Post from a Scientist: The Depth of Snow

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Have you ever wondered how deep snow can get in the mountains? How about on top of glaciers? After all, glaciers only exist because they get enough snow falling on them in the winter. Some scientists have been measuring snow for many years using probes to feel for the bottom of the snow (a lot like a tent pole and a tape measure), and stakes to see how high the snow reaches against them. Snow density must also be recorded and multiplied by the depths to get the mass of snow. Of course, scientists want these measurements to be as accurate as possible. But by looking at past results, we can try and see if there are better ways to take snow measurements. By using statistics, we can find out where are the most representative places to probe snow, and then work out snow masses.

Some glaciers have a long dataset for many years, and show changes in mass balance; that is, the mass of snow landing on a glacier minus the mass of glacial ice that is lost in a year. Knowing the changing mass of glaciers can be used to understand global climate changes, so getting accurate results is very important. Not only that, but the hydropower industry is also keen to know how much snow there is per year, so they know how much energy they can produce from it.

So now you know about improving snow measurements and why it’s useful, but why is this important for you? Well, glaciers are often used as a sensitive indicator of climate change, which has the potential to affect us all, from low lying areas, to mountain areas. Freshwater is also a vital resource that we use every day, and is expected to become more important in the future; surely it’s important that measurements of how much there is are accurate. So the next time it’s snowing, have a think about how deep it’s getting, and how knowing that accurately has big implications.

- Alex, Oslo University, Norway

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Post from a Scientist: Freeways of Ice

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Growing up I spent most summers playing in the creeks around my house in Santa Cruz, CA. The water flowing out of the ground and its connection to the water table fascinated me. I went to college and graduate school to study how fluids, like the water in the stream, flow and found out that glaciers are just large frozen streams. In my current research I study how liquid water flows within glacial ice.

This liquid water turns out to be very important in West Antarctic ice streams—regions of relatively fast flowing ice within the Antarctic ice sheet. Ice is melted at the edges of these ice streams due to friction—try rubbing your hands together and feel how they warm up. This water then trickles down to the bottom and soaks into the ground. As more water enters the soil, the strength decreases—compare bending a dry sponge to one filed with water, which is easier to bend? In other words, if more melted ice is generated at the edge of the ice stream, the strength of the soil is decreased and the ice stream can widen. However, as water collects under the ice, a channel of liquid water can form and drain the excess water. The soil then does not lose strength as fast. The width of an ice stream is then a competition between the water flowing into the soil, which decreases the strength, and the flow of water into drainage channels.

My fascination with creeks near my childhood home is carried over to the complex ice streams of Antarctica and the liquid water flowing within the ice. Moreover, these Antarctic ice streams are important features in the ice sheet—they are the freeways for ice to move from the interior of the ice sheet to the coast. Ice streams are also sensitive to climate warming in the sense that they will begin to flow faster and drain more ice from the interior of Antarctica. The interesting fluid physics and relevance to a changing climate are what make me passionate about studying ice streams.

- Colin, Harvard University, USA

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Post from a Scientist: Model Glaciers

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What do you think of when you hear someone say “climate change”? Maybe you think of sea level rise, maybe fossil fuel usage, or maybe the future of polar bears. I think of computer modeling. The idea of computer modeling can seem intimidating at first, but it is one of the most powerful and exciting tools we have in order to make decisions about how to adapt our communities in a changing world.

When I was in second grade, my class made a model volcano from paper mache, chicken wire, and baking soda and vinegar. Though it didn’t work exactly like a real volcano, it helped contribute to my understanding of volcanoes and chemical reactions. (And as a bonus it was fun and messy!) Now, I’m modeling glaciers. Instead of having a physical model of paper mache, I have a series of equations in a computer. These equations describe how a glacier melts, grows, and flows. They aren’t always perfect, because they are an idealization of the very complicated processes that occur in ice and snow – some of which we don’t fully understand yet – but they do a good job at replicating the way we have observed glaciers changing over many years.

Once we know that the equations that we have to describe a glacier are a reasonable representation of reality, we can conduct experiments using this model. If we want to know what could happen to glaciers if the temperature warms up and the amount of rain increases, we can change the variables in our model, and then run the model to find out. It is impossible to conduct this experiment in reality. We can’t go to a glacier and warm up the air around it to see what happens, right? (Though, in a sense that is what is happening with climate change, but it is important that we understand the possible results of this experiment, instead of just waiting to find out). We know that climate change will have drastic effects on glaciers. Using a model allows us to consider how those effects might unfold before they happen, so that we have a chance to make decisions about adapting our water ways, agricultural systems, and other infrastructure connected to glaciers.

I will be starting my graduate school and research journey this coming fall at the University of Alaska Fairbanks. At this point, I’m not sure what my specific research question will be, but I do know that I want to model how glaciers could change in the future, and what that means for communities that rely on the water resources from those glaciers. Glaciers are a critical freshwater source for people around the world, and we need to start thinking about how access to that water will change as glaciers change, and about what things we can put in place to lessen the forces of a changing world. It is easy to think of computer modeling as trying to predict the future, but nobody and no model can do that. Instead, computer modeling provides a space to consider possible scenarios of an uncertain future, and I’m excited to explore these scenarios in my research and hopefully provide relevant information for communities that are tied to glaciers and their changes.

- Aurora, University of Alaska Fairbanks, USA

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Post from a Scientist: The Gravity of Ice

tyler_blogDid you know that the force that keeps you on the ground changes from place to place?  This force is known as gravity and describes why apples fall from trees as well as why planets orbit the sun.  On the Earth, the strength of gravity at your location is related to the mass around you.  I use gravity to measure the mass of the Earth’s great ice sheets, which are as large as continents and thicker than our tallest skyscrapers.  The ice sheets are currently changing, losing mass into the oceans and causing the seas to rise.  My research looks at smaller regions of the Greenland and Antarctic ice sheets, measuring their mass month-by-month.  These smaller regions are like river systems, flowing ice from their interiors to the coasts.  Minute changes in snowfall, ice melt, and iceberg production can change how much mass is in each of these regions year to year.  With gravity, we are getting a better picture of these regions, as well as other glaciers thoughout the world.

So!  How do we measure the Earth’s gravity?  Well, in 2002 as twin pair of satellites was launched.  These satellites are named GRACE (Gravity Recovery and Climate Experiment), and they chase each other in their orbits around our planet.  When one satellite approaches a region with more mass, it speeds up, attracted by the gravity of that mass.  We measure when and where the satellites speed up and slow down by measuring the distance between them.  When the leading satellite speeds up it will gain distance on the trailing satellite, just as a fast runner will beat a slow runner in a race.  The trailing satellite will speed up when it approaches the same region of mass, creating a game of cat-and-mouse with the leading satellite.  With GRACE, we can create maps of how the Earth’s mass shifts around the globe due to water cycles, ocean circulation, ice sheet melt and more.  It is almost like putting regions of the Earth on gigantic scales. 

In my research I’ve spent the most time monitoring Greenland.  With GRACE we can see that Greenland is losing a lot of ice, but we don’t know why right away.  With other datasets we can try to get a better picture of what is causing the mass to change.  We look at how much snow falls, how much ice melts, and how much ice is put out into the sea.  Putting everything together helps us understand what is happening.  We can see that Greenland overall is both melting and losing additional ice by creating more icebergs.  This is not good news.  Greenland is big and Antarctica is much larger.  So I continue to monitor Greenland as well as Antarctica to try to determine their overall health, which may help us understand how our sea levels and our climate will change into the future.

- Tyler, University of California Irvine, USA

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Cryoconite Holes: Tiny Features with Big Implications

Albedo is a fancy way of saying that you will feel cooler on a hot day if you wear a white t-shirt instead of a dark t-shirt. Anyone from Miami certainly knows that. But Alaskan glaciers know that too. Albedo refers to the amount of light that is reflected off a surface, relative to how much light hits the surface. For glaciers, the white is the ice, and the dark is the earth. White is more reflective than darker colors, so the white ice of glaciers do a good job of reflecting sunlight, helping to keep them cool. As glaciers melt with changing climate and environmental conditions, the exposed darker ground absorbs more sunlight, which further warms the surface, which can lead to further melting, which can expose more dark ground… and the cycle continues. This is one of the reasons why glacier melting is both an indicator of a changing climate, and why it is something that is globally important, because as more ice melts, it affects sea level and coastal areas, communities’ freshwater sources, etc.

That’s the big picture, but as we trekked along the glacier, we saw this same effect on tiny scale as well. The tiny holes of a couple inches diameter that you see in the surface of the glacier are called cryoconite holes. Cryoconite is windblown rock and dirt, and as this dark material is deposited on the white glacier surface, that area warms, locally melting the ice underneath, and the dirt and rock sink into cylindrical holes of melted ice. So these tiny holes on this Alaskan glacier are signs of a phenomenon that has global effects, even in Miami.

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Standing by a cryoconite hole

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Cluster of cryoconite holes

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Post from a Scientist: The House of Snow

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I am Sathiya, from the Indian Institute of Technology in India, and I am doing my PhD in atmospheric sciences and climate change. You will laugh when you hear the reason why I got into my research field. It was an awesome winter in 2010 when I was in Manali, Himachal, India for a student exchange program. It was my first time in the Himalayan region. One fine evening the weather turned wild, and there was a snowfall. I was excited and running around. This is what tempted me to read more about Himalayas. (“Himalayas” actually means “house of snow.”)

So I started my research without any knowledge of glaciology, or anything about snow or glaciers, but have now studied various reports about water security and receding glaciers in the Himalayas. And that is why I am here, to learn as much as I can about glaciology, the physics of glaciers, and more. I am most eager to learn about how the glaciers are melting, why they are melting, and the causes and mechanisms of the melting.

If the white snow melts, the area of darker barren earth will increase, which will in turn lead to more warming of the Earth. So I would like to work on understanding this feedback mechanism and the albedo (how much light is reflected off the Earth’s surface versus how much light hits the surface) over the Earth’s surface, particularly over the retreating glaciers of the Himalayas. In my research I intend to find out what has happened to the Himalayan glaciers in the past, so that I can build a model to project the future changes f these glaciers. I am confident that my model will work well for the case of the Himalayan glaciers.

If you are interested in this kind of research or doing work in the Himalayan glaciers, please feel free to get in touch and work with me. But if you have passion for research, I am sure you will find great adventure.

- Sathiya, Indian Institute of Technology Delhi, India

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Post from a Scientist: Seeing Underneath a Glacier

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When you see the Greenland Ice Sheet for the first time, it’s very difficult to understand, intuitively, that it’s undergoing significant changes.  It’s enormous, and very still.  The nearest simile I can come up with is that it’s like looking at the ocean in slow motion.  With a closer look, however, you start to notice all the strange and subtle things that are occurring.  At the ice edges, the landscape is like a construction site, as the ice bulldozes rocks into haphazard piles.  Moving inland, you notice rivers, not unlike the ones perhaps meandering through your town, but carving their channels through ice and flowing impossibly fast due to their steepness and smoothness (sometimes they just disappear into frightening voids in the ice).  Moving even further up, you’ll find yourself in a snow-swamp or on a lakeshore, both of which mark the beginning of the portion of the glacier that never melts.  Even higher towards the top of the ice cap, if you spend enough time there, you may find that you start to notice subtle hills and valleys that are barely noticeable amidst the expansive, blank, white plain.  The cycle of snow turning to ice, ice melting into water, and water running off the surface and down into the depths of the glacier are on display here, and each part of this cycle is connected with its other parts. The trick is knowing where to look for these connections.

It’s important to understand, however, the difference between observing all of the (understated) drama at the surface of an ice sheet, and understanding how they are all connected in a way where you could start to make predictions.  It’s even more difficult to extrapolate these observations to things that you can’t see, like where does all of that water flowing off of the surface, and into holes in the ice, go?  Does it reach the bottom of the ice sheet and flow into the ground, or does it get squeezed out the sides of the ice sheet between the glacier and the bedrock?  And do these questions even matter for humans, particularly in the context of a changing climate?  As it turns out, the answer to this last question is very likely yes. What happens to water at the surface is very important in determining how much of the Greenland Ice Sheet turns into water that goes into the ocean, even beyond the amount that melted in the first place.  The answer to the question of where does the water flowing into holes go, is that it mostly gets squeezed out the sides.  We know this because there are very large rivers that flow out from under the ice sheet at its edges. 

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Thus, we can watch water go in, and we can watch water go out, but what happens in between?  This is a very difficult problem.  How do you observe the bed of an ice sheet?  One thing that we can do is to drill holes through the ice and measure the pressure of the water, and what the bed of the glacier looks like.  These are powerful measurements, and they can tell us many things, like how fast the water is flowing, how long it’s been since the water flowed in from the surface (if that’s where it came from), and how hard it’s pushing back on the ice above it.  This last bit is important because ice can, in some cases, when the water pushes back hard enough, float.  When this happens, the ice starts to slide, and the ice sheet can start to deliver more ice to low elevations (where it’s warm), or directly into the ocean, which is what drives sea level rise.  So why not just drill holes everywhere?  Drilling a hole through an ice sheet is incredibly expensive, and we couldn’t possibly drill enough to say something about what the water is doing everywhere on an ice sheet bed.

The alternative, and what I do in my research, is to come up with models that simulate the movement of water under an ice sheet, as well as the ice itself (because ice is fluid when it gets deep enough).  This sounds complicated, and in a practical sense, it is.  However intuitively, a model ice sheet operates much like a model airplane; the parts are simplified and scaled down into a machine that we can work with at home, in the office, on a computer.  This allows us to make educated guesses about what might be happening down there (hypotheses, if you will), and to test them without having to go to the ice every time.  We determine how good our hypotheses are by comparing the results of our models with the data that we collect in the field (like the pressures that we measure in the few holes in the ice that we have the resource to drill).  More often than not, we get it wrong; but this is a great opportunity to rethink our beliefs about the factors that influence glacier movement.  Sometimes this means that we learn about some key piece of data that we didn’t know that we needed, and this educates what we do in the field next time.  This process of trial and error is ongoing, and makes for an exciting research environment, where we continually test and reform the theory about ice sheet movement, made more exciting by the importance of ice sheets to climate change.  And it’s very satisfying when you find that your snippet of computer code accurately simulates some component of the natural world.

- Doug, University of Alaska Fairbanks, USA

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Post from a Scientist: Melting Ice, Raising Sea Levels

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When you pour pancake batter on a griddle, it will spread out. And if you pour too much on the griddle, it will spread right over the edge. That’s exactly what’s happening today in Antarctica, but it’s the ice instead of pancake batter, and the ice flows really, really slowly. When the ice spreads off the “griddle” of the Antarctic continent, it hits the ocean where it floats for a while before breaking off or melting.

I’m a graduate student at the University of Colorado Boulder, and my advisor and I study the floating bits that haven’t broken off or melted yet. We call these floating bits ice shelves. These ice shelves often hit islands or bumps in the bedrock below, which help hold them back the vast amount of ice flowing off the continent behind them. In the last couple decades, a few of these ice shelves have completely fallen apart. We’re studying what made them fall apart, and what could make others fall apart in the future. There are two ways to destabilize an ice shelf: melt it from above or melt it from below. Melting from above happens when the atmosphere warms, leaving big ponds on the surface that can force open cracks. Melting from below happens when the ocean warms, eating away at the underside of the ice.

The ice shelves that have fallen apart so far have been melted from above. They have been relatively small, without much ice behind them. However, some ice shelves that are currently being melted from below are much bigger. If they collapse in the future, it will have global consequences, and our most recent research is showing that some of these shelves are very slowly starting to break. Think about a glass of lemonade in the summer. Every time you add an ice cube to your lemonade, the level of the lemonade rises. If you add too much, it will overflow. Even after that ice melts, the level of the lemonade does not go down, because you’ve just added more water to the glass. If the big ice shelves fall apart, the ice behind them won’t be held back anymore, allowing Antarctica to dump huge ice cubes into our oceans. This will cause the water level to rise and eventually the oceans will overflow onto the land, flooding coastal towns and cities.

Ice shelves are a small but very important piece of our ice systems on Earth. They have major control over our future sea levels, which will affect millions of people around the world.  I encourage you to learn about other parts of our ice systems and how they affect sea level. You can use all the information on this website, or lots of other scientific sources (For example, check out the National Snow and Ice Data Center at www.nsidc.org). We’re working on learning as much as we can, but there is still a lot we don’t know. It’s going to take a lot more work from a lot more scientists before we can predict where you should buy beachfront property in the next few decades!

- Karen, University of Colorado Boulder, USA

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Post from a Scientist: Don’t Tell Me You’ve Never Heard of Surging Glaciers!

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I live and work on the northernmost inhabited settlement on Earth, on the Norwegian archipelago of Svalbard. There, the land is 60% covered by glaciers, and our neighbors are polar bears. What better place to be to study glaciers? In my job, I’m like a doctor for glaciers. I measure their temperature, try to find out how big and how healthy they are, and how fast they’re moving. Just like there are different species of trees, there are different “species” of glaciers. The ones I study are incredibly funky, and are called surging glaciers. Surging glaciers have bipolar behavior. Some years they are completely sleepy, not doing much, while other years they go crazy and move so fast that you can see them flowing!

I’m very excited about being in McCarthy, first because I haven’t seen trees in months! It is way too cold in Svalbard! Joke aside, I applied to the course for its unique concept of trapping lecturers and students in the same place for 10 days. It is a great opportunity to meet all these current and future rock stars of glaciology, while enjoying the stunning scenery of the Alaskan wilderness.

Despite all of the technological progress we’ve made, it might be hard to get that there is still a lot we do not understand about glaciers, and in particular surging glaciers. They are very difficult to study – I mean putting sensors on a mass of ice weighing millions of tons and moving at speeds of up to 40 meters per day isn’t easy! If we manage to understand why they behave so strangely, we would improve greatly our understanding of all the other species of glaciers, whether they are in Alaska or Antarctica.

- Heidi, The University Centre in Svalbard, Norway

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Glaciers: Size, Beauty, Power + Environmental Importance

Mountains. Valleys. Canyons. I’m not talking about rocks. I’m talking about ice. Seeing these features in photos can hardly do a glacier justice. The sheer size, beauty, power, and environmental importance of these structures are almost incomprehensible. But scientists are trying to comprehend all of the dynamics happenng in glaciers, and that is why we are here at this Glaciology Summer School. Students and instructors trekked to the Kennicott Glacier (which, as of several decades ago, reached all the way to McCarthy itself), to see it firsthand. For a few in our group, it was their first time on a glacier, and for the others, being on a glacier again was just as exciting as it was the first time. With every step, the vista is more breathtaking that the last. And there is science in every crack, color, flow, ridge, movement, and every other feature in and around a glacier, and we’ll tell you about it on the blog throughout the Summer School. For now, just appreciate the size, beauty, and power…

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The ice comes into view…

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Reaching the edge…

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Glacier first-timers!

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Details in every surface…

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Deep, deep ice…

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Ice cave!

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The view from a ridge above. For scale, the ice cave in the photo above is the dark spot at the bottom edge of the glacier (quite the hike on steep slopes of loose rocks).

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