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The reason many of us hear about glaciers has to do with sea level rise â€� which makes sense! If all of the glaciers on Earth melted, sea levels are predicted to increase by about 230 feet (70 meters), which would flood coastal areas, envelope a number of islands, and seriously impact human infrastructure, including our current water resources. But glaciers do more than safeguard Earth’s future â€� buried within them is our ancient past. In January of this year, a team of scientists drilled nearly 2 miles down into an Antarctic glacier. The 1.7 mile long cylinder of ice they pulled up, called an ice core, holds the equivalent of 1.2 million years of climate history. In this episode of Tiny Matters, we talk about what glaciers mean to us today, their importance for the future of our planet, and what they tell us about Earth’s ancient past.Ìý

Transcript of this Episode

Deboki: In January of this year, a team of 16 scientists completed a daunting task: Drilling nearly 2 miles down into an Antarctic glacier. The 1.7 mile long cylinder of ice they pulled up, called an ice core, holds the equivalent of 1.2 million years of climate history.Ìý

Alison Criscitiello: …which is unfathomable that ice could exist on Earth for over a million years.

Deboki: That’s ice core scientist Alison Criscitiello. Before Alison began drilling into glaciers to retrieve ancient samples herself, she was just someone who loved being outdoors, particularly in the cold. She loved snow sports including skiing and ice climbing. And for years she worked as a climbing ranger in Washington state, in Olympic National Park.

Alison Criscitiello: It was a lot of years of me post-undergrad just working very physically in these places that I was totally obsessed with and I really loved being, but obviously not in any sort of academic way. And I can kind of pinpoint some things that drove me back. One was when I was the climbing ranger in Olympic National Park, and just noticing things like increases in, I mean, both accidents and fatalities, but all having to do with increase in avalanche and the shifting landscape that was warming quite a bit where I was stationed up on Mount Olympus.

Sam: Inspired to better understand the rapidly changing landscape she loved so much, Alison went on to graduate school, getting a PhD in Glaciology from MIT. Today, she’s the director of Canada's National Ice Core Lab and an assistant professor at the University of Alberta, where she investigates the impact glaciers have on us and the history of Earth, as well as the human impacts on these frosty landscapes.Ìý

Welcome to Tiny Matters, a science podcast about the little things that have a big impact on our society, past and present. I’m Sam Jones and I’m joined by my co-host Deboki Chakravarti. I’ll be honest, I didn’t know that much about glaciers before working on this episode. I knew they were important â€� I think we’ve all seen the incredibly sad images of polar bears floating on diminutive icebergs or wandering around the melting landscape facing starvation. But it goes a lot deeper than that.Ìý

Deboki: Glaciers are not just important to ecosystems today â€� they’re keepers of the past. So how exactly do they form?Ìý

Alison Criscitiello: In locations where snow falls and it accumulates over long periods of time, it accumulates and accumulates and it compresses and compresses until eventually it gets compressed down to glacial ice. Then at some point it has enough mass to start flowing purely under its own weight and under the influence of gravity, and thus is born a glacier.

Deboki: When a glacier stops moving under its own weight and begins melting away, it’s no longer considered a glacier.

So why should we care? One of the big reasons many of us have heard of is sea level rise. If all of the glaciers melt, sea levels are predicted to increase by about 230 feet or 70 meters, which would flood coastal areas, envelope a number of islands, and seriously impact human infrastructure, including our current water resources. Glaciers also have practical use � for one, they generate hydroelectric power. It’s estimated that, across the Himalayas, glacial melt accounts for 15% to 40% of the annual hydrogeneration.

Sam: But glaciers are so much more than a potential source of energy or a massive block of melting ice with apocalyptic potential. Where Alison is in Alberta, she sees how glaciers have sculpted mountain ranges, carved valleys, and dramatically changed landscapes. They also deliver nutrients to their downstream lakes, rivers, and oceans.

Alison Criscitiello: And these nutrients are super important. They drive phytoplankton blooms in the ocean, little critters in the sea and the base of the marine food webs. At the same time, more gradual glacier melt also can sustain stream habitats for plants and animals. So in some ways, glaciers have this kind of indirect impact also on a lot of industries like fisheries, for example.

Sam with Alison: When people hear glaciers, one of the first things they think is about how we're being told that glaciers are melting. And so I'm wondering to what degree are they melting and are they melting much more in certain parts of the world compared to others? I hear there's a scary change, but I have a hard time sort of conceptualizing it.

Alison Criscitiello: Yes, we hear a lot about how glaciers are melting, and in some ways it's actually not a simple answer to say how much are they melting and what are the repercussions of that. It's a very different answer depending on where we're talking about on Earth. The world's glaciers as a whole, as an average, are melting at double the speed right now than they had in the last two decades. This number may or may not mean anything, but glaciers lost 267 gigatons of ice per year.

Deboki: That’sâ€� a big number. I was trying to find a visual of that and it’s just so much. But according to one article I found from the United Nations University Institute for Environment and Human Security in Germany, 267 gigatons of ice is about the mass of 46,500 Great Pyramids of Giza. Which is still kinda hard to wrap your head around.Ìý

Alison Criscitiello: I mean, the other kind of alarming statistic, which is thrown around and it's true, is that we are projected to lose around 50% of glaciers outside of Greenland and Antarctica by 2100. And this is even if warming is limited to the magical 1.5 degrees C.

Deboki: The 1.5°C climate threshold refers to an attempt to keep Earth’s average surface warming to no more than 1.5 degrees Celsius above pre-industrial temperatures, a time before huge amounts of fossil fuels were being burned, spewing greenhouse gases like carbon dioxide into the atmosphere. Limiting Earth’s warming to 1.5°C has been proposed by scientists as, like Alison said, the magical number for preventing the most severe climate change events, including devastating heat waves, storms, and droughts. Countries who signed the Paris Agreement have agreed to try to stay below that number.Ìý

Alison Criscitiello: And then the Arctic is kind of its own thing. The Arctic, because of arctic amplification, is warming more than three times faster than the global average.Ìý

Deboki: I hadn’t heard of Arctic amplification before�

Sam: Yeah me either.

Deboki: But on a basic level it’s the observation that the Arctic is warming significantly faster than the global warming average. Alison told us that, during the last decade, multiple factors have been proposed to explain the potential causes of this amplification. One of the explanations is that when ice melts, the much darker ocean below it is able to absorb more incoming solar radiation. And of course the Arctic has a lot of ice that can melt.

Alison Criscitiello: Another concept that I think is important to highlight is that we sometimes think of glaciers as “drought-proofersâ€� because they're these reservoirs. I mean, I think about this in terms of the Columbia Icefield here, but that term drought proofer, it sort of comes from this idea that for snowmelt-fed rivers, more rapid rates of snow melt and earlier melt onset can impact river dynamics.Ìý

Sam: But as glaciers recede, they will become less and less of a water supply buffer, which is scary. And humans are impacting glaciers in ways that go beyond speeding up their melting. Alison told us that where she is, you have the Columbia Icefield, the largest icefield in the Canadian Rockies. This ice field is where many people, including Alison, get their drinking water from. A project Alison and her lab have led over the last few years looks at environmental contaminants in the ice that may make their way into their drinking water as warming and melt continue.

Alison Criscitiello: The ones that we are looking at here are ones that we really care about in drinking water supplies. For example, PFAS, perfluoroalkyl substances, which lots of folks have heard about. And this is kind of a whole arm of work that we've been doing in ice core science here in Canada, which is thanks to a collaboration with Environment and Climate Change Canada. So we've partnered with them and done some really amazing work, not just here on the Columbia Icefield, but also in the Canadian High Arctic looking at PFAS as well as legacy contaminants � legacy pesticides that are no longer used, DDT, for example, various flame retardants, all sorts of different classes of chemicals that we care about potentially reaching drinking water, but also in the Canadian High Arctic example, reaching aquatic ecosystems and accumulating over time.

Sam: We’ve talked about perfluoroalkyl substances or PFAS, as well as DDT, in past episodes, including episode 29, which we’ll link to in the show notes.Ìý

PFAS is a category of thousands of human-made chemicals that are typically water, heat, corrosion, and oil-resistant, which makes them useful in things like jet engines and firefighting foams but also common stuff like non-stick pans and the lining of fast food wrappers. They’re also in a lot of plastics. And we’re learning more and more about the health risks they pose. At this point, they’ve been linked to cancer, issues with fetal development, and immune and endocrine disruption, among other things. And they stick around in the environment and your body for a long time. DDT, or dichlorodiphenyltrichloroethane, is a pesticide that the United States used a lot, particularly during World War II, to ward off mosquitoes carrying malaria. It was banned in 1972 after proving to be incredibly toxic to wildlife, but it has stuck around in our environment since, just like PFAS. So yeah, these contaminants need to be carefully monitored.Ìý

Deboki: So hopefully now you have a good sense of what glaciers are, how they impact us, and how we’re impacting them. But a lot of what we wanted to talk about in this episode relates to what we can learn from glaciers, particularly about the past. And to do that, scientists are analyzing ice cores.

Alison Criscitiello: It's just a cylinder of ice that you have drilled into a glacier or an ice sheet or an ice cap and removed from its happy home in that frozen place and brought to a lab to look at.

Deboki: Ice cores have layers â€� each layer representing a year of snowfall. As opposed to the rings of a tree which radiate outward to give you a sense of time, ice core layers are stacked, one on top of the other. Alison does love drilling her own ice cores.Ìý

Alison Criscitiello: They're in environments that I love to be so much. I was just remembering, not that it was deep at all, a bunch of shallow cores that I drilled in the Eastern Canadian High Arctic with the intention of looking only at recent decades worth of time. So we're talking like 25 meter cores…And in one of these cases, I actually went alone, but I commonly go just with one or two other people…You're basically just winter camping, doing your thing. You don't even need to bring, for the drill, fuel. In this case, you can drill with this small drill manually.

And so it's just kind of a really fast and light kind of setup where you're just out there and you can still drill down to 1950 in certain locations in the Canadian Arctic with 25 or 30 meters with this really lightweight system. And it just feels really different than a lot of the bigger campaigns. And the point of a lot of that work is to lay the groundwork for deep drilling in these locations.Ìý

Deboki: And by deep we meanâ€� deep. Like I mentioned at the top of the episode, the longest ice core is 1.7 miles long, the equivalent of 1.2 million years in climate history. It took four summers to retrieve the core, and keep in mind that “summerâ€� meant the scientists were still facing temperatures around -31 Fahrenheit or -35 Celsius.Ìý

And although this is the deepest ice core ever retrieved, and the longest continuous record of Earth’s past climate, in 2017 researchers did pull up an ice core from Antarctica that dates back to 2.7 million years ago. It was actually closer to the surface than the 1.7 mile long one, but that was just due to natural shifting that pushed the ice upward.ÌýÌý

Sam with Alison: Okay so you drill out this cylinder of ice and then you see that in a layer of that you have a certain concentration of some chemical that you're looking for. How do you know about how long ago that was?

Alison Criscitiello: That is a very good question, and one that usually takes the first years after you drill an ice core to answer.

Sam with Alison: Okay.

Alison Criscitiello: When we drill ice cores, we're standing at the surface of an ice sheet or glacier wherever we are, and we're drilling down usually until we hit bedrock. But then when we go home, we have this long, we drill usually in meter segments, but you have this core that is basically just on a depth scale. That doesn't mean anything. We can't do anything until we put that depth scale onto an age scale. We have to make a chronology and there is a whole art to it, and it can take a really, really long time to do. Near the top of the core, where the layers are not too smushed yet, they're not so compressed that you can't see annual signals in the chemistry. You can actually manually layer count by looking at a lot of different chemical species that vary seasonally.Ìý

Deboki: One example is the chemical compound hydrogen peroxide. Lower concentrations of hydrogen peroxide are found during the winter months and higher concentrations are found during the summer. That’s because there’s more sunlight in the summer, and that’s is key to peroxides forming. Different salts and oxygen concentrations also show seasonality, helping researchers go through the upper layers of an ice core with good precision.Ìý

Alison Criscitiello: But obviously you reach some point where the layers get compressed and they're too smushed and you can't do that anymore, and then you have to rely on ice flow modeling.Ìý

Deboki: Ice flow modeling is used to simulate how glaciers have moved and evolved over time. But still that modeling requires some known time points as reference.Ìý

Alison Criscitiello: And the most commonly used ones are volcanic layers. So the biggest volcanic eruptions that have occurred in our Earth's history have spewed their ash all over the earth.Ìý

Sam: Mount Pinatubo in the Philippines is one of those volcanoes that has had many eruptions across history, the most recent being in 1991. Krakatoa, a volcano in Indonesia, which erupted in 1883, was one of the most destructive eruptions in history. Alison told us that tephra, which are fragments of rock and magma from volcanoes that can date back thousands of years, can be found in every ice core on Earth.Ìý

Alison Criscitiello: And so we exploit that. Tephrachronologists have a library of these ashes. And so when we get to these layers that have those valuable volcanic ashes in them, they can fingerprint them, they can figure out which volcano it was and from which eruption, and we stick an exact date into our chronology.Ìý

Sam: It’s the chemical elements preserved in the ash that are what allow researchers to estimate what year the ash is from and, therefore, the age of that layer in the ice core.

Alison Criscitiello: When we get the core from wherever, whatever remote location we drill it, back to the lab, the first thing we do is make a cut plan. We take that cylinder on end and we draw exactly how we're going to cut it. We generally cut it straight down the middle and one half moon goes into an archive for future generations to use. And then the other half moon we use for our analyses. And at this point, we might have some clues here and there, but we don't know what depth corresponds to what age. We have no data. It's just a core that was drilled to a certain depth.

Sam: And from the half moon cylinder, the team will cut a square stick.Ìý

Alison Criscitiello: So the most pristine, beautiful, has not been contaminated, touched anything since it was laid down, center square stick, and it's that stick that's usually destined for this thing we call CFA continuous flow analysis.Ìý

Deboki: Continuous flow analysis is a high resolution way of measuring trace amounts of various elements, ions, and other particles. Alison says the device is basically an ice cream freezer with a little thing at the bottom called a melt head that slowly melts the stick. What’s melted comes off into little tubes that are funneled into a bunch of instruments where the liquid is analyzed.

Alison Criscitiello: We’re talking about many, many dozens of different things being measured all at once. So you're accumulating an enormous amount of data continuously, and then that stick is gone, not necessarily the whole core. You've hopefully preserved some, but you have this mountain of data that's still on a depth scale.Ìý

Sam: Right, so at this point it’s on a depth scale, not a time scale. So that’s when you go back to that chronology â€� measuring things like peroxides, oxygen, and volcanic tephra. One thing Alison didn’t mention because it’s not part of her research is the measurement of greenhouse gases like methane and carbon dioxide in these ice cores. That’s something that comes up a lot when talking about skyrocketing greenhouse gas emissions. The reason we know CO2 concentrations were so much lower before the industrial revolution is because of ice cores.Ìý

Deboki: Scientists can analyze tiny air bubbles containing CO2 that are trapped within ice cores. And because we have ice cores with these bubbles dating back hundreds of thousands to millions of years old, we can also study natural carbon dioxide cycling as the Earth warmed and cooled in the distant past, which is incredible that we’re measuring ancient air today. Like air that our ancestors were breathing in. It’s amazing to think about.Ìý

Sam: It really is. It’s like finding a relic of the past buried in your backyard, but likely thousands of years older. So what’s next on the horizon for Alison? When we chatted she was actually about to pack up for a two month trip to the Arctic.Ìý

Alison Criscitiello: I'm really excited about this upcoming project that myself and a lot of others are doing with Denmark. And we're going to Axel Heiberg Island in the Canadian High Arctic, which is on the western Arctic Ocean edge of the Archipelago.

So the reason I'm extra excited about this is not just because it's somewhere that hasn't been drilled before with this amazing potential to tell us something about Arctic Ocean sea ice variability in the past that other cores couldn't have. But it's also from a more human side, the fact that me and Canada are going with one drill and really incredible Danish Glaciologist, Dorthe Dahl-Jensen is coming with the Danish drill. And we'll have both drills going with two teams at the same time. And part of the idea here is that the Danish drill will be drilling a 620 meter surface to bedrock core for a full climate and environmental history from this region in the Arctic. And then the Canadian drill that I'll be running will be drilling a series of a hundred meter deep holes destined for measuring various environmental contaminants that require a lot of sample to measure. I've certainly never been in the scenario where we have two drills, two teams, under one big umbrella living on an ice cap for two months. It'll be just over two months.Ìý

Sam: Well, I guess Alison will have to listen to this episode when she gets back. What’s the internet situation like on a glacier in the Arctic? I think that’s a mystery to solve another day.Ìý

Let's Tiny Show and Tell. I think I'm remembering that you went first last time.

Deboki: I think so.

Sam: Wow. We never remember. So this is exciting. I can go first.

Deboki: Awesome.

Sam: Okay, so today I'm going to tell you about a new study on cold water immersion, AKA, cold plunges. Do you get ads for cold plunge tubs? My Instagram and stuff, I've never ... I understand if I was looking to purchase one that all of a sudden the algorithm's like, "We know you want this," but I have no interest in a cold ... I don't like being cold. So do you get ads?

Deboki: No. It's funny that you say, I have never gotten an ad for a cold plunge, but from when I was in track and playing volleyball and stuff, we would do ice baths and I always liked that. Especially in the summer in California. It's a great feeling. But I still would never want to do the full ice plunge. Like, no, that sounds awful.

Sam: Right.

Deboki: Also, this is very on topic for today's episode.

Sam: I know, I know. It was just a funny coincidence, honestly. But yeah, so there was a group at the University of Ottawa and they wanted to try to understand how our cells do or don't acclimate to cold water and the impact on something called autophagy, where cells will degrade or recycle damaged proteins, other stuff that's kind of just like junk within the cell. And so this is a super important process for keeping your cells and therefore you, healthy. So the question they were asking was, does consistent cold water exposure make your cells more resilient against stress? And the measurement for that is like, are they still clearing out all this junk?

So the study was done in 10 young healthy males as a starting point.

Deboki: Yeah, it's probably going to be super relevant to me then�

Sam: Yeah� So they underwent cold water immersion, which was at, it was Canada, so 14 degrees Celsius, which is around 57 Fahrenheit. And they would go for an hour.

Deboki: Oh!

Sam: I know, across seven consecutive days, which is long. I feel like what I'm seeing is people are somewhere between the 50 to 60 degrees Fahrenheit and they jump in and it's like if they can sit there for 10 minutes, that's a big deal. But some people are like, "I go in for three minutes." This is an hour. And then the researchers collected blood samples from the participants to look at their cellular responses before and after this acclimation period.

Deboki: Right.

Sam: And I think there were multiple time points in between. So apparently cell autophagy improved. There was this better clearing out of junk. However, they did see that autophagy was negatively impacted at the beginning, so they must've been taking measurements throughout.

So they did see that it was negatively impacted at the beginning and it was the consistency over the week that seems to have increased autophagic activity based on seeing less signals of cell damage is essentially what they were looking for in the cells that they were getting from these people's blood.

So yeah, it seems like consistent cold acclimation may help improve cell resilience in extreme environmental conditions. And then of course, if you have this better clearing of this junk out of your cells, that could have implications for preventing disease. That's part of why disease starts. Your cells are not clearing things that they need to clear. But also, again, this was for a week, it was in 10 young men and they were submerged an hour each time, not like three minutes. So I would say it's totally interesting. I think that's really cool. And for in seven days to see that big of a change, that's really interesting and it means something.

But a lot more work needs to be done to say that the standard cold plunges that you might be getting marketed are actually beneficial. I would say, jury is still out.

Deboki: Yes. Just do it if you want to.

Sam: Yeah, I think if it's like a mood lifter, if it's X,Y, Z� Go for it. But I wouldn't ... There are a lot of claims surrounding those cold plunges and at this point there's very little evidence.

Deboki: Yeah, part of me is like, did they only have 10 people in the study because that's how many people they could find who would sit in a cold plunge for an hour?

Sam: I thought that too. I was like, how much am I getting paid? Because that's a lot. I guess at some point your body's just like you acclimate or things go kind of numb a little bit. Yeah, and also it's like how long does this last? I would love to see follow up.

Deboki: Yeah, for sure. That was going to be one of my questions is what's the tail, I guess, of how long, if you stop at seven days, will you keep seeing results or is it like you got to keep doing it?

And then is there a point where it would just stop having the impact?

Sam: Right. Because I mean, in what world could someone sit in a cold plunge for an hour every single day?

Deboki: Yeah, just like timewise.

Sam: Yeah, no, exactly. I'm like, yeah, that doesn't exist.

Deboki: We're going to all just be Zooming from our office cold plunges.

Sam: Yeah. No, for real. I feel like that's the only way I could ever do it is if I worked my cold plunge into a work call.

Deboki: And I wonder how it compares to, on the other end, like a sauna. What is the similarity? What's the difference? Can you do the cold plunge and then go into the sauna and you get everything?

Sam: That's the thing. That's what people will do. They're like, "Oh, I love it," or "I go in the sauna and then I go in the cold plunge," and back and forth and it's like, are we just undoing everything we did?

Deboki: And can I just sit at a lukewarm temperature and be fine?

Sam: Can I just live my life? Not pay for more things?

Deboki: Yeah. Yeah. So again, if it seems like if it's fun for you, you should do it. That is always a good reason, well, not always, but that is a good reason to do most wellness-y things. I feel like most things I do that are wellness-oriented, I'm like, I don't know if this is doing anything, but I enjoy the act of doing it.

Sam: Right. Absolutely.

Deboki: But I don't know that an hour in the cold plunge would be my my-

Sam: No, that's not my happy place, for sure.

Deboki: Well, Sam, thank you for that. I have something on a very different note, which is just an article recommendation for anyone like me who owns a cat and has wondered why is it so hard to take your cat to the vet and learn anything about them? I mean, not just the fact that it's hard to take the cat to the vet. My cat has finally gotten to a place where he has learned to capitulate and just get into the carrier when we get to the vet. But if you were wondering why it's so hard to know anything about cats at the vet, there's a great article in the New York Times titled, Why Are Cats Such a Medical Black Box? And it's about the writer basically wondering about this time that their cat was sick and trying to understand why it was so hard to find out information about what their cat was sick with. And so it's really just about the fact that cats are super understudied, especially compared to dogs.

Sam: I was going to say, I'm like, I feel like when I take my dogs, they're like, "It could be these 50 things and let's evaluate them."

Deboki: Yeah. With cats, I mean, so my cat has had health issues in the past year. He's an old cat. He's dealing with the stress of a baby in the house and just, he's also in this weird place of now he's just become very picky about his food in a way that is very typical for cats but has not been typical for him. And so yeah, a lot of vets will just basically treat cats like they're small dogs, which they are not. A small dog and a cat are two very, very different creatures. And they'll actually use treatments for dogs that for cats, we just don't know how they're going to behave. They metabolize drugs differently. There are things that work fine in a dog, but are toxic in a cat. On the other hand of that, one of the things that we're actually, we've been wondering with my cat, is he's currently on this steroid drug because he has inflammatory bowel disease possibly. It's hard to know exactly for sure.

But we have him on a steroid. And one of the interesting things that my vet told me is that we can keep him on the steroid longer than you could keep a human or a dog on it, because cats apparently aren't as affected by steroids in terms of the negative side effects compared to dogs. Yeah. But do we know why? No. It's just one of those things that people apparently know.

So yeah, this article is just exploring this question of why are cats not as well studied? Is it partly because cats are a pain to take to the vet? Is it because they're really good at hiding symptoms? There's a lot of different factors around that, that make it hard to understand our cats, and part of it is that we just haven't studied them as well, and part of it is that they're cats.

Sam: Yeah. Wow. That's so interesting. Thanks Deboki.

Deboki: Thanks for tuning in to this week’s episode of Tiny Matters, a podcast brought to you by the American Chemical Öйú365betÖÐÎĹÙÍø and produced by Multitude. This week’s script was written by Sam, who is also our executive producer, and edited by me and by Michael David. It was fact-checked by Michelle Boucher. Our audio editor was Jeremy Barr. The Tiny Matters theme and episode sound design is by Michael Simonelli and the Charts & Leisure team.

Sam: Thanks so much to Alison Criscitiello for joining us. Go rate and review us wherever you listen, we super duper appreciate it. We’ll see you next time.

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