Short Wave - What The Heck Is A Rock Glacier?

Episode Date: October 11, 2024

Even though there are more than 10,000 rock glaciers in the western United States, most people would look at one without knowing it. Unlike the snowy glaciers we're more familiar with, rock glaciers are under-researched and hiding in plain sight. But inside these glaciers covered with rocks is a little bit of climate hope.Read more of science correspondent Nell Greenfieldboyce's reporting here. Want to know more about the hidden science of the world? Email us at [e-mail] — we might cover it on a future episode!See 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

You're listening to Shortwave from NPR. Hey there, shortwavers, Emily Kwong here. I am joined by NPR science correspondent, Nell Greenfield Boys. Hello, Nell. Hey, Emily. Hi. So listen, I know you used to live in Alaska, and I have to imagine you've seen plenty of glaciers, right? Yeah, I've stood on one or two.

They're beautiful. But have you ever seen a rock glacier? No. What is that? So when you are talking about the glaciers you stood on, you meant like white, snowy glaciers, right? Absolutely, yeah. Okay, so a rock glacier is like a glacier, but it's totally covered with rocks. Oh.

Unless you know what to look for, you would have no idea that this was a glacier. And they've barely been studied by scientists. But there's this guy, Scott Hotaling. Do you remember him? He's the guy who talked to us about ice worms, those little black worms that live in glacier ice? No, I love doing that episode with you. It changed my life, like the hidden world beneath our feet in the worms. And now you're saying there's rock glaciers too.

Okay, yeah. So this guy, he's like drawn to stuff in the mountains that people look at with their eyes but don't really register. Nice. There's like over 10,000 rock glaciers in the western U.S. states. They're way more common than regular old white snowy glaciers, the kind you were talking about standing on. And because rock glaciers are covered in rocks, Scott told me this. That debris actively insulates the internal ice. So amidst climate warming, amidst climate change, these rock glacier features are likely to persist on the landscape longer than surface ice, which makes them really critical to water supplies in the Western U.S., biodiversity, etc.

Now, it is totally refreshing to hear about a glacier that might not be disappearing. Or at least disappearing much more slowly. Today on the show, how to recognize a rock glacier. why it's been so hard for scientists to study them. And what the water locked up inside could mean for mountain critters and even people. You're listening to Shortwave, the science podcast from NPR. So, Nell, you said you went to sea a rock glacier. Where exactly did you go?

Utah. Utah is where I went. That's where Scott's working now at Utah State University. And Utah is this like deserty kind of place. And mountain snowpack there is a major source of water. but that snowpack is gradually disappearing. So naturally people are worried about water there and what's going to happen with climate change in the future. And what Scott was pointing out is that

what doesn't get much attention is these rock glaciers. And it turns out Utah has like 800 of them. And he told me there was one we could see pretty easily. So we met up in Salt Lake City and we went to this place called White Pine Lake. And, you know, it's this place where people go hiking. We were joined by Kendall Becker. She's a research technician who works with Scott.

So Kendall is actually carrying a cooler in her backpack. So if we do get a chunk of ice, we'll put it in Kendall's back. We marched up this trail. It's about five miles up through this mountainy trail. You're going up through all these beautiful aspen and other trees to this alpine lake. No, I'm honestly jealous. That sounds amazing. It was awesome.

Although, remember, I'm this out of shape middle-aged lady. So for me, the hike was kind of exhausting. It was relentlessly up. But, you know, maybe I can blame the altitude. I don't know. Probably not. How alpine is this lake? Well, it was like 10,000 feet when we finally got up there. Oh, my gosh. That's high. It's a really striking place. It's this, you know, eerie blue oval, you know, surrounded by bare mountain peaks and, you know, just boulder fields everywhere.

I mean, it's just like bare rock everywhere. And, you know, if I didn't know there was a glacier above this kind of like mossy stream that was feeding the lake, I would have no idea that there was ice there or that this stream was fed by a glacier or that it was anything else than just like a rock slide. But Scott pointed out it had this like unnaturally seeming steep front. The landslides are more just stuff falls and it scatters. Rock glaciers have this affront of them, which is the geologic term is that it's oversteepened. It's this like 80 foot high wall. Wow.

of what looked to be just like loose rock. Like you look at it and you think, I shouldn't go walk directly, you know, around that place, around that foot of that thing because like what if the rocks just like fell out onto you? I mean, it was steep and it was tall. And I asked Scott Hotaling, like, how far down would you have to dig to actually get to ice?

It depends on every rock glacier feature, but generally it's a couple meters of rock that you'll have to actually go through. Wow. That's a lot. And, you know, this glacier is kind of like a rock and ice mixture. So, you know, maybe it looks like a layer cake inside where you have ice and then rock and then ice. And then, you know, on top of this like weird cake, there's the icing, which is like a ton of rock.

And that makes it really hard for scientists to get to the ice. Right, because they're heavy rocks, right? Like, I'm picturing boulders. It's just not going to move. Yeah. I mean, I don't know about you, but like picking up heavy rocks, that is not my thing. No, no, it's for the Hulk. And remember, we're talking meters, like a layer that is like meters deep.

And so, you know, Scott did kind of scout along the top of the glacier. He climbed up there looking for some kind of natural hole. Like, you know, glaciers can have crevasses that sort of shift things around. And so you want to find one that's like exposed some ice, right? Like, that's the goal. And that's what a colleague of his actually found in this glacier one time. This colleague, Matthew Morris, he's with the. Utah Geological Survey.

And then underneath that was a big layer, as far as we could see down this dark hole, of really blue ice, glacier ice. He and a pal chinsawed out a big sample of it and hiked it in a cooler back down to the trailhead, and they sent it to the National Science Foundation's ice core facility. Now, you know, the thing is, almost like samples from another planet, samples from rock glaciers are pretty rare. I mean, he told me this was the second one he knew of. only the second one from a rock glacier in the United States, like the lower 48 states.

And there aren't that many of these samples from Europe either. I mean, what science has been done on rock glaciers has mostly been done in Europe because the rock glaciers there in the Alps, they're closer to people and are easier to get to. And also, like, the debris might fall on people. So people are really interested in them. So what could scientists tell from looking at this ice sample? A bunch of things. I mean, Matthew has this whole list of stuff he wants to look at. He already did one study showing that the ice in this glacier has got to be at least 60 years old.

You can tell that because you look for this chemical signature that would be there if it was deposited after widespread nuclear weapons testing in the 1960s. Anyway, he wants to see how old the ice really is, like not just a minimum. I mean, he wants to understand when and how the ice was deposited, how often it gets replenished, that kind of thing. Well, the day you went up there to try to see one, was there a hole or any of their hole? Unfortunately, no. Scott did not nab any ice despite, like, you know, carrying this chainsaw up for miles. But he and Kendall Becker did do some work to measure the flow of the stream coming out of the glacier. So, you know, obviously in the West where things can be dry, one reason to want to study these things is the water.

You know, what kind of water could it, you know, contribute? to the resources out there that can be so limited and precious. And this water coming from this glacier is super cold. You know, the temperature monitor said it was like 33 degrees Fahrenheit. That's like 0.7 degrees Celsius.

And studies have shown that especially in late summer, a significant amount of mountain stream water in Utah can be actually coming from rock glaciers. Wow. And Scott told me the thing is, water managers in the West,

a lot of them have not taken this kind of glacier melting into account when they think about, you know, what resources there are for water. In a future where the world will be warmer and drier, any stream that's going to persist with cold water in its current form becomes really important refugia for aquatic biodiversity, as well as just available water for things like, you know, deer and elk and moose and pika to have a water source in the landscape. Little critters like PICA could also like climb between boulders on the rock glacier and like enjoy some

coolness because they like it cold and on the rock glacier, it is noticeably cooler. Scott says it's like standing in front of the open door of a fridge. That's so interesting. And we're talking here about these rock glaciers serving as drinking water for animals. What about drinking water for people? It's an interesting question, right? So when I was talking with Matthew Morris, he told me that Salt Lake City gets a lot of its water from just a few canyons. And one of them is that canyon I hiked into, little Cottonwood Canyon. Something like, 12% of the canyon is covered with rock glaciers, but nobody's been talking about them. And I just find that sort of interesting and mysterious, but also a fun opportunity for research.

I asked him, like, how much of Salt Lake City's drinking water might come from rock glaciers, but he didn't know. I mean, that's the kind of thing they're working on now. Okay. All right. So I wanted to get back to this other point you made. You mentioned that rock glaciers are more resistant to climate change because of all that insulating rock they have on top. do we know how much more resistant they are? So there was this one study out of Europe.

And it looked at a rock glacier over like 70 years. And it found that its ice mass was basically unchanged. Wow. And meanwhile, other nearby surface glaciers, like what you think of as like a mountaintop glacier, those were shrinking. Wow. I've never heard of such a thing. Yeah. And Scott and some colleagues have done some work in the Teton Mountain Range in Wyoming.

he told me what they're seeing there is that surface glaciers are losing ice like seven times faster than the rock glaciers there. And so that's why he says, you know, rock glaciers aren't just scientifically interesting. They give people a little bit of climate hope. These things actually seem to be holding steady amidst widespread ice decline in the western U.S. And that's not only really exciting scientifically, but it's really exciting just personally about the landscapes and places that, I love and other people love. You know, he talks to people about rock glaciers all the time. And he says, like, if there's somebody like a water manager who hasn't heard of them,

you can see their eyes kind of like light up. Like, oh, you know, there's this other thing out there. Quick question. Now, are there any plans to protect these rock glaciers? They seem pretty precious. Protect them. Well, you know, there are efforts worldwide to protect glaciers, but like in the U.S., that one I just don't know.

Now, no one is saying the glaciers, the rock glaciers, are totally immune from any effects of climate change, okay? We don't want to be like Pollyanna-ish here. I mean, there was actually a paper this summer showing that the movement of these glaciers, these rock glaciers in the U.S. seems to be speeding up. Remember, glaciers are like frozen rivers, so, you know, they're flowing downhill.

So it's not like rock glaciers are totally unaffected by warmer temperatures, but they're just affected more slowly because they're insulated. And it does seem like they're going to hold onto their ice a lot longer because of all that rock on top. Well, now next time I look at mountainsides in the West, I will be looking for these rock slides to see and wonder if maybe underneath it is some ice. Thank you so much, Nell. Thank you.

This episode was produced by Jessica Young. It was edited by our showrunner Rebecca Ramirez and fact-checked by Tyler Jones. The audio engineer was Patrick Murray. Beth Donovan is our senior director, and Colin Campbell is our senior vice president. of podcasting strategy. I'm Emily Kwong. Thank you for listening to Shortwave from NPR.