It can be a little overwhelming to think about something as massive as a glacier changing drastically over the course of a single generation. But that is happening, and we are using all kinds of tools, new and old, to help us understand what is happening and why. Our glaciology project as part of this summer school is to calculate the mass change in glaciers in the Svalbard valley in Norway over time, and we started by looking at aerial photographs taken in 1966, 1977, 1990, and 2005. We want to calculate changes in the glacier’s elevation by comparing observations from these photos, which were taken over time and across glaciers. Using this information from historic photographs, we can see the glacier levels decrease over time compared to stable features in the surrounding mountains. We are using geodetics (which refers to a grid used to locate places on the Earth) along with these observations to understand the mass balance of the glacier – that is, how much it increases or decreases over time – to allow us to track how the elevation of the glacier has changed over time and area. By combining our observations of how much the glacier elevation is decreasing, with data on the area over which the decrease is happening, we can find out the total volume of ice mass that the glacier has lost over time. By also considering meteorological variables, including temperature and precipitation data that were taken during the same time as the melting, we can also relate the glacier retreat to the climate conditions at the time. Glacier retreat is something that will directly or indirectly affect so many around the world through sea level rise and freshwater access, so it is vital that we understand how and why it is happening.
- Caitlyn and Samiah
Surface elevation in meters of Austre Broggerbreen valley glacier in Svalbard in 1966 (left) and 2005 (right). You can see the mass loss at the terminus of the glacier (~100-250 m elevation) in 2005.
The reason that this Glaciology Summer School is happening in McCarthy, Alaska is because it is designed to be a chance for students to learn by experiencing, listening, trying, and doing. During each day, students listen to lectures from esteemed glaciology instructors from all over the world, try exercises assigned by instructors based on those lectures, and of course experience glaciers by going out on treks to see them firsthand. But the “doing” of this course is important as well. Students have been working on group projects with course instructors, to gain experience and knowledge on the processes and techniques involved in glaciology research. So every afternoon, the log cabins, picnic tables, and even the rocks by the nearby riverside, all become project places. Stay tuned to see what they are up to!
Have you ever used a compass to find your way through unfamiliar territory? Did you know that some thirty thousand years ago the compass needle would have pointed in the opposite direction? Yes, indeed, there have been times in the history of the Earth during which the north and south poles of the magnetic field were swapped! There is a complex set of mathematical equations – called partial differential equations, to be precise – that is thought to describe how the magnetic field is actually generated. The mathematical object that scientists believe is “responsible” for the reversal of the poles is called a heteroclinic cycle. Technically speaking, this cycle consists of several steady states (where the magnetic field does not change over time) and the connecting times, when the north and south pole of the magnetic field swap. This kind of stop-and-go dynamics is encountered in many other scientific applications as well, such as modeling the evolution of animal species competing with each other, or communication networks within the human brain.
This variety of applications is why I think it is highly interesting to study this phenomenon from an abstract, mathematical point of view. In particular, I study the stability properties of these heteroclinic cycles. The concept of stability is crucial for distinguishing pure mathematics from what we can actually “see” in real life. For example, think of a ball rolling along a hilly surface. We would never see the ball come to a stop right on the top of a hill – even though math says that is theoretically possible. Even the smallest movement will cause it to move away from the hilltop, and never return. This is a classic example of an “unstable state.” In my research, I am working on finding mathematical conditions for a heteroclinic cycle to be stable rather than unstable, so that we may understand better how the parts influence the systems in which we discover them.
So, next time you’re navigating through the woods with a compass, don’t despair when you get lost – there is a slight chance that it is just the Earth’s magnetic poles swapping positions that keeps you from finding your way…
- Alex, University of Hamburg, Germany
The old Kennecott mining town
Kennecott is an old mining town a few miles down the road from McCarthy. Today the abandoned copper mine and the still remaining town looks like a postcard of red buildings with white trim and machinery inside, built between a glacier and a mountainside. In the early 1900′s, this current National Historic Landmark site was found to have the richest known concentration of copper in the world. It was home to five mines, lots of miners, and a few families with children. As these children grew up in the mining town, their view down the hill was a massive glacier bed. The mines closed in the late 1930′s, and by the 2000′s, when the aging “Kennecott Kids” returned to their childhood home for a reunion, they were shocked to find a very different view than the one they remembered. The thick glacier bed was gone, and for the first time, they saw a whole mountain range on the other side of the remaining glacier.
In the photo below, Glaciology Summer School students are learning about the Kennicott (spelled with an “i”) Glacier in front of them and in the distance. The mounds of earth in the foreground at left are actually not mounds of dirt. They are mounds of ice. Where you see darker colored dirt, that is actually ice covered by just a thin film of dirt. Here you see where two glaciers, the Kennicott and the Root Glaciers, come together. As glacier flows merge as they move down the valley, rock and soil is gathered in a ridge between the glaciers. This is called a medial moraine. Moraines result in part from rocks falling onto the glacier from the mountains above, and they move along with the glacier. And as the glacier moves, it can also slowly grate the rock below, and bring them up to the surface. Rock cover of more than a few centimeters thick on a glacier is insulating, and will actually prevent melting under the rock cover. Therefore, as the ice around the thicker rock cover melts, mounds of ice covered by rock debris are left behind. As the glacier melts, even more rock inside and under the glacier becomes exposed, which continues the cycle, leaving behind more visible rock debris.
So, what you see below may not be white, but it is still part of the glacier. But here’s the big point here: just imagine the size and thickness of a glacier that can hide those mountains from view, and now imagine it decreasing to this point in just a few decades.
The Kennicott (spelled with an “i”) Glacier in the distance. Growing up, the Kennecott Kids never saw the mountain range to the left because the glacier blocked the view.
Here, it’s possible for you or the glacier to slip.
Dealing with slippery surfaces is perhaps one of the very first physical phenomena that we deal with as kids. It is always challenging to keep your balance, not to fall down, or not to break your bones. Similar to any other kids, I always asked my father why he drives slower on rainy days. The answer was the same to all of these questions. Friction!
Surprisingly, my research ended up being in a similar realm. Ice sits on the solid ground, a massive 2-3km thick cold block. But that poor block also suffers from the same imbalance that I had as a kid as my shoes slipped on the ground where I was walking when the ground was wet. That’s right, the block slides faster, just like me. It goes down the slope where it is sitting, and falls into the ocean. That’s why we want to know if the glacier’s “shoes” are wet or not!
A large number of physical sciences come together and help develop tools like satellites, in-the-field measurement techniques, and computer models, so that we can estimate the temperature at the bottom of the ice sheet. This way I can see whether the ice sheet and I are sharing the same slippery experience!
- Soroush, University of Kansas, USA
When I think of the tropics, I usually think of brightly-colored fish and palm trees. More recently, I also think about glaciers, which are not only in the polar regions, but also sometimes in the tropics as well. But as a warning, I wouldn’t plan my family vacation there – glaciers are on very high and remote mountains! Today, when I think of the tropics, I try to imagine what will happen to these glaciers in the future, and to help me, I use computer models to try to understand how these glaciers grow and shrink with climate change.
Glaciers grow and shrink depending on whether the long-term weather is colder versus warmer, or snowy versus less snowy. Imagine a see-saw at a playground. On one side are things that make glaciers grow, such as colder temperatures and snowy weather. On the other side are things that make glaciers shrink, such as warmer temperatures and less snowy weather. I use my computer models to figure out how changes in temperature and snowfall will affect each side of that see-saw, and whether the changes in tropical glaciers will be the same as or different from the changes in glaciers in higher latitudes, such as in the Rocky Mountains, Canada, and Europe.
Thanks to my research, when I think of the tropics, instead of just thinking about tropical fishes, I now think about a tropical ice cap that looks like an upside down frog from space. This is the Quelccaya Ice Cap in the Peruvian Andes, which is the world’s largest tropical ice mass. Since tropical glaciers are so hard to get to, scientists haven’t been able to study them until recently. But a few hundred years ago, the ice cap was larger than it is today, and in my research, I try to figure out how much colder and snowier it was during those times when the ice cap was larger. I have found that the ice cap can become significantly larger only with a slight cooling of temperatures, and that it can become significantly smaller with only a mild warming of temperatures. So next time you think about Miami, I hope you think about beautiful sandy beaches and ocean filled with stunning, colorful fish, but I hope you also think about a frog-shaped tropical ice cap, and wonder how it and other tropical glaciers are changing with global warming.
- Andy, University of Chicago, USA
The Quelccaya Ice Cap in the Peruvian Andes (see the frog shape?)
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
Now trekking an Alaskan glacier!
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
The saying “don’t judge a book by its cover” might be adjusted to “don’t judge a glacier by its surface.” Glaciers are stunning beautiful, dynamic structures the size of mountains, but a lot of what scientists study, and what they really want to better understand, is how glaciers work under the surface. Moulins are just one of the main features that may dominate a glacier’s surface. Moulins are well-like shafts that make up part of the glacier’s internal “plumbing.” As the glacier melts, water flows down the moulins, carrying water through the glacier. The flow of water might meet and merge with another water flow, it might exit via the glacier’s edge, or it might flow into the sea. If the water reaches the base of the glacier, it may also act as a lubricant, allowing the glacier mass to slide more easily against the earth, therefore contributing to glacier mass loss and perhaps sea level rise. So if you are ever standing at the top of one of these beautiful wells of marbled white and blue, first of all, be careful. Then make a wish that we can learn more about what’s going on under your feet, because it will affect us all, from Alaska to Florida.
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.
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
Here trekking an Alaskan glacier, near McCarthy