by Angela Spivey

A couple weeks into the new year, 2003, in the middle of Antarctica's Ross Sea. Since he arrived aboard the research vessel Nathaniel B. Palmer on January 4, Lou Bartek hasn't slept much. He gets about three hours at a stretch before someone wakes him with a problem to solve or a decision to make. Change course? Stop coring? Do we deploy the sidescan sonar towfish or the seismic array or both?

Left: The research vessel Nathaniel B. Palmer tows buoys and air guns in Antarctica's Ross Sea. In the background is Mt. Terror on Ross Island. Photo by John Diebold; click to enlarge.

No research cruise is easy. Managing the work takes almost constant attention. But this cruise has brought some surprises. Bartek, associate professor of geological sciences, hadn't expected to be spending so much time this far south. But the place where he intended to cruise was socked in with sea ice — the relatively thin, seasonal ice that covers much of Antarctica's waters in winter.

The team ended up spending most of their time in a different area, one that had once been pure, impenetrable ice — an ice shelf, which is thousands of feet thick, attached to land along one side, and floating in the ocean on the other. In 2002, the Ross Ice Shelf lost a berg 170 miles long and a thousand feet thick. Or, as geologists say, the berg calved.

So, in January 2003, Bartek and his students were taking samples from a part of this sea bottom that had not been mapped before. "Our survey is one of the densest — wide and deep — of Antarctica to date," Bartek says.

Why do these scientists care about the sea floor in Antarctica? This cruise is part of Bartek's search for "groundtruth" — data to determine whether geologists' current models of climate change really reflect what has happened over long periods of time. "It's flawed thinking to try to use what we see just from the most recent events," Bartek says. In Antarctica, Bartek says, geologists can learn from events that happened as far back as 40 million years ago.

For instance, many scientists have contended that the West Antarctic ice sheet is gradually decreasing because of global warming. Though enormous, this block of ice reacts to climate — circulation of ocean waters, snow accumulation. Scientists calculate that if this sheet were to collapse, sea level would rise five meters in 500 to 1,000 years — an event that could threaten coastal cities.

But the decrease of that ice sheet is debatable, Bartek says, and the only way to make accurate predictions is to find out what happened during several periods of "deglaciation" — when ice sheets broke off and retreated into the ocean. To go back millions of years, scientists sample Antarctica's sea floor. To a geologist, those layers can tell a story.

When Bartek explains all this, it's much more complicated. He's so immersed in his work that when he starts talking about multibeam seafloor maps, grounding lines, and icehouse worlds versus greenhouse worlds, he can lose you pretty quick unless you happen to be a geologist. But his excitement comes through.

Right: Associate professor of geological sciences Lou Bartek (second from right) talks with technicians on the back deck of the Nathaniel B. Palmer. Photo by John Diebold; click to enlarge.

In this search for groundtruth, Bartek spends the days just before Christmas 2002 packing up forty-three crates of equipment to ship across the world. A member of his church lends a hand with the loading. Finally, on December 30, Bartek and four students fly to New Zealand, where they get hard hats and waterproof work suits then wait for a cargo jet to Antarctica. After a six a.m. false alarm, they board the next day and spend five and a half hours packed into cargo webbing seats, knees wedged between knees. After an orientation and dinner, the team takes helicopters fifty-five miles to the ice edge, where they board the ship. The weather is what doctoral candidate Jeff Warren calls "decent" — in the twenties and thirties. They begin unpacking some of those forty-three cases of gear. To make pictures of the sea floor thousands of meters below, the scientists use sonar equipment — "guns" and "fish" that send out sound vibrations. When the sound energy hits a layer or other formation, part of the energy is reflected back as data. One piece of equipment — a Datasonic TTV-190 deep-tow chirp sonar sub-bottom and side-scan sonar tow vehicle — sends out sounds at a very high frequency, which results in high-resolution, detailed pictures. Warren says, "Any change in density such as fluid content or grain size causes an impedance contrast between the layers, and then sound will actually bounce off that and back to our receivers."

Left: A sonar towfish, which creates high-resolution images of the sea floor. Photo by Brandon Wood; click to enlarge.

But the towfish shows only the top twenty meters of the floor. "That's because the high-frequency sound energy is absorbed quickly by the earth," Warren says. The team complements those data with a lower-frequency seismic source gun, which makes images with less resolution at a greater depth — about a hundred meters. The team uses the data to choose areas of interest from which to drill cores — samples of the sea floor. The students bag the cores, label them, and store them in a refrigerator until they can take them back to Carolina for analysis.

On ship, Bartek stands watch twelve hours at a time. The students are on for eight-hour stretches. When they're off watch, they are likely to still be working — writing their theses and dissertations or processing data.

It's easy to get wet while hauling in equipment from the water, so the team must wear their rubber work suits and gloves whenever they're on deck. The clothes would also provide flotation if someone were to go overboard.

On watch, the researchers constantly monitor equipment and data. They check the team's computers. They make sure the ship is not straying off course, which can happen if someone communicates a wrong coordinate. Every fifteen minutes, the watch leader writes in a logbook — the current latitude and longitude, the date and time, the speed of the ship, the weather conditions, what equipment is deployed.

Even with the meticulous monitoring, crises happen. Computers crash. Equipment breaks. Weather threatens. Those events can extend Bartek's watch shift to sixteen or twenty hours. In April 2003, for instance, during the last two days of a cruise in the South China Sea, winds picked up, creating waves ten to fifteen feet high. Bartek was on deck supervising crew who were hoisting the 1,000-pound, lead-weighted coring device back onto the ship.

Seas were rough, and the coring device was slamming back and forth between the steel bulkheads. Three crewmen couldn't steady the device, and Bartek was afraid that one of them would be pinned between the device and the bulkhead. He immediately suspended coring and decided to continue to hold off until weather improved. But conditions didn't change much. So the team went home with about eight cores instead of the planned twenty-five to thirty.

To Bartek's team, such problems are all a part of venturing into the middle of the sea. But Warren says that, ten-foot waves and all, the experience of gathering their own data is like no other. "We're one of the only academic programs in which you can actually go out to sea for a month, acquire the data, process it, and then interpret it," Warren says. "A lot of students just have a data set that comes from an oil company, something that's already been shot and processed. But you don't really appreciate it until you actually go out and acquire it."

Right: The research vessel Nathaniel B. Palmer towing air guns in Antarctica's Ross Sea. Photo by John Diebold; click to enlarge.

Bartek and his students are swamped now, deciphering the data from the South China Sea and Antarctica trips, and their findings raise plenty of questions that they hope to answer. For instance, on the Antarctica cruise, the team found an unusual amount of plant matter — diatoms — in the area that had previously been covered with the Ross Ice Shelf. That didn't make sense. "Diatoms, of course, need the light," Bartek says. "So you wouldn't expect them to grow and be abundant underneath the ice shelf." He speculates that the diatoms may have grown in open water and were transported under the shelf after dying. "Regardless, this material being present there is not consistent with what people had hypothesized about what's supposed to be going on at the grounding line, and where that debris is supposed to go with the current models for ice-shelf and subglacial sedimentation with these big ice sheets," Bartek says.

Figuring out where the models are wrong will keep Bartek and his students busy for a couple years, he says. But that doesn't mean they won't be going back out on the ice. They're already planning another trip to Antarctica for 2004.

Left: On a helicopter ride to the ice edge: (left to right) Carolina master's student Brandon Wood, UC Santa Barbara undergraduate Michelle Thibauld, Carolina master's student Heather Ramsey, Carolina undergraduate Kate Sowder, and UC Santa Barbara undergraduate Karen Vasko. Photo by Brandon Wood; click to enlarge.

This work is funded by grants from the National Science Foundation Office of Polar Programs and the Office of Naval Research. Team members on the Antarctica trip were graduate students Jeff Warren, Heather Ramsey, Brandon Wood, and undergraduate Kate Sowder. Students on the South China Sea trip were undergraduate Dan Pignatiello and graduate students Heather Ramsey, Jeff Warren, and Brandon Wood.

Angela Spivey is associate editor of Endeavors magazine.