News this Week

Science  13 Aug 2010:
Vol. 329, Issue 5993, pp. 734
  1. Gulf Oil Spill

    A Lot of Oil on the Loose, Not So Much to Be Found

    1. Richard A. Kerr

    Now that the gusher that spewed oil for 85 days into the Gulf of Mexico has stopped, scientists are wondering where it all went. A federal report released last week should have begun to answer that question. Instead, political spin and media hype transformed the scientists' message even before it was released. According to one CNN reporter, the interagency report led by the Department of the Interior and the National Oceanic and Atmospheric Administration (NOAA) said that of the 4.9 million barrels of oil spilled, “75% has been cleaned up by Man or Mother Nature.”

    Nothing in the report supports that interpretation. But there are multiple ways to read the report's iconic pie chart while remaining grounded in fact. One is that responders have—with herculean effort—intercepted 25% of the oil, leaving 75% to have its way with the environment. Under this interpretation, “raising the flag and declaring victory is premature,” says biogeochemist Samantha Joye of the University of Georgia, Athens.

    Another take on the report finds that three-quarters of the oil is gone from the gulf or is dispersed in the water in its most easily degraded form. This remaining oil “is degrading quickly right now,” says marine geochemist Edward Overton of Louisiana State University, Baton Rouge.

    Overton and other optimists note that today official maps from NOAA no longer show any surface oil in the gulf. And the “massive” deep oil plumes of media fame now appear to have been faint shadows of their public images. Resolving the inevitable uncertainties and filling in the gaps of such an early report will no doubt take many months.

    Fuzzy budget.

    A federal report divvies up the oil (top) but allows for uncertainties (bottom).


    The report's most certain conclusion was that responders managed to collect or remove about 25% of the oil released from the damaged well. Seventeen percent was collected at the wellhead in an unprecedented technological feat. About 5% was burned at the surface, an exceptionally large proportion for a U.S. spill, experts say. But skimmers captured only 3% of the total, despite the high-profile effort. Such meager results are to be expected in the open ocean, says William Lehr of NOAA's emergency response division in Seattle, Washington, who worked on the report. Less than 0.1% had been recovered from beaches and marshes.

    That leaves 75% of the spill that remained in the environment, but just how it entered it—as oily scum on the surface, as more readily degraded microscopic droplets at depth, or as vapors into the atmosphere—is far less certain. That's because these flows were calculated, not measured. Despite the seeming precision of the pie chart, “there's a large degree of uncertainty,” says Lehr. Uncertainties crop up, for example, in calculations of “natural dispersion” involving the physics of oil and gas jetting into seawater from the wellhead. These calculations yield an estimate of how much oil ends up dispersing as droplets smaller than 100 micrometers in diameter. That's the size range that can drift away in a horizontal plume the way dust can float in the air.

    Add up all the uncertainties and they can be considerable. There are uncertainties in calculating the natural and chemical dispersion that produces deep plumes as well as dissolution in seawater or evaporation from the surface. Then there is the ±10% uncertainty in the total volume of the spill. All told, the “residual oil”—what could not be measured or estimated but is left to float as tarballs or be washed ashore—could be as high as 39% of the total or as low as 13%, by a simple accounting from charts in the report's supplement.

    Perhaps the most muddled calculation involves the fraction of oil that went into the dreaded subsurface plumes. The media “created an image of an underwater river of oil,” says Steven Murawski, NOAA's chief scientist for fisheries in Silver Spring, Maryland, who is overseeing spill science for NOAA. “In a glass, [plume water] looks like clear seawater.” He says that measurements of oil reveal a principal plume confined to depths of 1000 meters to 1300 meters that in spots contained 1 to 2 parts per million of oil (1 or 2 milliliters in a cubic meter of seawater). Most parts of the plume, however, had lower concentrations; farther than 10 kilometers from the wellhead, concentrations were in the parts-per-billion range.

    If something like 20% of the oil—15,000 barrels a day—dispersed into the deep sea, as the report has it, precious little of it has been showing up in plume observations. That raises the issue of biodegradation and how quickly microbes might be consuming the oil. The report states that according to early signs, the oil “is biodegrading quickly.” It provides no documentation for that claim, while hearsay about observations awaiting publication and public release is mixed. “The message I've heard is that everywhere we look, oil is degrading extremely rapidly,” says Overton. Joye, who has generated some of the relevant data, is more cautious. “Sure it's getting degraded, but we don't know how fast,” she says.

    Ultimately, determining the rates of oil degradation, evaporation, and dilution in the gulf rather than this report's parsing of the oil's immediate fate will show where the oil went. Such analysis should determine whether, as Lehr puts it, “Mother Nature is almost always the best removal mechanism.”

  2. Gulf Oil Spill

    An Audacious Decision in Crisis Gets Cautious Praise

    1. Eli Kintisch

    How BP came to spray 1.1 million gallons of chemical dispersants a mile beneath the ocean surface is a story of scientists turning to desperate measures during desperate times. And the government's decision to let BP do so, among the most gutsy calls of the entire Deepwater Horizon saga, was a classic case of pitting the devil you know against the devil you don't.

    Roughly a week after the magnitude of the gusher became clear in late April, former Exxon-Mobil scientist Gerard Canevari suggested that BP might try spraying chemicals called dispersants right at the billowing wellhead. Dispersants are usually used in small quantities on the surface of the ocean to break up slicks. Canevari's idea would mean releasing giant amounts of the fairly nasty chemicals in the cold and high-pressure world of the ocean floor, something that had never been tried. “At first we were going, ‘Yeah, right,’” recalls Charlie Henry, a top scientist on Gulf of Mexico issues for the National Oceanic and Atmospheric Administration (NOAA). “It was out of the norm”—a massive proposed undersea experiment.

    But, he says, the unprecedented nature of the problem meant nothing was off the table. While outlining the pros and cons on white boards in NOAA's New Orleans office, says Henry, the basic tradeoff seemed clear. Every drop of oil that made it to the surface was a potential threat to coastal ecosystems, fish, and marine mammals. Dispersants, which are mostly detergents, break up globs of crude into microscopic droplets that are more readily devoured by microbes. So keeping as much oil as possible below the surface would give microbes a leg up in eating the oil. And injecting dispersants into the hot, vigorously mixing oil of the busted riser would presumably mean they would work especially effectively. Smaller quantities would then presumably be needed at the ocean surface.

    Some drawbacks emerged during a conference call with 25 industry and academic scientists arranged by NOAA in early May: The risks to undersea marine life—eggs, larvae, fish, coral, and other bottom dwellers—were largely unknown. One possibility was particularly frightening: Giving microbes a feast of hydrocarbons might massively increase their numbers, starving the water column of oxygen and creating dead zones.

    Desperate measures.

    Spraying chemical dispersants at the undersea wellhead seems to have spared coastal ecosystems, but at what cost?


    So government scientists proposed a three-tiered plan to try the undersea injection as safely as possible. First, teams across the country began adapting existing undersea models of oil plumes to predict how they might move, referencing data on nearby sea life from the Department of the Interior. Second, they required that BP conduct aggressive monitoring, including ocean surface-to-floor water sampling, toxicity tests using zooplankton, and tests with fluorometers, which would continuously track the oil droplets. And if the dispersant injection created unexpected effects during tests, an “adaptive management” plan would enable the feds to halt the procedure immediately.

    The Environmental Protection Agency (EPA) and the Coast Guard agreed to the procedure on 15 May. “I don't think I've had to make a harder decision,” EPA Administrator Lisa Jackson told reporters at the time. BP deployed a specially built tube with tiny holes that was clamped in place to release the chemical right at the spurting pipe.

    On 27 May, the first real vetting of the new approach came at a meeting of scientists culled largely from academia and the nonprofit sector, hastily organized by NOAA. The outsiders were asked “to second-guess us,” says Henry. Chemist Jeffrey Short of Washington, D.C.–based Oceana recalls feeling skeptical on his way to Louisiana State University (LSU). “You don't want me down there; you know what I think about dispersants,” he told Nancy Kinner of the University of New Hampshire, the organizer.

    But the fluorometry data presented at LSU showed that the dispersant was working and had broken up the big globs into droplets between 1 and 10 micrometers—and the microbial feast wasn't starving the system of oxygen. So after 2 days of intense debate, Short and the rest of the group gave their approval in a report. “I was struck by the fact that all 50 were in agreement that continuing the sub surface injection was the best option in a bad situation,” recalls toxicologist Ronald Tjeerdema of the University of California, Davis.

    Since then, researchers have by and large stuck with that opinion. NOAA estimates that roughly 409,000 barrels of oil have been dispersed underwater by the technique. Toxicity tests have suggested an acute risk of dispersant-oil mixtures no greater than that of oil alone. Daniels says some of the dispersed oil has risen toward the surface, while some has formed a loose band, or plume, between 1000 and 1300 meters in depth. No negative impacts on deep-sea life have yet been recorded, although NOAA Administrator Jane Lubchenco says one of the worst case scenarios involving longer exposures due to dispersed oil—big losses of spawning bluefin tuna populations—may not be detectable for years. That's led some scientists to suggest that letting the oil rise to the surface would have been a better move, as it could be more easily collected.

    Jacqueline Savitz, an environmental scientist with Oceana, says because of the unknown risks of dispersants, it was “a lose-lose” decision—and despite optimistic projections (p. 734), all the benefits and costs may not be known for decades.

    • With reporting by Erik Stokstad.

  3. Infectious Diseases

    Yellow Fever Mosquito Shows Up in Northern Europe

    1. Martin Enserink

    AMSTERDAM—In the latest display of mosquitoes' predilection for modern travel, entomologists have found a small colony of the tropical species Aedes aegypti—also known as the yellow fever mosquito—in the Netherlands. The insects were found on and near two facilities of a company that imports used tires and presumably originated in the hot southern part of the United States. Ae. aegypti is an important vector not just of yellow fever but also of two other viral diseases, dengue and chikungunya.

    Foreign trade.

    Spraying started at a Dutch tire yard on 30 July to wipe out three exotic mosquito species, including Aedes aegypti (inset).


    The mosquitoes, found by a team led by Ernst-Jan Scholte of the Dutch government's Center for Vector Monitoring, don't pose a direct public health threat and are unlikely to survive the winter, says Scholte. Still, scientists are amazed, because the insects were last seen in Europe more than 50 years ago. “You're kidding. … Really?” entomologist Paul Reiter of the Pasteur Institute in Paris says when told about the find. “Wow.”

    Ae. aegypti originated in Africa but has colonized tropical and subtropical areas around the world. It's notorious as the vector of the dengue virus, which can cause severe malaise and fever, unbearable joint pains, and a fatal syndrome called dengue hemorrhagic fever. Ae. aegypti once roamed southern Europe as well but probably disappeared after World War II, says Reiter, perhaps in response to DDT spraying. Although the Dutch climate may be inhospitable for the species, a similar transplantation to southern Europe could trigger a recolonization, says Francis Schaffner, a French mosquito-control expert at the University of Zürich in Switzerland.

    The team found the mosquitoes during a routine surveillance program aimed at keeping out another species, the Asian tiger mosquito, or Ae. albopictus, which can transmit dengue and chikungunya as well. That mosquito has relentlessly colonized new territory over the past 2 decades, becoming a highly annoying fixture in many Mediterranean countries, from where it is now pushing northward (Science, 16 May 2008, p. 864). The “tiger” is known to hitch a ride in secondhand tires, shipped around the world in containers. In the Netherlands, tiger mosquitoes have also been found in greenhouses that import lucky bamboo, a popular plant from Asia.

    But Ae. aegypti was not known to be such a frequent stowaway. When Scholte's team first caught the intruder in one of their traps, they misidentified it as a tiger mosquito, which they also found in the same area. When a genetic test unmasked it as Ae. aegypti, “I couldn't believe it, a tropical mosquito flying around in Holland,” says Scholte. The team believes the most likely origin for both species is a tire shipment from Miami—where both occur—that arrived in late May.

    Both last summer and this year, the team also found a third foreign species, Ae. atropalpus, or the American rock pool mosquito, near the tire importer. That species inhabits the northern United States and southeastern Canada and probably would have little trouble establishing itself this far north in Europe, says Scholte. But Ae. atropalpus is not believed to be an important disease vector.

    The Dutch government—which ceased mosquito-control operations decades ago—has hired Schaffner and another French expert to help get rid of all three species, using a two-pronged attack involving deltamethrin for adults and biological control for larvae. Schaffner believes it's possible to nip the incursion of all three species in the bud. But countries that monitor for new invasions less rigorously may not be so lucky, says Scholte. “It's the shape of things to come,” says Reiter. “Everything can be imported everywhere.”


    From Science's Online Daily News Site


    Why Mongoose Moms Synchronize Births Four times a year, a female mongoose gives birth to her pups on the exact same night as more than half of the other females in her group. The small carnivores aren't planning a massive birthday celebration. Rather, they're trying to ensure the survival of their pups. Researchers report in Biology Letters that mongoose litters born a day or two earlier than others were 30% more likely to be killed by adult female mongooses. These females don't want competition for their own offspring, so they kill the pups while their mothers are out foraging. But if the litters are born together, all of the moms are out foraging at the same time—so there's no one left behind to kill the babies. Similar scenarios in ancient human societies may explain why women often sync up their menstrual cycles if they spend a lot of time together.


    Turning Scar Tissue Into a Beating Heart After a heart attack, the heart forms scar tissue dominated by fibroblasts, heart muscle cells that provide structural support. This leaves it with fewer cardiomyocytes, the muscle cells that beat—and thus less pumping capacity. But now a team has used a technique called cellular reprogramming to transform one cell into the other.

    Developmental biologist Deepak Srivastava and cardiovascular researcher Masaki Ieda of the Gladstone Institute of Cardiovascular Disease in San Francisco, California, and their colleagues identified a trio of genes that together helped fibroblast cells take on characteristics of cardiomyocytes (pictured). The team inserted extra copies of the genes into lab-grown cardiac fibroblasts. After growing for a month, the reprogrammed cells began to contract, like beating heart cells, the researchers report in Cell.

    Ideally, Srivastava says, researchers will find small molecules that can replace the three-gene cocktail. Such molecules could be applied directly to an injured heart and turn fibroblasts into cardiomyocytes.

    Busy Brains, Deeper Sleep Sound sleepers share a surprising secret: a bustling brain.

    Researchers long thought that people who can sleep through anything spend more time in the deeper stages of sleep. But Harvard Medical School sleep researcher Jeffrey Ellenbogen focused on something else: sleep spindles. These brief bursts of brain activity emanate from the thalamus, a brain region that regulates sleep and also processes and relays sensory information to the cerebral cortex.

    To show the connection, Ellenbogen and colleagues played sounds like flushing toilets, loud conversations, ringing phones, and car traffic to 12 sleepers, gradually raising the volume of each sound until each sleeper stirred. When the team matched the sleepers' spindle production—which ranged from three to six spindles per minute and remained consistent for each sleeper across the nights—to the loudness required to rouse them, they found that sleepers with higher spindle rates were harder to wake up. The spindles seem to indicate when the thalamus is blocking noise from reaching the cortex and disrupting sleep, the team reports in Current Biology.

    Researchers say the discovery could lead to spindle-enhancing techniques that offer lighter sleepers a chance at dead-to-the-world rest.


    Earth's Moving, Melting Core Earth's inner core acts in ways that befuddle scientists. But a new model might finally explain what's going on.

    Researchers speculate that the inner core, a solid ball of mostly iron 1200 kilometers across, absorbs and hardens molten iron from the liquid outer core. This should make the liquid at the boundary lighter; instead, it's denser. The model also doesn't explain why seismic waves from earthquakes travel faster on the eastern side of the inner core than on the western side.

    A new model published in Nature now gives the most plausible answer so far to these riddles, say experts. Lead author Thierry Alboussière, a geophysicist at the Laboratoire de Géophysique Interne et Tectonophysique in Grenoble, France, suggests that the inner core crystallizes in the west and melts in the east. The solid iron “moves” eastward at a pace of roughly 1.5 centimeters per year, melting when it reaches the eastern edge.

    The model would explain why the liquid layer at the boundary between the inner and outer cores is denser than the rest of the outer core: It's fluid that has just melted out of the dense inner core. The lopsided melting would also account for the difference in seismic wave speeds.

    Read the full postings, comments, and more at

  5. Paleoanthropology

    Lucy's Toolkit? Old Bones May Show Earliest Evidence of Tool Use

    1. Ann Gibbons

    Two nondescript scraps of animal bone that most fossil hunters would have left on the ground are being offered as the earliest known evidence for the first technological revolution in human evolution. A rib and a shaft of a thighbone bear “unambiguous evidence” of stone-tool marks made 3.4 million years ago by a member of the human family who used sharp stones to cut the meat off the bone and pound the bone open for marrow, according to a paper published this week in Nature. “This find will definitely force us to revise our textbooks on human evolution, since it pushes the evidence for tool use and meat eating in our family back by nearly a million years,” says Ethiopian paleoanthropologist Zeresenay Alemseged of the California Academy of Sciences in San Francisco. Alemseged directs the Dikika Research Project, which found the bones last year in the Afar Depression of Ethiopia.

    The age of the marks pegs them as the handiwork of Australopithecus afarensis, a species made famous by the 3.2-million-year-old partial skeleton nicknamed Lucy, says Alemseged. That suggests that our ancestors were already using sharp stones to cut meat when their brains and bodies were barely bigger than a chimpanzee's. The earliest known stone tools don't appear until 800,000 years later—also in Ethiopia—so some researchers say it will take more than two bones found on the surface to convince them that the marks were made by hominins instead of animals. Others, however, think the marked bones offer a glimpse of the earliest stage of tool use. “This is really a very exciting f ind,” says archaeologist David Braun of the University of Cape Town in South Africa, who is not a co-author. “This find emphasizes that tool use and carnivory have very deep roots in human ancestry.”

    The butchered bones were found at Dikika, just 222 meters from the spot where Alemseged discovered the remarkably complete skeleton of Selam, a 3.3-million-year-old child of the species A. afarensis (Science, 22 September 2006, p. 1716). In January 2009, Alemseged and other members of an international team of researchers were using a new method to collect every scrap of bone from large mammals at Dikika so they could reconstruct the ancient environment there. Archaeologist Shannon McPherron of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, says he picked up an unimpressive rib from a cow-size ungulate and saw two “obvious, V-shaped cut marks.” A few moments later, he found a thighbone shaft from a goat-sized antelope, with many cut marks on it. “In this case, they were incredibly obvious cut marks. But they were so old, we wanted to play it cautious,” says McPherron.

    Back in camp, the researchers examined the bones under a microscope and concluded that the marks were made when a hominin cut flesh from the bones and pounded the bones open for marrow. Later, paleoanthropologist Curtis Marean of Arizona State University in Tempe examined the bones and concluded that the marks were made by stone rather than by carnivore teeth. Other members of the team used secondary electron imaging and energy-dispersive x-ray spectrometry to show that the marks were created before the bones fossilized. They also found a tiny piece of rock embedded in a cut mark, perhaps left during the butchering.


    Fossil bones found in Ethiopia may show traces of early carving and pounding for marrow.


    Radiometric dating of the sediments at Dikika shows that the marked bones date to almost 3.4 million years ago—a time when the only known hominin in east Africa was A. afarensis. This means the animals could have been butchered by Lucy's species. But Lucy had a brain and body barely larger than a chimp's, suggesting that our ancestors began using sharp stones to carve meat long before they had developed big brains or specialized hands, once thought to be prerequisites for tool use.

    To butcher an ungulate as large as a cow, the researchers say, A. afarensis must have ventured into dangerous terrain to compete with other carnivorous scavengers, such as hyenas. That possibility should make researchers take a fresh look at scraps of animal bone from 3.7 million years ago, when A. afarensis arose, to 2.6 million years ago, when the first tools appear at Gona, Ethiopia. Others, though, say researchers have already scoured A. afarensis fossil sites for stone tools and cut marks and come up empty-handed. To push back tool use so early, they want to see more bones—and stronger evidence that the marks were not made by animals. “Extraordinary claims demand extraordinary evidence,” says paleoanthropologist Tim White of the University of California, Berkeley.

  6. Environment

    Russia's Forest Fires Ignite Concerns About Chornobyl's Legacy

    1. Dan Charles
    Hot zone.

    Fires ripping through Russia's forests (left) sparked fears of a blaze among Chornobyl's radiation-contaminated tress.


    In the midst of an unprecedented heat wave this summer, Russia has been scrambling to respond to a devastating epidemic of forest fires, some of which have threatened nuclear research and weapon facilities. Officials in Moscow last week warned of a further nightmarish scenario: Fires could spread to neighboring Ukraine, to its forests contaminated by the 1986 Chornobyl nuclear accident, sending radioactive smoke high into the air and downwind.

    As Science went to press, this had not happened, but several forestry experts in Ukraine and abroad say a catastrophic fire will eventually break out in the forests of the Chornobyl Exclusion Zone, which covers 260,000 hectares—unless Ukrainian officials take action to reduce the growing risks of a conflagration. The Chornobyl forest “is ready to burn, now,” says Chadwick Oliver, director of the Yale Global Institute of Sustainable Forestry. And a really big fire, he says, “can volatilize organic matter and move particles hundreds of kilometers.”

    Because the forest is contaminated, no one is managing it, thinning out trees, or harvesting those that are dying. It is even illegal to take lumber out of the Exclusion Zone; if trees are cut, they just stay in piles on the ground. On one recent visit to Chornobyl, Sergiy Zibtsev of Ukraine's National University of Life and Environmental Sciences in Kiev says he discovered “a really dangerous situation”: a huge area, inaccessible by road, filled with downed, dead trees.

    Although even the most ferocious fire in the exclusion zone would release only a tiny fraction of the radiation from the reactor accident, firefighters would face the clearest danger, mainly from the risk of inhaling particles of plutonium left behind by the nuclear reactor accident. “I worry about them, very much,” says Zibtsev, who has met the region's firefighters during his frequent trips to Chornobyl. Villages or cities downwind would not have to be evacuated, according to a computer simulation of a “worst-case” conflagration carried out by forest specialist Aaron Hohl of Humboldt State University in California. But such a fire might cause mass panic and force many farmers to discard contaminated crops.

    Hohl presented his preliminary results, which are currently going through peer review, at a conference last October in Kiev. Organizers of the conference, including Zibtsev, Oliver, and Johann Goldammer of the Global Fire Monitoring Center at the University of Freiburg in Germany, had hoped the gathering would win the attention of Ukrainian officials and persuade them to put more money—Oliver says $20 million a year would be adequate—into preventing, detecting, and fighting fires near Chornobyl.

    But top Ukrainian officials failed to attend—and since the country held elections in February, many key positions responsible for the exclusion zone have remained vacant. Zibtsev and others are still trying to lobby government officials, “but it's very difficult due to this political situation.” Other problems in Ukraine seem more urgent than a decaying forest, he says: “Until it burns, they will not do something, I think.”

    Goldammer sees the Chornobyl zone as an example of a wider problem. Many forests in areas of past or potential military conflict, he says, cannot be easily managed, and thus are vulnerable to fires, because they harbor land mines, bombs, or other unexploded ordnance. Last October's Kiev conference, in fact, included presentations on explosive contamination of forests across a broad swath of southeastern Europe and Asia, from Croatia to Armenia. One Turkish delegate reported that when fires break out along his country's heavily mined borders with Syria or Iraq, “what we do is, we do nothing.” This hands-off attitude could lead to cross-border fires and international conflict, he said.

    In a statement released after the conference, participants called for new international efforts to prevent and fight fires in contaminated areas. The recommendations were vague and have had little impact so far, but Goldammer insisted that the Kiev meeting was “an important first step.” Never before, he said, had forest managers shared so much information about dangers that were long considered military secrets. Russia's fires may help bring those dangers to wider attention.

    • * Dan Charles is a writer based in Washington, D.C.

  7. ScienceInsider

    From the Science Policy Blog

    The U.S. Department of Energy has revised its plans to sequester carbon emissions from existing coal plants. FutureGen 2.0 would retrofit a plant that burns coal the old-fashioned way, by pulverizing it into fine powder, rather than by gasifying the coal before it's burned. The decision cedes to China the lead in developing more sophisticated coal technologies, but experts say that the project will give key insights on retrofitting hundreds of aging U.S. coal plants.

    A U.S. judge has overturned a decision last year by the U.S. Fish and Wildlife Service to remove the northern Rocky Mountain gray wolf from the list of endangered species in Montana and Idaho but leave it in place in Wyoming. Conservationists applauded the decision, but state wildlife officials in Montana and Idaho say that the wolves' rebounding population should allow for some hunting under proper management.

    Scott Doney, a marine geochemist at the Woods Hole Oceanographic Institution, has been nominated to be the chief scientist at the National Oceanic and Atmospheric Administration. And Cora Marrett, a sociologist and acting director of the National Science Foundation, has been chosen to be the agency's permanent deputy director.

    Federal scientists want to close some Alaskan fisheries beginning in January to protect the Steller sea lions in the Aleutian Islands. While conservationists say the measures don't go far enough, industrial fishers are already objecting to the suggestion.

    A bill before the U.S. Senate would ban invasive research on the estimated 1000 “research” chimpanzees in the country that live in laboratories. Scientists say the measure, similar to one pending for the past year in the House of Representatives, would impose “extreme and unreasonable” restrictions.

    For more science policy news, visit

  8. Human Evolution

    Tracing Evolution's Recent Fingerprints

    1. Ann Gibbons
    Thriving in thin air.

    DNA studies (top) show that most highland Tibetans carry a mutation that helps them survive at high altitude.


    For Rasmus Nielsen, it was a revelatory moment. He was analyzing the frequency of different mutations in the genomes of Tibetans living at high altitude, searching for adaptations that allow them to thrive in thin air. His team's analysis had generated a graph in which most of the mutations were clustered together. But two stood apart, indicating they existed in almost all Tibetan highlanders but not in their close relatives, the Han Chinese. The high frequency of the mutations showed that this was a radical example of rapid evolution, with strong natural selection acting on a single gene. “I have done many scans of selection before, but I've never seen such a clear result,” says Nielsen, a population geneticist at the University of California, Berkeley.

    Then, when Nielsen Googled the gene to find out its function, he got even more excited: Both mutations were in the EPAS1 gene that regulates oxygen sensing in humans. One of the mutations was so advantageous that it had spread to 90% of all Tibetans in just 4000 years, Nielsen and his colleagues at BGI in Shenzhen, China, reported in the 2 July issue of Science (p. 75). But fewer than 10% of the Han Chinese sampled (who live at sea level) carried this version of EPAS1. Thus the team had discovered the most rapid and strongest example of selection known in modern humans.

    It was the most radical of a flurry of recent discoveries of human genes that evolution has strongly favored, a process called positive selection. Four years ago, researchers thought that they would find hundreds of examples in which an advantageous mutation spread rapidly in a particular population. That prediction, based on the first scans of human genome sequence data, did not pan out, and by last year, some researchers were ready to give up. They now realize, however, that plenty of positive selection exists, but it is subtler and harder to trace than originally anticipated. Using new statistical methods, they have found many less dramatic mutations that, for example, also help highland Tibetans survive at high altitude. Others allow Yupik Eskimos to stay warm efficiently, Europeans to thrive on cereal grains, and, perhaps, East Asians avoid alcoholism.

    A growing number of researchers now think it is rare for a particular mutation to spread rapidly to most people within a population, as was the case with the EPAS1 gene. Instead, natural selection often acts in more complex ways, leaving a much more subtle trail in the genome, population geneticist Jonathan Pritchard of the University of Chicago wrote in Current Biology in February. Several genes may work together to boost an advantageous trait. Or different versions of the same gene may rise in frequency at the same time to produce the same beneficial result, such as boosting height or altering skin color. Such polygenic selection doesn't leave the classic genomic signature of a “hard” selective sweep, like the one Nielsen saw in his Tibetan data, and is thus tougher to detect. “There have been a bunch of papers that show very consistently selection across a lot of our genome, but of a type that doesn't leave these massive footprints,” says Gilean McVean, a population geneticist at the University of Oxford in the United Kingdom.

    Although natural selection's trail in the human genome is less obvious than researchers had hoped, they are now crafting new methods to follow it. New data sets, including the complete genomes of 1000 individuals from diverse populations, will be online by December. And researchers are testing new ways to detect selection acting on many gene variants at once or on particular adaptive traits. “We're moving beyond the paradigm of whether selection acted on one newly arisen gene to more complicated models that think about selection on multiple pathways,” says population geneticist Joshua Akey of the University of Washington, Seattle.

    Seeking selection

    Many researchers have argued that most of the obvious differences between humans today are the result of recent positive selection rather than mutations that accumulated randomly over time. All living humans are remarkably similar genetically because we all descended from a small founder population that arose in Africa about 200,000 years ago. As these modern humans moved around and, eventually, out of Africa in the past 80,000 years or so, they evolved genetic differences that helped them adapt to new climates, digest novel foods, and fight off new illnesses and parasites.

    Sometimes, dramatic new mutations produced those differences. Other times, selection acted on standing variation: variants that existed but had been rare in a founding population. When the variants suddenly became advantageous in a new environment, they became more common.

    But identifying the underlying gene variants that make a willowy Maasai warrior different from a compact Yupik Eskimo, for example, was “frustratingly slow” until recently, says Akey. Researchers had to guess which gene might be involved in an adaptive trait and study it within families. This method produced a few well-known successes, such as the discovery of mutations in genes that protect Africans from malaria or allow adults in dairy-farming groups to digest the sugar lactose in milk.

    Cereal genes.

    Populations whose main food is cereal grains have higher frequencies of a PRLP2 gene variant than do people who have other diets.

    SOURCE: A. HANCOCK ET AL., PNAS 107 (MAY 2010)

    With the sequencing of the complete human genome for the first time a decade ago, researchers were able to get a better handle on how selection has shaped the genome. Several large-scale projects used different methods to identify millions of single-nucleotide polymorphisms (SNPs) from across the genomes of people in different populations in Europe, Asia, and Africa. By comparing SNPs at the same sites in individuals from different populations, researchers could detect those where positive selection had driven a mutation to high frequencies in a population.

    Some of the first scans of the genome-wide databases produced tantalizing results. In 2006, Robert Moyzis of the University of California, Irvine, and colleagues identified 1800 such genes representing 7% of the genome. Two months later, Pritchard and his colleagues scanned a SNP catalog called the HapMap and also found “widespread signals of recent positive selection”: high frequencies of alleles in some groups that were rare in others from Europe, Asia, or Africa. But neither group identified precise locations of the newly evolved mutations.

    As more researchers mined these data sets and added DNA from new populations, they dug out nuggets of positive selection in genes that seem to reflect adaptations to different environments or diets. Europeans have particular versions of the SLC24A5 gene—one of a half-dozen different genes now known to affect the color of skin, hair, or eyes. East Asians have variants of the EDAR gene that cause thicker hair and, possibly, changes in eyes, skin, and sweat glands, likely adaptations to a humid climate. Asians with high-starch diets have more copies of the gene for salivary amylase, which digests starch in the mouth.

    Interestingly, few of the mutations under strong selection were associated with dramatic stories of human triumph over dire circumstances, such as the bubonic plague. “Selection is not as sexy as you think,” says evolutionary geneticist Pardis Sabeti of Harvard University. “It's not just about mass famines and the plague. It's also about women who drank milk, gained a little more weight, and had seven kids to their neighbor's six. That's enough to have a huge effect over time.”

    In the past 4 years, these discoveries of selection for relatively mundane adaptations set off an intense competition to find more. Researchers were scanning data sets at a “frenetic pace,” Akey wrote last year in a review in Genome Research. He counted more than 21 genome-wide scans that identified 2465 genes in 722 regions of the genome thought to have undergone positive selection. The identification of so many regions of the genome under positive selection prompted some researchers to conclude that evolution had accelerated as humans spread around the globe and adapted to new challenges.

    But by the middle of 2009, enthusiasm began to wane. Researchers had scrutinized only a few of those 2465 in detail, netting only a handful of obvious mutations under selection, partly because it is so difficult to test function in the lab, says Akey. They were also unable to confirm that many of the genes discovered really were under strong selection. Out of 21 scans, 722 regions were identified by two or more studies, but only 129 regions were found by four or more studies, Akey wrote. “Sometimes, when people have gone fishing with the same pole and the same bait in the same lake, they have found completely different fish,” says Akey.

    Those researchers who did find interesting targets couldn't always rule out that demographics—the size and movements of populations—had produced signals that mimicked selection. For example, did certain populations share high frequencies of the same rare allele because it was under strong selection there, or just because the populations were recently descended from the same small group of ancestors? “I think people had naïve expectations about how easy it would be to detect positive selection in the genome,” says Nielsen.

    Finally, few teams have been able to prove that a particular allele actually affects the function of a trait under selection. In many cases, researchers couldn't even name the gene involved because the regions detected contain many genes or do not code for proteins. “In only a handful has there been much progress in identifying the causal mutations and extracting these biological insights about their function,” Sabeti wrote in the 12 February issue of Science (p. 883). Says McVean: “That's why the whole field—the program of trying to find selective sweeps—kind of ground to a halt.”

    Soft sweeps

    Yet McVean and others were convinced that positive selection had shaped much of the genome but lay beneath the radar of methods used to detect it. Those methods are particularly crude when it comes to detecting subtle signs of positive selection, such as when selection acts on several genes at once or on standing variation. “It's very likely that many traits that are different between populations are coded by different alleles; any one may not be so strong,” says population geneticist Pleuni Pennings of Ludwig Maximilian University of Munich in Germany.

    Consequently, earlier this year Pritchard and his colleagues proposed an alternative to strong selection on single new mutations. In Current Biology, they argued that selection on more than one gene at once could allow a new trait—such as increased height—to sweep more rapidly through a group.

    Detecting such polygenic selection is one of the new frontiers. Mark Stoneking of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, and his colleagues have identified what they think is parallel selection of three variants of the gene for TRPV6 that aids in the digestion of milk.

    Milky way.

    This Datog woman from Tanzania (left) and Turkana man from Kenya are pastoralists who can digest milk as adults.


    When Stoneking's team looked at the full sequences of this gene and others in 24 African Americans and 23 individuals of European descent, they found many variants of the genes in African Americans but just three types in Europeans. This distribution suggested that the three variants originated in Africa but were swept to high frequency in the ancestors of Europeans after they migrated out of Africa and became dairy farmers, Stoneking reported in PLoS ONE in 2008. They also showed in patch-clamp studies of intestinal cells that TRPV6 regulates the uptake of dietary calcium and, thus, may have co-evolved with lactose tolerance.

    Another tactic for finding selection acting on several genes at once is to look at phenotypes—or physical traits—in humans who live in extreme environments. Although the EPAS1 allele found in 90% of Tibetan highlanders was a dramatic case, it is just one of more than three dozen gene variants under positive selection that work together to help Tibetans survive at 4200 meters, according to work this year by three international teams. Their success in finding so much positive selection in one population “suggests if we want to find unique genes under selection, we should look in other extreme environments,” says geneticist Lynn Jorde of the University of Utah in Salt Lake City, leader of one team.

    A new way to spot subtle selection acting on more than one gene at once is to compare populations that have faced similar evolutionary challenges. For example, human geneticist Anna Di Rienzo of the University of Chicago and her graduate student Angela Hancock have looked at frequencies of SNPs in groups, such as the Chukchee and the Naukan Yup'ik of Siberia, that have adapted to life in polar regions, or that ate more cereal grains after the transition to agriculture, such as the French, Tuscans, Palestinians, and Druze. They gathered environmental and dietary data for 61 populations cataloged in various databases, including the Human Genome Diversity Project. Then they compared frequencies of alleles in all the populations sorted according to the environment in which they lived (dry, humid, polar, or temperate); mode of subsistence (agriculture, foraging, horticulture, or pastoralism); and diet (cereals; fats, meat, and milk; or roots and tubers).

    They identified the alleles that varied the most consistently in frequency across all populations (low in some; high in others). People who lived in similar habitats or ate similar foods had similar frequencies of the same alleles, they reported online 5 May in the Proceedings of the National Academy of Sciences. For example, more individuals in polar regions had the same alleles in genes associated with energy metabolism, and more people who foraged for roots and tubers had alleles that were rare in groups with other diets. Specifically, more Europeans and Middle Easterners have a variant of the PRLP2 gene, which encodes a protein important for breaking down fats in plant foods, which may reflect their ancestors' adaptation to agriculture. “This method has the power to detect advantageous alleles that escape other methods,” says Di Rienzo.

    While several teams are developing new methods to identify polygenic soft sweeps, others are working to pinpoint more precisely the DNA under positive selection. Sabeti and her team reported in their 12 February Science paper that they have increased the resolution of SNP data by 100-fold by combining five different statistical methods to detect patterns of selection in the genome. By analyzing the same regions of DNA with different methods, Sabeti's team was able to home in on 64 regions containing just a single gene, which narrows the search for a SNP that may boost an adaptive trait.

    Many groups are also ramping up efforts to do functional studies of the gene variants they have identified. Some labs are seeing if a gene variant is expressed in different tissues or at different times in development. Others are collaborating with labs that create mice with or without specific gene variants to see how they develop. And some are using microarrays to see how different gene variants affect gene regulation.

    Finally, many researchers are looking forward to the complete genomes of 1000 individuals in the 1000 Genomes Project. This project includes more diverse populations from Africa, which have not been sampled as well as Asians and Europeans. The data will be available by the end of the year. Others are searching for recent evolution in large, multigenerational data sets to spot changes in the age of first reproduction and menopause, or total blood cholesterol, for example, in different generations and populations, Stephen Stearns of Yale University wrote online 3 August in Nature Reviews Genetics.

    As researchers look forward to scanning these new data sets, they say that the key question is no longer how much positive selection is in the genome. “I want to move beyond simple laundry lists of candidate gene regions to understand what are the real stories that went on,” says Stoneking. “What did our ancestors have to adapt to as they spread round the world?”

  9. Profile: Pauline Wiessner

    Anthropologist Brings Worlds Together

    1. Michael Balter
    Engaged anthropologist.

    Polly Wiessner with her pet cockatoo and gifts from friends in the Kalahari and Papua New Guinea.


    SALT LAKE CITY—Late one night around 2003, University of Utah anthropologist Pauline Wiessner was awakened by a telephone call from some Kalahari Bushmen she had studied in Namibia. The Bushmen, also known as San, had managed to get hold of a satellite phone belonging to a safari company. They told her that they had just called the famous musician Yo-Yo Ma about an offer he had made when he toured the Kalahari a decade earlier: Ma had apparently agreed to buy shoes for their soccer team. Now the Bushmen wanted to draw outlines of their feet, send them to Wiessner in Salt Lake City, and have her buy the shoes and send the bill to Ma.

    Wiessner didn't worry that helping her research subjects, former hunter-gatherers now coping with the modern world, would compromise her scientific objectivity. She simply agreed, realizing that the Bushmen were using borrowed modern technology to expand their traditional social networks across the globe. And, as she had put it in a recent talk, such social networks had probably been key to the evolutionary success of our hunter-gatherer ancestors, allowing them to travel great distances and eventually “move out of Africa and colonize much of the planet.”

    As it happened, the Bushmen, lacking postal services, had no way to get the drawings to her, and the shoes were never purchased. But Wiessner, 62, known as Polly, sees no conflict in her dual role as both observer and participant in traditional societies. For nearly 4 decades, she has been carrying out anthropological fieldwork that links science with advocacy and ties the present to the past. Her research on exchange networks in Africa's Kalahari Desert and in Papua New Guinea (P.N.G.) has provided anthropologists with some of their best models for the cultural evolution of prehistoric societies. It forms “the basis of a lot of people's thinking about how we became human,” says anthropologist Alison Brooks of George Washington University in Washington, D.C. Adds archaeologist Clive Gamble of Royal Holloway, University of London: “Take away Polly's insights, and our view of the social world of our Paleolithic ancestors would contract back to the scale of the cave.” Along the way, Wiessner has helped the traditional peoples she works with navigate the modern world. She is regarded as a leading practitioner of “engaged anthropology,” in which researchers collaborate with the people they study. Although she now lives in Salt Lake City (with a pet cockatoo that drinks from her coffee cup in the morning and her margarita glass in the evening), she still works closely with African Bushmen and P.N.G. tribesmen and is considered a friend to both cultures. “Polly wanted to continue working with the people here,” says Akii Tumu, director of the Enga Tradition and Transition Center in Wabag, a cultural center that Wiessner helped to create and fund. Tumu, who has collaborated on Wiessner's research for 25 years, says this makes her “outstandingly different from all other foreign people.” Wiessner's ability to bridge the many worlds in which she works makes her one of anthropology's “great souls,” says anthropologist Sarah Blaffer Hrdy, professor emeritus at the University of California (UC), Davis. “She is the old-fashioned kind of anthropologist, … a scholar who studies human nature in all its diversity.”

    Long nights in the Kalahari

    Wiessner, who has spent years living among poor people in traditional societies, was born in Vermont into a comfortable existence, the daughter of a famed mountain climber. She began climbing and skiing early on, fostering her love of the outdoors. And she says her experiences at a strict Canadian boarding school prepared her for the hardships of fieldwork.

    Well connected.

    The late Chu!o n!a, shown here in the 1970s, had 25 Bushmen gift-exchange partners across the Kalahari Desert.


    But she was a troublemaker at school and unable to get into a good college at first. So she went to the now-defunct Bennett College in Millbrook, New York, which Wiessner says catered to wealthy young women who wanted to marry well. Wiessner thrived and soon transferred to Sarah Lawrence College. While at Sarah Lawrence, she volunteered for a summer dig at a prehistoric site in France. There she met Lewis Binford, a founder of the scientifically oriented New Archaeology movement, and later worked on his analyses of Paleolithic stone tools.

    After graduating, Wiessner was introduced to the new field of ethnoarchaeology, the study of modern people to see how the archaeological record was created. She hooked up with John Yellen, now archaeology program director at the National Science Foundation, and helped him draw maps of Bushmen camps in Botswana, recording the spatial patterns of discarded animal bones.

    These early experiences taught Wiessner that the present and the past were inextricably linked, a theme that would come to dominate her research career. As a graduate student at the University of Michigan, she started out studying the stylistic differences among Late Stone Age stone tools called microliths in Botswana. But after 2 weeks in the field, Wiessner says, “I realized this was probably the most boring project in the world. I was looking at variation in microliths when I should be looking at living people and the social processes that generate stylistic variation.”

    Wiessner set about recording the stylistic variations among artifacts such as projectile points and beadwork that were produced by different groups of Bushmen, who in the 1970s still lived mostly by hunting and gathering. She traveled all over Botswana, usually alone. “She is a really tough cookie,” says Yellen.

    Then months of heavy rains hit her field area. The rain knocked the nuts out of trees, triggered the growth of tall grasses that choked off more edible plants, and dispersed the large antelopes that the Bushmen relied upon. “The people went through a period of extreme hunger,” recalls Wiessner. But the episode was a “turning point” in her research. The Bushmen were often too hungry to talk about style. So Wiessner, who by now had some competency speaking Ju/'hoansi, the Bushman language there, spent her time sitting around the camps and writing down what people were saying and doing.

    She observed that the men and women were busy making objects, such as arrowheads, knives, beads, and clothing, and talking about loved ones far away and how much they missed them. Meanwhile, young men went off to areas up to 200 kilometers distant to see who was there and how well they were doing. Then, when the people were on the brink of starvation, they set off with their objects—which Wiessner soon realized were gifts—to visit other Bushmen camps. Thus Wiessner deciphered the gift-giving exchange that the Bushmen called hxaro, which ties Kalahari peoples together in farflung social networks.

    Between 1973 and 1975, Wiessner stayed in Botswana, tracking the hxaro networks. She found that adults had an average of about 16 stable partners in Bushmen camps near and far, some with more closely related people such as first cousins but many with more distantly related kin. Her study formed the basis of her 1977 Ph.D. thesis, which is still widely cited for its potential insights into how prehistoric hunter-gatherers survived rapidly changing climates and environments. “The central question … was how hunter-gatherers with no money in the bank, no grain in the larder, and no animals on the hoof deal with risk when the environment fails,” Wiessner says. Her findings had an immediate impact on anthropology, says Hrdy: “Polly showed not only how central such sharing and exchange systems were but also how strategic and innovative humans must have been in establishing and maintaining them.”

    After the rains had subsided, Wiessner continued her work on style and found that the styles conveyed information about the social identities of various Bushmen groups. Archaeologists immediately leaped on her work for its potential applications in understanding stylistic variation in past cultures. “She saw the functions of style more clearly than anyone,” says archaeologist Iain Davidson of the University of New England in Armidale, Australia.

    The engaged anthropologist

    In 1981, Wiessner landed a job as a research associate at the Max Planck Institute for Human Ethology in Andechs, Germany, and in 1985, still on the Max Planck payroll, she moved to Enga province in the highlands of P.N.G., where her then-husband had been hired as a health administrator. Although she hadn't planned to do research in P.N.G., Wiessner took advantage of her new circumstances to launch the next phase of her career: a 10-year oral-history project, with P.N.G. colleagues and the elders of 110 Enga tribes, that covered seven generations of Enga history. Once again, Wiessner was engaged in a project that used past and present to inform each other. Wiessner and Tumu cross-correlated the oral histories among tribes going back hundreds of years. They were able to trace the cultural evolution of Enga exchange networks and social hierarchies as the people transitioned from hunting and gathering and subsistence agriculture to a society with agricultural surpluses. This shift was triggered about 350 years ago by the introduction of the sweet potato, which grows more easily in poor highland soils than taro, the previous staple crop. Surplus production fostered increased competition, the emergence of ceremonial exchange networks linking tens of thousands of people, and the rise of leaders who managed large amounts of wealth, including pigs, which thrived on sweet potatoes and could be given as gifts or exchanged.


    A Papua New Guinea clan avoids war over a recent murder with payment of cash and nearly 200 pigs.


    The book that she and Tumu published in 1998, titled Historical Vines, is “one of the best case studies of cultural evolution in the literature,” says ecologist Peter Richerson of UC Davis.

    In 1995, when its director retired, the Max Planck institute closed its doors. Wiessner returned to the Kalahari, this time to Namibia, where social and political changes had forced the Bushmen into towns with few jobs and little means of livelihood. Wiessner teamed up with the late anthropologist and filmmaker John Marshall ( to both study and try to do something about the changes in land use and conservation policies that threatened the Bushmen's survival. One result was the 2002 classic documentary film series A Kalahari Family, for which Wiessner, Brooks, and Yellen served as advisers. Since Marshall's death in 2005, Wiessner has continued to advocate for the Bushmen.

    “Polly made the well-being of the [Bushmen] her priority as they made the transition from nomadic hunter-gatherers to sedentary rural workers and herders,” says anthropologist Nancy Howell of the University of Toronto in Canada. Wiessner has been “extremely generous with her time and money,” adds anthropologist Robert Hitchcock of Michigan State University in East Lansing. For example, she helped the Bushmen build protective structures for their waterholes so they wouldn't be overrun by elephants. She also provided “connections to funding sources, technical assistance, and recommendations to the [Bushmen] themselves and to the non-governmental organizations, government agencies, and international organizations working with them,” Hitchcock says.

    In 1998, Wiessner returned to live in the United States for the first time in nearly 30 years, taking first a temporary and then a permanent position at the University of Utah. She continued to make regular visits to both Namibia and P.N.G. In Enga province, she turned her attention to one of the deadly consequences of social hierarchy: warfare. Tribal wars had plagued the region for hundreds of years, but when she first came to P.N.G., Wiessner says, these wars were serious yet still largely contained. “In 1985, I would take my lunch, go up on a hillside, and watch. The wars were fought with bows and arrows and … to reestablish power balances, not to wipe anyone out.” After two or three deaths, Wiessner says, “they would call an end to the fight and pigs would be exchanged.” That all changed when M-16s came to Enga and fell into the hands of what Wiessner calls “young Rambos” who were poor and had nothing to lose. Once guns arrived, up to 200 people could die in a war, “and you wouldn't want to go near them.”

    Wiessner began collecting data on the wars and shared it with tribal leaders and local magistrates eager to stop the escalating violence. When the Enga Tradition and Transition Center—which serves as a museum, meeting place, and repository for Enga's cultural history—opened its doors last September, it was immediately pressed into service as a safe, neutral place where community leaders could come together. Tumu says Wiessner was the “driving force” behind the center. She personally funded half the $1.25 million price tag by selling land she owned in Vermont. (The Enga provincial government paid the other half.)

    The latest data collected by Wiessner's collaborators from Enga court records indicate that the total number of deaths from warfare has fallen over the past 4 years, accompanied by “a real change in attitude about how to deal with conflict,” she says.

    Not all anthropologists embrace Wiessner's highly engaged style; the field continues to debate just what the relationship between an anthropologist and his or her “subjects” should be. But Wiessner's approach, some researchers say, fits a recent trend in anthropology. Setha Low, an anthropologist at City University of New York, says that over the past 20 years or so the field has been undergoing a transition from a more detached to a more engaged attitude toward the peoples it studies. Low, who is coediting a special supplement of Current Anthropology on engaged anthropology scheduled for this fall, adds that “anthropology originally started out very engaged.” Thus early-20th-century researchers like Franz Boas and Margaret Mead were outspoken critics of racism and colonialism. But by the 1950s, a sharp increase in the number of anthropologists based in the universities— where scientific objectivity was prized— and the rise of McCarthyism, which targeted many anthropologists considered activist and left-leaning, took a big toll on engaged anthropology. The field is now reverting to its engaged roots, Low says.

    And Wiessner is confident that active collaborations with her subjects aids rather than hinders her research. “All the research I've done has been as part of a team. Many people feel this is something different than science. But if you are returning something to the people you work with, and working on their problems, you find out more and you go deeper.”

    For many of her colleagues, Wiessner is the ideal of what an anthropologist should be. “She pioneered a new kind of collaborative research, where you don't just use informants but you involve them in your research,” says Brooks. “She fulfills the dream of being a universal anthropologist, the kind we rarely see these days.”

  10. Paleoclimatology

    Climate Scientists Shine Light on Cave Ice

    1. Lucas Laursen

    Some cave ice dates back thousands of years.


    EISRIESENWELT, AUSTRIA—Tracing his glove along a chalky layer in a house-size block of ice that lines this cave in the Austrian Alps, Michael Behm can feel all that is left of an ancient warm spell. The ice, likely formed over the decades or centuries as calcium-enriched rainwater trickled deep into the cave and froze, must have once warmed enough on top to melt and release a few years' worth of the mineral, the Vienna University of Technology geophysicist explains.

    Behm is one of a small but growing number of researchers who are investigating whether persistent ice that drapes the inside of some caves can reveal what the climate outside was once like. At a recent workshop in Austria,* which included visits to several nearby ice caves, about 50 such scientists discussed this formidable challenge and reported tantalizing progress. One team, for example, has been using ice within a Romanian cave to reconstruct a 1000-year climate history of the local region.

    By dating layers of cave ice that form from ponds of trapped rainwater and then analyzing the isotopes and other substances that make up those layers, these scientists aim to chart past changes in temperature, rainfall, and other climate indicators such as carbon dioxide levels. It's a strategy paleoclimatologists have long pursued with ice cores taken from glaciers and polar caps, or with layers of lake sediment, but cave ice has proven much more difficult to study and interpret. Every cave is unique in how water trickles in and freezes, and researchers have to go to great lengths to establish whether the ice layers they see represent annual, seasonal, or other time scales of deposition. “Cave ice is a complicated business,” says Greenland ice core specialist Sigfús Johnsen of the University of Copenhagen.

    But it's one worth pursuing, say Behm and others at the Austrian workshop, as polar ice cores don't offer insight into the climate histories of temperate regions, where most people live. “There's an urgent need to look for ice archives outside the polar region,” says environmental scientist Dietmar Wagenbach of the University of Heidelberg in Germany, who attended the workshop.

    Mountain glaciers aren't the easy answer either, because they are less representative of the climate near settled areas. Glaciers require massive snowfall and long-lasting cold to form, but ice can form in caves and trap climate information even in regions that don't normally frost over. A cave with small temperature differences at its entrances can develop strong internal winds, as air moves to equalize the cave's internal temperature. If the wind gets fast enough, as in a constriction, it can also get cold enough to freeze standing or dripping water. Long before electric refrigerators, ancient Persians used the same principle to make ice.

    The study of tree rings, lake sediments, and other so-called climate proxies has provided some history of the climate in temperate regions, but paleoclimatologists are still eager for other sources of data to help them predict how future changes in climate might alter these locations. And ice is a paleoclimatologist's best friend because it can retain many different clues to the past climate. In polar regions, recently fallen snow slowly becomes compressed into a layer of ice whose ratios of hydrogen and oxygen isotopes reflect the atmospheric temperature at the time of condensation. Such ice can also trap grains of pollen and dust and air bubbles that reveal concentrations of gases such as carbon dioxide that are important to reconstructing past climates.

    Climate studies of ice cores from glaciers and polar caps took off in the 1960s, and some of those cores may record climate histories going back a million years. Similar studies of cave ice, however, have lagged far behind. Speleology, the scientific study of caves, dates back to the 19th century, but most such work has concentrated on the geology of the caverns, or the unusual flora and fauna found within them. Emil Racoviță of Cluj University in Romania, a pioneering cave biologist, may have been among the first to recognize the record-keeping potential of cave ice. In a 1927 report on his exploration of the Scărișoara cave in Romania, he notes that such ice must have formed under different climatic conditions and that it would be good to “decipher the passionate enigmas of the history of the ice.” Decades later, Racoviță's assistant Mihai Serban followed up on this idea, reporting in an Italian journal that he could measure certain isotopes in cave ice from Scărișoara, although the data didn't provide climate clues.

    The idea of doing paleoclimatology on cave ice attracted serious international attention about 11 years ago, when a pair of Canadian cavers—one a cave operator in Alberta and the other a geography master's student at the University of Calgary—published a study that identified different mechanisms of cave-ice formation. They reported in the journal Boreas that by looking in the right places in caves and taking into account how the ice formed, they could extract paleoclimatic information from isotopes in the cave ice.

    Cool science.

    Before extracting cores that might reveal past climate information, researchers use radar to measure the thickness of the ice.


    The idea gained more momentum from the first workshop on ice caves, held in 2004. But even now, few scientific papers have been published on the topic, as a variety of technical difficulties have stymied researchers. Small rocks in the ice have halted efforts to extract long ice cores. And Wagenbach's student Barbara May notes that cave ice is actually too warm for drills designed for extracting ice cores from glaciers; melted and refrozen ice jammed her drill until she added a lubricant, which she fears could interfere with many analyses, including those of air bubbles, isotopes, and particles in the ice.

    Teasing climate clues from cave ice isn't as simple as extracting a clean core, however. The most commonly drilled cave ice mimics the tidy horizontal layers seen in sedimentary rock. A single layer, however, could represent either a year's worth of rain that trickled into the cave or just a few months when a river poured in a torrent of water. Each process would preserve different clues to climate, so researchers need to determine how water has historically entered a cave. The size of the ice crystals, whether the ice froze from the bottom up or from the top down, whether it partly melted or eroded after solidifying—these and other nuances can affect measurements and require careful interpretation, Behm says.

    That complexity is one reason cave-ice studies have progressed so slowly. Another is that the topic is just a sideline for most researchers. Behm, for example, uses ground-penetrating radar (GPR) to study Earth's crust. He only recently began trying the technology on ice caves. “Cave ice is such a perfect insulator that the signal-to-noise ratio is very high for GPR,” he says.

    In studies of four Austrian caves, Behm has found layers in the ice that reflect his radar signal. He suspects that they may be accumulations of calcite from periods when ice melted and released its dissolved minerals, a possible sign of outside climate changes. In June 2007, May drilled a 7-meter ice core from one of the caves, but so far her isotope studies haven't nailed down firm dates along its length.

    Others have had better luck. At the 2006 ice caves workshop, a Danish-Slovakian team reported extracting a 14-meter core that they dated at about 1250 years based on carbondating of a bat found in nearby ice. Sharp changes in the accumulation of ice from year to year make the core hard to interpret, but it does show signatures of some climate oscillations found in other records.

    At this year's workshop, geology Ph.D. student Aurel Perșoiu of the University of South Florida in Tampa described even more promising work with ice from the same Scărișoara cave Racoviță studied. Using a 6.5-meter ice core drilled from the cave, Perșoiu and colleagues are making an ambitious attempt to reconstruct the past 2000 years of the region's climate history. By carbon-dating organic remains such as leaves and insects in the ice, the team has related core depth to age in the top half of the core. And they've used that ice to reconstruct temperature variations within the region. The trends appear to match other regional climate proxies such as lake sediments, pollen, and stalagmites, Perșoiu says. A paper describing their methods is under review at the Journal of Geophysical Research. “We are being helped by paleoclimatologists,” Perșoiu says. “They are pushing us toward more mainstream journals.”

    Frozen past.

    A close look at the isotopes in ice can reveal climate information.


    Some researchers at the Austrian workshop compared the debate over the usefulness of cave ice to a similar one that took place decades ago over stalagmites, towers of limestone that build up in active caves. At first, paleoclimatologists derided the idea that stalagmites could hold valuable data, but now studies of “speleothems” have become standard practice (Science, 27 July 2007, p. 448).

    To spread the word about cave ice to a broader audience, glaciologist Stephan Gruber of the University of Zürich in Switzerland is now overseeing a special issue of The Cryosphere devoted to research presented at the workshop. Improving communication with scientists in related fields will be vital; one workshop attendee wore a baseball cap with “Glaciologist” printed on the front to remind cave experts to cut the jargon. (Cave scientists favor logos featuring bats, their unofficial mascot.) Yet with results from Scă rișoara's ice in the pipeline and a book project to translate the backlog of European cave-ice articles into English in the works, Perșoiu is optimistic about the field's future. Cave-ice research, he predicts, “is about to reach a climax.”

    • Lucas Laursen is a writer based in Madrid.

    • * 4th International Workshop on Ice Caves, 5–11 June 2010.

  11. News

    Do We Have the Energy for the Next Transition?

    1. Richard A. Kerr
    Heated, but how?

    Fossil fuels have many innate advantages over renewable energy sources.


    Wind turbines dot ridges, distillers turn farmers' corn into ethanol by the billions of liters, and solar panels sprout on roofs. The energy revolution that will bring us clean, secure energy is under way, sort of. Never has the world so self-consciously tried to move toward new sources of energy. But the history of past major energy transitions—from wood to coal, and from coal to oil and gas—suggests that it will be a long, tough road to scaling up alternatives to fossil fuels that don't stoke greenhouse warming.

    A big problem is that, for the first time, the world is moving to tap new energy sources that are, in many ways, less useful and convenient than the currently dominant sources: fossil fuels. “Up to now, we've always gone to a better fuel,” notes economist Robert Kaufmann of Boston University (BU). And oil has proved the best of the better. Compared with wood or even coal or gas, it “is a great fuel,” Kaufmann says. Oil is densely packed with energy, easily transported and stored, and efficient at releasing its energy in modern engines.

    Renewables are another matter. Fuel sources like corn kernels or wood chips tend to be bulky. Their energy content is diffuse. Planting energy crops and building solar or wind farms is a land-hungry process, and the energy they deliver is often intermittent and hard to store. So far, “you can't run airliners or cars on photovoltaics,” Kaufmann says.

    “We are confronted with a society built on high-quality energy, dense forms of energy, fossil fuels especially,” says Kaufmann's BU colleague, ecological economist Cutler Cleveland. “Could you have the same standard of living with renewables? I don't think we really know. Things might have to change very fundamentally.”

    Looming large

    One of the most daunting aspects of the coming energy transition is its sheer size. It will have to be huge. Since 1800—when wood and animal feed provided more than 95% of U.S. energy—world energy use has increased by a factor of more than 20. Replacing even half of the coal, oil, and gas consumed today would require 6 terawatts of renewable energy, estimates systems analyst Arnulf Grübler of the International Institute for Applied Systems Analysis (IIASA) in Laxenburg, Austria. In contrast, renewables today produce just 0.5 terawatt.

    Fossil fuels, however, also had humble beginnings. For tens of thousands of years, wood and other plant products provided humankind's energy needs. Historians do not always agree on exactly which social, technological, and economic forces drove the momentous shift from wood to coal—and then to oil and gas—in the 19th and early 20th centuries. But one factor clearly was the growing scarcity of existing fuels, says environmental historian Brian Black of Pennsylvania State University, Altoona. During the War of 1812, for instance, wood shortages around Philadelphia prompted residents to experiment with burning coal for heat and industry. And when Edwin Drake drilled the first oil well in the United States in 1858, whale oil for lamps was getting harder to come by. U.S. kerosene from oil soon displaced whale oil as an illuminant, and Americans were out of the whaling business.

    Scarcity, however, is less of a factor today. The world is not yet running short of fossil fuels, notes energy analyst Richard Nehring of Nehring Associates in Colorado Springs, Colorado. Coal and oil production likely won't “peak” until something like 2030, give or take a decade, he estimates. Natural-gas production could keep pace with rising demand until 2050. Nehring's production peaks are on the early side of published estimates, but they still suggest that broad-based fears of energy shortages will not be driving a shift to renewables for the next decade or two.

    The continued abundance of fossil fuels—and their relatively low cost—has also helped highlight some of the other shortcomings of renewables. They include:

    Lower density

    Solid and liquid fossil fuels are packed with energy. A kilogram of oil, for example, holds three times as much energy as a kilogram of plant biomass, environmental scientist Vaclav Smil of the University of Manitoba in Winnipeg, Canada, estimates in his recent book Energy Transitions: History, Requirements, Prospects. The difference swells to almost five times if the comparison is made in terms of energy per unit volume instead of weight.

    The gap between fossil fuels and renewables grows even larger when analysts measure “power density,” or the amount of energy produced per square meter of Earth's surface. A coal mine or oil field, for instance, yields five to 50 times more power per square meter than a solar facility, 10 to 100 times more than a wind farm, and 100 to 1000 times more than a biomass plant. Even if analysts subtract the energy needed to extract, transport, and process coal, it still yields 50 times more energy than ethanol from corn and 10 times more than ethanol from sugar cane, according to Cleveland. Oil is now 13 times more productive than corn ethanol.

    Greater intermittency

    Leading renewables are far worse off than fossil fuels and even wood when it comes to another crucial energy quality: its continuity of supply. A coal-fired power plant—if not down for repairs or maintenance—can be cranked up as needed; not so sun or wind. Coal-fired, gas-fired, or nuclear power plants operate 75% to 90% of the time, Cleveland says. In contrast, wind turbines typically stand idle 65% to 80% of the time. And the sun is guaranteed to be unavailable half the time, not counting the passing cloud. Engineers haven't yet developed energy storage devices suitable for storing solar and wind power, and they would add to the ultimate cost.


    There is only one quality—geographic distribution—in which renewables reach parity with fossil fuels. Both are handicapped by their uneven distribution. Oil is famously concentrated in the Middle East, Russia enjoys an abundance of natural gas, and the United States is the Saudi Arabia of coal. But “many of the windiest and sunny regions in the world are virtually uninhabited,” Cleveland says, meaning electricity would have to be moved long distances to population centers. The same patchiness holds for other renewables, from geothermal to hydro energy. For biomass, everyone has some arable land for growing energy crops, but much of it is already spoken for. And even if the land were available, energy crop yields would fall short of the need. The ethanol from the whole U.S. corn crop, for instance, could replace just 15% of the country's annual gasoline use, Smil says.

    Top dog, for now.

    Fossil fuels each took half a century to dominate energy production (bottom). Renewables have gained (top left), but they are diffuse and therefore less attractive sources (top right).


    Ray of hope?

    The “sobering reality,” Smil says, is that there is only one renewable—solar energy—that could by itself meet future energy demands (see p. 786). Wind power could conceivably make a significant contribution, but each of the rest—hydro, biomass, ocean waves, geothermal, ocean currents, and ocean thermal differences—would provide just one-tenth to one-ten-thousandth of today's energy output from fossil fuels.

    So the bulk of the burden will fall on solar, but turning the sun's rays into useful energy has a long way to go, Smil notes. Today, photovoltaic electricity accounts for less than 0.1% of the world's electricity. Solar heating, such as solar water heaters, accounts for less than 0.1% of total global energy production.

    Such numbers would have to grow rapidly for a long time to make a difference, but renewables' handicaps do not bode well for speeding up the next energy transition. Fossil fuels “were phenomenally attractive,” yet it still took 50 to 70 years to bring them into widespread use, says IIASA's Grübler. That's because, no matter how attractive a fuel might be, it takes time to create the infrastructure for extracting and transporting the resource, converting it into a usable form, and conveying it to the end user. It also takes time for inventors to develop enduse technologies—such as steam engines, internal combustion engines, and gas turbines—and for consumers to adopt them and create demand. Renewables “will be slower because they're less attractive,” says Grübler. “They don't offer new services; they just cost more.”

    Ambitions to bring down the cost of renewables and accelerate the transition to clean, renewable energy have waxed and waned. In the United States, those hopes hit one acme in 2008, when former Vice President Al Gore challenged the United States “to commit to producing 100% of our electricity from renewable energy and truly clean carbon-free sources within 10 years.” Smil calls that the epitome of “The Great Energy Delusion.” It's not going to happen that way, he says. No amount of political commitment can erase the technological inertia in the energy production and consumption system or completely counter the quality shortcomings of renewables.

    Still, renewable energy does have one clear advantage over fossil fuels: It doesn't produce the greenhouse gas carbon dioxide. Given the dearth of other incentives for scaling up renewables, “we may really need to engineer a transition,” says Cleveland, “particularly if we're going to be serious about managing carbon.” In practical terms, that re-engineering would mean lawmakers embracing policies that drive up the cost of fossil fuels and heavily subsidize renewables. But public support for such ideas has been lukewarm in the United States—whose citizens are person for person the world's biggest greenhouse gas emitters. Even in the midst of the worst oil spill in U.S. history, for instance, a poll by The New York Times/CBS News released 20 June found that although 90% of respondents agreed that “U.S. energy policy either needs fundamental changes or to be completely rebuilt,” just 49% supported new taxes on gasoline to fund new and renewable energy sources.

    With those kinds of polling results, “the best thing to do is reduce consumption,” says BU's Kaufmann, given that “we've got the technology to reduce energy use tremendously.” Conservation would buy time for meagerly attractive renewables to make some inroads before fossil fuels begin to bow out.

  12. News

    Sending African Sunlight to Europe, Special Delivery

    1. Daniel Clery
    Try to concentrate.

    Collectors that concentrate sunlight to heat a fluid and boil water are key to Desertec's design.


    Gerhard Knies started seriously thinking about the problem of energy on 26 April 1986. Working as a particle physicist at the DESY accelerator lab in Hamburg, Germany, he watched in horror as the news broke that nuclear reactor number 4 at Chornobyl in Ukraine had exploded, spreading fallout across Europe. “Why do this to ourselves,” he wondered, “when there are other options?”

    Like a true physicist, he began asking some basic questions: How much solar energy falls on Earth? Where is it most intense? How many solar collectors would Europe need to meet its energy needs? For Knies, the questions led to only one answer: Build huge solar power farms in the Sahara and transmit the electricity through subsea cables across the Mediterranean Sea to Europe.

    Knies's vision has since blossomed into Desertec, one of the world's most ambitious multinational efforts to scale up renewable energy. The goal: to build solar and other renewable power projects across North Africa and the Middle East capable of producing 500 gigawatts (GW) of electricity and so meet 15% of Europe's energy needs by 2050. Planners predict it will cost €400 billion or more to cover tens of thousands of square kilometers of desert with solar collectors and wind turbines, connected by thousands of kilometers of power cables.

    The project—which backers compare to the Apollo space program—has yet to generate a single kilowatt. But it has attracted an impressive roster of political and industry supporters in Europe and North Africa. Still, analysts say Desertec faces an array of daunting challenges, from finding ready cash to overcoming thorny political and security issues. “Technology is not the problem,” says Max Schön, president of the German branch of the Club of Rome in Hamburg, a think tank that has helped nurture the Desertec concept. “It is getting different cultures and economic structures working together.”

    Growing momentum

    Such worries haven't dampened the hopes of Desertec backers. In June, for instance, European Union (E.U.) Energy Commissioner Günther Oettinger predicted that electricity could start flowing across the Mediterranean in just 5 years. And earlier this year, more than 200 bidders expressed interest in working with the government of Morocco on its first contribution to Desertec: a $9 billion, 10-year plan to build solar power plants producing 2 GW of power. Meanwhile, some heavyweight corporations—including engineering giant Siemens and finance titans Deutsche Bank and Munich Re—are now helping the nonprofit Desertec Foundation develop a business plan by 2012.

    Such momentum was a distant dream during the aftermath of Chornobyl, when Knies—now chair of the board of trustees of the Hamburg-based Desertec Foundation—says he couldn't find much enthusiasm for his idea. That changed in the mid-1990s, as climate change became more of an issue. One turning point came when Knies organized a workshop at the Hamburg University of Technology that brought together energy experts to ponder his idea. Among other things, that meeting tackled two of the biggest technical questions facing Desertec: how best to make the electricity and how best to move it. The answers to both, the experts said, involve harnessing some emerging technologies.

    Concentration is key

    To generate Desertec's power, a number of studies have concluded that the best bet is “concentrating solar power” (CSP) technology, which uses reflectors of various shapes and configurations to heat a fluid such as water, oil, or molten salt. The hot fluid is then used to create steam to drive a turbine and generate electricity.

    Experts say CSP has a big advantage over other technologies, particularly photovoltaic solar arrays: Plant operators can store the heat for a few hours by pumping the hot fluid into an insulated container or by transferring its heat to another material such as concrete. That way, once the sun goes down, the heat can be extracted and used to keep the steam turbines producing electricity. In contrast, the only practical way to store large amounts of photovoltaic energy is to use electricity to pump water up to a reservoir and then later release the water through a hydroelectric dam when consumers need power—a relatively expensive and inefficient process.

    And CSP has another ace up its sleeve. By using boilers that can also be run on natural gas or biogas, plants can keep producing electricity on the rare cloudy day or if a sandstorm blots out the sun. CSP “looks from every side to be a very effective method,” says Hani El Nokraschy, a Germany-based businessperson who has been involved in Desertec since the late 1990s.

    Other power planners have come to similar conclusions. The world's biggest solar plant, the Solar Energy Generating Systems facility in California's Mojave Desert, has been pumping CSP power into the grid since 1984. Another company, Tessera Solar, later this year will start installing CSP systems at two more Californian sites. And in Spain, on the back of generous government incentives, companies are building dozens of new CSP plants.

    Go direct

    To move the power from Africa to Europe, an influential 2006 study commissioned by Germany's environment ministry suggested that Desertec tap another emerging technology, high-voltage direct-current (HVDC) transmission. HVDC solves a big problem in moving electricity over vast distances: power loss. Typical alternating-current grids can lose up to 45% of their loads when lines are long, El Nokraschy says. DC systems do better but have been limited by a lack of switches that could handle high voltage. In recent years, however, engineers have developed switches that can sustain 800 kilovolts, enabling HVDC lines to move current as far as 4000 kilometers with losses of just 10% to 15%.

    Tied together.

    Planners dream of linking solar and other renewable energy projects in North Africa to supply 15% of Europe's energy by 2050.


    Desertec isn't the only project eyeing HVDC. Nine European countries around the North Sea are planning to build an HVDC grid, in part to smooth the flow of power from plants that generate electricity using intermittent sources such as wind, the sun, and ocean tides. The grid could, for instance, enable power generated overnight by the U.K.'s offshore wind farms to be stored in Norwegian pump storage facilities until the next day. Desertec “can learn from the North Sea grid,” says the Club of Rome's Schön.

    Progress and worries

    The vision of coupling CSP with HVDC has helped Knies attract a diverse network of backers to Desertec's cause, among them the German Physical Society, Greenpeace, and Prince Hassan of Jordan. Today, the project is managed by the Desertec Foundation and an allied business arm, the Desertec Industrial Initiative (DII). In addition to forging partnerships with industry, the foundation and DII are working with governments—including officials from Europe, Morocco, Algeria, Tunisia, Egypt, and Jordan—to build support.

    Desertec officials hope Morocco's move to build solar plants is just the start of realizing their ambitious, and expensive, long-term plan. It includes solar farms covering 17,000 square kilometers of desert in North Africa and the Middle East, an area roughly the size of Swaziland. A network of HVDC cables capable of carrying 100 GW would transmit power several thousand kilometers across the Mediterranean and into Europe.

    Paying for that infrastructure, however, could be difficult. Planners estimate that the grid alone will cost more than €45 billion, and the entire project could run to €400 billion. Those are big numbers for banks and investors recovering from the biggest financial crisis in decades.

    Other worries could also spook potential funders. One is that, despite CSP's promise, its power currently costs considerably more than electricity from traditional sources. As a result, Spain, the United States, and other nations have used an array of incentives to encourage growth, including direct subsidies and rules that require utilities to generate a certain amount of renewable power. Recently, however, even the incentives haven't been enough to overcome the credit crunch. “It's now virtually impossible to get investment” in the United States, says Thomas Mancini, CSP program manager at the U.S. Department of Energy's Sandia National Laboratories in Albuquerque, New Mexico. “This could be a death knell [for the CSP industry] if it goes on too long.”

    Knies thinks that one key to solving the economic challenge is mass production. If Desertec were to meet all of Europe's energy demand by 2050, for example, it would need to install 12,000 GW of CSP, or roughly 1 GW per day. That sounds like a lot, but making a solar collector is no more complicated than making a car, Knies argues. A carmaker the size of Volkswagen could easily churn out collectors at the required rate. “The industrial capacity to do such a task exists,” Knies says.

    Other worries facing potential funders include a fragmented European energy grid that could make it difficult to easily move power across national boundaries and the lack of any dependable grid at all in parts of North Africa. The region also lacks harmonized national rules for exporting and importing renewable power. Finally, there are political tensions among North African and Middle Eastern nations, as well as corruption and terrorism, that make large-scale energy cooperation seem a distant prospect. “It's complicated; it's not only about energy and climate, it's also about water, people, and migration,” says Schön.

    Desertec is beginning to address some of these issues through the Desertec University Network, a group of institutions that aims to train a new generation of North African and Middle Eastern engineers and technicians specializing in renewable energy. Desertec will need trained people, says El Nokraschy: “You can't bring them all from Europe and put them in the desert. You need to take them from the surrounding area.”

    Ultimately, Knies believes, Desertec could help reduce political tensions. Through cooperation, the countries of the southern Mediterranean could learn to build and run cutting-edge power plants, boosting local employment. They would get plentiful power for their own needs, such as water desalination, and could export power at a profit. At the same time, Europe would get electricity with few carbon emissions and an alternative to potentially problematic power sources like the Chornobyl nuclear plant that originally sparked Knies's efforts. “Where,” he asks, “are the losers?”

  13. News

    Is There a Road Ahead for Cellulosic Ethanol?

    1. Robert F. Service
    Fueling doubts.

    Making ethanol from switchgrass (far left) can't yet compete with corn.


    Just a few years ago, the idea of turning farm and forest wastes into “cellulosic” ethanol, a biofuel to power cars and trucks, seemed a sure winner. Some researchers were predicting that they would soon perfect the new technologies needed to crack the cellulose and lignin molecules that had made grasses, cornstalks, and wood chips so much tougher to brew into ethanol than corn kernels. Both government agencies and private investors were pouring money into the field. In the United States, for instance, the Department of Energy (DOE) in 2007 unveiled plans to spend $385 million to back six commercial-scale reactors, while Congress approved hefty tax credits for biofuel makers. Venture capitalists invested billions in new cellulosic ethanol companies.

    That was then. Now, much of the optimism surrounding cellulosic ethanol has faded thanks to the ongoing economic slump, a plentiful supply of ethanol made from corn, and uncertainty among policymakers. Numerous companies have either shelved plans to build commercial-scale cellulosic ethanol plants or walked away altogether. Even the promise of DOE's millions hasn't enticed them back. “In the current financial climate, existing federal policies are simply not enough to encourage the investments that will make these fuels a reality,” says Jeremy Martin, a chemist with the Clean Vehicles Program of the Union of Concerned Scientists (UCS) in Washington, D.C.

    The upshot: The U.S. government's flagship plan to reduce the nation's dependence on oil by scaling up cellulosic ethanol is in deep trouble, highlighting the complex technical, economic, and political forces buffeting global efforts to create viable alternatives to fossil fuels. And observers say decisions that Congress and federal agencies make this year could shape the nascent U.S. biofuels industry for decades to come. “It's an absolutely critical year for biofuels,” says Wally Tyner, an agricultural economist at Purdue University in West Lafayette, Indiana.

    A promising start

    The plan to build an American biofuels industry on cellulose had been starting to pay off. In 2005, Congress approved new rules mandating a steady ramp-up in biofuels use. By 2022, lawmakers envisioned cars burning up to 36 billion gallons (136 billion liters) of biofuel a year, an amount equivalent to about one-quarter of today's U.S. gasoline use. Much of the early increase was to come from “first-generation” biofuels, primarily ethanol made from corn kernels. That industry has grown steadily, from turning out some 3 billion gallons of corn ethanol in 2005 to 12.1 billion gallons today. Most is blended with gasoline (typically 10% ethanol to 90% gasoline) to help reduce urban smog.

    Congress, however, has capped the amount of corn ethanol it wants in gas tanks at 15 billion gallons by 2015. In part, that's because making corn ethanol is energy intensive, so the fuel doesn't do much to offset fossil fuel use or lower greenhouse gas emissions. Beyond that first 15 billion gallons, policymakers envisioned biofuels coming from “advanced” sources, such as ethanol and gasoline-like hydrocarbons made from plant materials high in cellulose.

    The ramp-up in cellulosic ethanol production, however, is already well off track. Demonstration facilities are expected to turn out up to 25.5 million gallons this year—far below the 250 million gallons that the U.S. Environmental Protection Agency (EPA) once wanted fuelmakers to produce. In a telling sign of cellulosic ethanol's struggles, over the last year the agency twice scaled back its expectations after it became clear that the industry wouldn't be building commercial-scale plants as quickly as once thought.

    What happened to the promise?

    Part of the problem in scaling up cellulosic biofuels continues to be technical. To brew ethanol, manufacturers use yeast to ferment simple sugars such as glucose. That task is relatively cheap and easy when starting with a raw material—or “feedstock”—rich in those simple sugars, such as sugar cane in Brazil. In the U.S., brewers using corn as a feedstock face a slightly more complex process, because they first must use enzymes to break apart the starch in corn kernels into their component glucose molecules. The task becomes even more difficult when using cellulosic feedstocks such as switchgrass, corn stalks, or wood chips. The sugars in these feedstocks are locked in cellulose, hemicellulose, and lignin, biopolymers more complex than starch. Breaking those biopolymers into intermediate compounds that can be converted to ethanol remains a difficult problem. Researchers call it “recalcitrance,” and it currently limits brewers to converting just 40% of the energy content available in cellulosic feedstocks to ethanol. Fermentation, by contrast, converts about 90% of the energy in simple sugars to ethanol. That means cellulosic ethanol plants currently need far more raw material than first-generation plants do to make the same amount of ethanol.

    Growing gap.

    Energy legislation from 2007 mandates an increasing share of cellulosic ethanol (dark green). But the industry is already falling behind.


    Researchers say they are making steady, if slow, progress in increasing the conversion rate. They've engineered novel microbes, for instance, that can break down cellulose into fermentable sugars. “The recalcitrance barrier will fall,” predicts Lee Lynd, a metabolic engineer at Dartmouth College.

    Hitting the blend wall

    Even if it does, however, that breakthrough may not rejuvenate the field. That's because there is already an oversupply of first-generation ethanol on the market, Tyner says. At the moment, he notes, most ethanol is used to provide the 10% share in blended gasoline. But with the U.S. using a total of about 140 billion gallons of gasoline a year, the demand for ethanol is currently capped at about 14 billion gallons. Biorefineries already make 12.1 billion gallons of corn ethanol annually, he notes, and idled plants are capable of boosting the total to 15 billion gallons. The result is that the industry has reached a “blend wall,” he says. “There is no room for cellulosic ethanol.”

    That could change if the government and carmakers start pushing cars that run on “E85”—a blend of 85% ethanol and 15% petroleum—or if cellulosic ethanol brewers figure out how to make their product cheaper than corn ethanol. (Cellulosic ethanol currently costs about double.) But neither development is likely anytime soon, and that partly explains why investors now shy away from backing cellulosic ethanol. The recent recession didn't help. “You can't get a loan to fund an ethanol plant of any kind right now because of the blend wall,” says Bruce Dale, a chemical engineer and ethanol processing expert at Michigan State University, East Lansing.

    Policy worries

    Investors are also skittish because they aren't sure that government requirements mandating biofuels, and tax credits supporting them, are ironclad. Most of the existing $6 billion a year in ethanol subsidies and tax credits are currently up for renewal by Congress. Lawmakers have already allowed one tax credit for biodiesel to lapse, adding to investors' worries that ethanol subsidies could be next on the chopping block. “Until the government makes it absolutely clear that this is a long-term policy, investors will be reluctant to support the industry,” says Sean O'Hanlon, the executive director of the American Biofuels Council in Miami, Florida.

    A final challenge facing companies is ensuring long-term supplies of feedstock. Commercial-scale cellulosic ethanol plants, which can cost tens to hundreds of millions of dollars to build, are expected to operate for 3 decades or more. That means making deals with farmers to ensure steady access to agricultural wastes and other feedstocks. But “we don't have the supply chain in place to provide that much cellulosic material,” Dale says.

    Driving forward

    Despite all these challenges, analysts say Congress, EPA, and others can still make cellulosic ethanol viable. One option is for the government to alter tax incentives for biofuels. The current ethanol tax credit simply pays fuel blenders a flat $0.45 for each gallon of ethanol they use. A smarter option, UCS's Martin says, would be to offer larger credits to fuels—such as cellulosic ethanol—that are cleaner than corn ethanol or that could displace more gasoline.

    Purdue's Tyner suggests taking this approach one step further by linking ethanol subsidies to oil prices. Current technology produces cellulosic ethanol at prices equivalent to $120 a barrel, he says, well above oil's recent price of about $77 a barrel. Taxpayers would make up the difference under Tyner's plan. If oil sold for $80 a barrel, cellulosic ethanol makers would get a $40-perbarrel subsidy; if oil rose to $120 a barrel, they'd get nothing. The sliding system would give cellulosic technologies time to become competitive and established, he argues. Another idea, say Dale and others, is simply to require that more—or all—new cars be able to use E85. The change could cost just $100 per car.

    Both ideas have at least some support in Congress, but the industry won't know how much until work on a new agriculture bill moves into high gear later this year. Meanwhile, EPA is considering another option: increasing the required amount of ethanol in blended fuels to 12% or even 15%. That would boost demand from the current 12.1 billion gallons to as much as 14.6 billion gallons. Not everyone is in favor. Carmakers say they've optimized their engines to run on current blends, and they ask who would compensate unhappy car owners if the new blends damage engines. EPA is expected to make its decision by November; Tyner believes an increase to 12% would be “the politically and probably technically safe move.”

    Even such a boost, however, won't do much to attract new investors to build cellulosic ethanol plants, Tyner notes, because companies could meet the extra demand simply by bringing idle corn ethanol plants online. “It's a temporary fix at best,” he says. Longer-term solutions to scaling up cellulosic biofuels, it appears, will need to come from the lab—and creative policymakers.

  14. News

    Out of Site

    1. Eli Kintisch
    Wilting at windmills.

    Tensions are rising as wind-turbine developers look for land.


    When a power company erected three towering white wind turbines on the Maine island of Vinalhaven last year, many residents welcomed the clean electricity the spinning blades would bring. Now, however, the mood has soured for some. “There is this amazing ‘wump’ as the turbine spins; you can feel the sound,” says resident Cheryl Lindgren. “It's very annoying,” she adds, and disrupts the “sanctity of the island.”

    Such complaints are becoming a growing problem for advocates pushing to scale up wind power and other renewable-energy sources. Around the world, an emerging network of groups are marshaling a wide array of arguments—from worries about excessive noise and wrecked views to threats to wildlife, air traffic, and even national security—in bids to block construction of new wind farms. And they are meeting with some success. In the United States, for instance, fierce local opposition has scuttled some major wind projects and delayed others for years.

    The siting fights threaten to derail efforts to ultimately use wind turbines to generate up to 20% of U.S. electricity. To reach that goal, U.S. wind-generating capacity would have to increase from about 35 gigawatts today to more than 300 GW. That would require the construction of as many as 100,000 new turbines. Backers argue that they would be cleaner than power plants run on fossil fuels and could reduce per-kilowatt carbon dioxide emissions by 99%. Those benefits, however, haven't quieted critics. “Siting issues will only get worse and worse,” predicts Robert Thresher of the National Renewable Energy Laboratory (NREL) in Golden, Colorado. And wind isn't alone: Similar resistance is facing plans to cover vast swaths of desert with solar collectors or scatter energy-producing buoys along coastlines (see sidebar, p. 789). The lesson, analysts say, is that even when new energy technologies are able to overcome substantial technical or economic hurdles—and offer real environmental benefits—they can still face substantial public opposition that backers ignore at their peril. To defuse the threat, government and industry are now taking a hard look at the problems posed by renewable-energy projects such as wind farms and how best to mitigate them.

    The birds and the bats

    One of the earliest efforts to understand wind power's environmental impacts began 2 decades ago, after thousands of dead birds of prey—including golden eagles—began showing up beneath turbines at one of the nation's first major wind farms on Altamont Pass in California. The kills made headlines and prompted studies aimed at solving the problem. It turned out that the site, a high ridge where many raptors roosted naturally, was unusually prone to bird strikes, says zoologist Dale Strickland of Western Eco-Systems Technology in Cheyenne. Engineers reduced the toll by spacing turbines farther apart and removing machines from the most problematic sites.

    Surround sound.

    Microphone arrays provide data to make maps of turbine noise.


    These days, those lessons are also being applied at other wind farms, and the bird-strike issue has become less of a concern. A newer issue is understanding how the extensive road and fence networks associated with wind farms might act as “barriers to local wildlife,” Thresher says. Breezy grasslands could pose particular challenges for turbine planners, he notes, because they host species such as sage grouse, which require extensive open areas.

    Scientists are also just beginning to learn about the threat turbines pose to another flying animal: migratory bats. The issue heated up last year, after researchers reported that a single wind farm in West Virginia was killing as many as 4000 bats each year, mostly during fall migrations (Science, 24 July 2009, p. 386).

    Some scientists hypothesize that the bats are at risk because they navigate along mountain ridges that are also favorable sites for wind farms—but researchers have also documented extensive kills on flat prairies in Alberta, Canada. Infrared video has shown that night-flying bats seem to have a fascination with moving turbine blades, and post-mortems suggest that bats may be dying from air-pressure differences created by the blades, along with blunt trauma from collisions.

    Scientists are already beginning to try some fixes. One idea is to turn off turbines before and after storms and on evenings with calm winds, times when studies suggest a lot of fatalities occur. Studies have also shown that raising a turbine's “cut in” speed—the minimum wind speed at which the blades spin—can lower kills dramatically. One unpublished study of 23 turbines in southwestern Pennsylvania, led by wildlife biologist Edward Arnett of Bat Conservation International in Austin, found that “curtailed” turbines killed on average 80% fewer bats than uncurtailed turbines did.

    Sound advice.

    Turbines are usually equally noisy front and back (left) but especially loud on the lower right of the turbine plane.


    Researchers are also experimenting with using sound to protect bats. Arnett and his colleagues have built so-called bat-aways, which blast ultrasonic sound out of 128 speakers per tower. Researchers say bats tend to avoid the ultrasound, perhaps because it jams their sonar. Last summer, in an unpublished study, the team found that turbines fitted with bat-aways caused only one-fifth to one-half as many bat fatalities as turbines without the devices. Still, Arnett says it's not yet clear the approach “is a viable solution.”

    Scanning the horizon

    Another problem causing static for wind farmers is radar. Turbines that are too close to radar stations show up on controllers' screens as individual flickers, and the spinning blades have electronic signatures very similar to those of small planes. Those signals can confuse military or civilian air traffic controllers, who have objected to a number of planned farms. Overall, radar-related concerns have delayed or scuttled U.S. projects pegged to produce 4200 megawatts' worth of wind power, a 2009 survey by the American Wind Energy Association concluded.

    The radar-interference problem will only get worse as the number of wind turbines skyrockets, predicts Gary Seifert of the U.S. Department of Energy's Idaho National Laboratory in Idaho Falls. But he hopes mitigation efforts will bear fruit. Computer programmers, for instance, are hard at work on new techniques to “tune out” the turbines' signatures, perhaps by incorporating supersensitive short-distance radar. Another idea is to make turbine blades “stealthy,” or less visible to radar. Danish turbine maker Vestas and a company called QinetiQ are collaborating on stealthy materials that could be used to build or coat turbine parts.

    Wumps and thwumps

    The toughest challenge facing turbine builders may be mitigating the noise associated with the coming wind storm. People who live near turbines can be subjected to an annoying mix of whooshes, whines, and “thwumps,” depending on the model and wind conditions. Wind developers in the United States, the United Kingdom, Canada, and New Zealand have all faced “vehement” local opposition due to noise, says Jim Cummings of the Acoustic Ecology Institute in Santa Fe, New Mexico.

    From a simply technical perspective, turbine blades that spin faster make more energy more efficiently—but they also make exponentially more noise. So “there's always a tradeoff between efficiency and noise,” says NREL engineer Patrick Moriarty. To get more power out of quieter blades, researchers are developing new tools to measure and mitigate the noise. Traditional noise surveys place single microphones upwind and downwind of turbines, but that provides coarse data, Moriarty says. So he and his colleagues have developed 32-microphone arrays that enable computers to create detailed “sound maps” that pinpoint which blades are producing sound and how it propagates through specific environments—an issue that can be as important as turbine design for nearby residents. The maps also help researchers see if new blade designs—such as serrated edges or holes—reduce noise by disrupting the way air eddies across the turbine.

    The easiest way to make turbines less noisy, however, may be simply to run them less. That can be accomplished by raising the cut-in speed, at a cost of cutting power production by a few percent. But some residents complain about noise produced when the turbines are spinning at speeds at which they produce most of their power; companies aren't likely to still turbines when the wind is most valuable.

    In the end, technical tweaks may never fly with people who simply don't want to hear—or see—turbines in their backyards. Changing negative attitudes toward wind farms “will mean more than little engineering fixes,” predicts Michael Vickerson of a renewable group called RENEW Wisconsin in Madison. One promising finding for wind advocates, Vickerson notes, is that people tend to become more comfortable with nearby wind farms over time: “The older a project is, we find, the more the turbines are accepted.” That's a trend many renewable-energy advocates hope proves true.

  15. Other Siting Problems

    1. Eli Kintisch

    Geothermal energy, which involves tapping warm or cool temperatures underground, has been deployed on a small scale for decades with few problems. But the technique can cause earthquakes. One project near Basel, Switzerland, was shelved after drilling caused a magnitude-3.4 tremor in 2007.

    Experts are also developing ways to retrofit historical buildings with solar panels while preserving their character. British preservation groups have created detailed guidelines for such projects. Meanwhile, the California Energy Commission has recommended against building a proposed solar energy installation in the Mojave Desert because of its potential impact on turtles.

    Greening coal faces its own challenges, too. Scientists studying the implications of storing billions of tons of CO2 from power plants underground say that concerns about causing earthquakes or polluting aquifers so far appear overblown. But such worries have already led to scuttled test projects in Germany, the Netherlands, and in Greenville, Ohio. “Not Under My Backyard” was how one paper put it.

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