Looking back on his threemonth trek across the frozen continent, Dartmouth senior Jim Laatsch recalls ethereal storms of “diamond dust,” sparkles of frozen moisture swirling in the Antarctic air.

“It’s amazing, in a minimalist way, to stand in such a vast emptiness. It’s almost like sensory deprivation; no horizons, no features; everything’s just white.”

Last November, Laatsch and a team of 14 scientists ventured across the snow-covered landscape from the McMurdo Research Station to the South Pole in what he described as a caravan of cramped, insulated boxes strapped onto sleds and pulled by Caterpillar tractors. This was the fourth traverse of the International Trans-Antarctic Scientific Expedition (ITASE), a collaborative effort by scientists from 17 countries to study West Antarctica’s remote environment.

ITASE has traversed the continent each year since 1999, collecting ice core samples and radar images across 4,000 kilometers of terrain in an effort to read the Antarctic ice sheet as an atmospheric history book, using clues inscribed in its frozen layers to discover how the planet’s environmental systems have changed over the past two hundred years.

“Think of a layer cake,” Laatsch said. “That’s what the ice looks like. The snow that was deposited in each season has different physical and chemical properties depending on what was going on in the atmosphere at the time.”

Scientists from the US Army Corps of Engineers Cold Regions Research and Engineering Lab (CRREL), along with student assistants from Dartmouth College and the Thayer School of Engineering, are currently analyzing different aspects of the ice cores that this year’s ITASE team brought back. Scientists believe that by looking at variations in the layers of snow deposited since the industrial revolution, they can better understand how humans have influenced the global climate.

“Antarctica is a trap for chemical deposition from the atmosphere, and it is removed from localized effects,” Laatsch said. “There’s not a factory down the street.”

Laatsch ventured to Antarctica as a research assistant for CRREL researcher Dr. Steve Arcone who has traveled with all four ITASE traverses, running a high-resolution radar system that serves both research and navigational purposes. Using his radar to see the layers in the top 100 meters of snow and firn, Arcone can choose the best sites to drill ice cores as well as detect crevasses, deep gorges in the ice that could debilitate the caravan. In addition to navigation, Arcone and Laatsch used the radar to investigate the history of Antarctica’s remote landscape.

“Each one of these layers represents a different event and shows up as a reflection on the radar screen,” Arcone said.

By investigating the origin of the reflections, Arcone hopes to learn what each layer of snow, ice and firn reveals about climatic history, as well as the date that each layer was deposited.

“We know that a famous volcano, called Tambora, erupted in 1815, leaving behind certain chemicals. You count all the major wiggles in the ice core chemistry concentrations upward from the appearance of those volcanic chemicals in the record and you’ll come up with 187 layers. Now we know that each layer represents a year, and so we can date our radar reflections and calculate historical accumulation rates to figure out how much snow fell in each one of those years.”

Arcone’s radar data allows scientists to put together a more complete picture of the ice cores than has previously been possible.

“In the past, scientists have used just one core or one snow pit to determine snow accumulation rates. However, we have long known that if you measure rates in a core taken from a valley on the ice surface you get a different rate than if you take the core from the top of a hill. The radar profiles allow me to get an average, so I will trace the layers over a hundred kilometers,” he said. The only undergraduate researcher to make the traverse, Laatsch was the youngest member of the ITASE team. “I was the kid of the trip,” Laatsch said, “I took a lot of ribbing for that.”

Laatsch’s age, however, did not limit his responsibilities. When harsh Antarctic snow and equipment problems delayed the traverse for two weeks, Arcone returned to his work at CRREL, leaving Laatsch in charge of the radar.

“When Steve left, I had to step up and run the radar show. When I finally got on the plane back from the South Pole, and I realized that I did it, I had just a huge sense of personal accomplishment.”

Laatsch, who will earn his degree in Earth Sciences this June, became involved with CRREL and their work with ITASE through a tour organized by Dartmouth’s Institute for Arctic Studies.

“We just hung out and listened to people give presentations,” Laatsch said. “One of the guys thought that the deposition of the ice and firn might mimic sedimentary processes. He was looking for a student with experience in sedimentary geology to help him. The next thing I knew, I had a job that was taking me to Antarctica.”

Between Laatsch and Arcone on the traverse team, and the researchers working to analyze the samples back in the labs, the ITASE project includes about a dozen local scientists.

Dr. Deb Meese, along with CRREL scientist Dr. Tony Gow and Dartmouth junior Robert Bialas, is conducting a four-year “stratigraphy” study to examine the layers in the ice cores collected by the ITASE team. Meese looks at the annual layer structure of the cores to determine the rate at which snow and firn are compacted. Collecting that information along the traverse, scientists can see how climate and elevation might affect the accumulation.

Meese’s study also examines the growth of snow and ice crystals, a process that also depends on temperature. She hopes that new measurements of the ITASE cores will help to bridge a data gap in determining the planet’s mean annual temperature.

Dr. Mary Albert, another CRREL scientist and adjunct professor at the Thayer School of Engineering, is working to analyze the top several meters of the snow and firn, the region where most post-depositional changes occur before it becomes compacted into the ice sampled in the ice cores. Along with Thayer School student, Ursula Leeman, Albert is looking at how processes that happen near the surface may have affected the way in which heat, vapor and chemicals in the air were incorporated into each layer of the ice record.

Albert and Leeman have found that large site-to-site differences exist at the ITASE sites, and that differences in the physical nature of the snow and firn have impacted the isotopic evolution of the firn. By understanding the processes of change, Albert hopes to model the postdepositional changes due to surface processes, in order to help clarify the climate signatures for reactive species.

The ITASE project should generate its preliminary results later this year. For now, the planning for future traverses is on hold until 2005 due to the large number of projects underway on the continent, Arcone said. He is hopeful about the project.

“This long-term climate is the big question right now, and Antarctica is a repository of information.”

Katie Martin ‘03 is a geography major and a second-time contributor to the Magazine.