How did you have the opportunity to go to Antarctica this year?
I'm here because the InBev Baillet-Latour fund was kind enough to help finance a research project, Be:Wise The Butressing Effect: Why Ice Shelves Are Essential we proposed in the Dronning Maud Land looking at the interplay between ice shelves (ice flowing off glaciers from the ice sheet that float out over the ocean) and the grounded ice at the edge of the continent of Antarctica.
What is your research project about?
Our research project is looking at the ice shelves and how they can affect how the ice flows from the interior of the continent towards the coast and eventually out over the ocean.
The boundary conditions – whether the ice is flowing over rock or the ocean – play a key role in how the ice flows. Ice that is grounded on rock - the bedrock of the continent at the coast – flows relatively slowly compared to ice floating over water. There's a lot of friction between ice and bedrock, which slows down the flow of the ice. But there is basically no friction between the ice and the water, so ice flow accelerates once it starts moving out over the ocean.
Ice shelves in Antarctica can be quite large, extending many kilometres out into the ocean. However they can become grounded by what we call pinning points – points where rock sticks up from the sea floor and comes in contact with the bottom of the ice shelf. As they create friction with the ice, they slow down the speed of flow of the ice shelf.
When ice comes in contact with pinning points, it also slows down the flow of ice further back on the continent. This is what isk nown as the buttressing effect. In our research project, we're interested in quantifying this buttressing effect to see how it affects the flow of ice in the ice sheet even before it starts flowing out over the ocean.
Why is it important to study the buttressing effect?
Because it controls the speed at which ice is lost from the ice sheet to the ocean. Ice flowing from the interior of the Antarctic Ice Sheet and into an ice shelf eventually calves off at the end of the ice shelf and enters the ocean. Since this ice was once over land, its loss to the ocean contributes to sea level rise.
What are ice rises and how are they different from pinning points?
Pinning points are simply raised areas of the sea floor that come in contact with the ice shelf from below. Ice rises are tend to be bigger – essentially undersea mountains that cause the ice flowing over them to become raised (hence the term 'ice rise'). But even small pinning points can have a dramatic effect on how fast an ice shelf flows.
How much have ice rises and pinning points been studied in this part of Antarctica before?
Scientists have known of the existence of ice rises and pinning points. What's new are numerical ice sheet models that model the ice flow. They're now getting sophisticated enough to be able to include the interaction between the ice and the ocean. This happens at the grounding line – the boundary between the grounded ice on the continent and the floating ice of the ice shelf.
The grounding line can move. It can extend further out towards the ocean or it can retreat inland, based on boundary conditions such as the temperature of the ocean (a warmer ocean can melt the ice shelf from below and cause the grounding line to retreat), or the surface mass balance of the ice sheet (how much ice it is losing or gaining and at what rate).
However pinning points also influence how the grounding line moves. This is why there has been a lot more interest in them within the glaciology community in recent years.
How long will you be doing field research this season?
The whole campaign from start to finish lasts seven weeks, to and from Brussels. We've planned to spend two to three weeks in the field. We arrived on time, so everything is going according to schedule.
How will you get to the coast to do your research?
The Princess Elisabeth Antarctica station team has been handling all the logistics. The technical support has been excellent. They've helped all of us out a lot!
We're doing the 200km trek to the coast by Pisten Bully tractor, which takes about 20 hours. The tractor is hauling the scientific and living containers that we'll be using during out time in the field, as well as all of our gear.
What kinds of measurements will you be taking?
For my project, we'll be using two main instruments:
The first instrument is a type of radar – an electromagnetic remote sensing technique capable of measuring ice thickness. It can also measure the ice-bedrock interface and the ice-ocean interface. This allows us to visualize the geometry of the pinning points and how well they're grounded.
The second instrument is a GPS, similar to what you use for navigation in your car. Over the next few weeks, we'll put markers on the ice shelf and measure their position with the GPS. These GPS measurements are very high precision. Then we'll return next year to measure the change in the position of the markers to determine the velocity of the ice flow.
What will you do with the data once you've collected it?
After we collect the data, we'll have to process it to see what we can find. Ultimately the goal is to feed this data into models that can simulate the behaviour of the ice as it flows, in particular how the ice deforms at the surface as it flows.
Who's going on the field expedition?
Our team is going to the coast with Frank Pattyn and his research team from the IceCon project. Once we get there, Frank and his group will split up from us to visit an ice rise not far from the coast. We'll continue out towards the King Bauduin Ice Shelf, where we'll do our measurements.
Our team will have two field guides – IPF President Alain Hubert and Raphael 'Raphi' Richard. And there will be two other scientists with me – Denis Callens, also from the ULB, and Kenichi Matsuoka from the Norwegian Polar Institute.
Are you looking forward to the field expedition?
I'm eager to go. We put a lot of time into planning for this field campaign.
We did most of the preparation using satellite images. So I know the geography of the area very well. But it will be exciting to finally see the ice shelf in person!
By Joseph Cheek