, you experience less sea level rise. And that's basically because of how the water moves and also how the land that's under the ice changes as the ice melts.

• 9:29Emily Kwong?

  Okay, that's really counterintuitive. So you're saying the closer you are to the melting ice that's causing sea level rise, the less sea level rise you personally experience?

• 9:39Speaker 02

  Yeah, the Earth is very weird and wonderful at times.

• 9:43Emily Kwong?

  Clearly. So the reason different places in the US are experiencing more or less sea level rise is because of ocean currents and how close you are to melting ice?

• 9:55Speaker 02

  Yeah, those are two of the reasons. But in the US, there's actually a third reason that's even more important. And that's about how the land itself is moving. So let's do a thought experiment. Emily Kwong, are you ready?

• 10:08Emily Kwong?

  I'm ready.

• 10:08Speaker 02

  Imagine, imagine, close your eyes, imagine.

• 10:11Emily Kwong?

  Yeah.

• 10:11Speaker 02

  Imagine that you live in a house next to the ocean.

• 10:15Emily Kwong?

  I wanted to before this story, but go on.

• 10:17Speaker 02

  Yes, and your front door is one foot higher than the water.

• 10:21Emily Kwong?

  Okay.

• 10:23Speaker 02

  If the water rises one foot, you get wet.

• 10:26Emily Kwong?

  Yeah.

• 10:26Speaker 02

  Right? If the land sinks one foot, you are also wet. If the water rises six inches and the land sinks six inches, you're still wet.

• 10:37Speaker 07

  That movement of land really does contribute to differences along the coastlines of the US. So for example, on the Gulf Coast of the US, where we have oil extraction, removal of things from underground, we actually cause the land to sink a little bit.

• 10:53Emily Kwong?

  So it's either the sea's going to rise to you, or you're going to lower to the sea.

• 10:57Speaker 02

  Yeah. So when you combine the sinking land with the rising water, effectively, what you get is faster sea level rise. And in fact, Ben says the Gulf Coast of the US has some of the highest sea level rise rates in the world because of this.

• 11:12Emily Kwong?

  That's fascinating. Okay. And I feel like some people must be listening to this. I certainly am, and I'm wondering about my own home. Is there a way to find out how much sea level rise is predicted for your town?

• 11:24Speaker 02

  Yes. So there are lots of different resources out there on the internet, including from local governments, but actually, almost all of them use the same source material. And you can just go to that source.

• 11:35Emily Kwong?

  Okay.

• 11:35Speaker 02

  Which is called the Sea Level Rise Viewer. Ben Hamilton, the scientist you heard from, worked on it. And we'll put a link in the show notes.

• 11:42Emily Kwong?

  Sea Level Rise Viewer. I'm going to check it out. Becky, in the meantime, is there anything that can be done to slow sea level rise, especially beyond 2050?

• 11:51Speaker 02

  Yeah, definitely. This actually goes back to the uncertainty piece we were talking about before. You know, sea level rise in the next few decades is pretty unavoidable. Like, cutting greenhouse gas emissions wouldn't make a big difference right away. But that doesn't mean it's useless to pivot to cleaner energy. If humans stopped pumping planet warming pollution into the atmosphere now, sea level rise after 2050 would be a lot less severe. So just by using sources of energy like solar and wind, sources that don't emit as many greenhouse gases, we can still avoid really catastrophic amounts of sea level rise. And we're talking, you know, three, four, even 10 feet higher than the ocean is today. That kind of extreme sea level rise will happen if we do nothing

• 12:35Speaker 02

  and let all the ice sheets melt. But our choices today can avoid that.

• 12:39Emily Kwong?

  Rebecca Hersher, NPR Climate Correspondent. Thank you for coming on Short Wave.

• 12:43Speaker 02

  Thanks.

• 12:45Emily Kwong?

  And thank you, Peter, for the great question. Shortwavers, if you have a question about changes in your environment, please email us at [email protected], and we'll consider it for a future Nature Quest episode. This series comes out the last Tuesday of every month. This episode was produced by Hannah Chin. It was edited by our showrunner Rebecca Ramirez and Burleigh McCoy. Tyler Jones checked the facts. Jimmy Keeley was the audio engineer. Sam Poulsen wrote and composed our Nature Quest theme music. Beth Donovan is our senior director, and Colin Campbell is our senior vice president of podcasting strategy. I'm Emily Kwong.

• 13:20Emily Kwong?

  Thanks for listening to Short Wave from NPR.

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