Antarctica lives large in our imagination. Capt. James Cook, sailing farther south than anyone ever had, was the first to come under its spell, in 1775. Hoping to find a storied “southern continent,” he found only craggy islands a few hundred miles from Antarctica itself. Blocked by ice, he turned around, and later remarked that further exploration was pointless as the area was “useless to mankind.”
It would be another 120 years before Norwegian explorer Carsten Borchgrevink made the first human footprints on Antarctica. On his heels came many others, including Australian geologist Douglas Mawson, who survived a 1912 expedition only by dragging his sled 100 miles through relentless blizzards after the deaths of his companions and all of the team’s dogs. “We had discovered an accursed country,” he said. Yet Mawson went back, again and again.
Throughout its short but remarkable history, Antarctica has been one of science’s most tantalizing venues, in part because its remoteness and the severity of its climate have preserved it from human degradation. But now the research in and around Antarctica has taken on a sense of urgency.
As scientists seek to determine the causes of global warming, they have learned that Antarctica offers unique information about the forces that govern climate change. Stanford oceanographer and climate scientist Rob Dunbar has been conducting research there for two decades, and his findings support the growing body of evidence pointing to a troubling possibility: that parts of Antarctica are melting.
This is significant for several reasons, beginning with the worst-case scenario: if the Earth were to become warm enough to melt the least stable portion of Antarctica’s ice cap (about 10 percent of its total volume), worldwide sea levels would rise about 20 feet, drowning parts of Manhattan, much of southern Florida and low-lying island nations around the world. Even if polar regions warmed only enough to produce a slight change in sea level—say, three feet—the results could be catastrophic, inundating some coastal areas, altering ecosystems and accelerating extinctions. If sea levels rose three feet, 100 square miles of Bay Area land would be underwater.
Much of the debate about global warming has centered on whether it is part of a natural cycle or the result of atmospheric changes caused by burning fossil fuels. “One of the million-dollar questions is: how fast and how much does Earth’s climate change without any human influences?” says Dunbar. “Only by answering that can we be certain we are seeing a man-made effect.”
For years, scientists have been studying global climate by looking at annual snow accumulations in cores drilled out of the Antarctic ice cap. But Dunbar thinks a better indicator lies in the remains of algae and other microscopic plankton on the seafloor.
Dunbar explains that when summer arrives in the chilly expanse of the Antarctic Ocean, sea ice breaks up and plankton begin an orgy of feeding and reproduction, racing to accomplish as much as possible before winter returns. The prevalence and type of plankton as well as the abundance of sea ice, Dunbar has postulated, are good indicators of the average temperature in the southern ocean for any given year. The warmer and sunnier the weather, the less sea ice and the more plankton.
But what really interests Dunbar is what happens at the end of the plankton’s Summer of Love. The frigid air cools the sea surface until it becomes almost gelatinous. Lily pads of floating ice grow, fuse and gradually congeal into an ice sheet that covers an area of ocean the size of North America. There, in the endless night of winter, most plankton die, sinking to a sedimentary grave at the bottom of the ocean. Layer upon layer, year after year, the remains have accumulated over the millennia, creating a kind of database of Antarctic temperatures. By interpreting these ancient deposits and comparing them with recent ones, Dunbar hopes to identify patterns of temperature variation and use them to understand if or how human activities influence climate.
Getting those sediments isn’t easy, however. Antarctica may be warming, but it remains inhospitable. Reaching the seas where Dunbar works requires weeks of travel on a giant icebreaker, navigating waters legendary for their ferocity and working in temperatures so cold that ice must be periodically hammered from the ship’s deck fixtures.
The researchers extract the sediment in tubes called jumbo piston cores, heavy instruments that are lowered to the seabed and dive several yards into the ocean floor. Each tube pulls out as much as 100 feet of material. Hauled up and opened in the ship’s lab, the contents unleash a powerful rotten-egg smell, the product of eons of decaying organisms. But that stinky stuff is priceless. If he and his crew have chosen a good site, says Dunbar, they will be able to glean 10,000 to 20,000 years of climatological history. “There are some places where you can look back at sediments half a million years old and see 1-millimeter layers that span one year each,” he says.
Dunbar and his lab manager, David Mucciarone, recently finished analyzing results from sediment taken between 1999 and 2001 during an expedition on the icebreaker Nathaniel Palmer. They have discovered that over the last 15,000 years, sea temperatures around Antarctica have fluctuated by several degrees, and sea ice has expanded and retreated by thousands of square miles. Much of this variability is linked to small changes in energy output from the sun. “We now have clear evidence that a change in solar output of well under 0.5 percent can have a big effect on the amount and distribution of sea ice,” says Dunbar.
In other words, Antarctica seems to amplify the effects of minor climate change in the rest of the world. Dunbar notes that air temperatures at one of his research sites have increased 3 to 5 degrees Fahrenheit since 1960, and that the floating sea ice is disintegrating at an accelerating pace. One of the most dramatic illustrations of Antarctica’s warming occurred last March when the 1,300-square-mile Larsen Ice Shelf broke off from the mainland and splintered into thousands of icebergs. Geologists estimated it had been there at least 12,000 years.
Scientists in Antarctica follow seasonal cycles. Every year, by February and March, 2,500 researchers and support staff journey south to join the 800 residents who hunker year round at polar research stations scattered across the continent. They race to accomplish as much as possible in the short austral summer, assisted by the 24-hour daylight and the swarms of serious, dedicated graduate students who trail their professors like drones attending the queen bee.
Undergraduates were seldom part of the mix when Dunbar arrived from Rice University in 1997 to develop Stanford’s ocean research program. Almost immediately, he began inviting them to accompany him south, and since then has taken eight of them on five separate junkets. The results have been uniformly good, he says.
“By the time undergraduates come to me as juniors or seniors with an interest in Antarctica, many of them already have some research experience behind them,” he says. “This means that I can raise the bar and expect them to think and contribute at a level equivalent to many of our graduate students.
“I expect each undergraduate student that I take to Antarctica to publish his or her results, at least via an abstract and presentation at an international science meeting, and often via a peer-reviewed paper in the scientific literature. Fieldwork in Antarctica is enormously expensive. We simply can’t afford not to publish our findings, and I expect every member of the team to share the burden and joy of thinking and writing about what we have done.”
Melanie Hopkins, ’02, Erohina Tzvetie, ’02, and Lauren Rogers, ’02, spent 60 days with Dunbar and Muccarione on the Nathaniel Palmer. They say it was an exhilarating—though sometimes monotonous—combination of science, scenery and sea life.
The students worked in 12-hour shifts, collecting and processing water samples. Their job was to record salinity and temperature, and filter the water to trap plankton for later analysis. Often, their laboratory was rising and falling 30 feet several times each minute as the boat plowed through the unsettled sea.
Tzvetie came to appreciate the fearsome nicknames sailors have given the latitudes surrounding Antarctica: the Roaring Forties, the Furious Fifties, the Screaming Sixties. When the 300-foot Palmer ran into a storm a few days after departing from Australia, gales tore white streams from the wave tops and whipped up 30-foot seas. Tzvetie watched from the bridge, where she could see the source of her torment. “Even five decks up, waves would break across the bridge,” she remembers. “But it was exciting.”
By contrast, the sky was gloriously blue when they steamed through the dramatic Iceberg Alley, where giant icebergs stand on each side of a narrow underwater valley. And when the Palmer docked at polar research bases to drop supplies, the students got a close-up look at Antarctica’s pristine beauty. “If you’ve seen glaciers in Alaska, they’re pretty dirty, but you get here and the ice is as clear as an ice cube, the sun shining right through them,” says Mucciarone. “When students first arrive, they are like kids in the snow.”
The research voyages, students say, have clarified their career choices. Rogers made a second trip to Antarctica with Dunbar to place a sediment-measuring instrument and is now a year-round resident at Palmer research station. Hopkins says she had been considering oceanography, but after the trip “realized I was more of a hard-rock geologist.” And Tzvetie says that while the experience was unforgettable, the long sea voyages didn’t suit her. “I wanted to be able to walk away to a tent sometimes,” she says.
For many researchers and students today, working in the Antarctic feels like being in the right place at the right time. There is something beguiling about the prospect that fieldwork there may influence international policies and even the future of the planetary climate. And the place itself still exerts a powerful pull. Just as it was for Cook, drawn to a seemingly enchanted otherworld, and for Amundsen and Scott, racing to the South Pole 100 years ago, Antarctica remains mysterious, primeval and enigmatic.
Last year, Luna Federici, ’03, sailed with Dunbar from Chile to pick up that instrument he and Rogers had set in place. Although Federici had been thinking about studying math or computer science, she had declared earth systems as her major shortly before the trip. One look at Antarctica and she knew she had made the right choice.
“One night we hiked up a glacier behind Palmer station so that the lights of the station were blocked. It was during the new moon, so we stood there in total darkness with the Southern Cross overhead, listening to calving glaciers. At some point when we were up there, I thought, ‘I would like to do this for the rest of my life.’”
Christopher Vaughan is a science writer based in Menlo Park.
