Serious science

Ted Scambos talks about disintegrating ice shelves, climate change and returning to Antarctica

Ted Scambos is the lead scientist at Boulder, Colo.-based National Snow and Ice Data Center , which supports research into the frozen places of the world, from Antarctic glaciers to the dwindling sea ice cover over the Arctic. A veteran glaciologist who has made nine trips to Antarctica, Scambos specializes in remote sensing, using satellites to study ice dynamics and processes, particularly how climate change affects the cryosphere.

The Antarctic Sun sat down with Scambos at his office on the east campus of the University of Colorado-Boulder (CU-Boulder)  in July to talk about climate change, ice shelves and his upcoming projects in the Antarctic.

“I’ve always been interested in science,” Scambos said. He ticked off a number of heady disciplines that caught his interest at an early age, when scientific inquiry for most of us might include zapping ants with heat using a magnifying glass. In first grade, he wanted to study astronomy. By high school, interest had turned to chemistry. Planetary science — the astronaut dream of many young boys — also stirred his imagination.

After getting his master’s degree in geology, Scambos said he needed a break from academia. He worked for five years in the lucrative oil industry, at Philips Petroleum. “Did I like it? Was that what I wanted to do? It wasn’t,” he said. “Even though it was like falling off an economic cliff, I went back to grad school.”

He got his PhD in geochemistry from CU-Boulder, eventually landing a job as a remote sensing specialist with another well-known glaciologist and polar veteran, Robert Bindschadler at NASA’s Goddard Space Flight Center .

“Even though I kind of still looked at planetary science jobs, things went so well and they were so exciting and there’s so many big issues to solve in terms of polar science and climate change, it just took over. Looking back, it really played out perfectly for me, because what I really wanted to do all those years thinking about astronomy and planetary science was go to the moon or go to Mars or be in space.

“That’s something a tiny fraction of people involved in the field get to do, but in glaciology and Antarctic science, it’s much easier to go there and be a part of it and have experience of being out there in an extreme part of the world and trying to measure and understand it.

“That’s really the thing I like the best about what I do: It’s outdoors but it’s serious science, so you have the challenge of trying to live and work in the deep field, and the challenge of trying to bring the instrumentation down there and make it work and answer a question and find out something. That’s great. I love the field for that. I sit here at the computer and look at a lot of satellite images, but it’s essential that every once in a while we get out and actually see it with our own eyes and instruments.”

“I’m committed to one of the longest field seasons that I’ve ever had. I’ve been there nine times to Antarctica, [but] I’ve never been to the South Pole or a traverse like this before. It’s a big commitment of time at this point. … I’m actually just going to enjoy it the whole way. I’m just going to have fun. It’s actually kind of liberating to not be the team leader and just be somebody who is helping as much as you can.”

“It’s definitely been instructive to see what’s happened with the Wilkins … What’s happening now looks to be related to basal melt. Warm water from the ocean is actually somehow mixing up in the upper layer that usually caps it called the halocline. There’s fresh, cold water that surrounds the Antarctic. Sea ice floats in that. Snowfall plus sea ice melt keeps that layer fresh and light. Underneath it is saltier water, but it’s much warmer.

“That is typically 200 to 300 meters down below the surface in the Wilkins, so it touches the underside of the Wilkins ice plate but it doesn’t usually get up to the near surface. Now we’re seeing that in the last 10 or 15 [synthetic aperture radar] images it looks as though thin areas in the ice plate, even though it’s winter, are just sort of disappearing, thinning to the point of melting away and disaggregating the ice shelf.

“I’m going to stand by with what happened in the summer has to do with surface melting. The lesson is that there’s more than one way to lose an ice shelf. People have talked about basal thinning. There hasn’t been as end-to-end a model for how basal thinning really does the job on the ice shelf, but I think that’s emerging.

“By thinning the ice shelf and keeping the inflow constant you change the stresses that you’re asking the ice shelf to bear, the thinner plate of ice to bear, and it begins to fracture as a result of that. Those fractures lead to icebergs drifting away.”

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“Summer after summer, you have warming in the Antarctic Peninsula, and melt on the surface of ice shelves year after year, and then all of a sudden one year they go through this runaway disintegration. What triggers that? It’s like having dominoes all stacked up, but then you need something to tap the first domino and they all start falling apart. That’s the scenario I’m working on now.

“We’re going to try and take a look at sea ice extent in front of these ice shelves during these breakup events, during these retreat events. The thought is that ocean waves, especially long-period ocean waves, are getting in and breaking off the first front iceberg of the ice shelf and then that leads to a runaway situation because of this water perched on top of that shelf that wants to get into any crack that forms.”

Scambos explained that waves created from distant, powerful storms can travel thousands of kilometers. “These aren’t surfing waves,” he explained, but waves with barely discernible crests, or amplitude, but extremely long periods, or troughs, between the crests. Imagine a brick floating in a bathtub, he said, and then drop a pebble in the water. The pebble has no influence; the waves merely bounce off the brick. But slam your hand in the water and the subsequent waves causes the brick to move.

“The wave doesn’t bounce as much as it interacts with the brick. That’s what it takes. You need a wave the size of the [ice] shelf to actually flex the shelf.