RESEARCH

If you Google the phrase “Great waters,” says Susan Lozier, professor the dominant pathway for Labrador Conveyor,” one of the first of physical and chair Sea water,” Lozier says. “This shows images that will likely pop up on your of the Division of Earth and Ocean that the concept of the deep flow computer screen is a map of the North Sciences at the Nicholas School. operating like a conveyor belt doesn’t study Atlantic Ocean with “If this hypothesis were true,” she hold anymore. The pathways are more Uncharted Interior Ocean Pathways color-coded arrows explains, “it would significantly diffuse. They spread out much farther showing a loop- affect how scientists measure into the -filled deep ocean, so it’s Using an Armada of Specially ing, conveyor climate signals in the deep going to be more difficult for scientists Designed Floats, Scientists Get a belt-like path ocean. But the hitch was, to measure climate change signals.” that deep we lacked the direct Lozier and Bower first conceived of New Look at the ‘Great Ocean ocean cur- evidence to prove it.” their ambitious project eight years ago, Conveyor’ with Major Implications for rents follow Now, a major study in response to earlier studies, including as they flow led by Lozier and long- a widely cited paper Lozier published Global Climate Change Research north from time research collaborator in Science in 1997 that strongly the equator Amy Bower, a senior suggested unknown interior pathways and south from scientist in the Department played an important role in deep by Tim Lucas the polar seas. of circulation of the North Atlantic. A It’s a model at Woods Hole Oceanographic study of floats in the Labrador Sea in that’s been used for Institution (WHOI), has provided the late 1990s by scientists at the more than 20 years to explain that critical evidence. Scripps Institute of Oceanography how the distribute heat and The study, published in the May 14 and Woods Hole seemingly confirmed influence our climate, and—more issue of the journal Nature, used Lozier’s hypothesis, but results recently—to shape scientists’ hypotheses data from computer models from this study were not about the amount and fate of carbon and an armada of sophisti- convincing, in part because dioxide that oceans sequester from cated Range and Fixing the submersible floats our atmosphere. of Sound (RAFOS) used to collect the data In the conveyor belt paradigm, floats, deployed during had to return repeatedly currents warmed by the research cruises in the to the surface to report move northward and release their heat North Atlantic over the their positions and into the atmosphere, leaving the waters course of three years, to observations to satellite themselves colder and denser. At their show that most of the receivers. This meant the northern terminus, the dense, cold southward flow of cold floats’ data could have been waters sink beneath the polar seas and water from the Labrador Sea biased by upper ocean currents flow back southward along a discrete, moved not along the Deep Western during the floats periodic ascents. well-defined path called the Deep , but instead “The challenge for Amy and me,” Western Boundary Current that hugs followed previously uncharted Lozier recalls, “was finding a way to the between Canada “interior pathways” in the collect direct evidence, free of possible and the equator. To replace this deep ocean. Groups of bias, that would test our hypothesis sinking water, warm surface six RAFOS floats were and either prove or disprove it.” waters from the tropics are released into the With funding from the National pulled northward again, Labrador Sea every Science Foundation and technical creating a continuous loop three months from support from the staff at Woods Hole, of climate-moderating 2003 through 2005 Lozier and Bower devised an elaborate currents. and were left in the plan they hoped would surmount that It’s a nice, neat, tidy water to collect data challenge. system. for two years. Bower and her colleagues built Oceanographers, however, Only 8 percent of 76 specially designed RAFOS floats have long known that this para- the floats followed the configured to submerge to a depth of digm for describing deep ocean circula- conveyor belt of the Deep Western 700 to 1,500 meters below the ocean’s tion is an oversimplification—a useful Boundary Current, Lozier and Bower’s surface—within the layer of water enough depiction of the general principle, study found. About 75 percent of them where a major portion of the cold, but missing key pieces of the puzzle. escaped that pathway and drifted into south-flowing current of Labrador Sea “We’ve hypothesized, based on the open ocean before reaching the water flows. studies using indirect evidence like Grand Banks. A RAFOS float weighs about 22 ocean salinities and temperatures, that “Eight percent is a remarkably low pounds (10 kilograms) and can be there are re-circulations, which cause number in light of expectations that dropped over the side of a small boat alternative pathways for these deep the Deep Western Boundary Current is by one person, although they are most

dukenvironment 18 DEANS P commonly deployed from large Lozier, Gary and Böning traced their released since the Industrial Revolution AGE oceanographic research vessels. The pathways and found that the spread of is stored in the ocean,” says Lozier. float’s electronics are housed in a thin, the e-floats was “very similar” to that “The question is, how much is stored With the Dean for six-and-a-half foot (two meter) glass of the actual RAFOS float trajectories at depth? And for how long? tube that vaguely resembles a giant after two years. “To answer these questions, we glass thermometer or overhead fluores- The combined observations from need to learn more about where these um cent strip light. the real and simulated experi- deep, cold currents flow, how they act Once deployed, the floats ments provided clear evidence as sinks for heat and carbon dioxide, drifted underwater with that southward interior and their ultimate fate in the ocean,” the currents for two years, pathways in the deep ocean she explains. recording location are more important than Toward this end, Bower and Lozier information as well as previously shown for the plan to expand their research in temperature and pressure transport of Labrador Sea coming years to study the southward measurements once a day. water to the subtropics, says flow of cold water originating even After two years, they returned Peter B. Rhines, professor of farther north in the remote waters of to the surface and transmitted their oceanography and atmospheric the Greenland Sea. Can They Stop the Impending Train Wreck? by William L. Chameides treasure trove of stored data to sciences at the University of Washington. Additionally, Lozier hopes to make scientists back in the lab through “Drs. Bower and Lozier have brought use of a new generation of high-tech The fall approaches; a new academic year begins and with of natural habitat to agricultural land at the expense of the the ARGOS satellite-based data the remarkable technology of neutrally underwater submersibles to speed and it a new class of bright and talented students arrived at the genetic treasures of a biodiverse world. retrieval system. buoyant deep, drifting buoys to bear on smooth the data-collection process. Nicholas School. This year’s class is especially noteworthy, not A reasonable response, indeed the only response to the To communicate with the floats a matter of great importance to global In the past five years, she explains, only for its stellar qualifications and size—one of the best and problem of depleting resources, is to adopt a more sustainable and to track their positions while they climate. The global ocean circulation researchers have developed program- largest we have ever seen—but also because this is the first approach: use less, conserve more, be more efficient, recycle. were still submerged, the researchers which ventilates the great depths of the mable, unmanned battery-operated class entering Nicholas since the great economic meltdown Converting our current unsustainable practices to more deployed anchored low-amplitude seas is often portrayed as a ‘conveyor units that can glide through the deep of 2008-09. sustainable ones would be hard enough under normal circum- sound beacons in the general area of belt.’ While this is a useful analogy, ocean, collect real-time data at pre-set Despite the sobering events of the past year, this year’s stances. But these are hardly normal circumstances. Today the experiment. The beacons were set their work establishes conclusively that depths and then surface and transmit group seems as idealistic and energetic as any. They are ready planet Earth is populated by some 6.8 billion people; a little less to “ping” automatically every day, ocean eddies—swirling water masses, the data back to scientists in the lab to roll up their sleeves and make the world a better place, and than half of these live on less than $2.50 per day according enabling the scientists to determine much like the rotating storms of the via satellite, avoiding the long time perhaps more so than in previous years, confident that they will the World Bank. Sometime near the middle of this century, the distance between the floats and atmosphere—stir the deep ocean. delays associated with RAFOS floats help make the world a better place. Perhaps having witnessed demographers tell us, there will be about 9 billion of us—give beacons, based on the time delay In doing so, the eddies spread the or the potential data bias of the and survived the meltdown, they feel empowered. Perhaps or take a billion. Demographers also tell us that much of these between when the ping went off and ‘conveyor’ over a vast region of the profiling floats used in the 1990s. having witnessed the meltdown, these young men and women 9 billion will be urban, with aspirations similar for the high- when it was detected by the RAFOS North Atlantic,” Rhines says. “The idea of being able to program see more clearly than before the unsustainable flaws in the consumption lifestyles of people now living in the developed floats’ onboard . Since the southward flow of cold gliders to go where you want, collect system that caused the crash and what needs to be done to economies of the world. Meeting these aspirations would seem The ambitious program would have Labrador Sea water is a major com- what you need, transmit it back to make a more sustainable system. Whatever the reason, being to require more not less of the Earth’s dwindling resources. been prohibitively expensive, Lozier ponent of the waters that flow toward you in real time, and then follow new awash in the energy and optimism of our new students is a And this is the train wreck the next generation of environ- notes, had it not been for a collaboration the equator as part of the global over- instructions about where to collect tonic that we in the academic world can look forward to each mental managers is going to have to find a way to avert. They with Eugene Colbourne of the turning circulation, this finding will data next—it’s an oceanographer’s year, and this year’s did not disappoint. are going to have to figure out a way to sustain a population Northwest Atlantic Fisheries Center significantly change how oceanographers dream,” she says. I am especially thankful for the energy and optimism of of 9 billion Earthlings while at the same time sustaining planet in St. Johns, Newfoundland. Colbourne observe and monitor the deep ocean. “I sometimes envy those scientists our students at Nicholas, because I fear that we are leaving Earth. Fail to do the latter and you can’t do the former. But fail regularly conducts hydrographic “We will need to make more who can collect a sample in the morning them with an impending crisis, a train wreck in the making to do the former, and I fear that many of the institutions that surveys around the Grand Banks and measurements in the deep ocean interior, and then go into their lab to do the that could make the great economic meltdown of 2008-09 sustain us as a society will fail. agreed to deploy the researchers’ floats not just close to the coast where we research that afternoon,” she laughs. look like small potatoes. How can this be done? I have some ideas, but I have to during his cruises. previously thought the cold water “Observational oceanography is many We already know that as a society we are depleting the confess I don’t really know. And I suspect that most of my Since the RAFOS float paths only was confined,” Bower says. things: fascinating, important and resources of our planet. Some 60 percent of the world’s ecosys- contemporaries at Duke and elsewhere don’t know for sure could be tracked for two years, Lozier The Labrador Sea is an area of rewarding. But no one ever said it tems, that provide us with clean water, timber, fisheries, food, either. What we can do is impart all the wisdom and knowledge worked with Nicholas School PhD special focus for climatologists, she was simple.” and fiber, have been degraded by human activities. Because and skills that we know on this new class of students and hope student Stefan Gary and German explains, because the effects of climate of our dependence on fossil fuels we are adding carbon dioxide and pray that they will be smart enough to avert the train wreck oceanographer Claus Böning of the change are magnified at higher altitudes. Tim Lucas is the Nicholas School’s to the atmosphere at a rate that far outstrips the atmosphere’s already in motion. Am I optimistic? Given the optimism of our Leibniz Institute of Marine Sciences— Surface waters there absorb heat-trap- national media relations and marketing ability to process it. As a result, atmospheric carbon dioxide new class of Nicholas students, it is hard not to be. both listed as co-authors on the Nature ping carbon dioxide from the atmos- specialist. concentrations are rising, causing a disruption in climate that paper—to run computer models that phere, and much of that CO2 is taken is unprecedented in modern times. The critical and very real simulated the launch and dispersal of to depth within the sinking waters Monte Basgall, senior writer at Duke need for more and more food has necessitated the use of huge more than 7,000 “e-floats” from the in this region, where it is no longer News and Communications, and amounts of fertilizers, which in turn foul our rivers and streams same starting point. available to warm Earth’s climate. communications officers at Woods Hole and cause giant ocean dead zones. Pressures to increase food William L. Chameides is dean of the Subjecting the e-floats to the same “We know that a good fraction Oceanographic Institution contributed production also are causing the conversion of enormous swaths Nicholas School and professor of the environment. underwater dynamics as the real ones, of the human-caused carbon dioxide to this article.

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