scientist post – Page 2 – Lindsay in the Arctic

Post from a Scientist: Hearing the Ice

Imagine a valley filled with ice, from wall to wall, miles wide. This is a photograph that I took of the Taku Glacier in Alaska when I first saw it, from an airplane:

What’s underneath all that ice? How deep does the ice go? Are there streams underneath? Rocks? Mud? This is what scientists want to know about glaciers–we need to know how much ice they have and what they are traveling over in order to know how fast they will melt and cause sea level rise. But we can’t just dig up a glacier to see what’s underneath–the Taku Glacier (pictured above) is 1000 feet thick! The Taku Glacier once floated on the ocean, where the warmer water melted it rapidly, and the tides pulled off icebergs. The glacier shrank because of this, until it was protected from the ocean tides by a thick layer of mud. But the mud is washing away, so someday the glacier will be in the open ocean again. So we wanted to see how much mud is left.

We cannot see what is underneath the ice, but we can hear it. If you had a metal thermos and you wanted to know how much liquid was left inside, you could tap on the metal to give you an idea about whether it was mostly full or mostly empty. For a thick glacier, you need to tap hard to listen to the echoes. Last spring, when there was still snow on the ground, we took a helicopter to the Taku Glacier and tapped hard on it–with explosives! (They weren’t big enough to hurt the glacier.) We spent ten days on the ice surface doing our survey. The view from camp looked like this…

…just a white expanse of 1000-foot-thick ice, hiding everything underneath. But by recording the echoes under our feet, we learned that there is still a layer of mud down there, dozens of feet thick. We’ll tap again in 2016 to see how much mud will have been lost in two years.

– Jenna, University of Alaska Fairbanks, USA

mini-SAM_2394 — Now trekking an Alaskan glacier!

Post from a Scientist: Ice Forecasts

The weather reports you watch on TV come from people who take measurements of today’s weather, and then let computers predict how it is going to change in the next few days. I do the same thing for the Juneau ice field, which is a large glacier next to Alaska’s capital of Juneau. I feed the results of the measurements into the computer, and the computer model tells me how fast the Juneau ice field is going to shrink in the next 100 years.

When we know the future of Juneau ice field better, we can better predict how fast its neighbors are going to shrink, and therefore how much they are all going to contribute to global sea level rise. This helps the authorities in coastal planning, which may need to include determining how high dykes need to be in the future to withstand the rising oceans.

– Florian, University of Alaska, Fairbanks, USA

Post from a Scientist: Greenland Ice, South Florida Water

samiah 1 — Hiking near our field site in southwest Greenland. Notice how rough and dark the ice surface is.

I remember when I was walking on the Greenland ice sheet for the first time in summer 2012. It was nearly midnight, yet there was sunlight still reaching the ice surface. I had just finished a long day of field work installing instruments and downloading data. Although it was a brief hike, I was able to take in my surroundings – the area I had been studying for the past year in a small office back in the east coast of the U.S. Here, I was able to witness the vastness of the ice sheet, the well-developed small surface streams that form during the summer months, its rough and ever changing surface, and see how much debris accumulates along the ice edge. This was the first, and certainly not the last time, I was able to step foot on the Greenland ice sheet.

Since 2012, I have been able to revisit the Greenland ice sheet twice. As a third year PhD student at Rutgers University, located in central New Jersey, I have been able to continue the research I set out to do in summer 2012. Currently, I am analyzing ground albedo measurements collected in summer 2013. Albedo refers to the reflectivity of the ice sheet – how much solar energy is reflected from the ice surface. These albedo measurements were collected from the ice sheet edge towards the interior, along a fixed transect more than 1 km long. Along the ice sheet edge, debris, including soot and dust particles, accumulates as it is deposited from the atmosphere above or exposed from the underlying ice surface. Typically, snow and ice surfaces can reflect sometimes more than 60-80% of solar radiation. But, along the lower reaches of the ice sheet, we see that the debris darkens the ice surface, reducing the albedo or reflectivity of the ice sheet. As a result, only 10-40% of incoming solar energy is reflected. The results of our research suggest that, as the ice surface darkens and more debris accumulates over the summer months, more of the ice melts and runs off the surface. This amplifying feedback – where a darkening of the ice surface allows for ice to melt, and thus darkens the surface further, may become increasingly more important as the climate continues to warm. As air temperatures are expected to rise, and forest fire frequencies and deposition of impurities on the ice surface increase, a lower albedo, and higher amounts of melting are expected to contribute even more water to surrounding oceans. This not only affects local populations, but has global implications for low-lying areas, such as the coast of south Florida.

samiah 2 — Growing parsley for fun near the Greenland ice sheet.

As I write this, I am currently sitting outside in perhaps one of the most remote areas of Alaska – in the town of McCarthy. Here, amidst mountainous and glacial environments, I am able to participate in an international glaciology summer school. I am currently for nearly two weeks in an attempt to broaden my knowledge in glaciology and network with future researchers involved in studying glaciers, ice and snow. I hope to grow as a scientist and as a person through these experiences, so that I can help us better understand the implications of Greenland ice sheet albedo in a changing climate, and how that will regulate current and future contributions of melt water to sea level rise.

– Samiah, Rutgers University, USA

mini-SAM_2338 — Here trekking an Alaskan glacier, near McCarthy

Post from a Scientist: The Depth of Snow

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

Post from a Scientist: Freeways of Ice

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

Post from a Scientist: Model Glaciers

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

Post from a Scientist: The Gravity of Ice

Did 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

Post from a Scientist: The House of Snow

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

Post from a Scientist: Seeing Underneath a Glacier

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.

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

Post from a Scientist: Melting Ice, Raising Sea Levels

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