Hot on the Trail of CO2

An alumnus with a degree in coastal environmental management and a "penchant for salty, sandy places" returns to the Nicholas School of the Environment and Earth Sciences to learn about the latest research and thinking on global climate change.
August 1, 2007

Pictorial tributes to the natural world and to crowning achievements in science, engineering, and medicine adorn the granite walls in the cavernous lobby of the National Academies Building in Washington. On the back wall, a giant salmon hovers, midstream, just to the right of Einstein's E=mc2. A much smaller fish, its design evocative of an Inuit totem, is inscribed in the middle of the salmon's body, perhaps as a tribute to native cultures or as a nod to the diminutive but central role of the human dimension in the natural world.

On a side wall, next to images of Darwin's famed Galapagos finches, is a model of carbon dioxide (CO2) molecules—the oxygen atoms protruding from each carbon atom like the prongs of a child's jacks. Below it, a graph traces the amount of carbon dioxide in the Earth's atmosphere starting in 1958, when scientists began keeping detailed records. The curve of the graph looks like a saw blade, each tooth describing year-to-year variations in atmospheric carbon dioxide, but the upward trend in the graph is unmistakable and speaks to the reason for my visit.

Earth Imaging

Inside, I notice the names of Duke's Gabriele Hegerl and Susan Lozier printed on placards at the center tables where researchers and policy makers from top institutions around the country will soon consider the need for an early-warning system for abrupt climate change. I take a seat near the snack table where, within minutes, I've overheard the assembled experts discuss climate projections and offer play-by-play insights into Massachusetts v. the United States Environmental Protection Agency, a case before the U.S. Supreme Court to decide whether CO2 should be federally regulated as a pollutant. (In April, the Court found that it should.)

Hegerl, a climate diagnostician working to understand the reasons behind climate change, is a member of the National Research Council's Climate Research Committee (CRC), which has convened the panel. Lozier, a physical oceanographer, has been invited as a featured speaker because, as she eloquently explains during her remarks, when it comes to climate, "the ocean is an equal partner with the atmosphere." When she showed me her invitation to speak during our interview a few weeks earlier, Lozier mused over "abrupt"—a word that means very different things to scientists and non-scientists. Lozier tells me that when talking about climate change, abrupt means decades.

Lozier's office at Duke had been the first stop on my personal quest for more than Al Gore's "inconvenient truth." In the handful of years since I earned my graduate degree in coastal environmental management at Duke, the global climate-change story has become the best show in town—Gore even won an Oscar for his version. Did I think about global warming this much while I was at Duke? Do I think about it enough now? After all, accelerated sea-level rise and intensifying storms, both with profound consequences for our coasts, are among the most dramatic of the changes we'll see as the planet continues to warm in coming decades. How could anyone with my professional bent and my personal penchant for salty, sandy places not think about global climate all the time? With the bliss of ignorance fading into distant memory, what is a card-carrying member of humanity to do? Searching for knowledge that would help me become more than just another contributor to the problem, I headed back to the Nicholas School to catch up on the latest in climate-change science.

In comparison with the other offices I visit that day, Lozier's is a sanctuary—serene and uncluttered. Warm light from a single desk lamp casts a halo on a tidy desk. A large, well-pruned, potted succulent occupies the window alcove inside one of the towers that distinguish the Old Chemistry Building.

Lozier is explaining that the disruption of the ocean conveyor, as ocean circulation is known, could "give the signal of rapid climate change" in the form of cooler temperatures in certain parts of the world, including Western Europe.

Warm water in the form of the Gulf Stream travels north from the equator along the western margin of the Atlantic Ocean. Once past Cape Hatteras, the Gulf Stream drifts to the northeast, and the surface waters transfer heat to Western Europe, becoming cooler in the process. When they reach the North Atlantic, the surface waters—now colder, saltier, and denser—sink and flow back toward the equator in the deep ocean, a 1,000-year journey that drives ocean circulation.

As the Earth's atmosphere warms from a combination of natural cycles and human factors, ice masses around the poles are melting at accelerated rates. The fresh water being released could reduce the salinity of nearby surface waters, changing their density enough so that they wouldn't sink and drive the cycle. Lozier cites data from 2002 that show "rapid freshening" of the North Atlantic since 1965; however, her own work has not yet revealed any recent changes in the ocean conveyor. Lozier uses high-tech floats—four-foot-long glass tubes housing delicate instruments—to study currents at specific depths in the North Atlantic. After the floats spend two years underwater measuring salinity and temperature and internally recording their own location, their ballasts rupture, and they pop to the surface. They beam all of their stored measurements to a satellite. Lozier and her colleagues retrieve the data and use them to map and characterize the particular currents that carried the floats.

If the ocean conveyor were disrupted, the rapid cooling of Western Europe would be only half of the bombshell. A recent report by a scientist at the National Oceanic and Atmospheric Administration revealed that 40 percent of the CO2 released by human activities since 1800—the same CO2 that has been implicated as the key perpetrator in the warming of the Earth's atmosphere—has been carried by the dense, sinking waters of the North Atlantic into a reservoir in the deep sea. The disruption of ocean circulation would mean the loss of our single biggest repository, or sink, for atmospheric CO2.

"Ninety percent of the deep waters in the Atlantic were once surface waters," Lozier explains, so we're able to monitor the penetration of CO2 from human sources into the ocean's depths. "The time scale here is decades," she says. "We are now picking up Helium-3 and Tritium in the deep waters from the nuclear tests in the 1950s and early '60s."

In this way, the deep sea is a record, as well as a reservoir. We know from geologic evidence of deep-ocean warming that the ocean conveyor has slowed or stopped at different points in the Earth's history. We also know that at those times, the surface of the Earth looked very different from the way it does today.

Sea sick?: Disruption of the ocean conveyor, below, could signal rapid climate change, says Lozier, bottom, who monitors how increased carbon affects ocean health; Arctic polar bear seeks stable ground amid melting ice


Aurora/Ty Milford

My decision to search for some perspective on climate predictions takes me only one floor up from Lozier's office in Old Chem; my footsteps clap off the aging concrete stairs, polished by seventy-five years of students in motion. To get to Thomas Crowley, I walk through two small lab rooms, past a finger painting tacked to the bulletin board, past teetering stacks of journals on the floor beneath an open file cabinet, and into an office covered from floor to ceiling in shelved journals. Piles of article reprints, two rows deep, conceal most of his two desks. (Later, in an e-mail message to a photographer who is attempting to lure him outdoors for a photo shoot, Crowley says, "I would much rather have a picture taken in my office—surrounded by the stacks of paper that are the fodder for my research.")

Crowley's professional identity is hard to nail down. A geologist by training, he has become a historian and modeler of past climates and is now dealing with contemporary climate issues and policy. He works with computer models that apply Newton's equations of motion and the laws of thermodynamics to a rotating sphere and are run on the biggest computers in the world.

Disruption of the ocean conveyor could signal rapid climate change


University Corporation for Atmospheric Research

At this, the warmest point in human history, Crowley recognizes that we need a wholesale change in our energy supply—85 percent of which is carbon-based—to stabilize the climate. (Like other experts, Crowley points out that despite valid concerns over the contribution of automobiles to global warming, "most CO2 comes from smokestacks not tail pipes"—which explains why none of my interviews involves more than a passing discussion of automobile fuel efficiency and emissions.) Even so, he is open to the idea of continuing the use of fossil fuels and to expanding the infrastructure, like offshore drilling, that provides them—as long as there are "tithes paid and horse trades made," he says. These tithes and trades might include money given to support production of alternative fuels or educational programs and scholarships funded by energy companies in states where fossil-fuel infrastructure is built.

"It takes time to rewire the energy economy, and clean coal or methane creates jobs and U.S. energy security," Crowley explains. But he draws the line at on-site drilling in the Arctic National Wildlife Area Refuge because the infrastructural footprint is just too big.

Crowley, who never eats lunch in his office because he prefers to eat with the students, invites me to join him. "Gabi doesn't like to sit up here," he tells me of his wife as he climbs to a table on the platform at the end of the gallery in the Union Building. Gabi is Gabriele Hegerl, the member of the Climate Research Committee I encountered at the National Academy. In line at the coffee counter after lunch, Crowley sifts through a handful of foreign coins, relics of Hegerl's service on advisory bodies like the Intergovernmental Panel on Climate Change (IPCC)—considered the authoritative source for climate-change predictions—which takes her all over the globe.

The oceans are assimilating up to 40 percent of the carbon byproducts of our daily lives, says oceanographer Susan Lozier.


Photo courtesy of Susan Lozier

I wasn't able to interview Hegerl that day because she was in Hawaii as part of a panel about changes in climate extremes. Later, by phone, she tells me that she recognizes the irony of flying all over the globe to climate-change meetings in emissions-spewing, fossil-fuel-swilling jets. Hegerl was a lead author of the IPCC 4th Assessment Report (2007), a comprehensive picture of the current state of knowledge about climate change—a four-volume report that was six years in the making and included the work of scientists from more than 130 countries. The report's take-home message is that the observed changes in climate over the past fifty years are "very likely" due to greenhouse gas emissions from human activities. "Very likely" is what Hegerl calls a statistical qualifier, because the scientific determination, as strong as it is, can't be considered 100 percent certain. (Remember, even evolution is referred to as theory, despite the fact that biologists see it as the foundation of the work they do.)

Hegerl says that her role as a scientist is to provide information to the public; it is up to the public to decide which consequences are acceptable. A self-described optimist by nature, she thinks that the public's will to act—regulation, legislation, changes in individual behavior—seems to be increasing.

Crowley, on the other hand, tells me, "I am never optimistic but veer between being hopeful and pessimistic." Walking back to Old Chem, coffee in hand, he explains that predictions about climate change have changed very little in the past twenty-five years. "We can predict a range of warming scenarios, depending on different population and emission scenarios, which is the sociological component of climate science," he says. "If we take the median value in that range of predictions, our climate will be warmer at the end of this century than it has been in between five and twenty million years."

There is no way, Crowley says, to explain twenty-first-century climate, with its Arctic sea ice retreat, summertime rivers on the Greenland Ice Sheet, and polar bears drowning for want of floating way stations, without factoring in the greenhouse gases that we've released into the atmosphere.

Organic exchange: Bernhardt, at the Sandy Creek wetlands near West Campus, focuses on the impact of greenhouse gases released during the restoration process


Jim Wallace

William Schlesinger's office is a sophisticated, airy space designed for receiving important people. A few months after our interview, I learned that Schlesinger would soon have new digs, as he announced that he would be leaving his post as dean of Duke's Nicholas School of the Environment and Earth Sciences this summer to lead the Institute for Ecosystem Studies, a world-renowned ecological research organization in Millbrook, New York.

I have come to Dean Schlesinger looking for the grown-up version of the mantra of every eighth-grade science teacher: Carbon is the building block of life. "There is no life on Earth that doesn't have carbon in it," Schlesinger says. Carbon—one of ninety-two natural elements on Earth and No. 6 on the Periodic Table of Elements—has a high valence, so atoms of other elements tend to stick to it and form more complex structures.

Wood, limestone, diamonds, and carbon dioxide, while bearing no outward physical similarity, all comprise carbon. I wonder aloud: How could it be that a principal building block of our planet is at the heart of our global climate crisis? Schlesinger chastises me for not taking his course on biogeochemistry and then begins to explain the movement of carbon between the Earth, atmosphere, and ocean—a subject that he knows as well as anyone on the planet.

Carbon cycle: The annual flux of CO2 in GigaTons (Gt) or billions of tons between each of the Earth's reservoirs. Each reservoir serves as both a source of and a sink for carbon, as indicated by opposing arrows. The carbon released by burning fossil fuels is an unbalanced contribution to the global carbon budget. The total contribution of carbon from the burning of fossil fuels has increased from 5.5 Gt to between 7 and 8 Gt since this diagram was published in 2003.


NASA Earth Science Division

"With regard to mass, the Earth has been pretty constant for three billion years," he says. When the Earth was just a coalescing ball of gases and ice, it was endowed with a certain amount of carbon. In the early stages of the planet's development, all of that carbon was in the mantle, the thick bulk of our planet that is between its innermost core and its thin outer crust. A period of intense volcanic eruptions redistributed some of the carbon to the atmosphere, in the form of CO2; when the planet cooled enough for the oceans to form, some of that CO2 dissolved into the water.

Schlesinger walks over to a bookshelf and retrieves a copy of Biogeochemistry: An Analysis of Global Change, a textbook that he wrote, and flips to a diagram of the carbon cycle. Curved arrows of various sizes create a series of closed loops between the Earth, oceans, and atmosphere—each a natural reservoir for carbon that serves as both a source of and a sink for carbon from the other reservoirs. The size of each arrow reflects the amount of carbon transferred from each source to each sink; in most cases, the arrows coming in and going out are the same size, indicating a balanced transfer.

The diagram also depicts a source of carbon that is unbalanced by an opposing arrow. In the 150 years since the Industrial Revolution, humans have been making a one-way contribution of carbon to the atmosphere. Carbon—in the form of coal, shale, and oil—is naturally locked up in the Earth's crust, where it would stay for hundreds of millions of years if not removed and burned by humans.

Schlesinger explains that each year, around the world, we release around seven gigatons—seven billion metric tons—of carbon into the atmosphere, mainly by burning fossil fuels. That carbon in the form of gaseous CO2—along with water vapor, methane, and other greenhouse gases—traps infrared radiation from the sun that, in turn, reradiates from the Earth's surface and warms the planet.

In comparison with the 90 or so gigatons of carbon each that terrestrial ecosystems and the world's oceans contribute to the atmosphere each year, our paltry seven gigatons—roughly 1 percent of the CO2 currently in the atmosphere—are pennies in the global carbon budget. But unlike the natural sources, our contribution is not offset by a corresponding sink—at least not entirely. As Lozier explained, the oceans are, for the moment, doing more than their share by assimilating up to 40 percent of the carbon byproducts of our daily lives.

The IPCC projects that our annual contribution of carbon could be 15 gigatons per year or higher by 2050 if the world continues to consume fossil fuels at current rates.

Schlesinger's distillation of the issue is basic and pragmatic: "We can decrease our emissions or try to increase natural uptake, either by increasing plant growth or decreasing decomposition, which would produce a net storage of carbon on land." Because absorbing part of our seven gigatons of carbon into natural pathways between sources and sinks would mean a relatively small change to the system, scientists contemplate assorted schemes for enhancing carbon uptake by natural systems. No one knows for sure how much of the unbalanced carbon will be taken up by oceans and other natural carbon sinks before we see fundamental changes in those systems, although several Duke faculty members are working to find out. Pencil in hand, I thumb through the Nicholas School's Experts Guide, the "reporters' handbook" to the school's "faculty expertise," and plot my trip around the carbon cycle via waypoints in the school of the environment.

Big picture: Barber, renowned for his expertise in the data-driven field of biological oceanography, at Duke's Marine Lab.


Jeffery Pollack

Wetlands have long been recognized as carbon sinks. In fact, we owe our modern-day supply of fossil fuels to the wetlands that abounded in the Carboniferous Period.

"Wetlands accumulate muck," says Emily Bernhardt, assistant professor of biology. Under the anaerobic conditions that result from standing water and saturated sediment, there is little decomposition of that muck by microbes, which means that carbon-rich organic matter accumulates. This organic matter, when compressed over eons, becomes fossil fuels.

Bernhardt and her colleagues have just begun to track the restoration of Timberlake Farms, a 4,000-acre site in the coastal plain of North Carolina that includes wetlands that were drained. A quarter of the site was actively farmed until two years ago. Now that the pumps have been turned off, the site will slowly return to its natural state. As this massive restoration project progresses, Bernhardt and her team will measure the net flux of three greenhouse gases—methane, nitrous oxide, and CO2—out of the soil, to monitor the farmland's transition back into wetlands: How it happens and how long it takes, among other things. While Bernhardt expects the site to be a source of methane and nitrous oxide in the short term, it will become a carbon sink as the site returns to its natural state over the coming decades.

In addition to working at Timberlake Farms, Bernhardt is among a handful of Nicholas School researchers conducting experiments at the Free Air Carbon Dioxide Enrichment (FACE) site in Duke Forest to determine how forest ecosystems will respond to elevated levels of atmospheric CO2. Robert Jackson, one of Bernhardt's colleagues in the Nicholas School and head of the school's Center on Global Change, is also an investigator in the FACE experiments.

The diversity of Jackson's work is captured in the titles of three of the books he's written: Methods in Ecosystem Science, a textbook; The Earth Remains Forever, a compelling case for environmental stewardship aimed at a broad audience; and Animal Mischief, an illustrated book of children's poems.

Jackson has a natural, easygoing manner; he is wearing a well-worn black T-shirt beneath a blue, short-sleeve linen shirt. An oversized spider hanging high above a corner of his office that is devoted to his three sons' artwork and a black wig on his desk hint at the playfulness that is part of Jackson's hopeful world view.

As average air and sea temperatures rise, ice masses such as these in Greenland melt, raising the sea level in the world's oceans


© Paul Souders/Corbis

Conversation about climate change quickly broadens to other issues: air and water quality, balance of trade, national security, energy security. Jackson is quick to point out that the concept of "greenhouse gases" is not new: Joseph Fourie coined the term in the 1820s, and scientists knew as early as the 1890s that we would eventually warm the planet if we continued to burn wood, coal, and other sources of carbon.

Jackson thinks we could see an atmospheric CO2 concentration of 700 parts per million—nearly double the present concentration—by the end of this century if we continue with business as usual. Jackson and Schlesinger did some calculations to see whether planting forests could be the solution to our runaway emissions—when plants take up CO2 for photosynthesis, some of the carbon gets locked in their tissues.

"We would need 100 million acres of forest to offset 10 percent of our annual fossil-fuel emissions in this country alone," Jackson says. That amount of land is simply unavailable, and the water and fertilizer needed to support those forests would create a separate suite of environmental problems, he adds. What's more, forests provide only a short-term holding tank for CO2; it is released when the trees die and decompose or are burned.

At an experimental site in Duke Forest that is part of the FACE project, Duke scientists have set up eight experimental "rings" around sections of forest. Air containing an elevated concentration of CO2—575 parts per million, about 200 ppm more than the concentration in the surrounding forest—is blown into four of the rings; the remaining four serve as the controls in the experiment.

Gravel crunches under the tires of Jackson's hybrid Honda Civic as we park next to three massive blocks of silver metal coils, each over twenty feet tall. These heat-exchange coils convert liquid CO2—about one tanker truck full a day—to its gaseous form.

I follow Jackson onto the forest trail. Gusts of wind swirl red and orange fall leaves over a bed of brown pine needles. At Ring 4, a blower wails welcome from inside a red wooden shed. A black, corrugated plastic pipe carrying air laden with extra CO2 snakes out of the shed and forms the border of the experimental ring. Every twelve feet, white PVC pipes, with holes drilled on one side, jut skyward out of the black ring. A computer-controlled system measures wind direction and releases the gas on the side of the ring that will ensure optimal exposure for the trees inside. According to Jackson, the pipes have to be extended up about a foot a year to keep up with the growth of the twenty-five-year-old loblolly pines inside the ring.

Inside Ring 4, experimental equipment litters the ground and hangs from tree trunks—researchers measure just about everything imaginable relating to carbon, nitrogen, and water inside the rings. Jackson and the other Duke researchers collect fallen leaves and small branches in "litter traps"—framed screens of fine mesh that are suspended just off the forest floor—and estimate tree productivity by measuring biomass (weight), leaf area, and tissue chemistry. They measure tree growth just as their predecessors did in the early days of forestry science, with metal dendrometer bands that encircle the tree trunks and expand as they grow. They core into the ground to measure the chemical composition of the soil and tree roots.

Jackson and his students have found significant increases in soil CO2, which has implications for soil chemistry, because the soil will become more acidic as the CO2 concentration increases. The roots of trees exposed to elevated levels of CO2 show a 30 percent increase in the biomass of their roots; the roots are a site of continuous respiration (the breakdown of sugar and oxygen to yield CO2, water, and energy) so more roots means more CO2 building up in the soil.

Plants have a fixed ratio of carbon to nitrogen in their tissues, which means that in order for plants to take up extra carbon, additional nitrogen must also be available. Jackson and his colleagues report that, in the absence of additional fertilizers, the trees in the FACE experiment exhibit only a modest increase in CO2 uptake. About two years ago, during year nine of the experiment, the researchers began fertilizing each of the experimental rings with ammonium nitrate in a concentration comparable to what a farmer might use.

At another research site in Texas, Jackson tests the response of native grasses to ancient climate conditions and has found that the increased CO2 uptake by green plants slows over time, even if the ambient CO2 concentration continues to rise. Some scientists think an atmospheric CO2 concentration of around 500 ppm—predicted by the IPCC by the middle of this century—may be an ecological tipping point based on the level of associated global warming. What's more, this projection assumes a massive assimilation of our CO2 burden by terrestrial systems. Jackson's work will help determine if we are overestimating the capacity of forests and grasslands to keep pace with our emissions.

I'm starting to realize that while planting trees (and cutting fewer of them) must be part of a holistic plan to stabilize the climate, carbon sequestration by forests—or wetlands, for that matter—will never be a silver-bullet solution. The trendy, conscience-salving practice of buying carbon offsets—in the form of trees planted in a far-off land, for example—for $20 a year over the Internet is not nearly enough to pay penance for miles driven in a Chevy Suburban.

One hundred ninety miles east-southeast of Duke Forest, at the Duke University Marine Lab in Beaufort, North Carolina, a Duke biologist of a different sort is exploring the sequestration capacity of our biggest natural sink for carbon. The blue star tattoo, primitive and fading, is one of the first things I notice when Dick Barber greets me. I remember pondering the mystery of that tattoo from a front-row seat in Barber's class years before. Not normally a front-row type of student, I made an exception because I didn't want to miss any of the profundities—often as easily missed as they were insightful—that Barber was bound to offer during each class.

"In our culture, people are either doers or thinkers," says Barber, early into our conversation. It's clear from the way he asks questions that he is a thinker and is eager to find out which of the two I am. Before even flirting with the subject of my visit, we talk for over two hours, in large part about my work as a coastal field biologist in Saudi Arabia, where I documented the impact of the oil spilled during the first Gulf War. My work in Saudi—counting species, making observations, and formulating hypotheses to explain what I saw—had been science of the purest sort. Barber laments contemporary scientists' emphasis on data and methods over pure observation—a surprising sentiment since biological oceanography, Barber's specialty, is among the most quantitative fields of marine science.

On climate change, Barber is not sure we have "the wit" to work some of the issues out, even though he is convinced that we have the technological capacity and fundamental understanding of the three key elements—science, politics, and economics. In his mind, political will is the missing ingredient.

Barber, like Jackson, Crowley, and nearly all of the other Duke professors I've spoken to about climate change, brings up nuclear power. Even energy experts disagree about the potential for nuclear power to supplant fossil fuels. But Barber describes the prevailing public sentiment against the use of nuclear power as "emotional and irrational," based on fear rather than on a real understanding of risk. I get the sense that Barber would rather see us build well-designed, secure nuclear power plants, for example, than coal-fired ones. (As Jackson told me, energy from burning coal contributes to at least 10,000 deaths a year in this country.) But he acknowledges his own hang-ups, among them addressing the real cost of waste storage in places like Yucca Mountain. He points out that while his reactions may be strong—"violent," he says—they are rational, and he recognizes that we have the capacity to address them. "Yucca Mountain is such a small risk relative to other risks. The real issue is whether the world is going to be a livable place, and Yucca Mountain is not even in the same ballpark as the danger we face from Iran."

Even though we need a wholesale energy alternative to stabilize our climate, Barber says, he's convinced that the use of nuclear power will never be a part of the discussion. He recalls a meeting of the American Association for the Advancement of Science fifteen years ago, when Chinese delegates asked for help developing nuclear power instead of coal, which they knew was environmentally detrimental. All but one of the U.S. panelists pushed for coal.

"It is a complex crisis," Barber says. "Nuclear power and global warming are the two things 'environmentalists' hate, and the evidence is that they think nuclear [power] is the real threat, because that is what they demonstrate against."

Weiner: making the case for using market-based strategies to address climate change


Megan Morr

Barber is someone with whom I could talk about politics and social issues all day long, but this day is quickly slipping by, so I push the conversation toward the subject of his work as a scientist. In 1993 and 1995, Barber was a principal investigator on research cruises to the Equatorial Pacific to test the idea that fertilizing patches of the ocean with iron would stimulate the growth of microscopic plants called phytoplankton. Scientists know that 18,000 years ago, before the last ice age, our atmosphere was around fifty times dustier than it is today. John Martin, a close friend and colleague of Barber who died right before the 1993 cruise, had hypothesized that the settling of iron-rich dust would have stimulated phytoplankton growth in parts of the ocean where other requisite nutrients—nitrogen, phosphorus, and silicate—were abundant, but iron was in short supply. Photosynthesis by this phytoplankton, Martin speculated, would have pulled enough CO2 out of the atmosphere to minimize the greenhouse effect, keeping our planet cool.

During both of the "Iron-X" experiments, and during a third experiment in the Southern Ocean in 2002, Barber and the other researchers spread a half ton of iron dust over 86 square mile sections of ocean. It worked. The ensuing phytoplankton bloom drew a measurable amount of CO2 out of the air at the sea surface. What's more, Barber and his team found that about half of the carbon pulled out as CO2 was transported by the sinking phytoplankton to depths where it would essentially be out of play for 500 to 1,000 years—the length of time, as Lozier had told me, that it takes the ocean conveyor to deliver it back to the ocean's surface in another part of the globe.

Barber says he doesn't feel that there has been any rational discussion of ocean fertilization because there are so many ethical objections to any large-scale manipulation of ocean ecosystems. He recalls that John Martin once said that the no-action scenario is much more destructive than any of the solutions on the table. Martin argued that those objecting to ocean fertilization on moral grounds were passively advocating for harm under the status quo.

The issue of iron fertilization has reached a critical stage because of two U.S.-based corporations, Planktos Inc. and its competitor, Green Sea Venture Inc. Both are staffed with world-class oceanographers, and Planktos is rumored to have approached the World Bank for a $1 billion loan to support ocean fertilization. Barber and two of his former graduate students from Duke have worked with Green Sea Venture to provide plans for a test fertilization.

Going, going, gone: Warming ocean temperatures have led to coral bleaching and threatened ecosystems in places like Belize's 200 miles of coral reef



Barber—the big picture always in focus—envisions commercial-scale iron fertilization, with tankers carrying 1,000 tons of iron dust in a single trip, as a way for even the smallest nations to share in the market opportunity created by engineering carbon sequestration. Barber has no feel for whether ocean fertilization will be in or out of climate-change discussions in twenty-five years, but he's certain that there will be more experiments to test it because, as he puts it, "it's so goddamned cheap."

Barber corroborates the conclusion I reached after talking to Robert Jackson: The potential of enhanced carbon sequestration by natural systems—forests, wetlands, and now oceans—is only a small part of a balanced strategy for stabilizing the climate. He emphasizes the role of financial markets and global politics and brings up the work of Duke law professor Jonathan Wiener. Barber even suggests, after hours of conversation about science, that these subjects might make for a more interesting story than the details of his own work. I am amused by the suggestion—I could never ignore his role in some of the most exciting oceanography experiments of this century—but I am not surprised by Barber's humility about his own contributions. Then again, when someone as brilliant as Dick Barber makes a suggestion, someone like me takes it to heart. I make plans for a visit to Duke Law School.

In his office at the very end of a very long hall, Jonathan Wiener builds a courtroom-caliber case for using market-based strategies to address climate change. He begins by echoing Schlesinger in advocating for consideration of both sources and sinks for greenhouse gases. On the shelf, book titles like Risk! and Collapse! suggest that I pay extra attention.

Wiener first proposed a comprehensive trading system for greenhouse gases while working for the Environmental Division of the Justice Department in 1989. Our current "command and control" system of regulations, largely unchanged since that time, prescribes specific means to reduce pollution to target levels. The narrow regulations of this type of system, Wiener explains, encourage the substitution of one unsustainable activity for another, such as the switch from coal to natural gas or fossil fuels to ethanol.

He proposes a "cap-and-trade" system, under which the EPA would allocate a certain number of units of carbon emissions to a company for a set period of time; the initial allocation would probably be based on the company's history of pollution. Companies that didn't use all of their units could sell them to companies that exceeded their own caps. That system would give all parties involved the freedom to select their own approach for reducing emissions and allow them to use the marketplace to fine-tune their individual pollution limits. At the end of each trading period, the established monitoring and enforcement entity would compare allowances and emissions and fine any participants whose emissions exceeded their allocation. This trading system would involve brokers and would even create the opportunity for environmental interests to purchase and retire pollution units.

I question the practicality of developing reliable monitoring methods based on good science for a multi-gas trading system, but Wiener points out that monitoring and enforcement are part of any pollution-reduction system; a trading system just adds the need for a mechanism for allocating and tracking emission rights.

Because there are no hotspots—specific places where emissions cause environmental damage—for CO2 and other greenhouse gases, the net reduction in emissions, not where those reductions occur, is what's important. A system of tradable emissions credits spurs dynamic innovation because players compete to offer the cheapest reduction strategy so that they can trade their surplus capacity. This, Wiener says, is a win-win for the economy and the environment.

Critics of pollution trading, of whom there are fewer today than even a few years ago, thanks to the success of the U.S. cap-and-trade system for acid rain, cite moral grounds for their opposition to the notion of granting the right to pollute. Yet it is our current regulatory system, according to Wiener, that gives a free right to pollute below the set limit. A trading system makes polluters pay for all units of pollution, because what Wiener refers to as the opportunity cost of holding onto pollution rights—the price that those emissions credits would draw in the marketplace—makes even unused pollution rights worth something.

The Climate Stewardship and Innovation Act, originally introduced by Senators Joseph Lieberman and John McCain, is one of three major climate-change bills currently on the floor in Congress. It includes a cap-and-trade system for the six major classes of greenhouse gases in the U.S. and has an entire section dedicated to the details of monitoring and recording. Tim Profeta M.E.M. '97, J.D. '97, director of Duke's burgeoning Nicholas Institute for Environmental Policy Solutions, served as counsel for the environment for Senator Lieberman and was one of the architects of the bill in its original form.

"Everyone in Washington thinks it's most cost effective to deal with all six greenhouse gases at once," Profeta tells me when I call him for details. "The biggest bang for the buck comes from reductions in non-CO2 gases, like methane and the CFC [chlorofluorocarbon] alternatives."

Profeta's grasp of climate policy extends beyond U.S. borders, and he believes that the U.S. must show political and economic leadership to inspire international participation in the next round of Kyoto Protocol discussions in 2009.

"CO2 has a lifespan of 100 years in the atmosphere. What's up there now is ours. What's going up there now is ours and India's and China's."

International treaties like Kyoto hinge on voluntary participation ("the bedrock principle of environmental treaty law," according to Wiener), which makes it critical that would-be participants perceive the benefits of participating. "The Stern Review," a seminal 700-page report released in late 2006 by the British economist Sir Nicholas Stern, cites emissions trading as a key element of any international effort to stabilize the climate. By Stern's analysis, developing nations like China and India stand to gain 5 percent or more of their GDP by participating in an international trading system for greenhouse gases. The path to an international climate treaty is imperiled by geopolitical issues, Wiener notes. "But those issues may also represent opportunities." In the case of China, so eager to be viewed as a great power, he is optimistic that the promise of a seat at the table might inspire participation.

Leaving Wiener's office, walking back down that long hallway, and stepping into the sunlight, I'm struck by the gravity of what I've learned. I returned to Duke in search of the finer points—the high-resolution view—of climate-change science. In several days of conversations with experts whose combined knowledge of all things climate would be hard to find under the roof of any other single institution, I have traversed the boundaries between academic disciplines, between political parties, between land and sea and sky. I have come to understand how much we tend to make of these boundaries and, ultimately, how little they matter. And now, with the proverbial forest back in focus, what have I learned from remapping my route through the trees? When we zoom out to the big-picture view, the Google Earth vantage, those boundaries disappear, and we face a single question: What makes this a livable planet?

The "issue" of climate change, if this all-encompassing phenomenon can be described as such, is a pure illustration—perhaps one of the purest in human history—that we are at once a natural part of the global ecology and in desperate need of means of reducing our global ecological footprint. What is a card-carrying member of humanity to do? Tread lightly.

Pollack M.E.M. '02 is a freelance writer in Corpus Christi, Texas, and heads In Translation, a consulting entity specializing in bringing coastal environmental science to decision makers.

Editor's note: Thomas Crowley and Gabriele Hegerl recently accepted academic appointments at the University of Edinburgh.