Doug MacAyeal wants to understand the secret life of ice-what it does when we’re not watching. Why it pushes across a continent, how it breaks up into icebergs when it meets the ocean and where those icebergs go when they drift out to sea. n And he wants you to understand, too. So while he uses sophisticated computer modeling, and his University of Chicago blackboard is often covered with complex math equations, he has no problem pretending to be an iceberg and bouncing around the room to demonstrate a theory on drifting. He’ll compare the cracks in an ice shelf to the scores on a Hershey bar, or liken the way icebergs collect melt water to a child wetting the bed.
“An iceberg,” says MacAyeal, employing one of his typical analogies as he explains his newest theory on iceberg drift, “thinks of itself as being salad oil.” In this view, an iceberg is the oil and seawater the vinegar in a big salad dressing ocean, where the oil is less dense and therefore floats buoyantly along the surface. He may use simple, everyday images to explain his work, but the laboratory where MacAyeal tests these and other hypotheses is anything but ordinary. Since mid-October, he and a handful of postgraduate students have been working out of Antarctica’s McMurdo Station, a 1,000-person U.S. research base on Ross Island, just 800 miles from the South Pole and one of the most isolated places on Earth.
MacAyeal, 51, a glaciologist in the U. of C.’s geophysical sciences department, has spent his entire 29-year career studying the planet’s most massive collections of ice-the Arctic and Antarctic ice sheets. Most recently he’s been concerned with a group of enormous icebergs floating off the Antarctic coast near McMurdo. Over each of the past five years, he has spent two months on the station examining them up close during what passes for the Antarctic summer.
While he readily demonstrates enthusiasm for his work, don’t expect him to brag about the value of what he’s doing. It’s not his style. “A career in science is sort of painful at times,” he says. “Scientists are underappreciated, and for good reason. We study things that aren’t that important. Very rarely do we invent Teflon or the microwave oven.”
But the truth is, MacAyeal’s work has serious implications. He is part of the worldwide effort, being pursued with increasing urgency, to determine the speed and ultimate consequences of global warming. The icebergs he’s studying will provide, if the so-called greenhouse effect indeed takes hold, a window into the future of Antarctica-and what that future might portend for the rest of the world.
“If you want to see what will happen to Antarctica when it warms, why not take a chunk of it and drag it up to Florida and watch what occurs?” MacAyeal said. “That’s what icebergs are. They’re natural experiments in global warming.”
In March 2000, an iceberg the size of Jamaica broke off the side of the Ross Ice Shelf about 350 miles from McMurdo. According to the arcane rules governing iceberg nomenclature, the berg was dubbed B-15. It was the largest recorded iceberg in history.
Observations from generations of sailors and close scrutiny of historical maps indicate that giant bergs calve, or break off, the Ross Ice Shelf roughly every 50 years This was the first time the scientific community had the equipment to study it.
MacAyeal, who calls himself the “minister of propaganda for icebergs,” leapt into action. He persuaded the National Science Foundation to give him an emergency grant of $150,000 to study the 4,189-square-mile B-15, along with its sibling berg, C-16, which measured roughly 200 square miles. B-15 has since broken into several smaller, yet still gigantic bergs, which have been dubbed B-15A through B-15P. MacAyeal proposed outfitting the entire armada with Global Positioning System (GPS) devices and automated weather stations to see where the bergs went when they left the area and what natural forces were affecting their travels.
Nothing is known of what happened to the Ross Ice Shelf’s previous spawn. Did they hang around the continent for years? Drift north and quietly melt away? Or did they meet their end by suddenly shattering, as did a large iceberg off the opposite coast of Antarctica three years ago? Perhaps they just drift off to “the Shady Acres retirement home for icebergs,” jokes Kelly Brunt, MacAyeal’s PhD student.
The fate of these behemoths is what MacAyeal’s team of researchers has set out to determine during their annual sojourns at McMurdo.
The station, the largest of the three U.S. bases in Antarctica, resembles an unattractive mining town, with drab-colored, metal-sided buildings. But it also happens to be situated in one of the planet’s most austerely beautiful settings. It occupies part of a volcanic island attached to the frozen continent by a permanent ice shelf and the seasonal sea ice of McMurdo Sound. Across the sound rise the dramatic 13,000-foot peaks of the Royal Society Range of the Transantarctic Mountains, while the still-smoldering Mt. Erebus volcano provides a backdrop behind the station. The rest of the scene is black volcanic rock underfoot and ice as far as the eye can see.
The National Science Foundation operates McMurdo as the main staging area for Antarctic science, which includes biology, geology, oceanography and astrophysics, in addition to glaciology.
MacAyeal’s group is trying to create a “user’s manual for icebergs,” he says, a foundation of information for the next generation of scientists seeking to understand major calving events.
Because there seems to be a 50-year pattern to the shearing off of giant bergs, MacAyeal says it’s not clear if B-15 and friends have anything to do with global warming. The Ross Ice Shelf must dump icebergs-occasionally massive ones-into the southern ocean lest the ice shelf extend all the way to New Zealand. This is how Antarctica stays in balance. It gains snow and ice through precipitation and sheds it through iceberg calving. The great question is: Has that system been thrown off balance by global warming?
Antarctica holds about 70 percent of the world’s fresh water frozen in its grasp. A total meltdown of the entire continent would cause seas to rise an estimated 65 meters, or 213 feet. No one is predicting such a catastrophic event, but if even a small portion of Antarctica’s ice sheets is warmed enough so that it dispatches icebergs more frequently into the ocean, global sea levels would still rise substantially. Half a billion people, MacAyeal notes, live within three to four feet of sea level, a precarious situation brought home by the devastating effects of Hurricane Katrina.
An indisputable melt is already under way in the Arctic, where the area covered by sea ice during the summer months has gradually been shrinking. A record low was set in September, and computer simulations show the summer ice vanishing over the coming decades, which would profoundly affect the native Inuit culture and animal life, and have serious consequences for the rest of the world. A recent journal article sponsored by the National Science Foundation took the pessimistic view that a seasonally ice-free Arctic is inevitable and can no longer be slowed by control of greenhouse gas emissions.
Scientists foresee a rollback of the Arctic tundra, drastic climate changes in the U.S., Europe and elsewhere and the danger of a meltoff of Greenland’s ice cap, which holds much of the other 30 percent of Earth’s freshwater.
At the other end of the world, MacAyeal is gathering crucial data from the icebergs to help scientists predict the global effects of climate change. But he would not deny that the study of icebergs can be satisfying in and of itself. Most Antarctic research is long-term science that goes on year after year-studies of penguins or the tiny organisms living in rare patches of dirt, or ancient geological phenomena. MacAyeal’s work, by comparison, is like catching fireflies in bottles to see how they light up, he says.
The global picture, though, is the real reason to study the icebergs. By tracking the northerly drift of the B-15 “baby bergs,” as they’re called, MacAyeal’s group hopes to clarify the relationship between rising temperatures and ice melt. If the scientists can measure how much the icebergs melt when they experience temperatures that are, say, five degrees warmer than back home, then they should be able to help predict what would happen to Antarctica’s ice sheets if the continent itself warms by five degrees. (Melting of the bergs themselves would not raise sea levels because, like ice cubes in a drink, they are already displacing an amount of water equal to their mass. But creation of more icebergs would displace ever more water). Built into this question is whether icebergs, and perhaps ice shelves, melt slowly and steadily or melt slowly at first and then explode catastrophically.
In March 2002, 1,235 square miles of the Larsen B ice shelf on the Antarctic Peninsula-the continent’s northernmost part, which stretches like a tentacle toward the tip of South America-shattered in the course of about a week. No one knows exactly how or why. A similar explosion, though, that of an iceberg that floated north toward South Georgia Island, about 1,000 miles east of the Falkland Islands, may shed some light.
MacAyeal pulls up on his computer a set of 2004 satellite pictures of the mammoth iceberg and a companion berg as they drifted north from the peninsula. Both started to melt as they hit warmer climes. One accumulated the meltwater on its topmost surface, like a bedwetting child lying on a rubber sheet. The other leaned at such an angle that the meltwater poured off. In the next photo, the berg whose meltwater stayed on top had shattered into thousands of pieces while the tilted one remained intact.
MacAyeal and other glaciologists believe that the meltwater acted as a wedge to break the berg apart. The water fell into existing cracks in the iceberg and, because water is denser than ice, started prying the berg apart. Eventually the iceberg reached its breaking point and exploded.
“The meltwater that goes into the crack starts to fill the balloon until the balloon bursts,” MacAyeal says.
If this is the case, it could explain why the Larsen B exploded as it did. And it would have major implications for the effects of global warming, MacAyeal notes. The Antarctic Peninsula is the warmest part of the continent and is something of the canary in the coal mine for the rest of Antarctica’s ice shelves.
“If you took a blow torch and tried to melt Antarctica it would take millions of years,” he says, likening the blowtorch to the normal process of climate change. “But if you get mechanical break-ups, then you’ve got a mechanism to change Antarctica really quickly.” Such sudden change, he says, could cause a significant increase in sea level while at the same time altering ocean dynamics. “Now we have something new to worry about in our angst over global warming,” he says.
MacAyeal hopes that by monitoring the Ross Ice Shelf icebergs as they move north, his team will help prove or disprove the fresh water wedge theory.
But in typical MacAyeal fashion, he doesn’t stop with the basic science of his field. He’s decided that it would be an added bonus to try to harness the fresh water potential of the icebergs to provide water for the billions of people in the world without an adequate supply. If B-15 were sold on the open market for fresh water in the Middle East, he says, it would be worth $320 billion. It could provide every person on Earth with a 10-pound bag of ice cubes every day for 75 years.
Ted Scambos, a scientist with the National Snow and Ice Data Center at the University of Colorado, remembers MacAyeal raising the issue at a scientific conference in Minnesota.
“You should have been there when he told us about the possibility of moving a large iceberg to a desert country [using] these giant, yet-to-be-engineered cables and anchors,” Scambos says. But the tangent didn’t faze anyone, he recalls. “We’re used to Doug. Even when he’s going off the deep end, there’s enough cleverness behind it to make people ask questions.”
While at McMurdo, MacAyeal and his team spend most of their time in the main science building, preparing for their trips to the icebergs via helicopter and small plane. Once they arrive at the floating giants, they assemble their instruments-a GPS device, thermometers, an instrument that measures solar radiation and another that measures snow depth-and attach them to towers anchored in the snow. Solar panels combine with battery power to keep the equipment running. Nearby, the team digs a pit in the snow with a space cut into one of the walls to hold a seismometer.
Sometimes the researchers can get their instruments in place during a day trip from McMurdo. Other times, they must pitch tents and sleep out on the iceberg. Their tools are simple-primarily shovels, ice picks and saws.
The icebergs themselves are vast, flat-topped chunks of ice. Standing on one, it looks like a familiar, Midwestern sheet of snow and ice stretching out to the horizon. It’s only at the edges, where the bergs drop up to 100 feet straight down to the icy water, that you know you’re floating on the ocean. Some of the edges are sheer and some are smashed up where the icebergs have bumped into each other or the shore, creating large piles of snow called “push mounds.”
In his off time, MacAyeal can be spotted eating with students in McMurdo’s large cafeteria, enjoying a glass of wine in one of the encampment’s three bars or attending a yoga class.
McMurdo Station may sit on the planet’s most remote continent-what brochures call “the highest, driest, coldest, windiest, and emptiest place on Earth”-but it doesn’t lack for creature comforts. There’s a gym, a climbing wall, a challengingly uneven bowling alley, a pottery studio and a small library. Activities organized by the recreation department and the residents themselves present seemingly endless choices of what to do in the evenings. A language class or a knitting group? Dodgeball or a science lecture? See a movie or hear a band?
MacAyeal knows he’s a bit of an anomaly in Antarctica’s scientific community. Iceberg calving might be a sexy, newsworthy topic right now, but it is likely to have less staying power than other Antarctic fields of study, such as plate tectonics or the ozone hole, or even long-term analysis of the movement of ice sheets.
“Normally [calving] would not be something that any self-respecting glaciologist would claim to be interested in,” he says. “How can you have a career that focuses on something that happens once every 50 years?”
MacAyeal’s interest in icebergs grew out of his earlier work studying the world’s ice sheets. But before all that came his first love-boats.
As a physics major at Brown University, MacAyeal dreamed of becoming a professional yacht designer. Then, he says, he came to the realization that the real world’s physical phenomena were more interesting than building ships, and he changed course. He remains an avid sailor, however, taking every opportunity to get onto Lake Michigan in his Cal-25 sailboat .
At Brown, he became interested in math, particularly in a field called catastrophe theory. As an approach to understanding complex systems, catastrophe theory can help explain abrupt changes in geophysical processes that usually progress steadily. He wrote a term paper using catastrophe theory to explain the large-scale climate changes of the Ice Age. The timing was good. Scientists at Brown were studying deep-sea sediments around the world to better understand the pace at which Earth’s climate was transformed during the Ice Age. They learned that, at times, it can change quite suddenly.
“I felt like I could contribute to an area of science that was brand new,” he says, “where even a dumb guy like myself could be at the cutting edge.”
MacAyeal’s paper caught the attention of his professor, who recommended that the 21-year-old do graduate work at the University of Maine, where scientists were studying the Ross Ice Shelf. MacAyeal spent six months in 1976-77 near McMurdo Station, studying the flow of the ice shelf.
“That’s the mosquito bite that infected me with the desire to study ice in all its forms, past, present and future, in both polar hemispheres. Both on Earth and on Mars,” MacAyeal says of that first trip.
Robert Bindschadler, a glaciologist with the National Aeronautics and Space Administration, who has worked with MacAyeal off and on for 25 years, remembers the young scientist racing around, trying to pack as much excitement into his season as possible, thinking it was great when the winds were blowing blinding snow around the tents.
“He does not mind rushing into the breach,” Bindschadler says. “He’s not foolhardy, he just welcomes the excitement that Antarctica sometimes can provide.”
MacAyeal continued studying ice streams, sheets and shelves, using mathematical models to explain their behavior. Ice streams are glaciers that flow seemingly freely in the Antarctic, unlike most glaciers on the other six continents that are guided by the mountain valleys they flow through. Ice sheets are the grand “pillow” of ice that sits on Antarctica’s solid land, and ice shelves are the floating extensions of that ice sheet where the continent meets the ocean. In keeping with the Antarctic tradition of naming geographical features after people who have devoted much of their careers to the region (and sometimes given their life to it) there is a MacAyeal Ice Stream, which runs into the Ross Ice Shelf. The Bindschadler Ice Stream is nearby.
“I liked the idea of complex systems that display a subconscious,” MacAyeal says, meaning that the Earth’s ice is predisposed to behave in patterns that can only be determined after drawing it out a bit. He talks about the “subconscious or collective consciousness” of glaciers, ice sheets and climates.
MacAyeal left the University of Maine with a master’s degree and went on to earn his PhD at Princeton University. Coming of age as a scientist at the time of the first supercomputers, MacAyeal recognized the insights that powerful computers could offer his field.
“He was really at the forefront of using sophisticated mathematical models in glaciology,” says Portland State University Professor Christina Hulbe, one of MacAyeal’s former PhD students.
MacAyeal describes his work as trying to find the E=mc2 for ice, the elegant formula that will explain why frozen water acts as it does. He does this by comparing computer simulations with real-life observations. When they match, he knows he’s on to something.
MacAyeal joined the University of Chicago faculty in 1983. He teaches several undergraduate classes for non-science majors, in addition to his work with graduate students and PhD candidates.
Three years ago, he decided to help create a new undergraduate course, one that would explain how natural forces have shaped the civilized world. “I wanted to find a way to point out to people that these seemingly exotic topics, like Ice Age stuff, really do make a difference,” he says. Chicago, for example, was attractive to early settlers because it sat along the drainage channel between an enormous Ice Age glacial lake and the Mississippi, and remains the best link between the Great Lakes and the river.
“Nature is the underpinning of human settlement,” he says. “Even this incredible urban environment of Chicago is built upon what was created by natural forces with the glacial cycle.”
MacAyeal’s typically ambitious plan for the class was to have not just a glaciologist and an archeologist, but a medical doctor talking about disease, a theologian discussing religion, climatologists, evolutionary scientists and anyone else who has a stake in the beginnings of the world, with the goal of “looking at the genesis of humans in every possible way you could.” His concept was whittled down, though, to a more realistic two-instructor class, whose registration has grown from 45 students to 145 in three years.
His travels to Antarctica have continued off and on over the years while he taught. His early field work focused on the movement of ice streams-how they can have sudden accelerations that discharge an unusual number of icebergs into the ocean all at once. The work tied in with the ocean-floor sediment he’d studied at Brown and graduate school-and with the work of other scientists focusing on “ice-rafted” debris in the North Atlantic. The debris is the dirt and rocks that glaciers picked up as they pushed across Canada and the northern U.S., and then dropped into the ocean after floating off as icebergs and melting in the warmer water.
“If you find a boulder in the middle of the Atlantic, it didn’t roll there and a bird didn’t drop it,” he says. The debris is linked to the processes that triggered abrupt climate change, and to enormous fleets of icebergs that were launched off the North American ice sheets 12,000 years ago.
MacAyeal helped write a paper that showed that each of the large ocean floor deposits was linked to a major climate-change event: Sudden bursts of icebergs from the great ice sheet covering Canada introduced so much fresh water into the ocean that it disrupted the ocean’s regular cycling of warm and cold water, which led in turn to colder global temperatures.
As this ice sheet work was winding down, the giant icebergs began to catch his attention.
MacAyeal says it’s typical for him to jump from one project to another.
“I like to do things first, but I often don’t do them that well,” he says. He may have been a pioneer in the computer modeling of ice flow, but he says Hulbe does it better now. And that’s his goal: to be the first to use a new kind of tool to solve a problem and gain more knowledge. Then he hopes one of his students will run with the idea while he turns to another project. That’s what he’s doing now with the iceberg-calving study near McMurdo Station.
During the previous four seasons, MacAyeal and his team have taken about two dozen helicopter and small airplane trips out to the Ross Ice Shelf icebergs to put GPS tracking equipment and automated weather stations on four of them. He says he’s not aware of anyone who has put weather stations on icebergs before, or used tracking equipment as precise as GPS devices.
MacAyeal almost didn’t get a chance to test out his new equipment. After securing the emergency grant and racing out to start studying the icebergs as they drifted north, the fickle bergs played a little trick on him: They didn’t move. C-16 became grounded on the seafloor, and the various B-15s stayed relatively still.
This did more than mess up MacAyeal’s experiment; it caused major logistical headaches for the National Science Foundation, because the bergs were blocking much of the entrance to McMurdo Sound from the Ross Sea. The sound freezes over most of the year, but at the height of the Antarctic summer in late December and early January, when temperatures creep above freezing, the sea ice usually breaks up and floats away. That’s when most of the year’s food, fuel and other supplies come to McMurdo by ship. Icebreakers have been able to open a shipping canal through the sound each year, but it hasn’t been easy, sometimes requiring the help of a second icebreaker. The amount of ice that the breakers have had to cut through has quadrupled since the icebergs arrived-growing from 22 miles to 84 miles.
This year, both MacAyeal and the NSF hope things will be better, since B-15A, the chief culprit, has moved out of the mouth of McMurdo Sound. In fact, it may have moved too much. After confounding MacAyeal with its sedentary behavior, it has traveled so far from the station that his team may not be able to retrieve its instruments.
Drifting at the fast clip of about 6 miles a day, it is now closer to the Italian station of Mario Zucchelli, and MacAyeal wants to figure out a way to use that as the staging ground to fly to B-15A. Plus, as he likes to joke, he could get a good cup of cappuccino there.
He’s particularly interested in retrieving a seismometer that his group put on the iceberg last year. It’s one of the devices that they’re using in a joint study with Northwestern University Geology Professor Emile Okal, who had noticed that seismometers in Tahiti were picking up odd vibrations around the time the giant bergs calved into the sea, and continued to register unusual sound waves. Okal and MacAyeal think these continued vibrations may be the noise the bergs make when they bump up against the shore and each other. MacAyeal’s theory is that one berg acts as a kind of giant cello and the other as a giant bow, and when they rub together they make seismic music.
The seismometer on B-15A should have recorded the 2004 Sumatra earthquake that generated the deadly tsunami. MacAyeal would like to know what it reveals, since it was the only seismometer on an iceberg that was free-floating and not grounded at the time.
Collaboration with an earthquake expert is in keeping with MacAyeal’s goal of using his research to “fertilize” other fields, including oceanography, marine biology and climatology. Back when MacAyeal was studying icebergs and ocean sediment, says NASA’s Bindschadler, most scientists either knew oceans or they knew ice. MacAyeal was able to connect the two fields and explain the issues to people on both sides.
Now his iceberg-specific studies include a Web cam that sits along a large crack-one of those scores on a Hershey bar-on the Ross Ice Shelf. MacAyeal’s team suspects another giant iceberg will soon be born there, and they want to know what the event looks like and what causes it.
“Is it like a loose tooth that you wiggle until it falls?” he asks. “Does the tide wiggle the tooth so much that it falls off?”
MacAyeal and Brunt, his PhD student, have made some headway on figuring out why icebergs drift the way they do. First they determined that the strong Antarctic winds had little to do with it. They thought instead that the icebergs were falling into golf ball-like dimples in the ocean surface created by high-pressure spots in the atmosphere that pushed down on the water.
They’ve now changed their minds some more. After analyzing last season’s data, they think barometric pressure is still the primary mover, but that the icebergs are drawn to areas of low pressure instead of high pressure. While this seems counterintuitive-icebergs moving up toward low pressure instead of falling down into ocean dips-it makes sense from a physics standpoint. Because ice is lighter than water, the ice rises more than water in areas of low atmospheric pressure-or, to use MacAyeal’s analogy, like olive oil in salad dressing.
In his research, MacAyeal found that one of the first people to discuss the possibility that barometric pressure was moving icebergs was James Clark Ross, one of the great Antarctic explorers and the name behind the Ross Ice Shelf, the Ross Sea and Ross Island, where McMurdo sits. Ross sailed to Antarctica in an 1839-43 expedition.
“For him to have come across, in the literature, how Ross discovered [the barometric pressure factor] just sent him over the top,” says Brunt, referring to MacAyeal’s excitement in finding a perfect blend of science, history and sailing.
Being able to think broadly and tie together seemingly disparate disciplines and tools is one of MacAyeal’s strengths, says Bindschadler. Most scientists, he said, “learn their trade and then go out and practice it and they stay pretty much with the same set of blinders on that they grew in grad school. Blinders just don’t fit on Doug.”
Nor does the label of a self-important scientist.”You have to have a sense of humor about science and the silly intensity that it has,” MacAyeal says. “If you take it too seriously, then you get depressed.”
Hulbe describes MacAyeal as having child-like enthusiasm for his work. She says he’s equally excited about the research of everyone around him, regardless of whether their theory contradicts his own-a trait not shared by all scientists.
“Doug’s a very frenetic person,” she says. “He gets very excited by a novel idea or an interesting observation. When he really gets rolling, he goes very fast and you just kind of have to hang on.”
MacAyeal’s enthusiasms are not restricted to science. Hulbe once took a long car trip with him when he was on a Winston Churchill kick and insisted on listening to all of the great man’s speeches on tape. Soon after that he became obsessed with Napoleon, and Hulbe raced to the encyclopedia after he compared her work to one of the general’s battles. Otherwise, she wouldn’t have known if he was complimenting her or not.
“I don’t think he’s lost his youthful excitement and joy in doing science,” says Bindschadler “He’s been successful as a professor and a teacher because he exudes that. That’s true whether he’s in a classroom or whether he’s at a conference or whether he’s talking to colleagues over beer, or in the field and it’s blowing 40 knots. He doesn’t change.”
