RESEARCH If you Google the phrase “Great waters,” says Susan Lozier, professor the dominant pathway for Labrador Ocean Conveyor,” one of the first of physical oceanography 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 eddy-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 Physical Oceanography 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 oceans 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 Gulf Stream 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 Boundary Current, but instead “The challenge for Amy and me,” Western Boundary Current that hugs followed previously uncharted Lozier recalls, “was finding a way to the continental shelf 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.