Studying Ice Flows for Clues to Climate Change

AMNH: Why should kids know about Antarctica?

Christina: It is truly a unique place, truly international cooperative.

AMNH: How can students everywhere be good stewards of our least known continent?

Christina: "There are many changes going on in our world right now. The ozone hole is closely watched in Antarctica, but it's big news all over the world. Soon tourism may be a factor in Antarctic exploration–kids will need to decide about issues big and small when they become voters. By being aware, by talking over the issues with friends, teachers, parents, and politicians, kids can make a difference."

AMNH: What's so important about your field of study in Antarctica?

Christina: I study the physics of ice flow, the why and how and where of the way ice sheets move. If we understand the way ice moves, we can figure out how climate changes affected ice in the past, and how the ice is a signal of climate change. Ice sheets are important because they are at sea level, where climate change shows up. Melting ice sheets can be an early warning sign of global warming. We need to know what's happening to the ice because it is a major component of the Earth's climate system; it affects the climate and is effected by it. Global warming is a big concern, and sea levels all over the world are affected if the ice melts–or doesn't. Ice is important everyday in other ways; for example, ice is a major component in the deep ocean circulation patterns, which keep the Earth cool. Ice shelves are also good recorders of past climate change–in fact, they are one of our best sources for observing long periods of climate change. In Antarctica itself, ice shelves are important because they support a tremendous amount of life.

AMNH: How do you study the "physics of ice flow"?

Christina: Observations in the field are the first step in understanding how ice behaves. I use my observations in the field to create computer models of ice sheets; this can help us understand how ice interacts with the global climate system. We can use our computer models to predict how the changes in the ice sheets might affect the global climate in the future.

AMNH: How do you make the computer models?

Christina: I use observations collected by other scientists, including satellite images, geological maps, measures of surface elevation and velocity of ice. That's how fast it's moving. I also use visual observations like looking at how the ice behaves and at the formations in the ice, as well as measuring the temperature of the ice at different points. I use these data to create my computer model. The rest involves figuring out an equation with an answerable question–for example, do velocity and mass and temperature over time relate to each other? How so? After I figure out the equation, I can apply it to a map and just plug in the numbers. The computer will calculate where the ice is growing and retreating. The neat thing about computer models it that once you have the data to put into them, they let you travel anywhere in time you want to go. I can create a contour map or a two-dimensional model and keep adding data. Then I can pose new questions or add features to see if ice flows faster in steep places or when it is hotter, and so on. Once we know that the model is working, things get exciting. We can start asking really specific questions. Why is the ice flowing this way? What makes it flow that way? How do the rate of snowfall and surface temperature affect the ice flow? How important is the shape of the bed underneath? Do other properties of the bed affect ice stream flow? How fast is ice melting at the bottom of the flow? Is meltwater a factor? The next step in process involves writing a paper about my finding and presenting it at a meeting where others are sharing their ideas. Often this sparks a whole new idea for a new study.

AMNH: How accurate is the model?

Christina: That depends on how careful we are! It is important to remember that just because you have a model, that doesn't mean that you understand the system. You have to test it. We do this by using it to check a problem whose outcome we already know. And even with a well-tested model, we must remember that the further into the future we predict, the less accurate we can be.

AMNH: What do you like about working and living in Antarctica?

Christina: The first time I went down there the plane was circling over the ice shelf before we landed and I started to get excited. It took forever to get out of the dark belly of the plane. Then suddenly we were out in the bright white; it was so disorienting. I felt like I was being born into Antarctica. I could see the vast expanse of the Transantarctic Mountains reaching up like claws. I've been to a lot of amazing places, but nothing compares to this. The beauty is strange and subtle. Antarctica has so many stories to tell because it is so remote and very stark. When you first stand on the ground there, you have a sense of what a small part of the system you are–not unimportant, just small. In terms of the work, I love my work because I can pose any question I want and the computer gives me a way to answer it. I love it even when it gets mundane to enter data and double check it again and again. There is a lot of double checking which is tedious but important. I also love the very real sense of community there among the people doing field work. It is very international and cooperative and people are willing to talk about what they do.

AMNH: How did you end up studying Ice Flow in Antarctica?

Christina: From the time I was a baby I was with my parents when they were doing field work. They really turned me on to science. My father teaches Astronomy and Geology and my mother is involved in natural history, Botany, plants, and animals. I spent time with them outdoors visiting mountains, deserts and beaches, learning to observe, to look at the world around us and ask, "Why is it like that?" That is what science is all about. I got excited about glaciers in my first college geology class. We studied glaciers and spent some time in an alpine environment. I found the Journal of Glaciology in some dark corner of the school library and read it regularly. And I focused on basics like learning to write well so that you can present your ideas to the world. In college I had this Geological Engineering professor named Dr. Dresser. He was very strict and everyone was afraid of him, but he pushed me to do more than I thought I could. He never gave up on me and was willing to stick it out with me until I could succeed. He had spent many years in the field and was wise, pragmatic, and formal. He helped feed my particular interest and helped me select the right graduate school.