An image of the Antarctic
As we prepare to announce the results of the 2023 Croucher Image Awards, we look back at the winning entry of the 2021 Awards, Antarctic Ice Streams, by Dr Felix Ng, which captures the converging pattern of ice stream flow in West Antarctica by using velocity data from satellite-based radar.
Croucher News recently caught up with Ng, who is a researcher and lecturer based at the University of Sheffield in the UK, while he was on a visit back to Hong Kong.
When Ng began his studies in engineering science at Oxford University back in the 1990s, he had little idea that his journey in science would take him all the way to the extremes of the planet, to Antarctica. “I grew up in Hong Kong as a school kid building electronic circuits, and it was my dream to be an engineer. I was picking apart radios and going to Sham Shui Po and buying components there in those days.”
But at Oxford, Ng was encouraged by the course to immerse himself in theory. “I became interested in broader principles and the models behind them that were continually being created and updated. And then this new interest found a focus on glaciers, initially through my experience of their beauty during climbing trips in the Alps. I was fascinated by how they moved and by the formation of crevasses, and I realised that all this was related to fluid mechanics, which I was studying as an undergraduate,” he told us.
“I began to look into the subject; in those days, that meant going to the geography library—in a different part of the university from ours. Reading the journal papers there, I came across a mathematician, Andrew Fowler, who was doing fascinating maths-based work on glaciers. He was also based in Oxford, at the Mathematical Institute. I basically went and knocked on his door, and, to cut a long story short, I later became his PhD student, and mathematical glaciology became my field.”
Ng’s research in this field eventually led to a trip to the Antarctic in January 2003, a trip of a lifetime.
“It’s an astonishing landscape, so flat—all you could see was blue sky and white snow meeting at the horizon. We were working on the surface of the ice in the far interior of West Antarctica. This is about 80 degrees south. It was like being on top of a huge pancake, a few thousand kilometres across, that is imperceptibly moving, very slowly in some places, a little faster in others. We landed at Byrd Station—which was then a small group of huts—then travelled on skidoos for a couple of days to field camp, just the five of us, where we lived in tents. We conducted GPS and radar surveys from there. The temperature was around minus 20 Celsius, but at least it was stable, and there weren’t any major storms. One good thing is that you can store food outside; it’s all one big freezer. The downside is that you have to saw the hard-frozen bread to make toast. It was tough, but incredibly rewarding and very beautiful.”
The image that won the Croucher Image Award covers an area nearer the coast, downstream from where they camped, in West Antarctica. “The reddish brown areas show diverging areas of ice flow, whereas the bluish cyan colours are converging areas. So this is really a map of convergence and divergence. I computed this in the paper I wrote for Nature Geoscience, giving us a new view of the real complexity and the pattern of the flow of the ice streams.”
The image is not only striking, but it also tells us something about the science of ice stream networks in Antarctica. How does all this link to what we hear about glaciers and climate change?
“This is an interesting question and a big one. It’s important because the ice streams are effectively conveyor belts transporting ice to the ocean. Coastal changes in Antarctica can propagate back to influence their flow, and faster transport can feed back on the ‘grounding line’—where ice becomes afloat to join the ice shelves—to accelerate coastal retreat. So this is one mega-environmental implication of changes on the ice sheets. A key question is whether West Antarctica might soon collapse under the background of climate change or at least shrink drastically. And our work focusses on Western Antarctica because this ice is sitting on the ocean bed and is vulnerable to this mechanism of retreat. If the ice sheets collapse, the ocean level will rise. Hong Kong, as an affluent city, should be well able to adapt to such a change. But coastal communities in many other places will find this a challenge. Several hundred million people may be affected worldwide. That’s the concern.”